turbo help

[s10350racer]

im gonna post the same thing i posted on s10v8.com and see what i get here:

i recently i blew up my 350 and am currently building it into a 383. i am certain i want to try a turbo set up on it and have seen a few members here with turbo setups and know there are other knowledgable folks here. so i am looking for advice. i would like to go with a single turbo set up so it isnt too radical and for simplicity. i would also like to run on pump gas as this would be a daily driver that gets run hard whenever im driving
heres a run down of my current set up:

383 splayed 4 bolt caps
forged dished pistons
forged rods and crank
hydraulic cam intake: dur-270 @.050-221 lift-.496 lobe sp.112
exhaust: dur-280 @.050 232 lift-.517
vortec heads with 1.6 rockers
rpm air gap with 750 carb
camaro t-5
ford 8.8 rear with 3.73 posi (may swap to 4.10)
with this setup i am expecting 375 hp and 440 ft lbs at the flywheel.
now here are my questions/concerns:

will the vortec heads be sufficient enough for a turbo?

what turbo would suit me for this application? i would like to find a junkyard jewel and rebuild it if possible.

what modifications need to be done to the carb? do i need a bigger one? what about making/finding a carb box?

is there a good location for mounting an intercooler?

what about the exhaust? im figurin i will set this up on the passenger side to avoid the steering shaft and other hazards. what is a good header/manifold to use?

as you can see, im not too familiar with turbos but im very interested and willing to learn. i guess i just want to do something i havent done before. i understand this is a big project and will require fabricating. i am employed at a garage with a tubing bender, welder, plasma cutter, and lots of other goodies for me to play with so i should be able to make brackets, piping, exhaust, etc. im just looking for information and ideas before i start doing this. i dont want to get in over my head without doing any research first. any ideas you have and problems you see would be very helpful. thanks

[Old Man]

I'm not a fan of turbo's so I wont go into it to deep, but I wouldnt suggest using a stroker motor with a turbo for various reasons I wont get into!

[s10350racer]

well i suppose if you were to elaborate i might take that into consideration...

[bonecrushins10]

shop around you can find turbos on the internet for 800 - 1600 bucks

im not sure if there are turbo carbs , gotta run a low boost so you wont get killed with prenuim

runing twin turbos will not lag on ya an are less complex than 2 in 1 than 1 in 1

[Dimemaster]

383 splayed 4 bolt caps
GOOD

forged dished pistons
GOOD, if the static compression ratio is in the 7.5 to 8.0 range.

forged rods and crank
GOOD

hydraulic cam intake: dur-270 @.050-221 lift-.496 lobe sp.112
exhaust: dur-280 @.050 232 lift-.517
TOO MUCH CAM Something in the 214/214 to 220/220 range would be a better choice. A stock cam is hard to beat for a mild turbo engine. Adding duration and lobe separation increase the amount of intake charge the turbo forces right out the exhaust valve during overlap. Also, too much overlap for the static compression ratio of a turboed engine results in lots of icky problems, like ZIP-ZERO-NADA throttle response and raw fuel flowing down the cylinder walls/. Crane used to market a grind specifically for mild turboed smallblocks. If you can find one, this would be the best cam for your application.

vortec heads with 1.6 rockers
GOOD

rpm air gap
TOO MUCH cross section for a mild turbo motor. Fuel puddling will be a problem. A Performer would be a better choice.

with 750 carb
TOO MUCH A square bore 650 would be a better choice. A Quadrajet would be even better if you really want more air flow (up to 800cfm), and you are willing to teach yourself to tune one. There are several good articles on the internet about tuning Quadrajets. You'll have excellent low speed throttle response with a mild cam and small carb.

camaro t-5
WEAK Rebuild and upgrade to World Class level, with close ratio gears. Better, use a Richmond Gear 5-speed. Better yet, with the torque available would be a Richmond Gear 4-speed.

ford 8.8 rear with 3.73 posi (may swap to 4.10)
WEAK 8.8s do not have sufficient support for the bearings in the pumpkin. You can get replacement covers with integrated girdles that will help some. Stronger gears, differential, and axles will also be desirable. Also, you can't put posi in a Ford housing. Fords have Twin Grip. Even a rebuilt stock Twin Grip will work well in your application unless you get some REAL traction. Then the clutches will wear rather quickly. 3.73 would be a good choice for a street driver if you have overdrive, and 3.42s would be perfect with a 1/1 top gear.


with this setup i am expecting 375 hp and 440 ft lbs at the flywheel.
YOU'RE KIDDING, right? Even a mild turbo 383, properly built and tuned, will pump out 400hp, 450 ft lbs.

now here are my questions/concerns:

will the vortec heads be sufficient enough for a turbo?
GOOD Clean up and port match.

what turbo would suit me for this application? i would like to find a junkyard jewel and rebuild it if possible.
I CHOOSE junkyard turbos by finding one on an engine, that when in normally aspirated form, has similar power and torque per displacement unit, and a similar displacement at similar RPM to the intended longblock. In your case, of the turbos I've had experience with, for the money, I'd use a pair of early Garret Buick GN 3.8 turbos, on custom tube exhaust manifolds holding the turbos above and beside the valve covers, with the intake Y-ed over a 650 square bore on an Edelbrock Performer manifold or similar.

what modifications need to be done to the carb?
NONE if the turbo sucks through the carb, or the carb is in a box. A LOT if the turbo blows through the carb. All vents, shafts, and other holes must be plugged. If you build a box (not recommended due to increased intake volume) you'll need to seal the throttle and choke linkages, and any wires going into the box. You'll also need a boost-sensitive pressure regulator to maintain fuel prssure 4-5 pounds over manifold pressure.

do i need a bigger one?
NO

what about making/
IF YOU WISH

finding a carb box?
NOT LIKELY Carb boxes add intake volume, reducing throttle response.

is there a good location for mounting an intercooler?
DIFFICULT. Not much room under the hood for air-to-air. You could run a wet intercooler above each valve cover, between the turbos and carb.

what about the exhaust?
DUALS. From the turbos down inside the frame to cats or turbo mufflers under the cab out at the beginning of the cab on each side. Fenderwell exit would be easier, with true duals. No need to run mufflers AND cats. The turbos will quiet the engine quite a bit, and cats alone will quiet it even more.

im figurin i will set this up on the passenger side to avoid the steering shaft and other hazards.
WHY? You'll have to plumb the driver side exhaust over to the other side anyway.

what is a good header/manifold to use?
CUSTOM. I don't know of any turbo manifolds or headers available for a turboed smallblock S10. Of course, you could bolt stock manifolds on upside down.

You forgot oiling. You'll need a high volume pump, teed into the sender unit opening, oil cooler, and added capacity, such as dual remote full quart oil filters.

You also forgot ignition. You'll need something to retard timing under boost.

If I was building an engine like this, I'd use the GN/Garret turbos on custom tube exhaust headers. Intake air would come through filters located in cold air boxes between the headlights and fenderwells, to the turbos situated above the valve covers and as close to the carb as possible, to a custom collector that feeds the carb (no intercoolers--not much benefit at low boost pressures of a mild turbo setup), through a sealed 670chm Holley 0-80670 through an Edelbrock Performer or similar dual plane from Holley, Offenhauser, or Wiend, through polished and port matched Vortec heads, over 8.0:1 compression pistons, custom tube headers, to the turbos, out down pipes over the frame just in front of the fire wall, under the cab, to quality turbo mufflers or high flow cats, and turn outs on each side just before the fuel tank (use a heat shield). I'd also wrap all intake and exhaust piping under the hood with insulation to lower under-hood temps.

This engine would drive like a stock lo-po big block and return over 20mpg with the right gearing, until you hit the throttle. Due to short, low volume tubing between the turbos and carb, and exhaust ports and turbos, throttle response would require 1/2 to 1/3 less time than intercooled pressurized intakes. Smaller twin turbos would spin up faster than a single larger turbo. No blow off valves would be necessary, but adding one would keep turbo speed up while shifting. Plumbing intake and exhaust would be much simpler than a single turbo. I'd expect 400hp and 550 ft lbs, with a 6000rpm redline.

Now, if money was no object and I was building a race engine based on the Garret GN turbos, I'd use the Garret T-s units with the ceramic impellers and the intercoolers from the 87 GNX, and expect 525hp and 675 lbs ft, but at the expense of throttle response in daily driving. Main girdles would be required. I would also back it up with a 4L80E instead of the 5-speed.

Now, if I built an engine with with the common steel impeller turbos, and wanted the performance of an intercooled engine with the T-s turbos, I'd drop a 100 shot plate under the carb. The nitrous would cool and condense the intake charge just like the intercoolers, with a lot less plumbing and better drivability. I wouldn't put such an engine in an S10 unless it was a funny car.

[s10350racer]

so you think no intercooler would be alright on this setup? i also dont think ill find any turbos from a grand national as theyre arent many around and im sure them gn boys have already violated them at the junkyards. do you know of any comparable after market units such as some of the kits on ebay? i was told the t70 would be alright. two turbos is what i really want to run but i kinda got scared with all the plumbing issues with the intercooler and especially the exhaust on the driver side since i saw how much clearance i really have over there. i think im going to do a blow through for the carb as well but i dont know enough about them to mod them since i grew up in the era of fuel injection so i have to find someone knowledgable enough to do this for me. i dont think my rear end will be a problem i do have the cover with the bearing cap studs and i have seen them 8.8s take some SERIOUS abuse. the t5 right now is stock but i do have another stock unit and a world class unit so i have some transmissions to go through before i have money to upgrade. i dont really want an automatic but it is in the back of my mind. i guess i can make the headers but i am still really concerned about routing the exhaust. can you detail more where you you would run it. i hope by fender well you arent talking about under the frame because the truck is lowered and that would be an issue. im also worried about mounting them. i wanted to put them where the battery normally is behind the headlights. if i put them above the valve covers im not sure it would clear the hood. and i do plan on using a bov because it is the only thing i like about the tuner crowd and i want to make em all jealous and maybe provoke a stop light rumble or two. i already have the nitrous plate setup and i think im gonna leave it on the truck and see what happens. i really appreciate the help.

[Sy-Clone]

I would skip the nitrous and go with an alky/meth kit to cool your setup. No need for
an i/c and alky is cheaper than nitrous. Do a search on the subject. PEACE>Tony

[Injected]

Dimemaster had some very good advice, but I will offer you a very brief and different view.

Because of the V-8, I would go for a twin turbo setup. I'm not a fan of this setup, but I'm not that big of a fan of V-8's althogether. Single turbo applications are very efficient when it comes to straights like the I-4 and I-6, but because you can keep the piping very simple and clean in the V-8 application, and flows very well. The easiest way is to make two turbo manifolds to hang the turbos. Exhaust is then clearly simple, and dual 3" will suit you very well. Intercooling is also very easy. Merely run the two turbo-to-intercooler pipes together into a bottom-to-top flowing front mount intercooler. Run that to the throttle body and there you go for piping. As for compression, you really should say what your boost goals are before you determine what you are going to run. If you want the great mid to high range boost (say 15-20 psi), then you can aim as high as 8.5:1 and be safe. I would switch to fuel injection though to better control the A/F, but as Dimemaster said, you should be alright. If you are hoing to only run up to 8 psi, then you probably could get away with a little over 9.5:1 and a smaller, or maybe even no intercooler. An intercooler is a good investment even on low boost applications because it will not only make more power on the same amount of boost, but will protect your investment. Nothing will kill a boosted engine faster than detonation. A destroked engine is very good idea. Most people don't think about how much more you can flow by increasing your RPMs vs. how big you can make your engine. A better rod ratio will definately benifit you. For blow off, you can put the valve on the cold side intercooler pipe. For turbos themselves, I would go with cheap units like you suggest. But I couldn't suggest a turbo, or set, unless you elaborate on your desired setup.

Just a few thoughts.

[Dimemaster]

injected, with the stipulated use of 87 octane, 8.5 compression ratio is too much, even with 8 pounds of boost. With 93 octane, no problem going with 8.5. 7.5 and 20 pounds of boost requires 106 octane Sunoco racing gas. Same with 8.5 and 15 pounds, or 9.5 and 10 pounds. Destroking and bunches of boost are out. This ain't no rice rocket. Besides, if smaller was faster, why are no AA/FDs running Japanese engines. Case closed.

With that 87 octane limitation, their simply ain't no substitute for cubic inches. The heavy duty bottom end will allow rpm, but the long block components must be tuned to run well on 87 octane in low and no boost conditions. At sustained idle and off-idle driving, like in parking lots and heavy traffic, the intake manifold will even see a vacuum. Therefore, the intake, carb, compression, ignition, and valvetrain must be compatible with 87 octane fuel as if it was a norrmally aspirated engine. Then, the static compression has to be dropped a point to allow for pressurizing the intake.

By pressurizing the carb the intake passages are kept short, and with a mild cam and small carb the no/low boost throttle response will be excellent. A pair of GN-sized turbos will be a bit large for a 383 in this state of tune, but displacement will provide lots of grunt. Power will build smoothly until the limits of the 87 octane are reached. Exiting corners will be interesting with the V8 torque, to say the least, even without turbos, so turbo lag will barely be noticed. Being slightly oversized, the turbos will provide boost at mid and high rpm where preignition is not so much of a problem, allowing the engine to turn over 6000 rpm to make 400+hp on top, with better than stock 5.7 drivability and economy in normal driving. At highway cruise, the couple or three pounds of boost generated by the turbos will allow the carb butterflies to open less, increasing fuel mileage. I can see this engine returning low 20s mpg on the highway. What more could you want from 87 octane.

[s10350racer]

well im still tryin to figure out what turbos to run. im liking the t4s but im still not sure in what trim. im not above pumpin in the premium if required either. i have ordered the headers, turbo timer, fuel pressure regulator, msd ignition, wideband, intake, and raptor blow off valve. right now im making the carb hat and still tryin to make it look pretty. i keep getting tossed around on what turbos i should run. again im looking for a quick spool and solid hp in the 1500-4500 range where it will be run at most of the time save for a few passes down the track. the headers i got have flanges for the t3/t4 so im tryin to figure out what trim i need and try to find a new pair on ebay.

[Dimemaster]

You found headers that fit a smallblock in an S10 and are set up for twin turbos? Amazing!

Well, if you don't mind the expense of 93 octane, up the boost to about 12-13 pounds and enjoy all the benefits listed above and a solid 500 horsepower and 500 lbs/ft from 300-6500rpm. Getting a nice, wide, controllable torque curve is easy with moderate pressure and cubic inches. You won't be disappointed.

With an adjustable waste gate you can turn the pressure down for 87 octane daily driving and turn it up for 93 octane weekends. Best of both worlds.

Oh, just remembered you asked about exhaust exiting through the fender wells. Look under the cab, between the rockers and frame. There's lots of space there for a muffler or convertor. Run the exhaust from the turbo, over the steering shaft and frame back by the firewall, through mufflers under the cab, and turnouts in front of the fuel tank. True duals without sacrificing ground clearance.

[Dimemaster]

By the way, if you size turbos for quickest possible spool you'll overspeed and quickly destroy them well before reaching the maximum horsepower and rpm your forged bottom end is capable of turning. Little chunks of compressor empeller are not good for your long block. You'll also find the power output extremely difficult to modulate while cornering. Don't tune this engine like a Japanese car, it will not work well. You don't want boost at low to mid rpm, you want boost where your normally aspirated econo-tuned 383 leaves off, from 3000 to 6500 rpm. Face it, an econo-tuned 383 pumps out 400+ lbs/ft normally aspirated. That's plenty for a street driven S10. You can't plant 400lbs/ft@3000rpm anyway, so more is just a waste. Use the turbos to extend your power curve, not boost max power. Your truck will be faster, easier to drive, burn less gas, and last longer. You'll shift twice while your opponent shifts 4 times, and you'll have 2 more to go when he's all done.

[Injected]

injected, with the stipulated use of 87 octane, 8.5 compression ratio is too much, even with 8 pounds of boost. With 93 octane, no problem going with 8.5. 7.5 and 20 pounds of boost requires 106 octane Sunoco racing gas. Same with 8.5 and 15 pounds, or 9.5 and 10 pounds. Destroking and bunches of boost are out. This ain't no rice rocket. Besides, if smaller was faster, why are no AA/FDs running Japanese engines. Case closed.


Thanks for responding Dimemaster. I was unaware that we are talking about an 87 octane limitation. I just want to know who in the hell cheaps out at the pump for a fully build force fed street engine? I buy 93 octane for my car (turbo charged running 22 psi on 8.5:1, intercooled, no detonation) because I know that it is a protection for my investment and for the performance I want. If there is in fact a fuel limitation, then you are of course correct about those compression ratios that I quoted being too high. But I don't understand how it is (please explain because I am eager to know) that my I-4 and this V-8 differ when it comes to fuel, compression ratio, boost and detonation. As far as I am aware, there is no difference in the detonation resistance offered by a higher octane fuel when it comes to this. The combination of intake temperature, compression ratio (the higher the ratio, the hotter the charge in the chamber) and the octane of the fuel are what determine whether or not it will detonate. as for the comment about the smaller engine, I was suggesting using a more favorable rod ratio in order to create a more rev happy engine. There will be enough stress on the engine as it is and destroking and a lot of boost are the way to go for more power. Case in point (forgive my engine references but I will go with what I am most familiar but the point is universal), a 2.4L 4G63 is great, but has a rod ratio of 1.5. 2.1 destroked 4G64 hybrid engine has a smaller displacement, but can easily rev to 10K rpms because of its superior rod ratio of 1.74. The smaller engine flows far more (making more power) and has a far wider rpm range to operate over. If he destrokes the engine for a more favorable rod ratio, he will be able to hold each gear longer and push all of that boost into the upper rpms, making far more power on the same amount of boost at a higher rpm with a smaller engine. Let's not make an exaggerated comparison please.

With that 87 octane limitation, their simply ain't no substitute for cubic inches. The heavy duty bottom end will allow rpm, but the long block components must be tuned to run well on 87 octane in low and no boost conditions. At sustained idle and off-idle driving, like in parking lots and heavy traffic, the intake manifold will even see a vacuum. Therefore, the intake, carb, compression, ignition, and valvetrain must be compatible with 87 octane fuel as if it was a norrmally aspirated engine. Then, the static compression has to be dropped a point to allow for pressurizing the intake.

Actually the intake will mostly see vacuum. Untill he reaches that magic volumetric point where the engine ingests enough air to create boost, he will be in vacuum like a naturally aspirated car.

By pressurizing the carb the intake passages are kept short, and with a mild cam and small carb the no/low boost throttle response will be excellent. A pair of GN-sized turbos will be a bit large for a 383 in this state of tune, but displacement will provide lots of grunt. Power will build smoothly until the limits of the 87 octane are reached. Exiting corners will be interesting with the V8 torque, to say the least, even without turbos, so turbo lag will barely be noticed. Being slightly oversized, the turbos will provide boost at mid and high rpm where preignition is not so much of a problem, allowing the engine to turn over 6000 rpm to make 400+hp on top, with better than stock 5.7 drivability and economy in normal driving. At highway cruise, the couple or three pounds of boost generated by the turbos will allow the carb butterflies to open less, increasing fuel mileage. I can see this engine returning low 20s mpg on the highway. What more could you want from 87 octane.

Can someone find a compressor map for these turbos? I have a great article full of formulas (none too hard) for calculating the perfect turbo for your application. I even made a nice spreadsheet from it, but you need a compressor map to compare it to. How about just the dimensions?

[s10350racer]

By the way, if you size turbos for quickest possible spool you'll overspeed and quickly destroy them well before reaching the maximum horsepower and rpm your forged bottom end is capable of turning. Little chunks of compressor empeller are not good for your long block. You'll also find the power output extremely difficult to modulate while cornering. Don't tune this engine like a Japanese car, it will not work well. You don't want boost at low to mid rpm, you want boost where your normally aspirated econo-tuned 383 leaves off, from 3000 to 6500 rpm. Face it, an econo-tuned 383 pumps out 400+ lbs/ft normally aspirated. That's plenty for a street driven S10. You can't plant 400lbs/ft@3000rpm anyway, so more is just a waste. Use the turbos to extend your power curve, not boost max power. Your truck will be faster, easier to drive, burn less gas, and last longer. You'll shift twice while your opponent shifts 4 times, and you'll have 2 more to go when he's all done.

well, with that said, what turbo size would you reccomend with a t4 flange? its driving me nuts. i like to have everything planned out in my mind before i sart building and this is a pretty major detail.

http://www.turboneticsinc.com/turbomatrix.htm
that is a link to a turbo matrix. maybe someone can make some sense of it and help me out. im a little lost when it comes to this. it is all new to me.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1,1&item=8005918131&sspagename=STRK%3AMEWA%3AIT

those are the headers i have. i think i should be able to run the exhaust where i had it before without any problems. and by before i mean where the exhaust exits with the shorty v8 headers.

thanks a lot for the help guys, i will try to get some pics up soon of everything i am doing if anyone is interested.

[Injected]

well, with that said, what turbo size would you reccomend with a t4 flange? its driving me nuts. i like to have everything planned out in my mind before i sart building and this is a pretty major detail.

http://www.turboneticsinc.com/turbomatrix.htm
that is a link to a turbo matrix. maybe someone can make some sense of it and help me out. im a little lost when it comes to this. it is all new to me.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1,1&item=8005918131&sspagename=STRK%3AMEWA%3AIT

those are the headers i have. i think i should be able to run the exhaust where i had it before without any problems. and by before i mean where the exhaust exits with the shorty v8 headers.

thanks a lot for the help guys, i will try to get some pics up soon of everything i am doing if anyone is interested.

To properly select your turbo, you need to set your boost pressure and rpm goals in order to calculate how much your engine flows. Then plot this information on a compressor map and you will know exactly what the turbo is capable in your setup. Just give me the two numbers and I'll do the hard work.

[s10350racer]

thanks a lot injected. i dont want to run anything over 10 psi since i wont be running intercoolers so im looking to run around 8 or 9. as for rpm goals i dont think the motor will ever see anything over 6000. im not exactly sure what this new combo will do for top end. i know that it is a daily driver/weekend warrior so i was kinda lookin for power in the 2000-4500 rpm range but what dimemaster said about wideing the power band made sense to me so im not sure what direction to go. i know i want two turbos with a t4 flange to work with my current 8.5:1 compression ratio and make 8-9 psi. other than that im not too sure and am in desperate need of help here.

[Injected]

thanks a lot injected. i dont want to run anything over 10 psi since i wont be running intercoolers so im looking to run around 8 or 9. as for rpm goals i dont think the motor will ever see anything over 6000. im not exactly sure what this new combo will do for top end. i know that it is a daily driver/weekend warrior so i was kinda lookin for power in the 2000-4500 rpm range but what dimemaster said about wideing the power band made sense to me so im not sure what direction to go. i know i want two turbos with a t4 flange to work with my current 8.5:1 compression ratio and make 8-9 psi. other than that im not too sure and am in desperate need of help here.
thanks a lot injected. i dont want to run anything over 10 psi since i wont be running intercoolers so im looking to run around 8 or 9. as for rpm goals i dont think the motor will ever see anything over 6000. im not exactly sure what this new combo will do for top end. i know that it is a daily driver/weekend warrior so i was kinda lookin for power in the 2000-4500 rpm range but what dimemaster said about wideing the power band made sense to me so im not sure what direction to go. i know i want two turbos with a t4 flange to work with my current 8.5:1 compression ratio and make 8-9 psi. other than that im not too sure and am in desperate need of help here.

Okay, now for a chance to flex my intelligence (I'm pretty full of myself).

I first of all want to recomend running an intercooler. I posted this in another thread:

On the intake side. Whenever you compress gas it adds heat because of the natural properties of gas (I'll skip the high school physics here). On a normal turbo setup, the gas is then sent to an intercooler where two main things occur. The gas is cooled, and the pressure is dropped. Today, intercoolers are very efficient and do a great job in providing great intake charge cooling and heat dissipation, especially bar and plate intercoolers. In addition, the intake can be easily routed to the front of the car to reduce initial intake temperatures.
...
And now, more about the intercooler. As I said earlier, I don’t really understand why people hate them so much. In the remote turbo setup, you don’t have one and the pipe that comes off the compressor housing goes to the intake. This is a long route, but because it is not obscured, it is very quick to pressurize and yields good boost response. But the location is not what makes it okay to run without an intercooler, it’s the low amount of boost. Much like an old roots style blower that sits practically right on the intake manifold, it offers quick boost response and no need for an intercooler. Running without an intercooler is commonly found in many aftermarket turbo- and supercharged systems that run fairly low boost. However, running an intercooler will allow significantly more power to be made on the same amount of boost.

I'm going to spend a lot of time going through the two setups (with and without the intercooler).

Okay, start with the no intercooler. First calculate the absolute turbo outlet pressure which equals boost plus atmospheric pressure plus intercooler pressure drop (none).

Pco = 9psi + 14.7psi = 23.7psi

Now calculate the pressure ratio (over atmosphere).

23.7psi / 14.7psi = 1.61

Okay, but how hot is that air? We need to know because it will tell us how much oxygen is in the charge. A good assumption (if anyone has an actual measured temperature, that would be perfect, but I will go with good assumptions for now) for turbo outlet temperature is about 200*F. Now to calculate the density of air.

Di = (boost + atmosphere) / (R X 12 X (460 + intake temp)).
Di = (23.7psi) / (53.3 X 12 X (660)) = .00005614 lb/in^3

These variables come from various places. R is from the Ideal Gas Law, 460 converts the temperature to Rankin and 12 keeps things in inches which helps the calculation. Now we can calculate the Mass flow of the engine. That is your air desity times your displacement in cubic inches times your desired RPM/2 X volumetric efficiency. I'll assume a happy 5500 target RPM since you will be proping up your high end, but want this to be a street motor.

Mf = .00005614 X 383 X (5500/2) X .85 = 50.26 lb/min

Corrected Mass Flow (CMf) = Mf X (√(Compressor inlet temp/ambient temp)/atmoshpere)/turbo inlet pressure

CMf = 50.26 X (√(545/545)/14.7)/13.95 = 47.7 lb/min

Now you have the two numbers that you need to find the right turbo for you. A turbo compressor map will have two axis, one for the pressure ratio (y-axis) and one for CMf (x-axis). Also, if you want to find the twin turbo turbos, just divide CMf by two, but keep the pressure ratio the same.

I’m trying to get Garrett’s catalog now and will post a compressor map. Also, I will do these calculations WITH an intercooler. It's about 3:15AM so I'll see about doing this tomorrow.

[Injected]

I forgot one very important calculation for the non intercooled setup: the power output potential. For this, we multiply the CMf by 60 to convert to hours, then divide by air:fuel times the BSFC. Let's use a street-safe tune of 10.5:1 and a conservative BSFC of 0.6.

Horsepower = (50.26 X 60) / (10.5 X .6) = 478.7

Close enough to 500 hp for you?

[Injected]

Now we can do the calculations with the intercooler. Again calculate the absolute turbo outlet pressure which equals boost plus atmospheric pressure plus intercooler pressure drop (none).

Pco = 9psi + 14.7psi + 1.5psi = 25.2psi

Now calculate the pressure ratio (over atmosphere).

25.2psi / 14.7psi = 1.71

Okay, here is where the most significant difference will occure. Since this engine setup is intercooled, you will see significantly cooler, and thus far more dense air. For post intercooler temperatures we will use a reasonable 92*. Now to calculate the density of air.

Di = (boost + atmosphere) / (R X 12 X (460 + intake temp)).
Di = (25.2psi) / (53.3 X 12 X (552)) = .00007138 lb/in^3

Mf = .00007138 X 383 X (5500/2) X .85 = 63.9 lb/min

Corrected Mass Flow (CMf) = Mf X √(Compressor inlet temp/ambient temp)/(atmoshpere/turbo inlet pressure)

CMf = 63.9 X √(545/545)/(14.7/13.95) = 60.64 lb/min

And now for the final results of running an intercooler vs. not.

Horsepower = (60.64 X 60) / (10.5 X .6) = 577.5 hp.

A one, hundred horsepower difference simply by using an intercooler which will protect your investment and significantly cool your intake charge.

[s10350racer]

i understand the great advantages of running an intercooler. unfortunately routing the piping and whatnot becomes an issue. also i got the headers for just about nothing and i think its kinda neat how they mount and looks real good. im also kinda in a hurry as well since right now im in massachusetts with a tore down truck and need to get to ohio for school in less than a month. this whole project is really overwhelming and as with all projects i safely multiplied by projected cost by 2 and came up with what ive already spent. :( this thing better be badd ass or im driving it into an oncoming train...

[Hammer]

the only thing i question about the formula's is that they are static.

in other words, you are taking a snap shot of one assumed scenario to get a ball park number.

case and point:
if the intercooler alone makes a 100hp difference, how much of a difference would a 300 degree outlet temperate make vs the 200 degree temp? the reason i ask is because i see several operatin temperature ranges scenarios that could severly or adversly affect the performance of the turbo, especially dependant on vehicle speed (or air flow volume or speed over the intercooler)

A start up temp
B normal operating daily driven temps after start up
C temps after a wot run
D temps after multiple wot runs.

we all now turbo's eat heat. and they require cool down, but controlling the heat is so difficult and dependant on air temp, flow and volume over the intercooler and the turbo itself.

a logical solution may be to treat the intercooler as if it were a radiator and put a couple of fans in front of it when iat reaches X degrees. this will give you potentially a far more consistent input temp. or really you could liquid cool the air charge with a costum setup for the intercooler :)

if you send the air over liquid cooled tubes with fins on them.... then you could really control the air out of the inter cooler.

liquid nitrogen is heavy and the best place for it is in the back of the truck. and farmer use liquid nitrogen for supplementing the ground so it can't be that expensive or inaccessible.

think about that, it isn't conventional but could be VERY effective for both weight transfer and iat consistency.

anyways i'm just wondering how bad the fall off is once the turbo's are hot and how that affects the math...

good work injected!

[Injected]

Intercooler piping is very easy, and actually just about as easy as not running the intercooler. If you mount the turbo with the compressor inlets facing the front of the truck, and the compressor outlets facing down, then you can but a 90* elbows going foreword into a Y pipe to the bottom of the intercooler. The intercooler itself can be a tall bottom to top, or even a short side to side flowing unit to bring the intake charge to the top of the engine and into the throttle body. Very simple and worth the time and you can still use the headers you have.

I'm thinking about the old saying, "Do it right, or do it twice." But with the time frame you are looking at, I would possibly think of getting the engine running in naturally aspirated form and working on the turbo assembly on the side. Realistically, a complete and operational turbo kit will take more than a month to complete, and you still have quite a bit of purchasing and fabricating to do. That is not to mention getting all these parts to actually work together the way you want them to.

[Injected]

the only thing i question about the formula's is that they are static.

in other words, you are taking a snap shot of one assumed scenario to get a ball park number.

case and point:
if the intercooler alone makes a 100hp difference, how much of a difference would a 300 degree outlet temperate make vs the 200 degree temp? the reason i ask is because i see several operatin temperature ranges scenarios that could severly or adversly affect the performance of the turbo, especially dependant on vehicle speed (or air flow volume or speed over the intercooler)

A start up temp
B normal operating daily driven temps after start up
C temps after a wot run
D temps after multiple wot runs.

we all now turbo's eat heat. and they require cool down, but controlling the heat is so difficult and dependant on air temp, flow and volume over the intercooler and the turbo itself.

a logical solution may be to treat the intercooler as if it were a radiator and put a couple of fans in front of it when iat reaches X degrees. this will give you potentially a far more consistent input temp. or really you could liquid cool the air charge with a costum setup for the intercooler :)

if you send the air over liquid cooled tubes with fins on them.... then you could really control the air out of the inter cooler.

liquid nitrogen is heavy and the best place for it is in the back of the truck. and farmer use liquid nitrogen for supplementing the ground so it can't be that expensive or inaccessible.

think about that, it isn't conventional but could be VERY effective for both weight transfer and iat consistency.

anyways i'm just wondering how bad the fall off is once the turbo's are hot and how that affects the math...

good work injected!
The potential output of any engine will be adversley affected by the addition of the heat produced by the system. However, if you do all that you can to lower the intake charges temperature, you will be very successful in combating this affect. An intercooler is great. Water/Alcohol injection is good to, especially when used in conjunction with an intercooler. Then you have intercooler sprayers that can spray anything from water to nitrous oxide on the intercooler. It all depends on how far you want to go. I will point out that placing a fan infront or behind an intercooler will adversly affect it though. You want as much flow around it as possible and a fan will block this flow, even at very low speeds. A bar-and-plate style intercooler can act as a heat sink and dissipate much of the heat that is generated by the system. Without the intercooler, the heat would transfer to the pipes, not dissipate, and the air in the intake charge would remain very hot. The numbers used in the calculations are temperatures and density at full boost (WOT). A cold start up or daily driving would produce lower intake temperatures. After multiple runs, as with most cars, people like to ice down the intake system, but time to cool off will definatly be an advantage to the car no matter what kind of setup it has.

[Hammer]

cooling the intercooler with fans would be adverse? maybe intercoolers work different than radiators but having fans in front of the cooler would push air through the cooler at low speed and still allow a massive flow of air during high speeds otherwise they wouldn't work on a radiator right?

thanks for the info.

[Injected]

cooling the intercooler with fans would be adverse? maybe intercoolers work different than radiators but having fans in front of the cooler would push air through the cooler at low speed and still allow a massive flow of air during high speeds otherwise they wouldn't work on a radiator right?

thanks for the info.
It would work, just not as well as putting the intercooler in front of the radator, and allowing as much air to flow over it as possible. If you put a fan on the front of, or behind the intercooler, then at speed, the fans actually interupt and obstruct airflow. Remember that if the fans on the radiator are actually mostly for before this occurs, pulling air through the fins when you are not going fast enough in order to sufficiently cool the car. If you stop, the fans on the radiator will still pull air over the intercooler.

[s10350racer]

monday ill go look at my mock up and take a little peek and see if i might be able to slap an intercooler somewhere. as it is ill go to work at 8 get off at 5, come home to eat, then go back down to work on my own truck to at least midnight. i dont think this is really going to happen for next month so ill haver to fly home and finish it over turkey day and xmas. i hope...

[s10350racer]

http://www.ssautochrome.com/level.itml/icOid/1489

ill probably get my turbos from here. i was thinkin about two of the super t70s. any other opinions? they even have compressor maps injected! maybe you could help me understand them...

[Injected]

Running an intercooler, you are looking for a compressor that is efficient at 30.32 lb/min and a 1.71 pressure ratio.

Here's what you need to do with the numbers I calculated. Your aiming for that island in the middle of the map. I'll also add the super T 70 (which is way to big for a twin turbo setup according to the map).

[Injected]

If you find a good turbo compressor map, post it and we can look at the other features like A/R, wastegate, etc.

[Injected]

I'll look for a very slightly larger turbo. This is a Garrett T04B H--3.
http://www.turbocalculator.com/compressor-maps/t04b-h3.jpg

[Injected]

Here's another:
http://www.turbocalculator.com/compressor-maps/t04e-60.jpg

[s10350racer]

man i still dont understand these friggin things. im sorry im dumb as a rock.

[Injected]

man i still dont understand these friggin things. im sorry im dumb as a rock.
At least you can admit you have a problem. :D You are looking for the intersection of about 30 on the bottom axis and 1.7 on the left axis. Let me know if you still don't understand because it can be fairly intimidating if used to looking at the damn things.

[s10350racer]

i dont understand the various values, what they are, and how they correspond to other values. im just not seeing the big picture and how they work. i kinda need to understand all the little things before i understand how everything works together if that makes any sense?

[Injected]

i dont understand the various values, what they are, and how they correspond to other values. im just not seeing the big picture and how they work. i kinda need to understand all the little things before i understand how everything works together if that makes any sense?

Basically you need to know if a turbo is efficient at providing the pressure you desire from the amount of air your engine is flowing. The first calculations are to determine the desired pressure ratio (how much boost the turbo needs to provide/you want it to provide). The rest of the calculation determines the amount of air that flows through the engine at this pressure ratio. In order to keep a certain pressure in the intake manifold, a turbo needs to flow enough to replace the amount that flows out, and enough to keep it pressurized. That is why you need to know the desired pressure ratio (left axis) and the amount flowed (bottom axis). The flow properties of the turbo are mapped on the compressor map and you can then determine whether or not it will provide you with enough flow. Make more sense now?

[s10350racer]

alright i understand the desired pressure and the amount flowed theory but im not sure where exactly the numbers come from

[Injected]

alright i understand the desired pressure and the amount flowed theory but im not sure where exactly the numbers come from
Total outlet pressure is the amount of pressure that the turbo must create to pressurize the system. That is why you calculate it by adding the desired pressure (9psi), the intercooler pressure drop (1.5psi), and atmospheric pressure (14.7psi). When you divide by atmosphere, you get the ratio (1.71 times the atmospheric pressure of normal air). That is the first calculation.

[Injected]

The second calculation starts with finding the density of the air. Air at a lower temperature is more oxygen dense. This is where the two calculations realy part. Why? Well the more dense the air, the more air that gets into the cumbustion chamber allowing more fuel to be added and more power to be made. The top of the air density (Di) calculation is boost plus atmosphere. The intercooler pressure drop isn't calculated in because at this point, it has already occured. As noted earlier, R is from the ideal gas law, 460 converts the temperature to Rankin and 12 keeps things in inches which helps the calculation. Now that we calculated the density, we need to find out how much air the engine flows at that density. That is the Mf and CMf calculations. As stated earler, Mass Flow is your air desity times your displacement in cubic inches times your desired RPM/2 X volumetric efficiency. Corrected Mass Flow is Corrected Mass Flow (CMf) = Mf X √(Compressor inlet temp/ambient temp)/(atmoshpere/turbo inlet pressure).

[Injected]

Now you have the two numbers that you need to find the right turbo for you. A turbo compressor map will have two axis, one for the pressure ratio (y-axis) and one for CMf (x-axis). Also, if you want to find the twin turbo turbos, just divide CMf by two, but keep the pressure ratio the same.

[Injected]

How's the project comming? To a halt? Just checking in.

[s10350racer]

nope i ended up gettig two of the t3/t4 hybrids and right now im mocking everything up and cleaning up my interior. today im driving back to ohio with the dime in tow so ill be busy getting my stuff back in order but ill try to get some pics by mid week hopefully.

[InProgress]

also, just a side note on the compressor maps. Don't plot only one point of efficiency on the map. You need to plot several points based on different driving conditions. Usually you want to put the RPM at which you make peak torque in the maximum efficiency range of the compressor. Problem is most people stop there. You also need to plot for higher RPM's to ensure that you don't hinder top end performance. Also, it's a good idea to plot for higher pressure ratios as well, as most people will at some point decide to up the boost in the name of power.

[Injected]

also, just a side note on the compressor maps. Don't plot only one point of efficiency on the map. You need to plot several points based on different driving conditions. Usually you want to put the RPM at which you make peak torque in the maximum efficiency range of the compressor. Problem is most people stop there. You also need to plot for higher RPM's to ensure that you don't hinder top end performance. Also, it's a good idea to plot for higher pressure ratios as well, as most people will at some point decide to up the boost in the name of power.
For the most part you are correct. It is good to plot several different points as to where you 'travel' across the turbo's efficient zone, but the RPM at which you make peak torque seems irrelevant to me, maybe you could explain this in more depth. Torque is just something you can feel and torque = HP @ 5250 rpm. HP is what really matters, though you don't really feel it since it is time relevant.

[GARETT]

get a supercharger!!!

[s10350racer]

screw that my man. turbos are more efficient and..well this has been debated many a times so im not going to get into it. i have my reasons and im already half way through it.

[Injected]

get a supercharger!!!
Are you going to support this argument or are you just here to annoy those who know better?

s10350racer, post some pics if you get a chance. I'd love to see the progress. Did you get a compressor map for the turbos?

[s10350racer]

he has no argument. hes probably a straggler from over at s10forum.com. if you look at his profile the only things he has done are mods to look it look pretty. anyways i do have a map somewhere that ill try to post. i showed it to the performance professor here at the university and he said that they should work very well for my application and that it wouldnt be hard to swap out if i want to go bigger or add an intercooler. i was trying to wait to take pics because the headers and tubos are backordered and i wanted to get a shot of everything together but ill just post what i have for now in a day or two.

[Injected]

he has no argument. hes probably a straggler from over at s10forum.com. if you look at his profile the only things he has done are mods to look it look pretty. anyways i do have a map somewhere that ill try to post. i showed it to the performance professor here at the university and he said that they should work very well for my application and that it wouldnt be hard to swap out if i want to go bigger or add an intercooler. i was trying to wait to take pics because the headers and tubos are backordered and i wanted to get a shot of everything together but ill just post what i have for now in a day or two.
What are your headers like? Log, 2:2:1, 4:1? Length?

[s10350racer]

these are the headers:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1,1&item=8005918131&sspagename=STRK%3AMEWA%3AIT

and these are the turbos:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1,1&item=8010180567&sspagename=STRK%3AMEWA%3AIT

[Injected]

Are you planning to top mount the turbos like the pic? How will you fit that under the hood?

[s10350racer]

well im hoping that my massive intake,carb, and bonnet will fit under the hood and then i was going to make some fiberglass scoops and cut two holes in my hood to clear the turbos if the glass wont melt. another thought i had was a big cowl hood but im not sure how far apart the turbos will be yet so i dont know if they will sit up into the cowl section. another thing i recently realized is that the turbo might not clear my master cylinder on the driver side so i might have to reposition that turbo :(

[Danny_SS]

If you want all that power from twin turbos and are willing tu put in so much money into a TT setup, why are you going for a carb setup?
Carbs and Turbos, just dont get a long too well. The same TT setup on a EFI fuel delivery would work so much better.

[s10350racer]

If you want all that power from twin turbos and are willing tu put in so much money into a TT setup, why are you going for a carb setup?
Carbs and Turbos, just dont get a long too well. The same TT setup on a EFI fuel delivery would work so much better.

the only money that iv really spent is on the bottom end with all forged internals. im a full time student so im kinda budget focussed. im not going to say that an efi system wouldnt be better, but i cant afford one nor do i have any knowledge with using/tuning one yet. the whole turbo system is new to me so im just taking things one step at a time so its refreshing to have something familiar like a carb working in my favor. in addition i got a hell of a deal on the brand new double pumper only paying 200 for it and 350 for the new heads. gotta love having an insider at the parts store! the igniton system was the most expensive part of this so far. i have the boost refrenced msd box which cost over 400. doing all the work myself between work and school saves a lot too.

[Injected]

Anyone wishing to follow the development of this turbo system should follow this link. Just thought I'd add this just in case someone was like,"I wonder WTF happened to this project?"

http://mys10.net/showthread.php?t=1503