LT1 help

[nickr5208]

hey guys
im planning on swapping my slug 2.2 out for an LT1. im just looking for some info on the motor itself, and different options that i have to chose from. im pretty sure the common trans is a 460le.

also besides the common juckyard/ebay or finding a wrecked camaro which are all options im aware of, what are my other possibilities for getting one with low mileage, with a trans, and computer?

[Dimemaster]

Goodwrench, if you have the money.

[screamn91]

fbodyjunk.com

[Rob]

If you get a hold of a used engine and plan on working if over, I would suggest getting the LT4 conversion kit that form GMPP. It runs for about $2400 or something. Includes cam, rockers, heads, intake manifold, and gaskets. I've heard this is good for at least 400 hp. Here is a link. (http://www.fbodymotorsports.com/engine_packages)

[colin]

Rob,
You are incorrect. The LT4 was rated 330hp, nowhere near 400hp. I think you are confusing that motor with the ZR1 which was rated 400hp.

nick,
If you are wanting to swap in an LT1 that's a great idea. It is an awesome motor, makes gobs of power, and will perform very well in your truck.

I am currently putting an LT1/T56 into a '72 Chevrolet Vega. The swap is very straightforward in my car, but not so easy in your truck. I believe that the swap parts are available. You can get headers for a good price nowadays.

I would definitely recommend getting the V8 swap book from http://www.JagsThatRun.com I have the book and it's invaluable.

Also, you will need to check up on the fuel pump output between the 4.3L and the LT1. I'm not sure about that.

The wiring is easy. Since the PCM is under the hood you really only need a key-referenced 12v input to the PCM, and a 12v lead from the battery to power the PCM. It's pretty much standalone, although you will need to check up on how to get your gauges working correctly (I'm not sure how to do that, as I am going to be running Autometers through my whole car and only need the reference lead from the PCM for that).

The only year of LT1 without a 4L60E was 1993, with that engine being a Speed-Density-based motor. It is also batch-fired, like Tuned Port Injection. The harness on this engine is much simpler to work with! I am putting one of these into my car.

There are three variants of the LT1 after 1993. The first two are aluminum-headed and the only difference is the optispark drive and the front cover. Earlier engines have the optispark driven off of a small driveshaft that's keyed into the cam gear. Later versions (95+) had a vented optispark that's driven off of a pin on the end of the cam. The later version is more desirable as camshaft choices are more widely available, although there are workarounds to allow the use of any cam in an earlier LT1. I considered this very closely when choosing my motor, and decided that I would go with an earlier engine for simplicity (no routing of an intake, just a K&N cone filter on the throttle body). The workaround on the older LT1 is to use an electric water pump (like a Meziere) and not use the water pump drive that's located above the camshaft gear.

The third type of LT1 came in the ImpalaSS or 9C1 (police version). These engines all were cast-iron head engines and were rated at 260hp. I have talked to owners on NAISSO.net and they say they can match an LT1-based F-Body off the line because the camshaft profile is setup for torque not horsepower. I also have one of these engines (a '95 version) and it is SFI and MAF-based.

So, to sum it up, you can definitely do the swap but do your homework.

If I were you I would choose any LT1 that I could get my hands on. Expect to pay around $1000 for a motor/trans combination. I paid $1000 for my ImpalaSS motor alone (shipped from New York or something) and $700 for my '93 LT1 motor. Mind you, that was a few years ago.

If you have any questions at all, feel free to message me on AIM. My handle is BOpseth.

Later,
Colin

[Rob]

Rob,
You are incorrect. The LT4 was rated 330hp, nowhere near 400hp. I think you are confusing that motor with the ZR1 which was rated 400hp.

I apologize if I was incorrect, I was going by what the info in Summit said explaining the kit.

[colin]

I forgot a few things:

There are actually 4 LT1 styles. The 4th is a 4.3L version that came in some Caprices. These look exactly the same as the 5.7L variant. Make sure you look at the bellhousing on the driverside to see what the displacement is.

Secondly,
A set of AFR heads with a good cam will lay down a lot more power to the wheels than an LT4 car. An LT4 engine is mostly bling: taller ports in the intake and heads (negated with a quality aftermarket cylinder head and some port-matching to the intake), roller rockers, different cam, and a red-colored intake manifold.

Interestly, the LT4 engine has an almost identical power/torque curve to the LS1.

Later,
Colin

[colin]

I apologize if I was incorrect, I was going by what the info in Summit said explaining the kit.

My guess is they are rating crank horsepower. Gross, not net.

[Rob]

Not sure.

[colin]

Well, I checked. And Summit says a "potential" for up to 430hp.

That's quite a bit of "potential" increase for an engine that originally made 330hp. I think they are referring to a horsepower that the cylinder heads will sustain given perfect conditions (i.e. PCM work, more aggressive camshaft, higher ratio rockers). Put it this way, the Z06 broke new ground because it made over 70hp more than the LT4. Enough said.

For more info on the LT4 check out: http://www.grandsportregistry.com/lt1vslt4.htm

Also, notice that the LT4 has higher compression than an LT1 (10.8:1 compared to 10.4:1), larger fuel injectors, and a few other minor things that have already been mentioned.

As I stated, AFR cylinder heads, roller rockers, and a good aftermarket cam (like the CC305) will make at least as much or more power than a stock LT4 and still leave a few bones in the bank.

My $0.02,
Colin

[dark_bowtie]

Also, it helps to get the donor car's Under Hood Harness with fuse block. This will have all the fusable link connectors to the battery, the fuses for the PCM and injectors, relays for your fans, ABS, AIR, A/C and has wiring for gauges and brake sensor. Altenator wiring may have to be different.

It would also help to have a wire diagram from a Hayne's or Chilton's manual and even better, a pinout for the computer or PCM.

I made a pinout for 94/95 F-Body PCMs when I first plumbed the wiring for an F-Body LT1 I installed in my truck years ago. That was a stock engine then and the truck has had two different built LT1 setups since with no harness change necessary except for the inclusion of an LTCC Coil Conversion Harness in my last build-up. Pictures of this setup and the truck are in my gallery.

Anyone interested in a scanned copy of this pinout, email me and I'll send it to you.

dark_bowtie@yahoo.com

In regards to fuel pumps, if your currently feeding a TBI motor (2 injectors) you'll need to change it to a pump that can feed up to 40 psi. You can get this from the donor car as well. I'm not 100% sure about that since I used an inline pump and fuel cell from the start, but TBI runs at lower pressure (9-10.5 psi) and should not be enough for an LT1. I went with an inline because its a pain in the ass to change out a fuel pump on an S-10 wether dropping the tank (full or empty) or taking the bed off, you still gotta crack that tank open.

Just some thoughts,

Adam

[Austin]

im actually in the middle of putting a ls1/t56 into my truck. actually a lot easier then it seems. as far as mounts and headers, go they have conversion ones. goto www.currentperformancewiring.com, that guy is out of florida and is amazing! he'll make you a harness specific to your motor.trans app. and tie it in with your specific truck. he made me a harness to adapt the ls1 to my truck, so i have factory gauges and everything to work with the motor.it was comletly plug and play, no wire splicing at all. harness ran me about 800 bucks, but worth every penny. he even re-flashed the ls1 ecm for my truck and with a performance program, good for another 20 or so hp. www.ls1performanceparts.com and www.jagsthatrun.com have a lot of info. check out this guys lt1 swap, simply amazing... www.slammed98gmc.com and you can find a lot more info on www.ls1tech.com in the conversions/hybrids section. thats where i got a lot of my info from. Any questions, email @ raziel1985@hotmail.com.

Austin

[screamn91]

All ofthese guys are right. I have done this swap. 94 LT1 6 speed. What a hell of a fun ride. Lots of power. One thing you need to consider though is the Optispark. That is the LT1 distributor. This thing in the LT1 world is called the Opticrap. It is mounted on the front of the motor underneath the water pump and in front of the timing chain cover. They are prone to go out with out notice. Could be driving down the road and it just dies, or they could never go bad. But you ask anyone what is the biggest downfall of the LT1 and they will tell you the Opti. if the get wet they will go out in a hurry. Also they are not cheap. Between $265-$380 depending on the year. Dynotech engineering has one that is rebuilabled but it is about $800. The MSD one SHOULD be out this summer but that is still not for sure. What ever you do do not buy anyone but a GM replacement. If have to tear down the whole front of the motor to the tiing cover to replace and you do not want to have to do this twice. This swap is almost just like a carb swap. The blocks are the same pre LT1 era's. The difference is the heads. The coolant in these motors runs in the reverse direction that you are use too. So only LT1 heads can be used with LT1 short blocks. Like stated ealier that the timing componets are different. If you go to electric water pump on the 95 -97 LT1 you can use any timing set that you want except for a gear drive. The gear drive will produce to much vibration and give the knock sensor a false reading. i will give you a coupleof websites to check out for info on this. Hopefully I have answered questions that were still unasnwered.

Wiring; www.lt1350.com $275 for stand alone $500 for a graffed
Fuel: Use a Walbro intank pump $100 ebay.
info: www.lt1tech.com www.ls1-lt1tech.com the guys over at LT1tech are a great group of guys with a ton of knowledge that is free to question. Use it!!!

Fuel

[colin]

All ofthese guys are right. I have done this swap. 94 LT1 6 speed. What a hell of a fun ride. Lots of power. One thing you need to consider though is the Optispark. That is the LT1 distributor. This thing in the LT1 world is called the Opticrap. It is mounted on the front of the motor underneath the water pump and in front of the timing chain cover. They are prone to go out with out notice. Could be driving down the road and it just dies, or they could never go bad. But you ask anyone what is the biggest downfall of the LT1 and they will tell you the Opti. if the get wet they will go out in a hurry. Also they are not cheap. Between $265-$380 depending on the year. Dynotech engineering has one that is rebuilabled but it is about $800. The MSD one SHOULD be out this summer but that is still not for sure. What ever you do do not buy anyone but a GM replacement. If have to tear down the whole front of the motor to the tiing cover to replace and you do not want to have to do this twice. This swap is almost just like a carb swap. The blocks are the same pre LT1 era's. The difference is the heads. The coolant in these motors runs in the reverse direction that you are use too. So only LT1 heads can be used with LT1 short blocks. Like stated ealier that the timing componets are different. If you go to electric water pump on the 95 -97 LT1 you can use any timing set that you want except for a gear drive. The gear drive will produce to much vibration and give the knock sensor a false reading. i will give you a coupleof websites to check out for info on this. Hopefully I have answered questions that were still unasnwered.

Wiring; www.lt1350.com $275 for stand alone $500 for a graffed
Fuel: Use a Walbro intank pump $100 ebay.
info: www.lt1tech.com www.ls1-lt1tech.com the guys over at LT1tech are a great group of guys with a ton of knowledge that is free to question. Use it!!!

Fuel

Yo man,
Good info. May I ammend your post slightly just for clarification?

The LT1 has a crossover tube on the rear to prevent vapor lock inside the heads. This tube MUST be used or you will overheat like crazy.

Also, changing the optispark is EASY if you are using a serpentine belt system. On my Vega I am using a slightly different motor mount system where the motor mounts bolt on the front of the engine. But, I set it up so that the motor mounts allow me easy water pump clearance.

Basically, changing the opti requires:
1) Removing the belt
2) Removing the water pump
3) Removing the optispark
4) Changing the seals on the water pump driveshaft and the front cover. YOU MUST DO THIS OR YOU WILL LEAK OIL LIKE CRAZY.
5) Re-install everything.

Another option to do away with the optispark is to go with the Delteq setup. It only requires the use of the optical sensor portion of the optispark which is usually undamaged when the water pump pees all over the opti.

If you decide to do a stock R&R I agree with your recommendation. Aftermarket replacements are junk. The vented later style is quite a bit cheaper than the earlier non-vented style.

False knock counts can be mitigated with an upgrade of the knock module to the LT4 style (reasonably cheap and VERY smart upgrade).

I agree that the LT1 swap is a great idea. My Vega should run low 13s with the stock motor and get over 30mpg. Can't beat that, eh?
Colin

[screamn91]

Colin,
You are right not hard to change the opti but it is all of the little things that you have to do. Gaskets, water pump, etc.

My s10 has been programmed by PCMsforless.com. Bryan did a great job with it. I haveone of those windshield mount 1/4 mile things that is a buddy of mine. I knowthatthey are not the most accurate piece in the world but it says that the little truck should go about a mid 12. I believe that it will be close. Has some suspension stuff done so it hooks decently and runs even better.

Mine gets 16 in town and 26 on the highway. Not to bad for a 8 cylinder motor.