intake manifold

[blazer99]

is there anyway to bore the intake manifolds on the 4.3 im lookin to put a pretty decent cam in this... so i was thinkin bout doin something to the intake manifold just dont know what ... if anyone has done anything to theirs or known of someone who has i would appreciate any info thanx

Tim

[mdmilburn]

seen one person here is useing a edlebrock in place of the stock vortech intake with a special adapter made for the throttle body and individual injectors placed on each port .this intake would be in ether induction type to convert to now if you have the spyder vortech system may want to convert to one of the others .....http://www.hotrodders.com/forum/journal.php?action+view&journalid=19031

[Old Man]

The only reason to look for another intake is when you can surpass what the current setup can offer. You have to be able to surpass 275 Flywheel before such option would be needed. I havent seen anyone NA been able to achieve such for a 4.3 yet. Then you have to have the ability to be able to do your own tuning for such intake again to be attempted. The intake doesnt offer anything beyond the ablity to tune for larger injectors, air flow differences just arent really there. This is a great deal for forced air guys where the other factors dont come into play, NA forget it!

[Hammer]

I guess that would be true because a bored and stroked or destroked 4.3L isn't really a 4.3L anymore.

i can't imagine how headers, dual exhaust a good mid range cam larger dissplacement and higher compression couldn't get you to 300 na with a tune done to accomodate the modifications.

i don't know how far you can punch it out to and stroke it too but surely you can 300hp out of it na if you wanted to.

that said, working on the intake manifold is really useless because you can get a cam that will cater to the restricted manifold and spend your time and money on exhaust and computer tuning.

[blazer99]

the hp to be gained from the manifold is the least of my worries. im looking to tune the manifold to the cam. the effective powerband of the cam im thinkin up will be around 2800 or so to 6000. i may be wrong but these manifolds on the truck are aimed towards low end tq and start to die out in the upper rpms( feels like 4600 where it starts to fall out) and on a truck thats going to need to rev more then that.

[Old Man]

I can see where you want to go, but the 2114 intake is done at just over what the factory one does with the factory cam. What the factory mani will do with its large plenum is help out upper rpms, least thats according to the ideals of plenum size and medium length runner. Small plenum very short runners does better low than high rpms which is what a 2114 is. But the dyno numbers that were posted on a site show the 2114 really not helping out low and middle, but just managed to push the fall off at 4400 a couple hundred rpm.

No one so far has enough evidence of a cam working better with the 2114 against what the same cam did for a factory mani. One guy some years back cut down a TPI intake and adapted it to the vortec head, his attempt and numbers were the only solidly positive I ever saw. Both lower and mid rpms power came up, and upper rpm power went right to the factory limiter at 5400. Made somewhere around 230 RWHP and he wasnt done yet with the tuning part.

I can also say looking at the marine motors which always run higher rpms numbers it has no troubles making 40 ponies over ours at higher rpms, and yet its only difference it the fact it uses a rail and seperate normal bosch style injectors. No one has really explored the marine end, but I can say there are alot of marine users that at just plain carb people so that intake has to be floating around cheaply!

[blazer99]

old man u seem to know whats goin on with these motors. i havent decided on a cam yet but im thinking of keeping the numbers around here. 210/220-512/512 114. keepin it on a 114 for the possiability of a supercharger in the future. I have been working on and off with comp cams on the regrind trying to figure out what would work best. the cam will give me a power band from 2400- 58xx mated with a 3k stall and 4.56's ill be able to keep the truck in the rpm band. but if i cant get the manifold to make power, this will render the cam useless. you wouldent happen to have any pics of inside the 2114 would u? cuz if i start cutting the runners down alittle more this should start raising the rpms that the manifold will be good for, with the sacrifice of a lost low end but thats the least of my worries, from what i sid before about the stall n gears the truck wont spend very much time down there ne ways.

"No one so far has enough evidence of a cam working better with the 2114 against what the same cam did for a factory mani. One guy some years back cut down a TPI intake and adapted it to the vortec head, his attempt and numbers were the only solidly positive I ever saw. Both lower and mid rpms power came up, and upper rpm power went right to the factory limiter at 5400. Made somewhere around 230 RWHP and he wasnt done yet with the tuning part." do you have any more info about this motor and the truck?

[Old Man]

The guy lived on and island I believe was Aruba. He hasnt been around in maybe 2 years and what ever came about with the manifold after the original postings???? This was before tuners were out like they are today and he was mail ordering tuning. I dont remember where he made the cut for the split, but what he did was cut the length of the TPI down and welded it back together. Did some light work to match the ports up and whalla, had the mani that was the best concept to date IMO.

You dont need 512 lift nor even want it. Vortec heads lose there breathing ability as beginning at 450 lift. At .400 lift it flows into the 225-230 CFM range and he extra .100 lift only creates 9 CFM more and 7 of that was seen at .450. Unshrouding the valves doesnt work on Vortec. I se to have the links but lost my bookmarks, but it was quick novas and one other site that went into some depth about the heads. I believe some of those links are in other topics about heads on this site that I added. Little bit of bowl opening on the intake and larger exhaust valves and heavier bowl work on the exhaust side does the best. 240-250 is about all you will see intake, but the exhaust side can see over 40 cfm if done right.

Duration is the key to Vortec heads, lift is .470 max so with a .020 clearance, .450 is wanted, knowing it isnt gonna flow enough of and increase to warrant the extra machine work for .500+ lift, why? Key is going to be able to find the duration that works with the ECM and intake flow. If I was looking to go that route it would be 112 lobe seperation and around 230 duration max!