Engine SwapEverything about swapping an engine into your Third Gen.....be it V6, V8, LTX/LSX, crate engine, etc. Pictures, questions, answers, and work logs.
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Since I had great success with my 5.7 lt1 build with all stock parts. I am thinking of a new engine project only using factory stock gen1 &2 parts or oem replacement to see how much power i can get. (not including intake and exhaust of course)
This is going to be budget minded, using mostly used parts from wrecking yards and swap meets. When finished I'm going to throw it in my 89 formula and video the dyno run.
I'm going to post cost of parts and casting/part #'s as I go.
I'm thinking over 400hp out of small displacement. 302in and less than $1000. At the end maybe I'll give this engine away for the cost of the build.
Unless you already have the L99 crank and rods, forget the short stroke. It might be the challenge you want, but it'll cost you another couple of hundred dollars to get the L99 crank rebalanced with expensive, heavy Mallory metal for the heavier 4" pistons. You're only shooting for 400 horses. Besides, neither the stock LT1 block nor the stock L99 crank and rods will survive the kind of rpm it takes for the shorter stroke to be an advantage. Any stock '92-'97 LT1 with GM HOT cam, and headers, will reach 400 horses. If you were planning to put the L99 crank and rods in a pre-LT1 block, then you're stuck with iron Vortec 350 heads, where most LT1 heads are aluminum. There's a great LTx section over at ls1tech.com, and it's also a good place to find used LT1 parts cheap. Good luck.
If you could get it for your $1000 figure, an LT4, then add the HOT cam. This is good for over 420 horses. The LT4 had the best-flowing, regular-production, pre-LSx heads GM ever stuck on a small-block V8. But these aren't in the budget.
The aluminum LT1 heads are slightly better than the L98/ZZ4 heads, but the intake ports aren't quite as good as the L31/iron LT1 heads.,which share a good intake port design, but don't interchange. The L31 heads have a really poor exhaust port, no better than the older B2L heads.
So starting with an LT1 is good, but the opti-spark might blow your budget. So might trading the SFI for carburetion, and running a traditional distributor, though this is possible. But if you're going carbureted, better to skip the LT1, there is an RPMAirGap for the L31s
If you go with a pre-LT1 block, start with either a 350 from '87-up, or a 2-bolt-main 400 from '70-'80, and top it with L31 heads. Then choose a cam with a bunch more exhaust duration and lift. Comp's smallest hydraulic roller Thumpr would be great for a 350, the medium retrofit hydraulic roller Thumpr for a 400, or if you stroke the 350. Longer stroke likes more overlap. L31 heads just aren't good enough to let any larger cam show worthwhile improvement.
with the L31 heads or iron LT1 heads, try for 9.9:1-10.0:1 compression, and for an aluminum-heads, 10.4-10.5:1 carbureted, 10.9-11.0:1 SFI. Then get a set of Hooker SuperCompetition 1.75" long-tubes. But these are half your budget.
If peak hp matters more than useful power, the Edelbrock Super Victor Vortec might be best. Top with at least a 750 carb.
This won't be emissions legal, but you asked for the most power.
This is just a fun experiment. I don't need this engine for anything. And I can only use engine parts that came original from the factory. No aftermarket cams heads rockers or timimg chain. I ve built a couple of engines before, I'm just doing this 1 to see how much peak hp can be squeezed out of stock engines. Don't need torque, drivability, or emissions.
Anybody can buy afternarket parts to make hp, this is more of a challenge. I know what I think is best combo of stock parts, what do u guys think would be the best combo. Best cam? from 55'-99 best heads? Pistons? Crank? I might try different combos just to see who got it right.
Peak HP with mass-production, '55-'99 assembly-line parts? That clarifies. Get a '99 LS1! but seriously, a forged-crank 327 with the '70 LT-1 cam, using '96-'99 Vortec 350 L31 heads and powdered-metal rods, and the '96 LT4 1.6:1 full-roller aluminum rocker arms, then twist it past 6500 rpm! I don't think a DZ 302 will prove any better than a 327, But the '70 LT-1 cam was bigger than the 375 hp 327 cam used in '65. Even better, cost-no-object, would be a complete '96 LT4 but with the '70 LT-1 cam. These are the absolute best heads and rockers and rods, and this is the absolute biggest cam, within the rules. reach for 7000 rpm either way. I think the LT4 heads are enough better to cover the extra 23 cubic inches, but if not, the L99 crank and rods might survive one quick blast to 7000 rpm.
On further reflection, I wonder if your rules require a carburetor? If so, then no LT4. But unless you're allowed an aftermarket intake manifold, the LT4 intake truly is the best. And speaking of aftermarket, if you're allowed aftermarket rod bolts, then a 302 with L99 rods and LT4 pistons would be best. The lightness of the pistons is more important than the static compression ratio a domed piston would give you. A 5.7"-rod 302 has heavier pistons than a 5.7"-rod 327, so the 302 pulls the stock rod bolts apart at a lower rpm than a 327, so you lose the advantage of the short stroke if you can't use ARP bolts. But an L99-rod 302 with an LT4 piston will beat the 327 if you can use ARP bolts.
The LT1 and LT4 intakes are the same internally. The ONLY difference between them is that the LT4 didn't have the finish machining done for the EGR, and it had a little bit of extra metal cast in on top of the port exits just to cover the LT4 head ports. The internal dimentions of the ports are identical, as is the plenum. One will not make more power than the other. They are the same.
Now we're getting into it. 1st/2nd gen only. I decided to run carb since the test car is already setup for carb only. I have a 95 LT1 all stock converted to carb with 70 LT1 cam. this engine is crazy fast. and reliable. Atilla knows his stuff.
When I mentioned 302cu I was thinking pm rods and crank from 94-96 4.4l lt1 caprice eng. in a 5.7l lt1 block, with stock bore and pistons.(destroked LT1) with the rods being 5.94" long and short 3" stroke the rod/stroke ratio is great. Cast iron LT1 head
and the LT4 rocker is a good idea. 2 problems I see with this combo... 1 according to my calculations with these rods the stock piston will be .25 in the hole. and with the 1.6 rocker and this cam there might be valve to piston clearance issues.
Sorry Adam, not so. The LT4 had taller intake ports.
The LT4 heads did, the intake did not. The LT4 intake ports did not match the LT4 head ports. The LT4 intake ports are the same size as the LT1 intake ports. The LT4 intake just has more metal so that the intake actually covers the taller ports on the LT4 heads, and can be ported to match the LT4 head ports.
And you contradicted yourself. First you say they're identical, nevermind the red paint, because it doesn't matter, now you say they have more metal. Not identical. I've had both in my little pink hands at the same time.
And you contradicted yourself. First you say they're identical, nevermind the red paint, because it doesn't matter, now you say they have more metal. Not identical. I've had both in my little pink hands at the same time.
I said internally they are the same. And the LT1 intakes don't match LT1 heads either. The ports are slightly bigger on the manifold than the head. Heres an LT1 intake and stock LT1 head:
