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V6 to V8 swap thread

140606 Views 48 Replies 32 Participants Last post by  Injuneer
One of the most common questions we get from the V6ers is how to perform a V6 to V8 swap. My goal for this thread is to find as much information as I can find for our members in order to make the swap as easy as possible. In addition, if you have anything to add, please feel free to add your own information here. I would also like to keep all discussions on the v6 to v8 swap in this thread if possible. On to the links:

3.4 / 3.8 V6 to LT1 Swap Chart - This covers all the differences and what you will need to swap the 3.4 / 3.8 to an LT1.

3.4 / 3.8 V6 to LS1 Swap Chart - This covers all the differences and what you will need to swap the 3.4 / 3.8 to an LS1.

3.4L V6 to LT1 Complete Swap - This site takes you through the entire 3.4L V6 to LT1 swap, and includes a parts list and other information you will find useful.

More to come...
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this is probably the dumbest thing you've ever heard of but here goes. So I have a Ford van sitting in my garage and I got this dumb idea of swapping out my 3.4sfi v6 for a 5.4l triton v8. So now I'm trying to figure out if I'm gonna have to swap the transmission in my firebird or it if it'll work in the new engine, if not what would I need to make it work?
Your profile info indicates your V6 has a "6 speed manual". Since the T56 was not available with the V6, appears you have already done a transmission transplant. If that is correct, do you have the LT1 version of the T 56, or the LS1 version? McLeod makes a universal, modular, explosion-proof bell housing that connects the LS1 version to virtually any engine.

On the other hand, if your V6 actually has a T5 5-speed manual, which is the only manual available with the V6, it's most likely too weak to stand up to a truck engine that produced torque rather than HP. You would be looking at a Tremec TKO 500 that could stand up to the torque. Those are available for Ford engines.

Personally, based on 150,000 miles on a Ford F-150 with the Triton engine (company supplied truck), it has issues of its own, the major problem being the spark plugs with the ridiculously long nose required to reach through the bulky head. Typically, the nose breaks off when you try to unscrew the plug since the annulus between the head and the plug nose is packed with compressed carbon. That engine is also very wide, due to the OH cam heads. Simply measuring the width of the Triton engine should enable you to determine if it would even fit in the F-Body's narrow engine bay.
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Easiest swap would be a Gen 1 small block Chevy (SBC). They put that engine in the 3rd Gen Firebirds and Camaros. That would mate well with a 700R4 4-speed overdrive automatic trans, again, what GM put in the 3rd Gens. Do you want to stay with a fuel injected engine (recommended) or use a carburetor? The L98 350ci (5.7L) V8 engine was used in the later 3rd Gens and has excellent low end torque, but runs out of steam above 4,500 RPM. That can be solved with a set of cast iron Vortec heads from a late model pickup, and a matching intake. The L98 has a bit too much torque for the Tremec 5-speed T5 manual that was used in the 3rd and 4th Gens, GM wouldn't even offer the L98 with a manual trans. However.... best of both worlds - a T56 6-speed manual from a 4th Gen V8. Adapter kit required.

Alternatives include the Gen 2 SBC LT1 350ci (5,7L) V8 engine that was used in the 4th Gens from 93-97. Torque almost at good as the L98, and another 1,000 RPM if heavy breathing. T56 bolts right up with no adapters. But, the LT1 has issues with the Optispark distributor, which GM conveniently located under the weep holes for the water pump. But.... you can easily make up to 500HP at the flywheel, normally aspirated. And the block is good for in excess of 1,000 HP at the flywheel with nitrous, turbo(s) or a supercharger.

Another alternative would an engine from the LSx series.... known as the Gen 3 SBC (but totally different in most aspects). Introduced in the Corvette in 1997, and in the Firebird/Camaro in 1998. Virtually unlimited HP, dependent only on your wallet or the credit limit on your cards.

Inherent to the installation of any fuel injected engine is the matching wiring harness and ECM/PCM. Interfacing the later model harnesses to your body connectors becomes a bit of a challenge. Again, sticking with the L98 solves the harness mismatches.
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A 383 cubic inch engine is built from the 350ci engine, by boring the cylinders "30 over", which is increasing the cylinder bore from 4.000" to 4.030", and replacing the 350's 3.48" stroke crank with a 3.75" stroke crankshaft. An opportunity to add almost 10% extra displacement, and relatively inexpensive My LT1 is 381ci, same 3.75" stroke, but we limited the bore to 4.020", to provide a bit more cylinder wall thickness/strength, to handle the 300-shot of nitrous.

Also popular, when rebuilding an L98 350 to only bore it to 4.030, keeping the 3.48" stroke. That yields 355ci.

The SBC is a very flexible engine, capable of displacement upwards of 427ci. $$$$ goes up with the displacement.
Depends on your budget and how much work you want to do. The L98, with some upgrades can provide "tire melt", particularly with a high stall torque converter, and some 3.73:1 gears. It's a direct bolt in. Will need suspension upgrades, but that's true for any case where you upgrade HP and torque.

The other two engines will need to be adapted to the 3rd Gen chassis. The computers (PCM)/harness will need to be interfaced to the body. I really think you are better off with the L98 and some upgrades, given your description of your goals.
Should provide a noticeable power increase :D
Why not use the factory GM PCM that came with engine you choose? Why go aftermarket? With the matched LS3 engine, wiring harness, and PCM the only issue will be interfacing the new engine harness with the 2002 body harness. Or verify that you can run the LS3 with a 2000-2002 LS1 F-Body PCM and harness. That would probably encounter few if any body harness interface problems. Or just get a front clip from a wrecked 2000-2002 LS1 F-Body, drop your V6 out the bottom, roll the LS1 engine, trans, harness, K-member, full suspension package under the V6 body, drop the body on it and bolt it together.

Beyond the engine, you will need a new trans (the T5 can't handle LSx power), clutch hydraulics, limited slip differential, revised fuel system, mechanical throttle actuator, etc.
Tremec T56 6-speed manual. Trans used for 1998-2002 LS1 F-Bodies.
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