3.5 to 3.7 swap

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HMINUS3505

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I was given a 3.7 and transmission from a wrecked 2019 MKZ with 40,000 miles on it as part of a trade. I've pulled it apart and it is one clean motor. From what I researched, it is the same block as the 3.5. I was thinking about pulling my 3.5 from my 2016 SHO as I've already bought new turbos, EPP full pipes and CAI, XDI fuel pump, PPE catless DP's So I kinda have the itch to see what the 3.7 would do twin turboed.

What do you guys think?
 

rubydist

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I think you will quickly discover that the internals of the 3.7 are not happy with being boosted.
 

HMINUS3505

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I think you will quickly discover that the internals of the 3.7 are not happy with being boosted.
Quite to the contrary. 3.7 breathes so much better than the 3.5 just need to go with bigger turbos. I've done some research, I'm not the only who has had the same idea. Besides, I'd probably beef up the internals since i have it opened up anyways. But, it is very doable.
 

Ta2dResqr

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Quite to the contrary. 3.7 breathes so much better than the 3.5 just need to go with bigger turbos. I've done some research, I'm not the only who has had the same idea. Besides, I'd probably beef up the internals since i have it opened up anyways. But, it is very doable.
1. You say you are going to beef up the internals. This eliminates the problem @rubydist was pointing out. Boost creates higher pressures. The 3.7 was not designed to withstand boost in it's stock form. If you are going to beef up the internals, you are basically just using the 3.7 block to avoid the step of having to bore out a 3.5.

2. You are discussing how the 3.7 breathes so much better. Breathing is achieved by the intake and the exhaust. The heads are different because you comparing the 3.7 that injects fuel prior to the cylinder above the valves to a 3.5 that injects it directly into the cylinder. It also has a different intake manifold (and complete intake system) to match to the different heads. On the opposite end, the exhaust manifold (and complete exhaust) are different as with every NA/Turbo comparison.

I am not sure why you asked for peoples opinions just to tell them they are wrong. You have 2 options here. 1. Use the 3.7 block to get the bigger displacement, replace the internals so they can withstand boost, forget the "it breathes better" mindset and put all the EcoBoost parts on it to make a 3.7 EcoBoost. 2. Use all of the 3.7 components that you can, beef up the internals, custom fab mounting of turbos and intake/exhaust to make a 3.7 Cyclone turbo.
 

skyshadow07

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I like the idea of the 3.7 simply because it is port injection. You would not have to dick with the expensive high pressure fuel pump and your valves would stay cleaner, longer.
 

rubydist

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They use direct injection on those boosted engines for a functional reason, not because they want to make them more expensive. With only port injection you will not get as much power from the engine and you will be dealing with pre-ignition issues. So, imho, using the 3.7 heads on a boosted setup would be a poor choice.
 

skyshadow07

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Aside from being able to increase efficiency and dial back the possibility of detonation, DFI is not needed nor a god send when using boost. The strongest and best performing engine designs are not DFI. SR20 (boosted), RB26 (boosted), 2JZ (Boosted), 4B11 (boosted), K Series... and on and on. The reason they used DFI on the ecoboost was for the eco side of that name, not the boost and definitely not for power or longevity.
 

Bluezone

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Aside from being able to increase efficiency and dial back the possibility of detonation, DFI is not needed nor a god send when using boost. The strongest and best performing engine designs are not DFI. SR20 (boosted), RB26 (boosted), 2JZ (Boosted), 4B11 (boosted), K Series... and on and on. The reason they used DFI on the ecoboost was for the eco side of that name, not the boost and definitely not for power or longevity.
Exactly. You get more cooling effect when the fuel has more time to atomize. It's not as efficient for fuel mileage but the port injection is superior for power production.
You also need the Pistons that are specific for Port injection. EcoBoost Pistons are set up for direct injection.
 

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