3.8 vs 4.2 for enduro race car


New Member
Mar 3, 2021

Is there any drawbacks with building a 250whp 4.2 instead of a 3.8?
The mustang 5spd bolts right up?

Same weight? (Crank might be a tad heavier, that is ok).

This is for a Nissan enduro race car.

I need to make sure I get a split port 4.2

Regardless of 3.8 or 4.2 I would do:
- Stock bottom
- Stock head (mild home port)
- After market cam
- Aftermarket intake manifold
- Whatever exhaust mani/header fits (ideally lone tubes)
- Catless 3" or so exhaust
- Most likely Aftermarket ECU

Seems like only benefits, curious how the extra 10% displacement would transform into power. In a perfect world it's 10% more power but my gut feeling is that the head is a limiting factor here.

Also, what is your take on a 4.2vs SBF 5.0 for 250-300whp? My hope is that the 4.2 might be ~100lbs lighter and also shorter, since it's a race car that could affect handling.
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15 Year Member
Mar 7, 2002
The 3.8 from the Mustang does surprisingly well in Chumpcar and Lemons from what I've read on their forums and watched on YouTube, while the 5.0 does surprisingly bad.

It's weird. BMW engines that fall apart in daily driver usage dominate the cheap road racing circuits, while GM, Toyota and Ford engines known for their durability in street and/or drag racing use prove time and time again to be time bombs in budget endurance racing.

The exception? Ford and GM 3.8L V6s (which are somewhat related). They'll go 150,000+ trouble-free miles on the street AND run all damned day in a 12+ hour budget enduro race.
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