I have a 95 jeep cherokee high output and it has a 4.0. I took it apart to put in new lifters and camshaft and found that the pistols have a 40 over stamp on them. Is this factory or aftermarket?

 

I doubt it's factory.

 

No not with .40 cal pistols in it

 

Sounds like a heck of an engine. My son's xj has tons more back end than my zj, always wondered if it was a HO.

 

There's not a huge difference in power between the older engines and the HO.

 

Max allowable overbore for the 4.0 is .030".


With .040" overbore it's not an HO, it's a time bomb.

 

I will post this for anyone who is curious:

HO myth buster


Renix in 90 made 182 HP. HO in 91 made 190 HP. That's 8 HP difference.

HO only made more HP than Renix at higher RPMs and not a bit more torque. HO had a 58 mm throttle body versus a 52 mm throttle body on a Renix. That’s 20% more air available through the HO throttle body. The HO also had a better design header. See where I'm going with this?

It’s only a 4% horsepower increase…..

The whole 8HP was not mostly from the head, but from the bigger TB and better exhaust manifold.

Put a 60mm TB from www.strokedjeep.com on your present manifold using the Renix head, eliminate the "crush" in your headpipe with proper re-routing, and go for it.

HO stands for Highly Overrated.
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Hot rodding tips from cruiser?

In the future, we will expect more from you on the subject. Supercharging, perhaps! Or maybe how to swap in an AMX 390? 🍻

 

Whaddya wanna know? Simple stuff?

 

HO stands for Highly Overrated. Nailed it dude!

 

3.875 bore on a 4.0L, amiright?

he could certainly have .040 pistons.... why not? but, what are they referencing being .040 over? another AMC/Mopar/Jeep 4.0L?

break out the micrometer, you.... and get a pic of those faces!

 

I can appreciate this since it's exactly what I was thinking