Jeepster05
New member
My 4.2 killed a 4.0 racing on level road. I have 33s with stock gears and the other guy had 32s with stock gears and it was no competition. 4.2 all the way if you replace that darn carter. Plus they sound freakin awesome
4.0 vs. 4.2
- Thread starter mingez
- Start date
Forget the factory rating. Throw a free flowing air cleaner on there, ditch the cat, and throw on a good muffler and you'll have a good 140hp. A header, optimizing the ignition, and stepping up to decent carb in the 350cfm range and a good intake manifold will stretch that out to about 160hp and 250torque. That's without really going into the engine where the biggest limiters of power are, the cylinder head and the camshaft. Stepping up to a modern cam grind like the Comp 254H-11 will add 20-30hp and dramatically broaden the torque curve while not really changing the rpm at which peak numbers occur, which is important because the cylinder head limits flow at higher rpms.
Stepping up to a 4.0 HO head or porting and installing larger valves in the factory one lets you go alot further. At that point you can step up to something like the Comp 262H-11 camshaft and raise the compression a notch or two, and after tuning that combo I'd dare to say 230hp and a very broad torque curve that peaks at around 300#s are at your disposal. You put that in a properly setup SWB Jeep and you'll put ALOT of V8s to shame.
I have no dyno numbers to back any of that up, but I'd bet I'm not too far off. I LOVE Jeep I6s. It makes me chuckle when I hear about dudes wanting to swap in 350s for more power.....then they throw in a factory late 70s or early 80s 350(because they are abundant and cheap) that would only make 165hp on it's best day. A V8 swap is nice, but if your just gonna throw some little weak punk-assed V8 in there.....why not hop up the I6 and have the "cool points" to go along with it? Just my opinion.
Stepping up to a 4.0 HO head or porting and installing larger valves in the factory one lets you go alot further. At that point you can step up to something like the Comp 262H-11 camshaft and raise the compression a notch or two, and after tuning that combo I'd dare to say 230hp and a very broad torque curve that peaks at around 300#s are at your disposal. You put that in a properly setup SWB Jeep and you'll put ALOT of V8s to shame.
I have no dyno numbers to back any of that up, but I'd bet I'm not too far off. I LOVE Jeep I6s. It makes me chuckle when I hear about dudes wanting to swap in 350s for more power.....then they throw in a factory late 70s or early 80s 350(because they are abundant and cheap) that would only make 165hp on it's best day. A V8 swap is nice, but if your just gonna throw some little weak punk-assed V8 in there.....why not hop up the I6 and have the "cool points" to go along with it? Just my opinion.
