modding the intake manifold

I am almost done with my stroker, and was wondering if anyone has changed there intake runner lengths or plenum for more HP/TQ. I know that the best option is a 99+ manifold but those are expensive and impossible to find, while 91-95 manifolds are easily found and dirt cheap around here. I would like to experiment with the idea to try to move my peak power down in the rpm range, because my stroker cannot rev past 4900. Is there any math I can do to figure what I want to know or am I going to have to take shots in the dark?

A TB spacer will drop your HP/TQ peaks by about 100rpm so you could try that. Otherwise your only choice is to use a milder cam in your stroker.
Why can't it rev past 4900rpm? My 4.0 revs to the 5250rpm limiter with ease.

My cam choice is what is limiting my rpms (Comp 250 h). The head will not handle higher revs than 4900, at least that is what AP and my machine shop told me. My rev limiter doesn't work all the time, I have had it up to 6000 before, and I will probably install an aftermarket rev limiter. I am just trying to think of ways to get power into my rev range, and most of the intake mods don't do much for low revs.

Last time I had checked on www-car-part.com the99 and neew intakes were only 25 bucks but If you can't find one there was and HO intake and TB on ebay fairly cheap last night. What year head did you go with?

I think you're on a wild goose chase. If you somehow have a cam that won't rev beyond 4900 RPM (although I can't imagine why anyone other than a professional drag racer would ever want or need to rev a Jeep I-6 engine anywhere near 5000 RPM), you must already have a low-RPM/high torque grind. Add in the increase in torque all across the power band due to the stroker engine, and you're going to have so much more torque than you had with a stock engine that there should be no need to worry about lowering the torque peak a few hundred RPM.

Redxj4fun, www-car-part.com doesn't work, that sounds like a really good deal. i went with a 91 HO head on my 87 renix block. I was thinking wrong about the whole thing. The peak torque of a 4.0 is at 4900 rpms and I wanted to move that down away from the red line, but a 4.6 I am assuming now, has different properties. Does anyone know the peak torque/ hp rpm's on an AP stroker?

OOOOOOOOOOOOOPS

Sorry about that maybe this will work a little better.
http://car-part.com/
I've been on some good pain killers since my neck surgury so things aren't quite what they seem at times. but just a KO intake and TB mayne even bred out would work well.

CW. said:

Redxj4fun, www-car-part.com doesn't work, that sounds like a really good deal. i went with a 91 HO head on my 87 renix block. I was thinking wrong about the whole thing. The peak torque of a 4.0 is at 4900 rpms and I wanted to move that down away from the red line, but a 4.6 I am assuming now, has different properties. Does anyone know the peak torque/ hp rpm's on an AP stroker?

Click to expand...

The peak torque is quoted by DC to be at 3950rpm for the '91-'95 4.0 and at 3000rpm for the '96 and later 4.0 in the XJ. Real world dyno runs have shown peak torque coming in at about 3000-3600rpm.
An AP stroker produces ~263hp @ 4800rpm and ~328lbft @ 3800rpm with a virtual torque plateau from ~2800rpm-4300rpm.