90xj06
NAXJA Forum User
- Location
- Peabody, MA
is there a huge difference in power with a 99+ intake on a renix engine with the 7120 head?
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99+ intake on renix
- Thread starter 90xj06
- Start date
old_man
NAXJA Forum User
- Location
- Loveland, Colorado
If I remember correctly, the ports don't line up exactly and ideally you should do some port matching work on them. You won't have a place for the EGR on the newer head. I also think the mounting for the power steering pump is different. I seem to remember that it is missing a mounting hole for the air charge sensor as well. All of this is doable, but might be more work than you want.
JeepNoob
NAXJA Forum User
- Location
- Pueblo, Colorado
Fourwheeler seemed to sum it up pretty well- "Myth: According to that great wealth of information that is never wrong, the Internet says you'll get a 5-30hp gain thanks to the '99-up 4.0L's swooped, equal length runners and larger plenum volume.
Our Thoughts: While a free-flow intake manifold can deliver more power, it's only going to allow as much air to flow as the cylinder head and camshaft will call for. Upping the intake runner volume too much will cause the intake charge to lose velocity, killing low- and mid-speed power and torque. On a '98-earlier engine running a stock camshaft and unported cylinder head, it's wasted effort."
http://www.fourwheeler.com/how-to/engine/154-0911-jeep-4-liter-engine-myth-busting-true-lies/
Our Thoughts: While a free-flow intake manifold can deliver more power, it's only going to allow as much air to flow as the cylinder head and camshaft will call for. Upping the intake runner volume too much will cause the intake charge to lose velocity, killing low- and mid-speed power and torque. On a '98-earlier engine running a stock camshaft and unported cylinder head, it's wasted effort."
http://www.fourwheeler.com/how-to/engine/154-0911-jeep-4-liter-engine-myth-busting-true-lies/
- Location
- Salem, OR
Problem is, the 99'+ was never meant for horsepower, kinda like the neon injectors were not meant for hp, they tested hp but never torque. which in theory with the longer, smaller runners is suppose to give the older 4.0l a little boost of torque. And the injectors were only suppose to give a smoother throttle response
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90xj06
NAXJA Forum User
- Location
- Peabody, MA
ok that sums that up. im probably going to swap in a 91+ exhaust manifold. and at the very least pop the 7120 head on. that should not be too much work and i wound have to fiddle with electronics and fuel rails.
cruiser54
NAXJA Forum User
- Location
- Prescott, Az
Much better plan.
HO exhaust manifold on Renix
As far as exhaust, you can use the Renix exhaust manifold and be fine.
If you want to use the HO exhaust manifold, you must go with an HO headpipe and screw your O2 sensor into that headpipe. Standard Renix harness is plenty long to do so.
A bung can be welded into the HO manifold to accept the EGR tube also.
Get rid of the "crush" in the down pipe also.
Have you indexed your distributor?
http://cruiser54.com/?p=68
90xj06
NAXJA Forum User
- Location
- Peabody, MA
i may forgo the egr and it also seems like the HO exhaust manifold is much easier to find aftermarket ones. i would like to go 100% stainless on the exhaust.
