Miscellaneous Performence Add Ons

[Jeepsporter]

:repair: Does anyone know how big of an increase in power would a person would get if they bolted on a set of aluminum roller rockers. Or something like headers, a performence chip, or a throttle body spacer. Do any of these do any good, or are they just a waste of money???

 

[XJhabitat]

those all give small gains id say a waste of money. the motors got tube headers stock so i wouldnt bother buying somthing else. all i ever hear about the chips are they suck.

 

[Dr. Dyno]

:repair: Does anyone know how big of an increase in power would a person would get if they bolted on a set of aluminum roller rockers. Or something like headers, a performence chip, or a throttle body spacer. Do any of these do any good, or are they just a waste of money???

I'll give you my own first hand experience of these mods.

1. Yella Terra 1.6 ratio roller rockers: More stable, quieter valvetrain (no more pesky rocker ticking) but HP/TQ gains minimal. Do them for engine reliability, not for performance. They also look a lot sexier than the stock stamped steel rockers and I have them in my 4.6 stroker.

2. Header: Not much of a gain by itself but works much better in conjunction with mandrel-bent downpipe, high-flow cat, and performance catback. I like my Borla header for the improvement it made to the sound so for that reason alone, I think it's a worthwhile mod.

3. JET chip. Absolute waste of money. Small gain in HP at top end but you lose a little torque in the midrange. Some JET chips cause problems so best avoid them altogether. I removed mine and didn't regret it.

4. TB spacer. It's a $50 mod so you can't expect much, but it'll yield a small HP/TQ gain and you may see a small improvement in gas mileage. Worth a try (I still have mine).

 

[WHITE420XJ]

How much do those roller rockers cost and can I put them on a stock 4.0?

 

[Dr. Dyno]

I bought mine directly from Yella Terra in Australia for $364. The 1.6 ratio rockers carry part no. YT6627 (the ones I have) and the 1.7 ratio rockers carry part no. YT6628. Both sets will bolt directly in place of the stock rockers under the stock valve covers without any clearance issues. They're very easy to install. I did mine in about an hour and I was taking my time to check the lifter preload in the process.

 

[xjh3]

No single one of the performance upgrades I've done has made a huge difference. However, the intake, bored TB, TB spacer, updated intake manifold, header, magnaflow cat and 2.5" Flowmaster and tailpipe all in conjunction together have made a very noticeable difference. I now have 30's with stock gearing and my piece does 0-60 atleast a second faster than it did even with stock tires. Throttle response is excellent and I can feel much greater torque throughout the entire RPM range, even as low as 1K RPMs I am surprised at how little it downshifts.

 

[streetpirate]

if you read dino's web site, the bolt ons only do so much, until you stroke it. thats what really brings the mods alive.

 

[aparke4]

this is true

i have a jet stage 1 chip on my 99 which helped my throttle response - thats about it but also i have done:

k and n fipk intake, rustys tb spacer, banks header, unkinked downpipe - 2.5 to hi flow magnaflow cat to 2.5 flowmaster 40 series, bored stock tb to port match intake at 60mm, screamin deamon ignition upgrade, stock champion plugs, optima battery,

with this all together with the chip i love the feel of my engine - i get great torque on the trails, i have gotten it to run cool now - 3 core radiator, hood spacers, hood vents - and the HP is fine for my 35's and 4.56 gears - it is not a big 350 or 454 but it is reliable, fuel efficent (not great but ok for me for a few times a week driving), sounds great and gets me where i need to go. i run synthetic castrol syntec for the last 50k, k and n oil filter with a stp oil additive or lucas every 3k, use fuel injector clean or acetone on regular basis like every 30 gallons and just had a compression test and the motor runs like a top. it idles super smooth and i love it. if i were to take the money i have in it on all the bolt ons added up i could about stroke it ( i have bought and sold some stuff so overall) which i would do next on my next cherokee build with a new header and exhaust even before lifting it or anything. anyways these mods gain some in hp and some in torque but i think overall they give more life to the engine, better throttle repsonse and an overall better feel to the 4.0. i love the way mine runs and would not change a thing. (except stroke it one day perhaps )