trans_am7935

so i was making this thread to find out what blowers are out there, what they cos, and how much boost the 4.0 can actually take before blowing up. is it worth it over a V8 swap? i have heard people making over 300hp and 320lb of torque with them. is this a reliable and fast way to make good power for offroad?

jeepxj19

read this artical on them http://www.4wheeloffroad.com/techart...kit/index.html

hercman

I read through the article. Did they ever put it on a dyno to see what the numbers are? I also didn't see how much boost they are using.

blasto9000

According to Corky Bell’s book “Maximum Boost,” a 50% power boost is a rule of thumb on a stock engine. (You could go higher of course, but for every extra HP you run the chances of failure are higher.)

I have used that rule of thumb on road-going car engines with some success. The 50% rule itself seems fine. But what you have to watch out for is detonation. Fortunately the speed/density system of the Jeep is simple and easy to add forced induction on top of. You will probably have to add a method to retard ignition advance under boost; an MSD Boost Timing Master will probably do. The MSD is not an ideal solution but it definitely works. I have personally seen several sets of conrods that were bent into an “S” shape due to detonation in an otherwise well-running setup.

One thing you should be aware of when using the stock fuel injection system with a rising-rate boost-indexed fuel pressure regulator and a Boost Timing Master is that it will absolutely kill your fuel economy.

The boost-indexed regulators can only provide fuel in a linear relation to boost. The engine will require fuel in a non-linear fashion so in order to prevent a situation where you have a few RPM and load points that run lean, the boost-indexed regulators are typically setup to run very rich – usually about 10:1 at the leanest point.

A way around this is the Accel DFI system. They make one specifically for the Jeep 4.0L. I have used Accel DFIs on other cars with great success. This is really the best way to set up a speed/density engine like the Jeep no matter if you’re supercharging it or just running an otherwise stock setup with an aftermarket performance cam.

Also, the boost amount depends on flow of the supercharger and a few other factors, so you can’t definitively say “X.X psig of boost.” A smaller supercharger will reach max boost at a lower RPM and throttle angle, and a larger supercharger will reach max boost at a higher RPM and throttle angle. A more efficient supercharger can run max boost in a broader RPM and load range. It’s best to get a supercharger sized for the engine flow.

With aftercooling you can run more boost. The amount of additional boost will depend on the flow and thermal efficiency of the aftercooler.

BTW the Eaton supercharger used in the link is a generic design, but it’s still pretty good. If you have the $ for this kit I would say it’s a tossup between a stroker and the supercharger. Personally I like the simplicity of the stroker… from the outside you can’t tell anything special is inside the engine. And no additional belts. If you decide to go for this kit, I would strongly, strongly recommend getting the Accel DFI.

JeepingDan

Alright everyone..
We are away's having problems with these kind of threads derailing.
Since this is a fresh new thread..
Lets keep it TECH and INFORMATIVE please so we have a useful thread.

Thank you.

cherokeeaddiction23

i would think a stroker would be more worth it, you can get very close to the 300 hp mark no problem, and as your doing the stroker, put in beefed up internals and you could probably run a supercharger and get another 50-100 hp on top of that, and i would think you would run less of a chance of grenading the bottom end of your motor

No4x4Yet

The stock compression of the cherokee, I think its 8.5:1 is actually Ideal for some decent boost without having to worry too much about detonation. You will be able to have a pretty safe setup with moderate boost. The weak link is gonna be in the internals.

trans_am7935

so the avenger sells a 8.5psi kit and is rated to 300+ hp...i dont really want the drama of a V8 swap right now and the strait 6 is a pretty good motor. i just wanted to know if it was reliable enough to get another 50,000 miles out of my motor without fear of detonation... i have a rebuilt motor with 25,000 miles on it. runs strong so far. crank was re-used and rods too, just the rod bolts, pistons, rings, re-bore (hone) and heads were replaced due to a damaged piston. (oh yea and rod #1 cause it was cracked) crank was also re-ground.

96_xj

Check out 505 performance in farmington, nm. They are the original makers of the turbo kit and also have the kit to make the 4.0 block into a 5.0 Hp/torque machine. They have all of the Dyno numbers to prove everything they do and I believe they are working on a super charger. Just give them a call or check out their website ALL of the information you need can be found there.

IXNAYXJ

They build really nice stuff. Their "Insane Inline" 4.0 based turbo motor made 692 hp and 780 lb/ft.

-Matt

96_xj

it is still running too. Saw it about 3 months ago. it is a reliable upgrade.

s14unimog

^ is it though. If the timing/fuel tables are managed correctly I doubt the internal components will be the weak link - to a point. I would bet the first problems would resonate from the head studs and head gasket. That's the typical fail point on most NA-T setups.

I don't agree with the 50% rule mentioned above. I've got a 4 cyl. pushing out over 400whp on a single turbo setup, on stock internals. I've had the setup for almost 2 years and regularly track this vehicle; and drive it home for that matter. This engine produced less than 200whp from the factory....

Like I said, engine management is the most important. I would not consider an FI setup unless you are prepared to go completely standalone and have the Jeep dyno tunned.

No4x4Yet

If your wheelin the Avenger kit would likely be better suited, the steady torque will be more reliable on slipper terrain than a turbo spooling up quickly. You could size a turbo to make good low end torque but it limits the overall power, but thats not really an issue when off road. I think a PD blower would be more reliable off road though.

Well a head gasket swap is a fairly easy upgrade if you needed, much easier than replacing the internals. I just read on Avenger's site, they make about 100 hp with 4.5-5 psi and say it requires no added mods. Thats not a bad setup.

s14unimog

I agree. I ran a turbo setup on a 4 cyl. 2.4L N/A motor once with the stock head gasket and made an additional 60hp/100tq. it was a small CFM turbo but with an intercooler, I was reliably running 10psi for over a year and half but that was a street car, not a 4x4. Unfortunately I was at the limit of that setup. Injectors were near 95% and the MAFS would periodically max out on cold nights causing the car to run extremely rich. Not to mention I was only retarding base time, running cooler plugs, and running a piggyback fuel converter. When I boost my Jeep, which I'm sure I will since I can't leave any of my engines alone, I plan on using a centrifugal blower since I'm a Rotrex OEM dealer. But I won't attempt it without a full standalone and wideband. Having that on my other car is just too comforting when you have that much work invested...

Bustedback

Really need a "dreamin" section in the forum.