Cherokee Sport - Why do I want to do this???

In reply to ProDarwin:

Cheapest solution to the engine is going with the 4.7 stroker. The jeep 4.0 is "lucky" in that an easy upgrade for the stock motor is to use some parts from the parent 4.2 engine. So for about 1500 give or take you can have a completely rebuilt stroker giving you >250HP. If you want it to rev quick, couple it with a lightweight flywheel.

Saves you on the complexity and cost of some hybrid swap.

As far as engine weight is concerned, yes the 4.X Jeep is 515lbs, similar to the 2JZ, 50lbs heavier than the 4.2 GM Atlas so short of going to a turbo 4cyl you wont be getting near the power level you're looking for and definitely not the reliability

Sonic wrote: If anyone playing with jeeps wants some parts, at my mother's house near Boston, I have a complete 1996 ZJ 4.0 engine, oil pan to valve cover, with the manifolds, NVH block, that is just sitting there. I bought it and tore it down and bagged/labeled all of the parts with intentions of making a stroker motor for my XJ at the time, but life got in the way and now 7 years later it is still in my mom's garage. Free to any GRMer that asks and can pick it up.

A friend of mine just rebuilt one of these after his motor failed the week before ESPR. We were supposed to use his Cherokee for heavy sweep. Instead we borrowed this:

Which deserves its own cool thread, but I don't want to hijack this one. We worked well together, and we're hoping to team up and bring his XJ out to sweep some other nearby rallies.

Anyway, I think his rebuilt motor is done, but I asked him if he'd be interested in a spare, just in case he blows it the week before a rally again.

eebasist wrote: In reply to ProDarwin: Cheapest solution to the engine is going with the 4.7 stroker. The jeep 4.0 is "lucky" in that an easy upgrade for the stock motor is to use some parts from the parent 4.2 engine. So for about 1500 give or take you can have a completely rebuilt stroker giving you >250HP. If you want it to rev quick, couple it with a lightweight flywheel. Saves you on the complexity and cost of some hybrid swap. As far as engine weight is concerned, yes the 4.X Jeep is 515lbs, similar to the 2JZ, 50lbs heavier than the 4.2 GM Atlas so short of going to a turbo 4cyl you wont be getting near the power level you're looking for and definitely not the reliability

I don't know that thats the cheapest solution. And with aftermarket companies offering them with a 5200rpm redline, I don't think they rev too well either.

As far as reliability - an SR20 will make >250hp very reliably and weighs significantly less than the Jeep drivetrain. Actually, quite a few 4 cylinders that will do that are listed here: http://grassrootsmotorsports.com/forum/grm/quickesteasiest-four-cylinder-at-350-hp-for-typical-challenge-motor-money-part-deux/64471/page1/

Cheapest solution is probably a gm 3800 built with supercharger parts but dressed out with enough Camaro stuff to be rwd and a turbocharger.

I'd still love to drive one with a 4.8l lsx motor.

I wouldn't give 500 dollars for any year jeep. I hate them, worked on them too much.

Thanks for your contribution. I usually only complain about working on a vehicle if it is NOT easy to work on, but hey, different strokes.

As far as engine weight is concerned, yes the 4.X Jeep is 515lbs, similar to the 2JZ, 50lbs heavier than the 4.2 GM Atlas so short of going to a turbo 4cyl you wont be getting near the power level you're looking for and definitely not the reliability

Uh.. non sequitur alert. How do you go from saying a 4.0 weighs 500 lbs to saying that you wont be getting near a modest power goal without swapping in a more highly-stressed motor that is somehow more reliable?

Yeah, the 4.0 is not light. On the other hand, it is also not so heavy that you cant WIN THE AUTOCROSS AT THE CHALLENGE with it in the front of your jeep. So how big of a problem is it, really?

A 4.0 with some other breathing mods will make 300hp on like 5psi. That is not exactly pushing the limits of ANYTHING, except maybe the STOCK injectors!

As far as reliability - an SR20 will make >250hp very reliably and weighs significantly less than the Jeep drivetrain.

Have you driven a 3000+lb car with a tiny turbo motor? They barely move until you hit boost. Ive personally never liked driving cars that have NO balls until they hit boost, and realistically it limits you to using a smaller turbo than you otherwise might. If you're planning to swap in a 4 cyl, id definitely focus on making sure it A. will move alright BEFORE boost, or B. hits boost very quickly with a tiny turbo (that will probably be maxed out and spitting fire at 250whp).

Vigo wrote: Have you driven a 3000+lb car with a tiny turbo motor? They barely move until you hit boost. Ive personally never liked driving cars that have NO balls until they hit boost, and realistically it limits you to using a smaller turbo than you otherwise might. If you're planning to swap in a 4 cyl, id definitely focus on making sure it A. will move alright BEFORE boost, or B. hits boost very quickly with a tiny turbo (that will probably be maxed out and spitting fire at 250whp).

Yeah. I raced a STX WRX for two years. It made approx. 225whp from a 2.0. It was pretty darn close to 3000lbs. I liked the powerband of that car, especially on the street. In autox, it was a bit annoying in the very tight corners though. The challenge Jeep weighed in a 2677lbs. Add a few lbs for a passenger seat/backseat, but subtract 200-300lbs for the weight one would lose replacing the 4.0 with an SR20, Neon 2.4, Ecotec, etc. and the final weight would probably be in the 2400-2600lb range... similar to an SR20 powered 240sx, right?

FWIW, I find that engines with tiny turbos that are pretty much maxed out are lots of fun. I love the powerband of an STU STi. ~300whp and right now response.

White_and_Nerdy wrote:

I know that truck! I drove behind it all day, and in front of it on day 2 in the Light Sweep (the not-a-jeep one)

ProDarwin wrote: The challenge Jeep weighed in a 2677lbs. Add a few lbs for a passenger seat/backseat, but subtract 200-300lbs for the weight one would lose replacing the 4.0 with an SR20, Neon 2.4, Ecotec, etc. and the final weight would probably be in the 2400-2600lb range... similar to an SR20 powered 240sx, right?

that 2677# did not include any of the turbo parts since we concoursed it before we were drunk enough to try installing the turbo in the parking lot.
the autox win $2012 weight included all the turbo stuff and to counter fuel starvation and slosh we simply filled the 20 gallon tank (future upgrades include either anti-slosh stuff or an external surge tank and pump), and it added about 100 lbs for a 2775# total.

ProDarwin wrote:

eebasist wrote: In reply to ProDarwin: Cheapest solution to the engine is going with the 4.7 stroker. The jeep 4.0 is "lucky" in that an easy upgrade for the stock motor is to use some parts from the parent 4.2 engine. So for about 1500 give or take you can have a completely rebuilt stroker giving you >250HP. If you want it to rev quick, couple it with a lightweight flywheel. Saves you on the complexity and cost of some hybrid swap. As far as engine weight is concerned, yes the 4.X Jeep is 515lbs, similar to the 2JZ, 50lbs heavier than the 4.2 GM Atlas so short of going to a turbo 4cyl you wont be getting near the power level you're looking for and definitely not the reliability

I don't know that thats the cheapest solution. And with aftermarket companies offering them with a 5200rpm redline, I don't think they rev too well either.

i built a 4.7L stroker years ago out of an '88 4.0L 'low output' block with a 91 H.O. ported head. the valvetrain was an interseting mix of crane cam, Oldsmobile spec springs, Ford retainers, Chevy stainless valves, and crane offset retainers. with everything fully balanced i'd say it wanted to rev pretty darn well. it seemed to like the 3-5k rpm range a lot more than it did before the build, though the headwork i'm sure helped a bunch there. but i dont think i'd have much worry turning it up to around 6k rpm.

i absolutely loved the engine and have put 50k miles on it, and it pushed my lifted 4x4 full weight XJ through the quarter at 15.4 without a good launch or a proper engine tune. when i junked the jeep it went in i kept the engine and i've thought about putting that into the XJ-R too.... makes me wish i'd built it with forged rods to feel more comfortable also turboing it

BobOfTheFuture wrote: I know that truck! I drove behind it all day, and in front of it on day 2 in the Light Sweep (the not-a-jeep one)

Well it's good to see you again!

Yeah. I raced a STX WRX for two years. It made approx. 225whp from a 2.0. It was pretty darn close to 3000lbs. I liked the powerband of that car, especially on the street. In autox, it was a bit annoying in the very tight corners though. The challenge Jeep weighed in a 2677lbs. Add a few lbs for a passenger seat/backseat, but subtract 200-300lbs for the weight one would lose replacing the 4.0 with an SR20, Neon 2.4, Ecotec, etc. and the final weight would probably be in the 2400-2600lb range... similar to an SR20 powered 240sx, right? FWIW, I find that engines with tiny turbos that are pretty much maxed out are lots of fun. I love the powerband of an STU STi. ~300whp and right now response.

I guess i misunderstood your desire for a 4 door body and towing ability to mean you wanted it to not suck as a street car, but your idea of getting a street cherokee down to 2500 lbs implies you dont care that it will suck.

The most you are going to lose from a motor swap is probably 150, MAYBE 200 lbs. I think you are overestimating the weight difference between the jeep 4.0 and the turbo (hint hint extra weight) 4cyls, and COMPLETELY overblowing the weight difference in transmissions which is likely almost nil (the jeep trannies are NOT heavy, they're completely normal size/weight!).

I honestly dont consider cherokees to be particularly easy to lose weight from other than the fact that all their side and rear glass is completely flat. They dont have much extra ANYTHING hiding in them. They start out pretty light, and i think expecting to drop 500 lbs from that on a street jeep is just asking to take a pretty unrefined vehicle into the PITA zone of noise and uncomfortable/useless seating.

As far as the turbo thing, i somewhat agree with you.. As long as you understand how much a 2.0 will suck off-boost and plan your turbo sizing around that, i have no further comments on that point.

I think what you should do is just get it into your head that you dont NEED to lose a bunch of weight to make the jeep do what you want it to. I honestly dont think weight loss was crucial to the performance of the challenge cherokee. I would settle for most of your (modest) weight loss coming from an engine swap (which is weight off the right place, btw), and leave the rest of the jeep pretty much alone as far as weight loss.

In reply to Vigo:

Agreed, the 90's Cherokees are lighter than a similar year Wrangler IIRC. I always liked the stripped interior look but it's just gotta be like being inside a drum driving around town with the kids.