I own a 88 Comanche with a I6 and would like to get some serious power out of it for as cheap as possible. I would like to gain at least 100 horsepower. I know there is alot of stuff out there for the 258. The main difference of the 4.0 from the 4.2 is the stroke. What are the others? Is it possible to put a crank from a 258 in the 242 to make it a 258? Any guidance is appreciated.

Stroke the 4.0 by using a 258 crank.

http://www.jeep4.0performance.4mg.com

and Yahoo Group Strokers Good info.

home made stroker is prob the cheapest i think it might cost around 1000-1500 bucks or somewhere around there maybe a little higher. you could get a supercharger i know avenger makes em for the 4.0L

Your asking to more than double the real stock HP. That is a lot to ask. To do that you might as well drop in a V8. But what do you need the HP for? A stroker kit won't get you 100hp I don't believe, someone correct me if I am wrong here but... The stroker is the way to go for off-roading... HP is for drag racing, Torque is for wheelin!... :)

The stroker makes some great torque gains especially in the low end.

Your asking to more than double the real stock HP. That is a lot to ask. To do that you might as well drop in a V8. But what do you need the HP for? A stroker kit won't get you 100hp I don't believe, someone correct me if I am wrong here but... The stroker is the way to go for off-roading... HP is for drag racing, Torque is for wheelin!... :)

The stroker makes some great torque gains especially in the low end.


I know the real purpose for jeeps. Its off-roading, but i have never seen a Jeep comanche designed for the street. This is my goal, to have my comanche perform on the street, not only because i have never seen one, but because the I6 is a wicked motor and the thing only weighs 2800 lbs.

Stroke the 4.0 by using a 258 crank.

http://www.jeep4.0performance.4mg.com

and Yahoo Group Strokers Good info.


This will turn the 4.0 into a 4.2. What kind of power gains are we talking about, because the 4.2 does not have a whole lot more power than the 4.0? Or does it?

I know the real purpose for jeeps. Its off-roading, but i have never seen a Jeep comanche designed for the street. This is my goal, to have my comanche perform on the street, not only because i have never seen one, but because the I6 is a wicked motor and the thing only weighs 2800 lbs.

That sounds cool. I have never seen one either... Ken Bell supercharger... Add an intercooler and then some N.O.S!

Tub the rear and add some slicks... !

This will turn the 4.0 into a 4.2. What kind of power gains are we talking about, because the 4.2 does not have a whole lot more power than the 4.0? Or does it?
No, the stroker 258 crank/4.0L block combo is 4.5L if you keep the bore close to the original 4.0L bore. If you bore it out 0.060" and use custom pistons with 4.0L rods, you get 4.7L. The specs on a well built 4.7L stroker are approximately 260 hp and 290 ft-lb. If you want to smoke the tires off that Comanche, you want torque, not just hp. Torque is what makes a vehicle fast in real world driving situations. Unless you plan on drag racing where the engine lives at or near max rpm most of the time, you will go faster if you have more torque than if you build for max hp. However, I would be surprised if you can get a stroker done well for less than at least $2500. A supercharger is insane money if you ask me - I would rather buy a spare stroker engine and throw a bottle on it for the cost of a blower. They run upwards of $4500.

No, the stroker 258 crank/4.0L block combo is 4.5L if you keep the bore close to the original 4.0L bore. If you bore it out 0.060" and use custom pistons with 4.0L rods, you get 4.7L. The specs on a well built 4.7L stroker are approximately 260 hp and 290 ft-lb. If you want to smoke the tires off that Comanche, you want torque, not just hp. Torque is what makes a vehicle fast in real world driving situations. Unless you plan on drag racing where the engine lives at or near max rpm most of the time, you will go faster if you have more torque than if you build for max hp. However, I would be surprised if you can get a stroker done well for less than at least $2500. A supercharger is insane money if you ask me - I would rather buy a spare stroker engine and throw a bottle on it for the cost of a blower. They run upwards of $4500.

What kind of hp and tq gains would there be if i stroked it, cammed it up, port and polished the head, swapped out the crappy manifold for a header, and gave it the full intake-exhaust treatment?

you could do a custom turbo setup on it. just fab up a header then get a turbo off of an mk3 toyota supra. add an intercooler off an EVO then just upgrade the fuel system. run about 7-8 psi and you should make around 250hp easy. which should translate to 14 second 1/4 miles. or you could do a system like STS does, but finding an oil pump thingy might be hard. as far as the stroker goes......look for maybe 20-30 hp but around 70-80 ft/lbs. it all depends on what your setup is.

i was thinkin of turbo in my car just to be unique, http://www.cartech.net/jeepturbo.htm Its bassicaly the same engine, but yours i belive is still has the carb, go with a new engine and get rid of the Tcase. Your rig will be much faster. I have seen those engine in the 2wd Cherokee, speddy little devils

If you want to go fast screw the I6. Drop in a V8 and be done.

If you want to go fast screw the I6. Drop in a V8 and be done.
or that

the reason i say turbo is because you can keep your i6 gas mileage, you'll be unique since you wont have a cookie cutter v8, plus a turbo will allow you to beat up on imports n such. atleast until aerodynamics come into play. also one of my friends here is inheriting a jeep commanche and i think i'm going to try to convince his dad to let us experiment a little. if he goes for it then say hello to a 13 second jeep.......lol.

that would defanatly be awsome, now i want a turbo!!!

the reason i say turbo is because you can keep your i6 gas mileage, ....

I6 gas milage???? who wants that crap! Full size chevy trucks with small blocks are getting better gas milage out of a heavier vehicle than the jeeps. If you wanna go fast, lose the 6. :no:

If you wanna go fast, lose the 6. :no:

:eek:

I've seen some I6's go pretty fast . . . :D

I've been in one too.

What kind of hp and tq gains would there be if i stroked it, cammed it up, port and polished the head, swapped out the crappy manifold for a header, and gave it the full intake-exhaust treatment?

As I said, with a 4.7L stroker (this is a 4.2L crank bored 0.060" over), you can expect 260 hp, around 300 ft-lb torque. All the polishing and loving in the world is not going to change the head design. If you are really going for broke, then bore it to 5.0L (need to UT the cylinder walls to ensure sufficient thickness - potential to scrap a block or two in the process), buy yourself one of these fancy aluminum heads (http://cliffordperformance.net/Merchant2/merchant.mvc?Screen=PROD&Store_Code=CP&Product_Code=4A2CH&Category_Code=J) , and then dig really deep for injectors, fuel system, and standalone engine management system to feed and control the beast. I believe this engine would be faster in real world street driving than a turbo'd 4.0L since you introduce zero turbo lag and you will have 320+ hp and upwards of 350 ft-lb of torque. Although in the 1/4 mi a properly designed turbo system might wamp the NA version. You need to carefully consider compression ratio and quench when going to turbo. It's certainly not as simple as slapping a turbo on a stock I6 unless you don't plan on making many dyno pulls as you set out on the many days of tuning it will take to properly set the fuel map with a turbo... This also costs $$$... Don't even think about turbo on a 258 - the head design is a power killer. I would be surprised if you could make more than 250 hp on this head with 10 psi of boost, let alone the modest 5-6 psi you will need to run to make one of these engines last. I am very skeptical that any of the "bolt-on" turbo kits will lead to engines that actually last more than a year or two, especially if you plan on using the turbo because of the above mentioned CR and quench factors on the stock engine...

I think you can build the 5.0L version for about $7-8k...

This Dino guy has a cool site with lots of stoker info and some specs on various forced induction (turbo and supercharger) kits: Dino's 4.0L performance site (http://www.jeep4.0performance.4mg.com/stroker.html)

:eek:

I've seen some I6's go pretty fast . . . :D

I've been in one too.



yea....dont supras have I6s...?

yes but those are turbo engines, my friends dads supra runs 645bhp!! thats at the tires LoL so much power