YJ 4.0 engine work

[vwtipeii]

Hi guys,

I am pretty sure I have settled on what I want to do with my egine in my YJ. I just don't have the skillz or knowledge on how to do it. I want to get about 40-50 hp and flbs of additional torque out of my 94 4.0L with 110,000 miles. I don't want to spend 7-9g's on a v8 swap. I hear the 4.6L strokers run hot...So here is what I am considering:

rebuild the bottom end to stock specks.
add a mild cam.
port and polish the head
add a 99+ intake manifold and jeeperz creepers 62mm throttle body.
i have a turbo city air intake with k&n filter and Borla header with high flow cat already.
(i know these aren't supposed to do much) Jet stage 1 chip.
I have the Performance Distibuters ignition system.
I also have a new 2 row alumimim radiator.

I am running 37 GY MTR's w Kevlar now on 17 Dick Cepeck II's black. I have 4.88 gears. All I want to do is be able to drive from the beach to the high desert and keep up with traffic on the inclines and remain in 5th gear (AX15 manual).

Any recommendations on who can help (I expect to pay for labor and parts) with pricing and gathering the required parts for the bottom end as well as help with the rebuild itself is greatly apprecaited.

Ideally I want to keep the cost of the project between 1500-3000. Any more and I might as well just go with a 4.6L stroker from Golan for 3500.

Thanks,
Brett

[Jeeperator]

When you increase horse power by bigger cam, porting and increasing the size of the runner you actually lose bottom end torque. Usually regearing is necesary when horsepower is increased to take advantage of the raised rpm horspower and torque curve. A tight quench and increased in compression will help you get back the loss of bottom end torque but who knows how high you can go on a iron head engine without having detonation problems and having to run super unleaded gas all the time. I know 10 to 1 with a tight quench is about the most you can go on an iron headed smallblock chevy. Seen as high 11.5 to 1 on super unleaded on a very tight quench aluminum headed 600hp smallblock 400 though. What is your gear ratio now??

[vwtipeii]

Gear ratio is 4.88.

[Jeeperator]

I think you need to go lower gear ratio with a 37" tall tire unless you increase your torque with a V8 or a supercharger. I cant believe your running that big of a tire with a dana 30 and especially a dana 35. D30 might be ok if your easy on the trails but the d35 is just asking for trouble. As you might of figured out a jeep with 37" tall tire on the road is not an ideal comuter car. Crappy gas milege, not to mention the wheel base too short to safely exceed the posted speed limit imho. I would take the $3000 and buy a car that gets good fuel milege and can keep up with traffic. I personally have a $1500 honda civic gets 30+ mpg and has more than payed for itself in gas compared to driving the jeep as a commuter in one year. Consider money savings a bank account for better jeep parts lol.

[6spdYJ]

Check with brokenujoint, he had a stroker for a good deal.

[vwtipeii]

sorry for not clarifying..... I have a Ford 8.8 in the rear now, and the Dana 30 has been upgraded with Chromoly Axles, and the 3 piece axle has been iliminated. Also, this is not my commuter car by any means. I don't have a trailer I just have to drive my Jeep to the trails for when I want to use it on the weekends.

[Jeeperator]

I guess it will work as long as your easy on the skinny pedal. If you are going to increase the hp with a bigger cam and head work its not a bad idea to go the stroker route but I seriously doubt its going to only cost you $3500 when its all said and done.

[aw12345]

Go stronger axles and 5.38 gears that works pretty well with 37" tires.
Souping up the engine than running at a low rpm because of the large tires and low gear ratio isn't really going to do what you want

[alittleoff]

You know, I can see the appeal of horsepower in a sand Jeep or a street Jeep that pulls Cajon Pass daily, but in a dirt/rock Jeep it's more about gearing and suspension travel. And I'll still get to the same place, only 5 minutes later.

Steve

[vwtipeii]

I hear ya. I have completed a coil conversion (Rock Krawler) so i now have a 4 link in the rear and 3 link in the front. I have plenty of clearance now in the front and just finished some mild fender trimming in the rear and the 37"s fit fine. I have a quote from Hesco for parts to rebuild the bottom end close to stock with just a mild cam..and their fancy smanchy aluminum head. I am not looking for crazy horsepower..just wanted to make sure my jeep is reliable and able to handle driving on the highway a bit better than now. I am not wanting to go with a stroker. The combo of head and cam along with rebuilding the bottom end to stock specs should give me about 240 hp and 260 torque according to Hesco. If i buy all the stuff from them I am just looking for a reputable shop to do the work or someone who is patient and bored and wants to help show me how to rebuild the engine and has room to help with the job.

The next thing to tackle will be rebuilding the NP 231 to have a 4to1 low range or just throw an atlas in it. Even with the 4.88 gears and my manual AX15 in first gear with the 37" tires my crawl ratio is pretty speedy I have seen a conversion kit by Tera for about 1500, or just replace the whole thing with an Atlas for about 2250. I will start to play with this project once I have the engine sorted out.

Thanks,
Brett

[vwtipeii]

link on the Tera 4-1 conversion for the 231...

http://www.4x4wire.com/jeep/tech/xfer/tera4_1/

[aw12345]

If you want horsepower and reliable, I would definitely skip the tera low, find a 241 out of a Rubicon or get a Atlas.
Aftermarket racing parts and reliability, for the most part don't go well in the same sentence.
My money would go towards axles that are strong enough to run 37: tires and could handle 5.38 gears, would be money better spend than trying to soup up the engine, Raise horsepower, the powerband becomes narrower and moves to a higher rpm range. Neither of which is desirable for rock crawling. To sum it up in short a Jeep with a stock engine, with a 4 or 5:1 transfercase, 37" tires and 5.38 gears works well on the street and in the rocks