High Performance Engine Modifications

[bluebelle]

1060608

i'm interested in muscling-up my tiny 4.0 and would like to tap your collective brains and experience. who's done what with what results?

already have new turbo cat/muffler exhaust sys; throttle spacer; alt, fuel, oil & h20 pumps engine has 100k (who really knows. . . ?) no smoke, no leaks.

interested in pistons, head, cam, intake & headers, will balance and blueprint engine.

or, has anyone dropped a 350 in a yj? now you're talking. . . :-O

michael
[addsig]

 

[Bounty__Hunter]

1060635

I've swapped a 350 into a YJ, and it's a lot of trouble and $$, avoid it if you can. A good mod to the 4.0L is to install a stroker kit and bumping displacement up to 4.7L, this along with a few other simple engine-building mods will easily get your power into V8 range. Moper Perfromance cam, port and polish the head, deck the block to up compression, all the usual engine building tricks. Don't forget a bored throttle body to help get more air into that beast.

For all you 2.5L owners, there are Mopar Performance cams for sale on Ebay, brand new from Koller Dodge of Naperville, IL. They are clearing out their stock. Search ebay for jeep camshaft and you'll find it, got mine for $39. It's the 256dur/.450"lift performance cam.[addsig]

 

[jps4jeep]

1060647

A 350 in a jeep is costly, A friend is in the process of doing this, and has been for about two years. A lt of times you need to replace the transmission as well. He put in a tremec T5 transmission I believe, so whe was able to maintain a 5 speed. I remember reading a while ago in JP that a Grand cherokee 318 will bolt up two a factory wrangler bell housing and that the computers are very similar.
If a motor swap is not your cup of soup, Performance companies such as Hesco and clifford specialize in jeep performance.
I have seen turbo chargers, super chargers (would not recomend for high mile motors)[addsig]

 

[Snitty]

1060648

like bounty hunter said... i'm all about stroking the 4.0... if you get a 4.2 crank and connecting rods.... and put them in place of the stock ones... you already have a 4.5L... you can also bore the cylinders to get anywhere from 4.6 - 4.9... i would suggest not going any higher than 4.7L. you can also get better injectors, cam, and do some head work. if you replace your fan with an electric fan... it has been claimed to gain up to 20 hp. i would totally go with the stroker if i had the money[addsig]

 

[Onager]

1060649

An RV-cam and heavier flywheel will give you more low-end grunt.

Better breathing (intake and headers) is good for more high-end hp.

Cheers,
Onager[addsig]

 

[jeepmaster]

1060650

is a throttle body spacer and a bored throttle body essentially the same thing?[addsig]

 

[Bounty__Hunter]

1060672

is a throttle body spacer and a bored throttle body essentially the same thing?

No. The TBS is a 1" spacer that mounts between the TB and the intake manifold. The bored TB is a Tb with a larger inside diameter that flows more air.[addsig]

 

[jeepmaster]

1060790

where could i get a bored throttle body? and is it possible to have TBS and the bored TB at the same time? would that even help at all?[addsig]

 

[Snitty]

1060818

the bored throttle body will help... some say they don't notice anything from the spacer... but it HAS been proven to work, but only at a small rpm band. though... both will help gas mileage well[addsig]

 

[MudDawg]

1060851

Well... nuthin beats cubic inches....big motors make more torque than little motors...but if you can get more fuel-air mixture into the cylinders...you get more torque...a few tips.. (assuming you are looking for low rpm power in the idle speed to 3 or 4 thousand rpm range) the cam needs to be short duration but high lift.. this will greatly increase the fill of the cylinders but with short duration, the power will stay down low in rpm...when decking the block keep the deck height as tight as possible without the pistons getting familiar with the head...if you are going to work the head..get stainless valves and have a good 3 angle valve job...this will really help with cylinder fill at low speeds..."port" the head if its in the budget..but if you do...have it done by a professional with a good reputation...you can easily make a head worse if done wrong. And the stroker motors..Wooo Hoooo...I LIKE that idea...and the supercharger idea is killer too...talk about GRUNT!!! Then there's Nitrous..but thats another story...... :evil:

Dawg[addsig]

 

[Quinners]

1060854

where could i get a bored throttle body?

I have had great luck with the following company called Jeepers and Creepers. They are located in San Fran....great people to do business with.

I also have a throttle body spacer which they also bored out to the same specs as my throttle body. I have noticed hp increases along with increased torque. Money well spent in my opinion.

Have fun, Patti ;-) [addsig]

 

[jeepmaster]

1060894

gracias[addsig]