Power on the 2.5?

MuddinYJ88 · #1 (**permalink**) 09-23-2005, 11:38 AM

I have an 88 2.5L 5speed YJ and im wondering if theres a way other thn a motor swap to get some more power on these? havent seen any air intake kits out? and not much else? Im going to run 35's, 6" of lift and 4.88's soon so i would like to figure out something if possible. But it is only a small distance commuter and a trail beast foir me. So anythig would be great thank you.

Bounty__Hunter · #2 (**permalink**) 09-23-2005, 04:54 PM

I haven't seen any performance parts for the 2.5L TBI other than internals like a performance cam.

4.88 isn't really low enough for a 4banger on 35"s, I'd consider an axle swap to at least D44's so you can run at least 5.38 to keep what little performance you have.

Also check out www.4bangerjp.com where a lot of us 4Banger owners hang out. We gotta stick together, brother

Junkpile · #3 (**permalink**) 09-24-2005, 09:03 AM

The two best suggestions I can give to the 2.5L owner is: 1.Don't be afraid to run it in the rpm range that it prefers. It likes to spin....and 2.Removing weight is like adding power. Strip it down to the bare essentials.

TwistedCopper · #4 (**permalink**) 09-24-2005, 08:59 PM

Quote:

Originally Posted by Bounty__Hunter

I haven't seen any performance parts for the 2.5L TBI other than internals like a performance cam.

You can get roller rockers for it from Quadratec:

http://www.quadratec.com/cgi-bin/sgi...05092421595353

TwistedCopper · #5 (**permalink**) 09-24-2005, 09:02 PM

You can open up the intake one of two ways, either removing the stock airflow restrictor in the stock intake tube and replacing the filter with a "drop-in"K&N, or just replace the whole works with a K&N (or other brand) cone intake. Another mod would be a cat-back exhaust like Gibson , Borla, or another brand.

Getting rid of the stock mechanical fan and replacing it with an electric fan can give 5-10 HP. YOu can use either a junkyard fan from a Taurus or a Flex-a-lite Model #475.

I don't know if using a 4.0L's throttle body would work on your '88, as yours is throttle-body injection as opposed to MPFI. Maybe someone else can answer that...

_(OIIIIO)_Jeeper · #6 (**permalink**) 01-01-2006, 08:02 PM

I have been running 36's with 4.88 for the last year have not had any prob. 4L has PLENTY of torque. JMHO

jakbob · #7 (**permalink**) 01-01-2006, 08:20 PM

Quote:

Originally Posted by Junkpile

The two best suggestions I can give to the 2.5L owner is: 1.Don't be afraid to run it in the rpm range that it prefers. It likes to spin....and 2.Removing weight is like adding power. Strip it down to the bare essentials.

what rpm range would that be?

Bounty__Hunter · #8 (**permalink**) 01-01-2006, 08:26 PM

Quote:

Originally Posted by jakbob

what rpm range would that be?

Above 3K

Junkpile · #9 (**permalink**) 01-03-2006, 11:57 PM

Quote:

Originally Posted by jakbob

what rpm range would that be?

Upper. It's just like any small engine, no torque down low. It won't even get out of it's own way until it hits 3500rpm. I used to launch mine at around 4000rpm when I was racing it.

THE most important factor is weight. Strip it down. That's a big compromise for some to make, but that's where the biggest payoff is considering the lack of "real" off-the-shelf performance parts available for that engine. I get it and my Ranger pre-runner confused because I owned them at the same time, but mine was either 2980# or 3020#, and that was set up on 36" Swampers. I could have probably shaved a couple of hundred more pounds if I really wanted to go crazy.

jakbob · #10 (**permalink**) 01-04-2006, 05:46 AM

thats actually what im trying to do to my jeep...strip every thing down and what not...o btw, the stock air restrictor, would that be on the mpfi engines?

currupt4130 · #11 (**permalink**) 01-18-2006, 01:10 PM

there actually is a cam for it, its just not made anymore. a buddy of mine has one in his kitchen. its a mopar purple part, i think... but headers get some pep out of it and ive heard that a good exhaust size is 2.25, it will keep a good amount of back pressure and open it up a little more. mine just has cold air, headers, muffler, and it turns 38's with 5.13s in 4th gear at 45 right at 2 grand, its still got tons of power in second and third gear. i havent put it in 4 lo yet but when i do i imagine ill have plenty of power, hell ive got a crawl ratio of 95:1

Sparky-Watts · #12 (**permalink**) 01-18-2006, 07:54 PM

Quote:

Originally Posted by currupt4130

there actually is a cam for it, its just not made anymore. a buddy of mine has one in his kitchen.

Couldn't find his rolling pin?

currupt4130 · #13 (**permalink**) 01-18-2006, 08:03 PM

something like that, he actually ubplugs his stove to run his welder on his back porch, has a press in his kitchen, and his air compressor in the closet next to his washer and dryer

Sparky-Watts · #14 (**permalink**) 01-19-2006, 04:19 AM

Does he have a sister that's single?

judge09 · #15 (**permalink**) 01-19-2006, 06:55 AM

Why not sell the 4cyl YJ and get a 6 cyl? We are not talking about alot of money when discussing an 88 YJ. I would look into that before dumping $1000s into upgrading an underpowered jeep.

currupt4130 · #16 (**permalink**) 01-19-2006, 10:45 AM

nope, sorry sparky. he does have a 5 year old daughter that is learning to weld though

Sparky-Watts · #17 (**permalink**) 01-19-2006, 08:32 PM

Quote:

Originally Posted by currupt4130

nope, sorry sparky. he does have a 5 year old daughter that is learning to weld though

Hmmm, 41-5=36
36+13=59

Ok...tell'em I'll call him in aobut 13 years when she's of age. My social security should be enough for the two of us to live on, combined with the money she makes welding, right?

TwistedCopper · #18 (**permalink**) 01-19-2006, 08:47 PM

Quote:

Originally Posted by jakbob

thats actually what im trying to do to my jeep...strip every thing down and what not...o btw, the stock air restrictor, would that be on the mpfi engines?

yes

ron521 · #19 (**permalink**) 01-04-2008, 03:31 AM

Here is a link to a page which gives some numbers for the 2.5 throttle body swap:

4.0L throttle body swap

If these figures are accurate, is seems that swapping out the throttle body is easily the biggest single improvement for the money, as bored out bodies are available on eBay right now for $90 plus a core charge. Other things, such as the electric fan conversion, air intake and exhaust modifications help too, but all cost much more, and their gains are smaller.

So, while a 4.0 still makes more total horsepower, given that the 2.5 engine weighs hundreds of pounds less than the 4.0, the difference in power to weight ratio looks to have just become quite a bit less.

jfrabat · #20 (**permalink**) 01-05-2008, 08:31 PM

Quote:

Originally Posted by ron521

Here is a link to a page which gives some numbers for the 2.5 throttle body swap:

4.0L throttle body swap

If these figures are accurate, is seems that swapping out the throttle body is easily the biggest single improvement for the money, as bored out bodies are available on eBay right now for $90 plus a core charge. Other things, such as the electric fan conversion, air intake and exhaust modifications help too, but all cost much more, and their gains are smaller.

So, while a 4.0 still makes more total horsepower, given that the 2.5 engine weighs hundreds of pounds less than the 4.0, the difference in power to weight ratio looks to have just become quite a bit less.

Great link! And I do believe that the 4.0L TB is a great investment. But so is the e-fan, which you can get at a junkyard for about $30 (with the Ford shroud, which fits my radiator). You can set up a simple system with relays to control it, and it should not go for more than about $60...