2.5 4-cylinder upgrades

Jordan K.

Jordan K.

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Joined
Mar 27, 2017
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Location
Saint Augustine, FL, United States
I know that the best upgrade for any 2.5 4 cyl is to replace it with a 4.0. That's not really in the budget for me right now and I'm sure there are people wheeling 2.5s. Short of the 4.0 swap, are there any modifications that you have made to your 2.5 motors to give them a little more pep and make them more street friendly?

Specs:
1997 Wrangler 2.5 4 cyl 5 speed
Stock ride height and stock wheels and tire size (for now)
 
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@StG58 has a thread on the power upgrades for the 2.5. They amount to zero, none, nada. Honestly, the only thing you can do is have it running in 100% condition, ie, new plugs & wires, air filter, cleaned throttle body, etc. Other than that, re-gearing is the only way to keep the rpm's in the power band and moving forward.
 
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Welcome aboard, and welcome to the four angry squirrel band in the TJ tribe!

Tire size choices for the SE are pretty straight forward. 31x10.50 or 32x11.50. I know, I know, there lots of folks running 33's and up. Wouldn't recommend that though.

Your gear choices are 4.88 or 5.13. The choice between the two is mostly preference, but 4.88 works well on the highway and the 5.13 works well off road. Don't fear the gear with the 2.5.

I would recommend that gears are one of the first things you do.
 
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I know that @PhantomX has put a supercharger on his 2.5.

IMHO, that's the best mod you can do to the 4 cylinder, adding forced induction.

Of course you'll have to have $2500+ for that.

But short of forced induction, your best bet is gearing. Other than that, you really aren't going to get much power out of it without dropping tons of money.
 
Jordan K. said:
I'm not going to consider re-gearing until I figure out what my tire size will ultimately be. Right now I'm considering adapters and stock JK wheels/tires.

Sweet! I didn't see these at all when I was looking!
https://wranglertjforum.com/threads/how-can-i-get-more-performance-out-of-my-2-5.4062/
https://wranglertjforum.com/threads/505-performance-for-the-2-5.4028/
Click to expand...
JK tires are probably in the 30-31 range with Rubi tires being 32ish. Either way, start thinking 4.88's and if 33's are in the future, 5.13. It may sound like a lot of gear but it really isn't with the 4 cyls. I run 4.88/31/6 spd in mine and it works great. Enough juice to pull hills when loaded down with the fam and can cruise at 65-70 all day at 3000 rpm.

You can run a supercharger but you would still need a re-gear. A sc does not make up for the fact that the engine still has to be in the correct rpm range to build power and that means proper gearing. Plus adding a sc takes away from the simplicity and reliability of the 2.5. I am sure everyone that has one will talk about how reliable it is. Let me know in 250,000 miles, what the 2.5 is easily capable of, how reliable it's been.
 
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Yes, 35 in rear, 30 in front. Being 4.10 like @StG58 stated, both carriers will work with any lower gear ratio you want. Of course it would be a good time to upgrade to some traction devices while the gear swap is performed. Which one's would depend on your particular usage.

Being a new Jeeper, you can begin to see that upgrading one thing usually leads to another. And another. That is why it is a great idea to decide on your intended use and see what, if any, modifications are needed to get you there. Some things can wait, others cannot. Example; install a lift and 33's, you will seriously need lower gears or you will have terrible performance and thus be disappointed. So take it slow, do it the right way, and all will be merry in TJ land :D
 
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I find running my 2.5 on premium gas makes a slight difference in power but ultimately there isn't much you can do to increase performance.


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My intended use of the Jeep is 90% as a beach Jeep. So for me, I guess that tire contact patch should be first. Then maybe a little more height to keep me from bottoming out in the ruts.

Any other Jeepers use their Jeeps in the sand a lot?
 
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Jordan K. said:
My intended use of the Jeep is 90% as a beach Jeep. So for me, I guess that tire contact patch should be first. Then maybe a little more height to keep me from bottoming out in the ruts.

Any other Jeepers use their Jeeps in the sand a lot?
Click to expand...
31 or 32" tires, an air pump to air back up and a good air guage. I run my 31x10.50's on 7" wide rims down to 8-10 psi and go pretty much anywhere in the sand. Hard or soft and fluffy. TJ's love sand.

Invest in a good cheap sprinkler to wash the sand and salt out from under the TJ after each beach trip, if it's a salt water beach. ($2 at a garage sale will save you hundreds in repair and maintenance )
 
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Jordan K. said:
My intended use of the Jeep is 90% as a beach Jeep. So for me, I guess that tire contact patch should be first. Then maybe a little more height to keep me from bottoming out in the ruts.

Any other Jeepers use their Jeeps in the sand a lot?
Click to expand...
For that, I would put some nice all terrains in 30x9.50 and rock on. No lift needed, no re-gear, will look nice, and handle the beach. As far as bottoming; are you contacting suspension/skid plates on the terrain or is the suspension worn and you are bottoming it? If the former, a small spacer lift could help; if the latter you are probably in need of some new springs and shocks.
 
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Jordan K. said:
I know that the best upgrade for any 2.5 4 cyl is to replace it with a 4.0. That's not really in the budget for me right now and I'm sure there are people wheeling 2.5s. Short of the 4.0 swap, are there any modifications that you have made to your 2.5 motors to give them a little more pep and make them more street friendly?

Specs:
1997 Wrangler 2.5 4 cyl 5 speed
Stock ride height and stock wheels and tire size (for now)
Click to expand...
Go turbo, I have one on my yj 2.5l and in get its, running 8# boost. I have about $800 into it. Been fun project.
 
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