Topic: new 2.5 how high of rpm can i run

[christopher]

just put a new 2.5 in my jeep and first time owning a 2.5 just wondering how far i can push it on a regular basis especially on the highway. :!:

[dunklervogel]

well the advice from the mechanic that installed my 2.5 was to take it easy on the engine till the 800-1000 mile oil change.  Soo I wouldn't be revving to hard early on.. I guess it is to just break the new block in a bit. buuut other than that... the 2.5 likes high revs so if you aren't getting higher than 3k rpm when you are accelerating you are missing out on a lot of power from the engine.

[christopher]

thanks for the info.  i only have 230 miles on it so far.  although there is a little burp in the exhaust when you hold it at a steady rpm.  can't figure it out.  put all new cap, rotor, plug wires etc.  seems like its missing but not that extreme.  only altercation i have done from the old motor to the new motor is put a tb spacer on it.

[dexetr30]

thanks for the info.  i only have 230 miles on it so far.  although there is a little burp in the exhaust when you hold it at a steady rpm.  can't figure it out.  put all new cap, rotor, plug wires etc.  seems like its missing but not that extreme.  only altercation i have done from the old motor to the new motor is put a tb spacer on it.

I suggest doing the 4.0l throttle body convrsion. It works wonders.

Here's the link if you haven't looked it over already.

http://www.4bangerjp.com/forums/viewtopic.php?t=8

Also, it's been my experience that the 2.5l loses a bit on the top end of the rev spectrum.

[dunklervogel]

What'd you have before the 2.5 if you don't mind me asking?

[jagular7]

Biggest thing to keep in mind with the 2.5l is the vast difference in rpm between torque and hp. Hp has a higher rpm point (lke in the high 4000) and the torque peaks at ~3200rpms. Break-in correctly is probably the best thing to do at this time. Once it starts to get some mileage under its belt, then drive like you stole it....LOL.

Nah, don't do that, then you'll be looking for another engine. Driving habits for a 4cyl Jeep is vastly different than a little coupe with a 4cyl.

[christopher]

to answer your question what size of motor i had before.  in this jeep was  also a 2.5. 351 modified in my 78 ford pick up now.iam pretty new learner with jeeps ive only owned this one for about 2 months before that the only jeep ive owned was shared with my brother about ten years ago and it was a cj7 with a 302 in it.

[keithert]

What did you guys pay for your new engine and install?

[christopher]

the motor itself was 1400 hundred me and a buddy installed it but i got another 800 hundred in water pump new radiator plugs wires oils etc.

[dunklervogel]

i think my total bill was 1500 that included engine with all the parts (not just the block) and a new clutch.

[YJmechanic]

you need break in period to set the rings.  that motor can handle a lot of rpm stock about 5500 easy and heavily modified, like mine, i run about 7500

[wrangler387]

babying a motor isn't the best way to set the rings. contrary to what many believe. Reving out 2nd gear and letting it decel in gear and reving out and coming back down a few times is what most people recommend on a new build. Its been used for a long time with racecars/motorcycles. Go look around the internet, numerous good sites showing comparisons between the methods of breaking in a motor. If you want to know where you should rev to, put it on a dyno and see where you should shift so that you always have the most power under the curve :D

[YJmechanic]

every body has a different break in for there engines.  i ran mine for 20 min at 1200rpms to set my cam them let it cool down and then drove 50 miles at reasonable throttle and then changed the filter and never looked back.  this is how i break in all my race motors and have never had a problem.  i just said about the rings because that is what most companies will recommend.  but everybody has different impressions but i will tell you with chromoly rings you have to push them a little or they will never seal right.

[supryj4]

yjmechanic how do you get 7500 out of your motor my computer shuts me down at about 5500?

[lanulos89]

i hav once redlined my motor  :oops:   not bragging tho,