Topic: Pistons

[Schmitty]

ok, so i wanna bore out a 2.5 for my jeep. but where can i find bigger bore pistons? or which are compatable? i also am not sure on what size bore i wanna do. i hear .30 is a common bore, but there is .60. which is more worth it? and which pistons would be compatable with each bore size?

[Mr_Random]

Simply find an online retailer for 4.0 performance parts and order pistons individually... Some places also stock sets for the 2.5, just search the internet... they're more plentiful than you would think... .030 and .040 are safe, but .060 is known to work... just make sure to have the cylinder walls checked by a machine shop to see if they'll be safe!

[Schmitty]

im gonna have the head put together by a machine shop. but .60 will work for sure? i just want the 2.5 to have decent highway power over stock. after the motor is done im gonna get the jeep regeared. but i found a kit online that has a whole rebuild kit and you could select the bore size of the cylinders. but the kit doent come with new valve springs, lifters, rockers, and a camshaft. so do you guys have any recomendations on good cams, rockers, lifters, and valve springs? . another question now is, do i have to make any modifications to the crank?

This is the kit: http://www.enginepartsstore.com/servlet/Detail?no=323

[Oilsmoke]

From my past experinace in rebiulding Banshee engine there is not much gain in HP from the little gain in boreing .030 to .060.  Go as small as needed to have room for the next Bore. Words of wisdom.
Now I am not saying the a rebiuld would add power to a tried engine.
If added HP is your Goal than other means with gian you alot more.
Headers with Better flowing Intake trac. Camshaft with a polish exhaust port done correctly.
Stoker crankshaft also.Remember HP cost Money.

[Schmitty]

well im not look for tons of horsepower, i just want that little extra power for keeping my speed on the highway. around town with 33s and stock gears, my jeep has plenty of power. but my only downside is i live in NJ and every road is just about a highway. but i dont wanna do a drastic change like a 4.0 or 350. i wanna keep it simple. so i just can get back on the trails. 

what is a good cam to use in the 2.5 anyways? and what size?

[countryboy514]

according to factory service manual, stock cam lift in a 97 2.5L is Int. 0.407in and Exh 0.414in. duration is 259 degrees, but note thats actual duration not "advertised". advertised duration is duration of the cam lobe after 0.050in of lift. its a more accurate way of measuring cam profile.

[Oilsmoke]

After beening around here for 4 + years.

33's & stock gearing of a 2.5L Manny trans Is not low enough.  I run alot of mods to my engine and it runs so much better than before I bought it. It had 30's on it & than I put on 31's and in rough stuff 4wheel Low is to fast. On the road I can only use 5th on a nice flat rooad with NO grade at all.

If your engine running OK I would Regear First.

[Schmitty]

well, regearing was going to be second after the new engine goes in. im gonna be doing 4.88s and a ford 8.8 rear

[Oilsmoke]

I really my 8.8 ford rear. I need 4.88 they are on the list for this spring. :)