Topic: 2.5L Rebuild using a commercial 3.0L stroker?

[RNandKT]

Has anyone tried using a 3.0L comercial GM motor to rebuild in place of the stock 2.5L. I understand the block and piston size for the 3.0 is nearly the same as the 2.5L. So would it be possible to get a 3.0L from a boat or commercial vehical rebuild it using the it's stock longer crank shaft, bore it to .020/.030/??? put in a nice cam etc etc then bolt on all the stock externals of the 2.5L (i.e. head fuel injection pulleys power steering etc etc) and come out with a 3.1/3.2/??? stroker 4 cyl for my YJ?

I understand that just using the crank and con rods into the 2.5 block would not work because it would have clearence issues with the distributer??? So the 3.0 block would have to be retained???

I think if this was all done "stroking it", nice cam, bored out, maybe some rocker rollers for the head, (along with some of the other external upgrades, like a throttle body from a 4.0, bigger injectors, and a nice header) perhaps the little stroker motor could be pushed into the 200 hp range? That would save all the headache of rewiring in a motor swap, and put it into hp range of the stock 4.0.

Any info or thoughts on this would be welcome.

[jwrape]

Welcome,
I see you made it over.

Sorry I got a little to excited and posted up
here http://www.4bangerjp.com/forums/viewtopic.php?t=720&highlight=

Hopefully, someone will answer one of us.

But I found some good info just by googling.
Turns out that the motor are pretty much the exact same motor.
From what I read the 3.0L block can be a direct bolt up for the 2.5L with the exception of the distributor and the flywheel. You would just re-use yours from the 2.5L.....
Go over to the other thread and check out what I found on Google.

Good info.

[jwrape]

Oh, also, the cams that come in the 3.0L is supposed to be the most radical you can get but I haven't verified the lift yet so right now that is just hearsay.

[RNandKT]

Yeah this forum is awsome already been reading a ton of stuff on here. It's nice to get away from all the people on other sites who just dawg everyone who doesn't think you have to spend lots of money buy huge axles and massive hp v8's. It's cool to find other people who like to take what jeep put in and just tweak it a bit.

[jwrape]

Yeah this forum is awsome already been reading a ton of stuff on here. It's nice to get away from all the people on other sites who just dawg everyone who doesn't think you have to spend lots of money buy huge axles and massive hp v8's. It's cool to find other people who like to take what jeep put in and just tweak it a bit.

Exactly! That's why Jeffy created this site. You get slammed hard on other threads for just asking questions when that is what we are all there for.

This site is very friendly and has a good bit of knowledge about Jeeps and the little 2.5L...

Glad to have a new recruit.

[jwrape]

I see you have the AX15 behind your 2.5L. Did you get the idea from YJ4rox?

[RNandKT]

Yeah I read that thread, i actually started mine the same time he did. So most of the problems he ran into with the pilot bushing and the clutch slave cylinder i learned the hard way as well. But I stayed with the stock slave cyl in the end, I just made my own custom spacer using tom exhaust pipe. But it was nice because I didn't have to find what belhousing I needed and what clutch disc.

I also got my ax-15 out of the only year they put it in a grand cherokee, (rebuilt out of a 93) supposedly the internals are beefed up a bit.

[jwrape]

Cool, YJ4rox is parting out his YJ and I bought his full kit from him for my Dad's Jeep conversion. He just opened the boxes tonoght and YJ4rox packed everything nice and clean and included EVERYTHING for the complete conversion.

Got the tranny and all the parts for $660 shipped. Just had to buy the Master cyl. Line kit and shorten the DS.
Gonna be easy to throw this one in....


It's a good thing you already did that conversion especially if you are adding a built 4 banger. That tranny should hold up a lot better.

[RNandKT]

Yeah I am trying to get my drivetrain preped BEFORE I throw hp at it so I don't end up stranded on the trail too much.

[Jeffy]

Well, I mentioned in the other thread that it can be done and has.  But Emission wise, it's not legal.

[RNandKT]

Well I would like to know the specifics of it. Which block did you use the 2.5 or the 3.0? What years are compatable? What flywheel? What cam to use and where to get it? etc etc etc.

Also how were the results? I think if you did this stroker with some of the other things as mention in the other 2.5 rebuilding threads, you could really make a nice motor.

And out of curiosity why would it be illigal people make stroker motors all the time? Is that a california thing because I live in OR currently and will be in UT permantly in the future. And as far as I know in both places as long as you stick to stock engines you can do pretty much anything to them (short of NOS) as long as it passes the emissions test.

[Jeffy]

I haven't done the swap but I've seen it done before.

It's illegal because the engine was never used in a street going vehicle.  So there are no emissions on the engine.  Basically if it hasn't got the DOT's seal of approval, it ain't Kosher.

Not to mention installing a carburated engine into a EFI vehicle is seen as going backwards emisison wise to the DOT.

But then, not every state enforces emissions.

[RNandKT]

Well I had actually had in mind of using the 3.0 block and then using my head fuel injection etc from my stock engine. Or if it would work just to use the crank and con rods and put them in my block. I only want to extend the stroke of my engine increase the displacement.  

Do you think that would work? I would still keep all proper emissions equipment on my vehical.

I would think if I had my head rebuilt right and if I put a different cam in the 3.0 where the carburated 3.0 is rated at 140hp with those changes and MPI injection maybe it would be closer to 190-200. Plus because it was a longer stroke it would be considerable more torque since the 3.0 carburated is 171 it should be closer to 210.

[Jeffy]

The biggest problem is that the engine is a GM and the Jeeps is an AMC.  They aren't even remotely in the same family.  This means that the dimensions of the block would have to be almost identical.  Spacing between the cylinders need to be the same also.  Then you have to match up the jackets in the block and all the push rods will have to align.  I think it would be a miracle if it all happened to work.

You'd be better off getting a TBI and a stand alone computer like a Mega Squirt to run the EFI, I think.  At least matching a TB onto the intake would be easier.

[RNandKT]

Hmm ok well good to know won't work. Do you know anywhere you can get a crank shaft that will stroke the 2.5?
Thanks
Ryan