Jeepjunky

so just yesterday, i was bored and thought about making a 5.0L stoker out of an existing 4.0 block. after a little research i found that 505 performance sold a kit that would get u a new crank, cam, roller lifters and rockers, connecting rods, and pistons and rings. after i put the numbers into jeepstrokers.coms calculator, it only was really a 4.85L at 296CI.

my question is does any one think that the 4.0 block can handle an 0.080 inch overbore to make it 3.955 (stock is 3.875), use a 4.2L crank that would be welded and offset ground to have a total a stroke of 4.060" (stock 4.0L-3.44" stroke, 4.2L- 3.9" stroke). use aftermarket stock replacement connecting rods for a 4.2 and then upgrade everything else. also, would it last for a extended period of time like 75,000-150,000 miles.

thanks



srry just realized it should b in chat

00jeepXJ

The rule of thumb that i was taught ( sbc and BBC) was that nothing over .065" Unless you wanted to see shrapnel. Now I don't know what you would need to bore your block to so that you get the 4.7L stroker kit. I think that if they are boring it out to something close then you might be able to do it.

Jeepjunky

^^ usually to get to a 4.7 u bore it out 0.060" (3.935" final bore), use a 4.2L crank, and 4.0 connecting rods. im just wondering if the block would be strong enough to handle a 0.080 over bore

99xj2.5

I looked into building a block to swap in to my 4cy.....but I don't think I ever came across anyone boring .080 over. Sounds like a lot to me

ct67_72

why? thats a lot of bore, you have to start thinking about quench area in the head and overlap around the piston in the combustion chamber. I would think that it would be very inneficient.
I diddnt do any numbers but what would the rod ratio look like? I bet a stock rod would not be near optimal for that kind of stroke either, and i would imagine you would have to have a piston made with a lower pin height, or super low compression height to get your top dead numbers correct. which if the piston ends up out of the hole you have that whole combustion chamber overlap thing again.
This is to not even mention structural integrity of the block with such a big bore. it may be fine, I dont know, but it seems very excessive and I dont think it would be worth the trouble unless your qoing to be trying to get every last HP out of it and having a custm cam ground etc. etc.
my $.02

Gee oh Dee

Forced induction would be cheaper and more reliable. Make more power, too.

ct67_72

I was thinking this exactly too

MallCrawlXJ

everyone that i know that has built a 4.7 has blown it up at right around 25-30k. if you could keep your foot off the skinny, you could prob make it last a little longer. but what fun is that?

i would say boring it .80 over is a bad idea....unless you are made of money! i dont think the cyl. walls are thick enough to handle it.

i agree forced induction would be way cheaper and way more reliable. plus prob better mpg's. or just swap in a real 5.0L.

Metmknice

A GM LSx ( or other V8 of your choice), is your best bet cost vs performance.
That's my plan eventually, either in a XJ, MJ or both.

HCCAFan

Not with the way our cooling systems work.

huntingman2706217

There's enough problems with the strokers as it is... why make it even worse... lol

Gee oh Dee

Upgrade it.

If your considering a stroker, larger motor swap, or forced induction it should already be on your list anyway.

HCCAFan

Turn it sideways and install some kind of trans axle? Inline, long motors always have a harder time staying cool.

Gee oh Dee

What?