Pistons

[Darkapollo]

Ok so Im taking the plunge and pulling the unfinished hybrid swap out and dropping in a low mile 2.4 that Ive had sitting around for about 4 years now.
I have read all of the debate about what internals to use but there are still questions that I have asked and have never had answered.

I know that I can run the SRT4 rod and piston for $200 but my local dealer is a PITA some times and I really dont have that kind of money to throw at it.

I can run the car NA for a while, just drop it in and go (ive got a few SMEC's in my garage that I can get a chip and tune for, also a wireing harness) I also have the full 2.4 wiring harness so I might be able to just pick up the ECU from a junk yard, but I doubt it would run the gauges.

OR I have 2 turbo engines, the 2.2 86NCB and a 2.5 89CB with good piston and rod.
I have heard that putting in the t1/t2 rotating assemblies will drop the compression into the 7.xx:1 range. Which I really dont understand since the piston shape changed in 86 and again in 89 for the 2.5's



I couldnt use the 86 pistons on the 89 rods and keep the compression in the 8.xx:1 range? Or is it the rods that are creating the problem, which I dont see how since they are the same length in the 2.4 as the CB.

Sorry, ive been out of the game for a while..

[rbryant]

The 86 rods and 89 turbo rods have different wrist pin types so they are not compatible. The 2.2 piston in the 2.4 block would probably stick out of the top of the block. It is a lot taller than the 2.4 or 2.5 pistons.

The 89 turbo rods and 2.5lpistons can work: http://www.bstockum.com/PTbottom.html



-Rich

[Darkapollo]

The 89 turbo rods and 2.5lpistons can work: http://www.bstockum.com/PTbottom.html



-Rich

Yeah I was trying to avoid the low compression problem, though many turbo cars run in the very low 8's to mid 7's in compression..

Like I said, ive been out of the game for a while. COMPLETELY forgot about the pressed pin and floating pin rods.

[rbryant]

Yeah I was trying to avoid the low compression problem, though many turbo cars run in the very low 8's to mid 7's in compression..

Like I said, ive been out of the game for a while. COMPLETELY forgot about the pressed pin and floating pin rods.

As long as you are near 8:1 you will be fine Even 7.5:1 will be ok. Our stock 8v engines are only 8.1:1

Remember you can intercool boost but you can't intercool compression!

If you want more compression just deck the head .020"-.030" and you will get your compression back. You should do the compression math yourself but it will be something like a tenth of a point for every .010 you deck the head by.

-Rich

[Darkapollo]

THANK GOD I decided to go ahead and pull the motor apart to swap in the 2.5l pistons and NOT run it NA. Remember, this engine has LESS then 35,000 miles!!
Two of these things are not like the others, TWO of these things just dont belong....




The crank isnt TOO bad. Nothing a good cut and polish cant restore, might take the journals down a bit and run oversize bearings.

[monkeyhead]

that would have been a huge bummer to get all put together and have it knock!