question about turboing

[sgt. minivan]

OK i acually have billions of questions but il start one at a time, im dealing with a 1987 plymouth voyager 3.0l v6, it has a swapped 1994 3.0l, my questions, do 87 and 94 have same compression ratio? and im 99.9% sure that the 87 3.0l has 8.6:1 CR, ive heard rummers of 8.9:1.. but i think its acually 8.6, anyway, is this CR to high for a turbo? is 8.9 to high? i was thinking even if it is to high... cant you just retard the timing to make up for it?

[irocelectric93]

I always thought that our compression was 8.25:1 or something. I know our compression is good for boost. Unless of course your brent

[lookin]

My 95 3.0 is 8.85:1 I believe.

[Ondonti]

old 3.0 are 8.85 and have chrysler pistons. 92+ (somewhere around there) are 8.9:1 mitsubishi pistons.

The chrysler pistons look a lot stronger because the top ring is lower and 3.0 pistons break on the intake valve relief because there is not enough material between the valve relief and the ring. Lower placement = more beef.

[sgt. minivan]

so is 8.9 ok to run a turbo?

[kreel]

Quote:

Originally Posted by sgt. minivan so is 8.9 ok to run a turbo?

It'll depend on what your goals are. 5 psi...probably not going to be a problem. 15 psi...I wouldn't expect reliability. An 8.9:1 CR is not really that high either. As long as you don't have any outrageous hp goals the stock (chrysler) pistons should be sufficient.

[sgt. minivan]

Quote:

Originally Posted by kreel It'll depend on what your goals are. 5 psi...probably not going to be a problem. 15 psi...I wouldn't expect reliability. An 8.9:1 CR is not really that high either. As long as you don't have any outrageous hp goals the stock (chrysler) pistons should be sufficient.

im curently using mitsu pistons (as said by ondonti) will these work? what kind of hp would i see out of say 8psi boost? is 8 a reliable amount of boost for a daily driver?

[lookin]

Myself I am going to go with 3 maybe 4 lbs. Five lbs at most.

Yeah I know famous last words.

[irocelectric93]

Couple things.....with forged internals....8.9:1 compression is fine for actually quite a bit of boost....as long as its intercooled. If you are going to keep the stock internals 8 psi would probably be doable if you regapped the rings....but probably not safe for a daily driver i would guess. I could be way off here though.

[sgt. minivan]

another question... can i have a waste gate with a auto trans? i guess it wont make cool shifting noises tho... i odviously dont know shit about turboing.. + i noticed a "plug" in the side of my oil pan, about center... would that be a good spot to put the oil return line??

[mwinkle353]

I think you are referring to a Blow off Valve or a Bypass Valve. The waste gate is the valve that helps control the amount of boost in the turbocharged system.


Don't use that "plug" for an oil drain. That is there for an oil level sensor. The location will be too low for effective oil drain from a turbo into the pan. I would remove the pan, and have a look at the internal baffles. I would locate the drain above the baffles in the pan.

[Ondonti]

Im just saying the 8.85:1 pistons are stronger. The compression ratio difference is almost nothing.

Stronger ringlands are a good thing since thats the first thing to break (intake ringland) on a turbo 3.0.

[sgt. minivan]

oh i see.. i wounder if beside the dipstick hold would be ok? so is there a particular place to drain oil on that would benifit... like makeing sure its not being drained on one of the crank arms

[DustyR/T]

best bet if you have the pan off is to eyeball it and have a bung welded/brazen on to the pan. Make sure it's a huge oil return, or that turbo is not going to last.

[c2xejk]

Quote:

Originally Posted by sgt. minivan oh i see.. i wounder if beside the dipstick hold would be ok? so is there a particular place to drain oil on that would benifit... like makeing sure its not being drained on one of the crank arms

Are you talking about the front (aka forward on the vehicle) side of the engine? Is that where you plan on putting the turbo?

Most people (myself included) put the turbo toward the rear of the engine compartment. That is where the manifold I fabricate puts it.

The other place the turbo is located is over the transmission. Then you could place the oil drain back port on the front of the engine, however, I would still consider putting it on the back side of the block...

The best way to find the optimal placement for the oil return is to pull the pan and look...