On a '88 2.8L, how much room is there between the piston and the valves in the head????? I want to have the heads machined down a little to get a higher compression but not sure on how much I can take off safely.

 

Thats not something I could begin to help you on but just thought I'd add, I do believe I read on here not too awful long ago that if you use the pistons from a late 90's alero(and some other stuff with the same motor) you'd end up with like 9.7 or 9.8:1 CR or something like that. Seems that would be cheaper and easier than messin around with machining your heads.

 

hi, ive asked the same question previously and the most common answer/thought seems to be .020"

 

u can go upto .060 but the manifold has to be machined to match and u have to dbll check the pushrods after.

 

Let me get this straight; the MAXIMUM amount of material that I can machine off the heads is 0.060" (sixty thousandths of an inch)?? But only as long as I machine the intake manifold to match?? Does this mean that I have to take the SAME AMOUNT of material off the intake? Do I only machine the lower intake or do I have to do the middle and upper as well? Can anyone give me a "rule of thumb" on how much more compression I will get per amount of material that I remove?

 

If you want more compression why not just stroke it w/ a 3.1 crank and have the 2.8 pistons milled to fit? There was a german guy that did something similar a while back and got about 10:1 cr.

If you have the heads milled you need to have the bottom of the lower intake manifold (section that mates to the block) milled the same amount. I believe six hundredths (.06") is the most they can be milled. Not sure what cr that will give you, you'd have to measure the chambers to find out.

 

If I used a 3.1L crank, will it just drop right in??

 

That would require the heads and intake and a bunch of other parts.

To use the FWD pistons with the iron heads would drop the SCR in the toilet, IIRC around 7:1 SCR.

Maching the heads would be easier and cheaper, though the gains would be much less.
----------
The top ring land would be so thin, that I would be afraid to run an engine like that. If FWD head gaskets are used, you might be able to get away with maching the pistons down some, and retain a good quench distance, but I'd still be leary of that.
----------
Yes, the 3.1 crank will drop into an '85.5 and up block.

 

Like I said there was a german fellow who stuck milled 2.8 pistons in his 3.1 sucessfully.

 

Ok. If I did nothing but change the crank to a 3.1L crank, I will get a higher compression?? If everything except the 3.1 crank is stock on the whole engine, can anyone tell me the exact CR?

Btw, how do you find the compression without using a compression tester? What's the "formula"?

 

Yep, you will for a fraction of a second until the piston hits the head and breaks something.

The only way to find the static compression ratio is by using a forumula. A "compression tester" just tests that a cylinder will hold pressure, not how much compression it has, or at least not what compression ratio it has.

SCR = Volume of cyl @ BDC / Volume of cyl @ TDC

 

Ok, since nobody here can give me a straight forward answer to my questions about the heads or crank idea, lets try this: can anyone tell me where I can get new piston heads for a 1988 2.8L 60degree V-6 that will give me a compression between 10.5:1 - 11.5:1???????

 

How were my answers not straight?

They are as accurate as they can be, given the questions you asked.

**** now I remember why I stopped posting in this forum, no one seems to be able to read the replies.

Are you wanting to stroke to the 3.1 or stay 2.8? The answer to that question wil dictate where you can get pistons from.

Why do you want such high Static Compression Ratio? There are plenty of other things that will increase power before trying to raise the SCR will do any good.

 

Your best bet is just get you a 3.4l out of a 93-95 camaro and put it in.

 

Not when you tell me that I can just drop in a 3.1L crank to give it a higher compression and then turn around and tell me that it will not work b/c it will hit and destroy the head.

I want to keep the 2.8 but with a much higher compression and build it up like a high-performance engine for a "show camaro" so I can take it out to places and show it off.

The main reason is my buisness. I just want to know how to get it safely.

 

Now here's my next question; can YOU read the replies Six_Shooter?!?!?

 

If you're going to be snotty you're either not going to get a response, or one you don't like.

If you put a 3.1 crank in and did nothing else the pistons would hit the head. If you put a 3.1 crank in and had the 2.8 pistons milled for 0 deck height you would have ~10:1 cr.

 

ASK THE RIGHT QUESTIONS.

You asked if THE CRANK WOULD FIT, which the answer is YES. I never said it would raise compression, I just said the crank would fit, which is what you asked:

All that is in that question is asking about the crank.

Will the crank fit?

Yes, the crank will fit the block.

If you wanted to ask about using a 3.1 crank to raise the SCR you should have asked:

"If I install a 3.1L crank in my 2.8L, will that raise the compression ratio? What other parts would I need?"

Ask a complete ****ing question, and you will get a complete answer. Don't assume we just know what you're thinking, most of us haven't developed the mind reading skill yet.

You didn't ask about the ****ing pistons to go along with it.

Like I said raising compression is one of the LAST things to be considered when building a performance 2.8.



Your business? You mean you do this for a living? Or are you just trying to be all e-tough?