Build question

SiLeNcEbOnE
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Joined: Tue Aug 19, 2014 4:02 pm

Build question

Postby SiLeNcEbOnE » Fri Apr 07, 2017 3:39 am

Wanted to ask if it is possible to run 11.0 pistons with 16v bigport without needing to do anything to the head?
So basically if it's possible to run stock head without needing to upgrade anything in it.
If it will run without a problem.

I have read somewhere that with the compression that high you would need higher camshafts.
Saw that you would need at least 250 cams, 20v camshaft are 250 while 16v are 232.
This is what I read and hoping if anyone can give me some more clarification on that matter.

Wanting to run that comp pistons and 1mm headgasket.
See what people have to say before making any decision. Don't want to run into problems.
I'm all open for any suggestion or advice.

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davew7
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Location: Michigan

Re: Build question

Postby davew7 » Fri Apr 07, 2017 5:39 am

You normanlly modify the piston Vs the head. You would not want to countersink the valves into the head which reduces flow.
Typically those mild duration cams are not any problem. It's the lift [ ck spec's ] of the camshaft and that would require the piston needing a relief in the valve pockets. If you are selecting low lift cams and only loosing .013" with the head gasket you will not have a piston to valve clearance issue. If you want to be 100% sure you can add clay to the top of the piston, cycle the engine by hand and verify the clearance. Dave w

SiLeNcEbOnE
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Re: Build question

Postby SiLeNcEbOnE » Sun Apr 09, 2017 12:12 pm

I understand.
But I don't have the pistons yet so no way to try out your suggestion.
But maybe i'll just get them and see how it goes from there.

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oldeskewltoy
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Re: Build question

Postby oldeskewltoy » Sun Apr 09, 2017 6:39 pm

SiLeNcEbOnE wrote:I understand.
But I don't have the pistons yet so no way to try out your suggestion.
But maybe i'll just get them and see how it goes from there.


BE CAREFUL...... many aftermarket piston companies list static compression ratios for their pistons... and they are frequently WRONG!

What you want to know from the piston supplier is the crown, or dome volume. Anything more than 1.5cc will put you over 11:1 with a stock head.
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

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SiLeNcEbOnE
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Joined: Tue Aug 19, 2014 4:02 pm

Re: Build question

Postby SiLeNcEbOnE » Tue Apr 11, 2017 5:17 am

oldeskewltoy wrote:
SiLeNcEbOnE wrote:I understand.
But I don't have the pistons yet so no way to try out your suggestion.
But maybe i'll just get them and see how it goes from there.


BE CAREFUL...... many aftermarket piston companies list static compression ratios for their pistons... and they are frequently WRONG!

What you want to know from the piston supplier is the crown, or dome volume. Anything more than 1.5cc will put you over 11:1 with a stock head.


Okay will keep an eye out on that.

Still wondering if I still need to upgrade the camshafts to run those pistons or if I can just go with stock ones.
Running turbo on C85 fuel. Was thinking of boosting up to 20-22psi.. Wanted to run it that way. No time to upgrade the head.
Got a few weeks before the next race.

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