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Piston rings for a AQ171 penta 2.5

Volvo uses as many standard parts as possible in their engines.
B230 an B234F use the same piston rings.
So it would be highly unlikely they used other piston rings for the penta 2.5.

The pistons are 3 mm shorter than B230 or B234F pistons, but they do have the same bore.
 
mark244turbo said:
Volvo uses as many standard parts as possible in their engines.
B230 an B234F use the same piston rings.
So it would be highly unlikely they used other piston rings for the penta 2.5.

The pistons are 3 mm shorter than B230 or B234F pistons, but they do have the same bore.
Click to expand...

I'm curious to know if Volvo put the piston grooves in the same location for both PENTA 2.5 pistons and the B230. I've got both, need to measure....

I did find some PENTA ring part#s from little searching, but don't they they gave the specs. Here is the PENTA rings for both 151C and 171A: Volvo #275369

Who could answer this, besides Volvo Engineers and piston designers?

Related....did the factory use the same rings for B230 on NA and Turbo engines?
 
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DET17 said:
I'm curious to know if Volvo put the piston grooves in the same location for both PENTA 2.5 pistons and the B230. I've got both, need to measure....

I did find some PENTA ring part#s from little searching, but don't they they gave the specs.

Who could answer this, besides Volvo Engineers and piston designers?

Related....did the factory use the same rings for B230 on NA and Turbo engines?
Click to expand...

1) Relative to crown no. Pin yes.
2) Rings are the same.
3) Turbo and N/A different part number.
 
You could put a set of B230 rings on a Penta piston and measure your clearances.
 
poulson01 said:
1) Relative to crown no. Pin yes.
2) Rings are the same.
3) Turbo and N/A different part number.
Click to expand...

We know the Penta pin is 3mm closer to the top of piston to compensate for the 86mm stroke. You are saying they positioned the ring grooves relative to the pin CL? I've always ASSumed the rings were a relatively fixed distance from the block deck, or piston top. Never looked into it.....and should never assume...

Now I'm gonna have to pull out the Penta 151 piston and compare to my B230FT piston to see if you are right ;-)
 
poulson01 said:
.

3) Turbo and N/A different part number.
Click to expand...

That would be the top ring...probabaly the same (brittle) moly inlay that everybody else lurves so much on turbo applications.. Ya know? The moly inlay that chips so readily? That's what makes it turbo top ring..
That said it means you can use turbo rings in n.a. application but prolly shouldn't the other way.
 
DET17 said:
We know the Penta pin is 3mm closer to the top of piston to compensate for the 86mm stroke. You are saying they positioned the ring grooves relative to the pin CL? I've always ASSumed the rings were a relatively fixed distance from the block deck, or piston top. Never looked into it.....and should never assume...

Now I'm gonna have to pull out the Penta 151 piston and compare to my B230FT piston to see if you are right ;-)
Click to expand...


It's all hair splitting anyway..
 
John V said:
It's all hair splitting anyway..
Click to expand...

The OP in this little piston thread says he machined 3mm off the top of factory Turbo pistons, so he could run with the PENTA stroker crank. What does your experience say John, is there a sacred position for that top ring in a turbo application? N/A application? Or it makes no never mind, put 'em anywhere you want?
 
DET17 said:
We know the Penta pin is 3mm closer to the top of piston to compensate for the 86mm stroke. You are saying they positioned the ring grooves relative to the pin CL? I've always ASSumed the rings were a relatively fixed distance from the block deck, or piston top. Never looked into it.....and should never assume...

Now I'm gonna have to pull out the Penta 151 piston and compare to my B230FT piston to see if you are right ;-)
Click to expand...

Well? Am I right? :cameron:
JK

Yes the rings on the 2.5L are 3mm closer to the piston crown.
 
John V said:
That would be the top ring...probabaly the same (brittle) moly inlay that everybody else lurves so much on turbo applications.. Ya know? The moly inlay that chips so readily? That's what makes it turbo top ring..
That said it means you can use turbo rings in n.a. application but prolly shouldn't the other way.
Click to expand...

I think so too.
I've used NA rings on turbo engines.:oops:
NOS ring sets come up on eBay often, and gasket too.
I snipe that kind of stuff and hoard it in my "medicine cabinet".
I slapped one together a few years ago and those NOS NA rings were just sittin right there.....
 
poulson01 said:
Well? Am I right? :cameron:
JK

Yes the rings on the 2.5L are 3mm closer to the piston crown.
Click to expand...

Don't doubt you....just haven't had time to pull my pistons and check for myself.

My burning question is....where SHOULD they be for boosted motors? This weekend maybe I'll get some Google time an see what piston designers think. I honestly don't know, but am suspicious....:roll:
 
DET17 said:
Don't doubt you....just haven't had time to pull my pistons and check for myself.

My burning question is....where SHOULD they be for boosted motors? This weekend maybe I'll get some Google time an see what piston designers think. I honestly don't know, but am suspicious....:roll:
Click to expand...
Google search
pistons :blah: site:turbobricks.com
Click to expand...
You may even find pics I posted ten or twelve years ago.

I'm not gonna get into what stock pistons are the best because JV will probably kill himself it people start rehashing that head horse.
Besides, OP asked a question and it was answered.
 
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