Question about a 3.0T build...I'll use a 2.7t block bored out to 82.5mm and a 3.0L crank with
01-22-2008, 10:45 AM
#11
AudiWorld Senior Member
Thread Starter
Thanks for your help so far. 1 more question...
How do I spec out the custom pistons?
I guess first I would need to measure a stock 2.7t piston. Then raise the piston boss up 3.2mm.
Heres the math:
2.7t stroke =86.4, Radius= 43.2, rod lenght=154
Total 2.7 stroke lenght: 43.2+154 = 197.2
3.0 stroke =92.8, radius=46.4, rod lenght=154
total 3.0 stroke lenght: 46.4+154 = 200.4
200.4-197.2 = 3.2mm
Am I on the right track?
I plan to run 8.5:1 compression ratio. I dont want this thing to detonate!!
I guess first I would need to measure a stock 2.7t piston. Then raise the piston boss up 3.2mm.
Heres the math:
2.7t stroke =86.4, Radius= 43.2, rod lenght=154
Total 2.7 stroke lenght: 43.2+154 = 197.2
3.0 stroke =92.8, radius=46.4, rod lenght=154
total 3.0 stroke lenght: 46.4+154 = 200.4
200.4-197.2 = 3.2mm
Am I on the right track?
I plan to run 8.5:1 compression ratio. I dont want this thing to detonate!!
01-22-2008, 12:24 PM
#15
AudiWorld Senior Member
Thread Starter
Think I got it, Its all about the compression height measurement.
OEM is 30.15.
So I think I need a compression height of 26.95.<ul><li><a href="http://www.musclemotorparts.com/comp_ht.htm">http://www.musclemotorparts.com/comp_ht.htm</a</li></ul>
So I think I need a compression height of 26.95.<ul><li><a href="http://www.musclemotorparts.com/comp_ht.htm">http://www.musclemotorparts.com/comp_ht.htm</a</li></ul>
01-22-2008, 01:10 PM
#17
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You're already ahead of me!
I only know the general theory. I haven't figured any of this out in practice yet. So I'm not about to give you specific instructions on how to do it.
But I do think you're going to have to take account of the shape of the crown of the piston. It is all really about the total volume at the bottom of the stroke virses the volume at the top of the stroke. That will depend in part on the shape of the top of the pistons.
Stephen
But I do think you're going to have to take account of the shape of the crown of the piston. It is all really about the total volume at the bottom of the stroke virses the volume at the top of the stroke. That will depend in part on the shape of the top of the pistons.
Stephen
