Oversized Pistons
12-06-2003, 05:54 PM
#13
Not sure where you're getting your information but....
..it's incorrect.
Audi turbo engines have always been 81mm bores. The 2.7 is as follows:
Piston Diameter: 80.95mm
Cylinder Bore: 81.01mm
There's is NO over-bore allowed by factory specs.
You're listing data from an NA Audi engine.
Audi turbo engines have always been 81mm bores. The 2.7 is as follows:
Piston Diameter: 80.95mm
Cylinder Bore: 81.01mm
There's is NO over-bore allowed by factory specs.
You're listing data from an NA Audi engine.
12-06-2003, 06:46 PM
#14
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why would there be no overbore allowed? I did notice his numbers where wrong, but not sure about.
that second part... is it audi attempting to force a new block purchase of is there something different with the 2.7 block?
12-06-2003, 07:25 PM
#15
Not sure, but the factory info I have doesn't show an overbore for the 2.7......
I would just use the overbore that they use on the other turbo engines.
<b>First overbore:</b>
Piston-81.23mm
Cylinder-81.26mm
<b>Second overbore:</b>
Piston-81.48mm
Cylinder-81.51mm
Audi's really conservative on boring with the turbo engines. They REALLY want wall thickness in these engines. If you use the dimensions above you'll be able to find Audi forged pistons (or use JE pistons). Second overbore is probably easier to find items for.
<b>First overbore:</b>
Piston-81.23mm
Cylinder-81.26mm
<b>Second overbore:</b>
Piston-81.48mm
Cylinder-81.51mm
Audi's really conservative on boring with the turbo engines. They REALLY want wall thickness in these engines. If you use the dimensions above you'll be able to find Audi forged pistons (or use JE pistons). Second overbore is probably easier to find items for.
12-06-2003, 07:27 PM
#16
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Re: Not sure where you're getting your information but....
Well, I got my information from this Bentley Owners manual I have here, I don't doubt its wrong thou I noticed for some reason they list the same specs for the 2.8l and 2.7 biturbo..something is fishy..Thanks,
Mark
Mark
12-06-2003, 07:31 PM
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Re: Not sure where you're getting your information but....
So just to be clear you don't think the 2.8L N/A pistons available from Audi would work in the 2.7L. I'm speaking in terms of size and fitment with the 2.7L connecting rods and pins?
12-06-2003, 07:40 PM
#20
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actually they would prob. bolt up,,, but I believe they are cast...
both motors share some common parts.... since they do, you could most likey bore the motor to the 2.8 piston specs and go from there, but a few major problems.... 1: if the 2.8 pistons are cast, your gonna desptry them with boost, 2: how are you gonna run that motor? There is no software commercially avail. to run a 2.8L biturbo 9 with the exception of Chris' GIAC software, but I don't know who owns that)
APB --> 2.7 L
AHA --> 2.8 Manual
ATQ --> 2.8 Automatic
APB, AHA, ATQ Crankshaft 078 105 101 AB
APB, AHA, ATQ Conrod assembly 078 198 401 C
APB --> 2.7 L
AHA --> 2.8 Manual
ATQ --> 2.8 Automatic
APB, AHA, ATQ Crankshaft 078 105 101 AB
APB, AHA, ATQ Conrod assembly 078 198 401 C