My 3B-AAN 400 HP project

[Pirvu Eugen]

I have skimmed the pistons flat at the lower part of the oem piston.
I have removed the material untill the lowest part of the piston... hope i explained right.
Sorry my english!

[AndyP]

Yes, I understand, I'll measure one of my std pistons and work out how much you've taken off.

[Pirvu Eugen]

Thank You Andy!

[LHD_Kid]

I thought you took off 1 mm?

[Pirvu Eugen]

Is about 1 mm indeed....the squish area was a little higher.
Were not skimmed more than the bottom of the oem ones....just the "surrounding area"

[AndyP]

I have measured today the head chamber volume and the piston to block volume...
I am confused...or i do something wrong?
So....
Head volume: 44.4cc, piston to block surface: 7,1cc due to the fact i skimmed the pistons flat. The head gasket has 10,3 cc because is 2mm thick...the 034 cr reduction gasket wich has 7 layers.
Considering this...the cylinder volume is 445cc and combustion chamber is 61,8.
This gives me the 7,2 CR.
Is something wrong in my calculations or the engine is not 9.3 CR in the stock form?

I think you've skimmed 1.3mm off the piston, which means I agree with your 61.8cc TDC volume, but your BDC volume needs to be the cylinder volume + TDC volume which means 445cc + 61.8cc / 61.8cc = 8.2:1

[JariP]

Stock CR seems to about 8.8. The factory claimed numbers are most likely to be marketing bs. Even Mahle catalog gives 8.8 CR for MY 89 200 3B engine, then it changes up to 9.3 for later 20vt engines (3B, ABY, AAN). And 9.0 for ADU? Claimed CR changes, but engine parts stay the same. And I don't think the difference comes from head gasget change either.

[Pirvu Eugen]

I think you've skimmed 1.3mm off the piston, which means I agree with your 61.8cc TDC volume, but your BDC volume needs to be the cylinder volume + TDC volume which means 445cc + 61.8cc / 61.8cc = 8.2:1

Ohhhh!!! Jesus!!! What a mistake!!! This is it!!!
Thank you Andy!
Now is more like'it.
Thank you!

[Pirvu Eugen]

Stock CR seems to about 8.8. The factory claimed numbers are most likely to be marketing bs. Even Mahle catalog gives 8.8 CR for MY 89 200 3B engine, then it changes up to 9.3 for later 20vt engines (3B, ABY, AAN). And 9.0 for ADU? Claimed CR changes, but engine parts stay the same. And I don't think the difference comes from head gasget change either.

I think you are right!!! I have skimmed the block deck and the head...and i have this CR. Is no way that, with stock internals, this engine to be 9.3 or 9.0 CR.
Thank You!
All the best!

[AndyP]

Stock CR seems to about 8.8. The factory claimed numbers are most likely to be marketing bs. Even Mahle catalog gives 8.8 CR for MY 89 200 3B engine, then it changes up to 9.3 for later 20vt engines (3B, ABY, AAN). And 9.0 for ADU? Claimed CR changes, but engine parts stay the same. And I don't think the difference comes from head gasget change either.

My calculations for a stock engine give 8.97:1

[Pirvu Eugen]

head on....

Head is on...after some hours....off...
Without the right tools...installing the valves springs can be very difficult.
But...is done.
Tomorrow i will start with the manifolds.

[Pirvu Eugen]

I tightened the arp bolts with Sport Quattro washers at 80 ft lbs. 110 NM.
I will retorque them after the first heat cycle.

[DJones]

I tightened the arp bolts with Sport Quattro washers at 80 ft lbs. 110 NM.
I will retorque them after the first heat cycle.

Wow that's high, I only do mine 55-60 ft lbs.

[Pirvu Eugen]

Woops!!! Hmmm... On my ARP paper was 80 FT lbs recommended torque settings.
Hope i didint done something wrong.
80 ft lbs in 3 equal parts.

[Pirvu Eugen]

BTW... it was MUCH more easy to tight these at this torque than the oem ones at 30/ 60 NM plus 180 degrees.
At the last 90 degrees..wow i had to use a big bar...
I am not soo powerfull though
Soo i think that this 110 NM is way less than the oem bolts torque.