williamr91

Hey fellas, probably a dumb request however I would like to get an idea of what I should be putting down. I have an 86' turbo with a chris white cylinder head, upgraded camshaft, piston and rods. Fabspeed 3" exhaust, 46?mm wg from Tial, a K27/8 turbo ,MAF sensor (brand unknown) I want to say it is a 2.8l but I'm not 100% sure of that. My AFM is in a happy zone mostly 14 to 16 and I run 12psi most of the time, with a mbc and race gas switchable tune. As for supporting goodies, it has a stock gearbox, with a lightweight flywheel and 930 clutch. The PO had Rouge do the tunning. Thanks in advance anyone, also any help/ideas about my car would be great.

ChrisJ951

A lot depends on the displacement but I'd say 300-330 rwhp, but again tough to nail down unless you know the exact build. A 2.8 is a stock 2.5 piston and rod with a 3 liter crank, I believe. Someone with more knowledge will chime in I'm sure.

Take it to a dynojet dyno to find out.

333pg333

Or go do a 1/4 mile.

Scott H

Way too many variables to estimate.

74goldtarga

I have the same turbo. I have M-tune and a Lindsey head. I have a stock cam. My car is a 2.5L

Dynoed at 266whp at 11.9psi, estimate 266 x 2.8 / 2.5 = 298 whp at ~12 psi.

Dynoed at 328whp at 14.5psi, estimate 328 x 2.8 / 2.5 = 367 whp at 14.5 psi.

Not sure if this is accurate, might not be right to multiply my numbers by 1.12 for displacement but it gives an idea.

williamr91

For what ever reason I think the PO had it trapping 117 to low 120's depending on boost and all the other factors.

Tom M'Guinn

A 3 liter crank with stock 2.5 piston and rods doesn't work. The pistons would come up way too high, and the factory rods would make contact in the bottom end (without a little grinding). Andial used to sell special storker kits with rods that cleared, and pistons with special offsets to work with the 3 liter crank in a 2.5 block. If you had one of those motors, you'd most likely know it.

williamr91

No I'm pretty sure it is 2.8 l block with a 3.0 crank. Looking back I don't think I included that in the initial post. I really need to get the documents from the mechanic who built it, Steve Kramer in Michigan if anyone knows him. I spoke to him a few times on the phone just haven't gone to the shop.

Tom M'Guinn

These motors came from Porsche with one of two different bore sizes --100mm or 104mm. The 100mm blocks are the 2.5 liter blocks, and the 104mm blocks are generally known as 3 liter blocks. Check the water passage at the front of the head and see if it is bolted to the block with one or two Allen head bolts--or get the block number and post it up. Separately, Porsche made two basic crank sizes--78.9mm and 88mm. The 78.9mm crank with a 100mm bore makes a 2.5 liter motor. The 78.9mm crank with 104mm bores makes a 2.7 liter motor (which Porsche made only as an n/a and only in 1989. An 88mm crank with 100mm bores makes a 2.8 'stroker' motor, which Porsche never made but was a fairly popular modification back when Andial was selling the parts. An 88mm crank with 104mm bores is a 3 liter, which is currently popular. Beyond that, anything is possible with sleeved cylinders in non-stock sizes (common) and custom cranks (not as common).