Wormhole

Besides the obvious, crank and pistons are the short blocks identical? Any differences??

fast951

Blocks are the same. (Head bolts are different between the 8V and 16V)

Tom M'Guinn

Balance shafts are different too. (Although I used 2.7 shafts on my 3 liter and don't notice any difference in smoothness.)

Wormhole

What about the oil pans?

Tom M'Guinn

I used a 968 pan/baffle on the 89 2.7 block. Other than the baffle, it "looked" the same as the 2.7 pan. PET seems to show different part numbers for the pans for what its worth...

Olli Snellman

Does 2.7L pan have attachment point for a turbo oil return hose? At least S2 pan have it. We used a S2 pan for a friends 951 S engine and it was a direct fit.

Chris White

As far as attachment point the S2 block is identical to the 2.5 block, the S2 oil pans have the turbo drain hole (with a threaded plug). For what you want the S2 block is a better choice – its stronger and, most importantly, it has the windage holes. I believe that the holes make it a much superior design for a track engine.
The only thing that you will need to deal with is different head studs – you will need the head studs from a 2.7 if you want to run a 8v head.

Wormhole

Hey Chris, what makes the S2 block stronger then the '89 2.7 block? What are the windage holes?

Chris White

The block 'floor' is higher than the 2.5 so the free standing cylinders are held in place better. The windage holes are large holes above the crank that allow air to move between cylinders 1&2 and 3&4. Remember that all the air being moved as the piston goes down has to go somewhere, as piston 1 goes down piston 2 is going up so the volume of air has to move through the crank case from cylinder 1 to cylinder 2 – and it has to do that at 200 times per second at 6krpm. That’s a lot of air moving back and forth. In the 2.5 block the air has to pass under the crank and girdle – right by the oil on the oil pan. That’s a lot of air moving around and it will move the oil around too.

The S2 block has the windage holes located so the windage can move back and forth above the crank – away from the oil!

Mike Lindsey

Chris, Going to have to arm wrestle you on this one. All 104mm blocks has the windage ports. 2.7L, S2 and 968. We don't feel there is any difference in the S2 or 2.7L blocks strength wise as the are both 104mm bore and have the same cylinder webbing, at least visually. The girdles however are different on the two. The girdle on the S2 has more clearance for the rods (larger stroke crank). The 2.7 block is more or less like a S2 block with a 2.5L girdle on it. So clearance is required doing a 3.0 crank in the 2.7 depending on connecting rod being used.

We do the windage port modifications on the 2.5L blocks for reasons you mentioned for a modest $325. Customers report a quicker revving engine. We do it for that, and crank oiling purposes.

Chris White

Well I was working out my Bicep ready for a good match...and then I reread the thread title - I thought it said S2 vs 2.5...duh. S2 and 2.7 are the same block...exactly the same, just with different head studs.

I just read the titles closer…

BTW - thats a good price on the 2.5 mod - that is a real pain in the butt job.

Mike Lindsey

CNC!!!

Chris White

Chicken 'n' Chips?

FRporscheman

The oil pan on the 2.7 is different than the S2. The S2 metal baffle (on the shallow part of the pan) has more clearance for the larger stroke.

Tom M'Guinn

Agreed. Carrillo rods work well out of the box in a 2.7 block/girdle with 3L crank and no mods. Stock 951 rods not so much...