Matt Sheppard

Anyone know when they went to the longer duration exhaust cam profile?

Indiana

Wasn't it 1988? I know the HP increased from 147 to 158 that year in the U.S.

M758

Nope.. Cam changed in 85.5.

In 88 the pistons change to a 10.2:1 CR vs the 9.5:1 US only spec.

nine-44

85.5 and it was 8 degrees more duration on the exhaust side.

snappy

In 1987 the 944 n/a increased it's compression to 10.2 : 1 versus the 9.5 : 1 of the 1986. Both engines have the same bore and stroke of 78.9 x 100. The yielded an increase of 158 @ 5900 in the 87, versus the 150 @ 5500 of the 86. Why does it only make such a small difference. That is quite a bit of difference in compression. Now this could be a guesstimate as I don't have any data yet. But the higher compression and rpm needed "COULD" mean that the cam duration could have changed. There's 2 option s listed for the cam shaft. 944.105.155.09 and 944.105.155.05 the (944.105.155.05) model seems to have 2 Model numbers M44.50/51 and M44.52 so looking at this there is 2 different ones. Hopefully armed with this info you could track down what you are after. It could just be that one cam was for the US and the other for Europe. Gl

snappy

ahh. so it seems that the (944.105.155.05) part-number Cam shaft was for the 944 (83-84) and turbo (1989-91). And the (944.105.155.05) part-number Cam shaft was for the 944(1985.5 and up), except turbo and 16 valve. I don't have time now to dig for it but i know i have the stock grinds of those two models somewhere.

Tom Carson

could be all in here:

http://members.rennlist.org/951_racerx/

M758

This is incorrect. Only the 88 models had the 10.2:1 Compression Ratio. This was done by a piston change.

There are 3 pistons for the 8V 944 in 2.5L trim

9.5:1 US Spec 82-87 (Dished)
10.6:1 Euro Spec (No dish - Flat top) 82-87
10.2:1 US & Euro Spec 88 (Slight Dish)

The cam change occured in the 85.5 models and I as far as I know there are 2 cams for the 944 in US Spec. The early 82-85 model and 85.5 to 88 model.

We in 944-spec racing have done alot of diggin on these motors to learn these things so we KNOW they are right. Bet you did not know that the balance shafts changed on the 85.5 model as well. They added a shroud on the shaft to reduce friction in the oil. The older ones are all steel and have a cresent shape. The newer onese still have the cresent shape, but have a plastic shroud to make the shaft a full disk. This allows it to run more smoothly through the oil.

The racer X site has the right info for cam duration and profiles for the US spec 944 both early and late.

Matt Sheppard

M758:

Your info jives w/ what I've dug up. Actually, the cam qustion was for a turbo engine, but I just bought an '86 NA car that I'm considering SPEC racing.

What seems to be the ideal combo for the spec racing engine? What compression can you get away with in that series and does it have to be done w/ pistons or can you mill the head to get there to be legal? Do you have to have an 88 chassis to take advantage of the 10.2:1 allowance?

TIA

M758

Max Compression is 11:1 for all cars. Head shaving is legal to get there.
I have seen cars with 88 pistons and with 9.5:1 pistons all put out the same power. Some with shaved heads and some without.

Take a look at my webpage. I have a dyno chart from 3 944-spec motors. All are about the same and have different prep levels.

Bottomline is there is no MAGIC 944. They are pretty much the same. No matter what chassis or engine you get you can win races if you can get 100% from the car. There is no magic engine spec. They are all within a couple HP. Chassis are pretty much the same. Driver makes the biggest difference and that is how we like it.

Tom Carson

I didn't know that change was at 85.5...

Danno

They also changed the balance-shaft bearing cap at the year as well.

M758

Yep..
... and the balance shaft covers are a match set to the engine block.

Tom Carson

in a thread regarding the differences between the '86 vs '87 951 engines

so is the 'early' NA balance shaft covers same as the 951 '86 ?