mjensen

I am curious to any differences between 86 and 88 engines. I understand the 89 951 S has a larger turbo, but is there any truth to the 88 being "part 86-7/part S? Any performance advantages?

Cory9584

the only change i know of was in 87 with the spring tensioner

hosrom_951

The 'S' cylinder head studs are 72mm height and the standard is 73mm (the S is deeper when installed), but they are still the same studs, and the main difference was the turbo charger and KLR/DME were 28pin (86 is 24-pin).

The spring tensioner was on pretty much on all 8v 944 models (from mid 87? onwards).

KuHL 951

The OPRV is different after the 86 model year. The 86 951 used the older 3-piece or the retrofitted 1-piece OPRV. The later engines eliiminated the venturi tube at some point also.

Tom M'Guinn

There are two answers really, one is the sales brochure answer and the other is the mechanic's answer.

At the sales brouchure level, the difference was that in 88, Porsche sold both the regular 944 turbo and the 944 turbo S. The regular turbo motor is "the same" from 86 to 88. The S motor made more power via a "bigger" turbo -- i.e. a k26/8 vs. the k26/6 found on the regular turbo. This and remapped chips gave the S an extra 30hp or so.

At the mechanical level, these motors evolved every year. As pointed out above, the oil pressure relief valve was upgraded to a 1-piece unit; venturi mess was deleted; balance shaft bearings were changed; oil level sender was added; oil pan and baffle was updated; timing belt tensioner was changed; water pump idler/ramp was changed; accordian added to headers; cross-over exhaust pipe changed; oil cooler line support bracket was added; extra vacuum port added to intake manifold; DME changed to 28-pin ROM from24; a few coolant hoses changed; dipstick and tube changes; probably lots of other stuff not coming to mind...

Tom M'Guinn

Hos, have you found anything from Porsche that confirms this? I've not searched exensively, but have not found any actual specs on stud heights.

Mike1982

Tom M'Guinn Glad you bought out all those little things. I didn't want to type all that out!! Also, don't forget about in '87 they put in a 2 piece cross over compared to 1 piece. Not engine related but close, the transmission is different on I think turbo S with a stronger 1st/2nd gear.

Tom M'Guinn

I actually think we all should put together an updated FAQ with questions that really are frequently asked around hear. Who wants to take the lead?

mjensen

Thanks for the info. I will be more specific to my question. I was at the PCA Mid-Ohio race in may and one of the other 951 competitors was running a 1988 turbo. I had inquired about the car to another racer as to the car being "fast" and I was told that this particular '88 was "blessed" being a late-built '88 with certain items from the factory which gave this car a mechanical(possible turbo/inj/head) advantage but was not badged a "S". If this is true with some sort of documentation we are allowed to update/backdate with in the model, turbo 86-86 in our specific PCA race class. Any idea?

mjensen

What about the 87 club sport differences?

M758

Sounds to me like a cheater trying to play off his bigger hp car.


Seriously the 86 and 88 (non-S) engines are are the same except for detail differences that don't impact hp. In fact the S and non S engines are the same except for the Turbo and DME.

Ski

I have a question related to this: the 86 and I think early 87 have actual caps on the balance shaft bearings...when did Porsche have the cap housing made into the balance shaft covers?

mjensen

Joe P., I was sleptical when I was told that about the "special 88". The performance advantages I thought were the turbo and dme. Just checking.

Luis de Prat

I believe the quality of the rods varied during the late 951 model years. MY86 engine rods are noted for being forged, but I've heard a number of descriptions for 87-91 although most are cast.

jerome951

Definitely sounds fishy.

Although I will say that some cars from the factory seem to be stronger than others. A good friend, who I trust completely, has an '86 which dyno'd at more torque than my car, which dynoed at an expected healthy, stock engine level (verified in that I can't catch him on the straight at Mid-O). His engine has never been opened and neither has mine.