Saab 95 Aero engine rebuild

[dicklague]

I am in the process of rebuilding my Saab 95 Aero 2001 2.3 engine. I thought I would start this thread to share some of my experiences so far and perhaps post a few pictures as well.

I decided to redo my engine after 170,000 miles to try to get rid of a bit of oil burning and most of all to get those Darn low friction pistons out of there. Saab deiced to go for more fuel economy and they took what was a great engine and put in weaker piston with less friction in an attempt to get greater fuel economy.

I have owned many Saabs 8 4 cylinder turbos and 3 2 stokes.

I love the 95 Aero and wanted to get it back to where my 9000 1997 Aero was in the way of a great engine. Don't get me wrong, the 95 Aero is a great car as it is, but can be improved.

[jadewombat]

I thought those coatings were supposed to be a good thing,

Newton's Law 9

??

Saab are great cars, too bad GM didn't exactly improve the company all of these years. Just borrowed a lot of the Swedish technology. Gotta believe in the underdogs though (look at Hyundai and Kia the last couple of years, I still wouldn't buy one yet but hats off to them for improving). Check this out:

http://www.streetfire.net/video/european-rallycross-2011-highlights_2323628.htm

[dicklague]

The low friction part was not the coatings on the pistons. It had to do with low resistance rings and piston design. Controlling the blowby was a big problem so much so that the best PCV system is revision #6!

They wanted optimum fuel economy and these low friction pistons and rings were supposed to be the answer.

Also the stock piston is cast and not forged. They are adequate, but are a week point in a very stout motor.

JE and Wossner make very nice forged pistons for this engine that are much better and have more conventional rings that really work.

With the OEM pistons your oil is black with carbon 500 miles after an oil change!

[dicklague]

Here are some photos of the project


new Wossner forged pistons




Spec aluminum flywheel. 12lbs lighter than stock

[dicklague]

[dicklague]

by the way that is not me in the photo. That is my mechanic Betor proudly standing by the engine he assembled for me. He is an amazingly experience Saab guy and has worked on so many he has lost count.

I put 200 miles on the Saab yesterday have almost 700 miles on the new engine and will do an oil change in the next day or so.

It is really working well. The difference with the new lighter flywheel is just amazing. It really accelerates will in the lower RPM ranges. the engine feel much more flexible with the lessened rotating mass. Also the engine is very smooth in that it is very well balanced. the crank, flywheel, and pressure plate were all balanced separately.


This the cover plate with a small piece of rod welded in place to balance it. This is a Sachs OEM Aero unit. I am surprised that the factory balance was not better. Maybe they balance the disc be for assembly and not after??



This is the 11lb Spec brand flywheel with the balance drillings to bring it to perfect balance.

[dicklague]

One little glitch we ran into was flywheel bolts. The Spec flywheel is 5mm thicker than the standard Steel one. The stock bolts are 25mm long, but you need 30mm to engage enough threads.

here are photos of the stock and the Spec and the thickness difference is obvious.