Hi All

I finally got around to investigating the poor running issues of the 5 door 99 Turbo.
A compression test revealed the following results:

1. 120
2. 140
3. 140
4. 70

Pulling the motor out and inspecting the pistons revealed that 3 of the 4 pistons were cracked!
Unfortunately, I do not have any spare 7.2:1 pistons and the usual internet sources seem to have run out as well.

So what are my options?:
- Beg, borrow and steal from Saabists around the world?
- Install 16V 900 Turbo pistons? - however this will increase the static compression ratio. Is this advisable?
- Aftermarket suppliers – any preferences?
Your thoughts?

As to why the pistons have cracked, it appears that the car has been driven in the past with a stuck waste gate (original Saab 99 Turbo type) – too much boost – with the usual results.

Unsticking the valve in the waste gate is another challenge … I can get the valve to spin and move in / out a couple of mm but it is not showing any enthusiasm of coming out any time soon.

The turbo has been rebuilt recently so I am reluctant to change to a later 900 turbo / waste gate combination at this time.

Any Ideas?

Thanks Neil

If one of them is still good you might be able to send it to a piston builder like Ross or Wossner. They can make a forged copy of it which is much lighter and stronger.

You could put a set of pistons in from an 8v 900 engine...they were around 8.5 compression as I recall. If you could get an 8v 900 exhaust manifold then you could run a wastegate and APC.

Where are you located ?
I'm outside Portland, OR and may have some options for you.

Thank for the replies.

The suggestion of getting a local manufacturer to make a new set was a great idea that I did not think of. Luckily one of the pistons is still OK and could hopefully be used as an example to remanufacture a new set.

Regards
Neil

As much as I like Seth's suggestion, considering the rarity of 5-door 99Ts, I think I'd actually want to keep it original.

John

I believe Luke paid around $600 for a set of custom pistons with rings and pins for one of his engine builds.

Thanks to a local Saab enthusiast for the NOS turbo pistons and rings.