Thread: Petrol 2wd TURBO tech

Lovely cars, Saabs, but woeful offroad.

Originally Posted by abaddonxi

Lovely cars, Saabs, but woeful offroad.

They make quite good rally cars though...

Large component of driver error in my case.

Originally Posted by isuzurover

The saab has a fairly nifty system for boost control. The standard wastegate setting is very low (e.g. 4psi). There is then a system to bleed off pressure in the wastegate actuation line, to increase boost, provided the knock sensor etc report all is well...

I think nissan do the same. I've never owned one but their turbo petrol cars have a solenoid in the wastegate line.

I've been talking to a friend about these turbos, he loves his 900 turbo, for my 4BD1. I know basically nothing about turbo-ing engines. Would this knock sensor system be effective in a diesel engine? I can probably get the saab bits for cheap.

As mentioned by one of the er "British" posters, I have found a lot of low end to be gained in petrol turbos by freeing up the exhaust immediately out of the turbo.
I had a Charade turbo (don't laugh now) and a Porshe 924 Turbo , and my son a Cordia Turbo . I am pretty intimate with turbos ( and Dynamic Turbos Ltd) as a result.

I had a great low down gain from a large contoured dump pipe from the turbo instead of a right angle bend they had into an empty cat housing (84).

My son also gained quite a bit from a boiler tube exhaust manifold into the turbo in his 84 Cordia pre emission which was FAST. BUt they usually are buggers of things to fit as they often don't allow for such things as actually bolting the turbo on the flange.LOL.
Both will help with quicker spool up but not increase waste gate pressure.
Regards Philip A

Originally Posted by isuzutoo-eh

Would this knock sensor system be effective in a diesel engine? I can probably get the saab bits for cheap.

Diesels are less sensitive to knock than petrols. Knock in diesels is unlikely to (rapidly) destroy an engine like it will in a petrol. It is unlikely that a petrol knock sensor would work in a diesel due to the diesel "clatter".

On top of all that, extra boost (in general) in a diesel will reduce EGTs, whereas extra boost in a petrol (without sufficient fuel), will increase EGTs.

In short, turbo diesels and turbo petrols are very different.

Originally Posted by PhilipA

As mentioned by one of the er "British" posters, I have found a lot of low end to be gained in petrol turbos by freeing up the exhaust immediately out of the turbo.
I had a Charade turbo (don't laugh now) and a Porshe 924 Turbo , and my son a Cordia Turbo . I am pretty intimate with turbos ( and Dynamic Turbos Ltd) as a result.

I had a great low down gain from a large contoured dump pipe from the turbo instead of a right angle bend they had into an empty cat housing (84).

My son also gained quite a bit from a boiler tube exhaust manifold into the turbo in his 84 Cordia pre emission which was FAST. BUt they usually are buggers of things to fit as they often don't allow for such things as actually bolting the turbo on the flange.LOL.
Both will help with quicker spool up but not increase waste gate pressure.
Regards Philip A

Thanks Philip, The dump pipe and start of the exhaust seems quite large and free flowing. However I will see what can be done further.

Thanks Ben, i'll cross that set up off my list. Sorry for the hijack