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11/03/2006 13:16:21   Rob   hi im considering doing a twin turbo v4 conversion on my saab,
what engine specs would you guys recommend?

so far:
use two gt12's - i know these come on smart cars but unfortunately they have acustom manifold - anyone know any other petrol turbos?

use forged taunus pistons, sorpio rods, arp bolts, 1700 crank and copper head gaskets.
intercooler.

rockers? valves? springs?

probably use a 2bbl manifold and use a megaquirt ecu or similar.

what can a "good" gearbox stand?

thanks
Rob
 
11/03/2006 15:45:18   julian   Rob, I cant help you with the rest, but as far as I know, a "good" gearbox is ok for about 130bhp if treated with respect. That means pulling away steadily and no drag starts. Abuse would surely kill the box in no time. I understand that you can beef up the box to take more than 130bhp, but I am not sure how it is done. Thanks, Julian.  
11/03/2006 22:11:05   Alex   A twin turbo with Smart turbos were my thoughts as well, but you need to resolve the fact that one turbo must be the mirror image from the other in order to get the inlet pointing forward to the place where the intercooler would be at its best. I have no idea if this mirroring can be done easily. Bolting the turbo to the exhaust manifolds shouldn't be too much of a problem; basically it comes down to bolting a big hole onto a big hole. Who needs a manifold? You need a cast iron gearbox casing to get a better change of survival, unless you manage to come up with other technologies to keep the gearbox together. If you are succesfull in that field and are willing to share your knowledge you will be worshipped in the V4 community. Take a look at the Grean Beast website. Kalle is converting his V4 into a Turbo, although he is using existing Saab technology. He has an interesting approach towards the inlet manifold. Don't use a 2bbl for it. With a bit more tinkering with alumimium tube and someone who can weld aluminium you can make yourself something less restrictive (I realize that writing this down is far simpler than doing it:)).  
12/03/2006 14:41:05   Rob   where can you get an cast iron housing from?  
12/03/2006 19:19:11   Al   As Rich Simpson has mentioned frequently, his "standard" box (casing, not ratios!) has coped with close to 150bhp, but that's a revvy 1815 N/A motor, not a turbo with stonking great dollops of torque low down. Additional gearbox mounts like the "Mexico" brackets will help reduce casing flex.

If you can find a cast gearbox casing it will certainly help prolong the life of the box, but may not help the components inside forever. Early 4 speed strokers had a cast box casing IIRC so this MAY be easier to find than the S&R item, but both are VERY rare now.

"Anyone know any other petrol turbos" - yes loads, take yer pick of any Saab installation for the last 30 years, but all too big to run for this project!

Have you given any thought to what CR you'd want to run and how you would get it down to a level low enough to cope with the turbo(s)?

The old Daihatsu Charade GTti would have something that might be small enough to use two, no idea what model of turbo they are, though I guess a trawl round the Net would help...

Out of interest, why do you want to go for the complexity of two turbos and not one? As well as the complexity of fitting two, if you end up with turbos that are too big they won't spool up very well or quickly and you'll have horrendous lag and/or knack all boost.

Fuelling could also be a problem with the 2bbl manifold, I doubt it would flow enough, from memory about 125bhp was the max on a single carb no matter how fat. A custom intake manifold (or a moose-horn) would be the way to go.  
13/03/2006 11:05:27   Derek   Random thoughts and not based on experience!
To keep a turbo working well it needs to be close to the exhaust manifold. Gas is then hot and fast moving which is what the turbo needs to work best. Unfortunately the V4 doesn't really have an exhaust manifold and to place a single turbo in a 96 means a long run to Siamese the 2 equal length pipes. By then the gas will have lost a lot of it's energy even with exhaust wrap etc.Means the turbo will have to centre front or back. neatest at the back with an intercooler and pipe to whatever carb/inj unit unit/inlet manifold you decide to use. 2 small turbos tucked under each side would solve the heat loss problem but the exhaust pulse would far from smooth. Exhaust pipes could exit in approx the same place though and the intercooler wouldn't have so much heat to contend with. Looks a better idea on paper. There are 1 or 2 motor cycle turbos around.
Think I'd have some bonnet vents :-)  
13/03/2006 16:53:09   Richard   You might be better taking the exhaust into one behined the engine and using one turbo where the heater box is. The exhaust can go through the back of the floor and the turbo is close to the inlet manifold. I have a photo of a setup like this I will email you it.  
14/03/2006 00:02:14   Al   Here is some stuff on the Mike Woolfe/Barry Marsden 96V4 turbo built in the 80s, as posted by me on Central some time ago, based on info from an article in one of the classic mags...

1500 crank, +30 thou overbore (so not quite +1mm, ~ 1520cc)

Heads ported & gasflowed, combustion chamber opened up to lower the CR (doesn't say to what), bigger exhaust valves, std size inlet, all in 214N stainless.

Asymmetric Burton cam, timed to standard. Polished & lightened rockers, standard pushrods, all blue printed & equalised.

Baffled sump, additional rocker cover breathers & oil return for the turbo.

Weber 32/34 DMTT carb on modified manifold.

T3 turbo, fabricated exhaust, fabricated intercooler to LHS of slightly relocated rad, oil cooler in front valance. Early V4/long-nose 2 stroke round lamp grille.

All flexible fuel & brake lines in proper Aeroquip, solid lines in Kunifer 10 brake piping.

Pukka Saab 5x15 minilites, 185/65 tyres (IIRC he had BF Goodrich on when I saw the car) S&R front springs, I know from speaking to Mike at the time that they tried S&R rears but didn't like the progressive nature as "the car kept swapping ends" and ended up with custom static rate rears. I believe they fitted billies all round too. 1 deg -ve camber up front with 4.5deg castor. Custom strut brace in 18/80 stainless.

Fly off handbrake. Totally refitted interior with custom dash using Sport gauges, 900 seats incl rear head rests, leather/ally s/wheel. Electric mirrors, modified rear wings to move the swage line up giving more space for the tyres, 96GL DRLs, 96L rubber bumpers.

116bhp at the wheels...

Without doubt this was/is??? one of the best 96s I have ever seen and beautifully engineered by Mike & Barry. Just wish I knew where it was now...
 


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