turbocharger??

[mikev_33]

i am in the process of buying a 86' 944t. I wanted to know what size of turbo i can put in to replace the exsiting one without having to do major modifications and gain some hp?

[AaronM]

My recommendation for street use is a K26-8 from a 944 Turbo S with either Lindsey or Guru chips and a manual boost controller at 15 PSI and a 3.0 bar fuel pressure regulator.

Should put you at ~275 RWHP (a gain of ~80 WHP) and ~300 ft/lb of torque at the rear wheels.

Anything more than that and you'll want a new head gasket and new injectors and probably a MAF. in other words, it starts getting really expensive.

At the levels I talked about above, the car is more than fast enough to get you into serious trouble though, so unless you're going for bragging rights at the dyno, there's no real reason to go further on a street car.

[mikev_33]

thanks for the advice

[Tapage]

Originally posted by AaronM
My recommendation for street use is a K26-8 from a 944 Turbo S with either Lindsey or Guru chips and a manual boost controller at 15 PSI and a 3.0 bar fuel pressure regulator..

Aaron I'm a newbie and I wana know .. last saturday, I go to ran hard in my 951, and wooouu it do it ..

When I reach 140 mph I see the boost gauge very near to 2Bar, maybe at 1.7 or 1.8 Bar .. is normal .. ?

Then 1Bar = 14.5 PSI but you said get a boost controler for 15 PSI .. obuisly I'm confused, can you explain me ..?

thanks .. !

David

[natey]

Yes, it's normal for your boost gauge to read 1.8 bar at full boost for a factory stock setup. Mine certainly does.

I think the confusion might come from what the boost is read in reference to. In the 951, "1 bar" on the boost gauge means that the manifold is at the same pressure as the outside air (about one bar). Some other cars have the boost gauge set up so that 0 is the same as the outside air, less pressure in the manifold is read as vacuum, and more is boost.

I think when AaronM says set the boost for 15 psi, he means 15 psi over atmosphere, which would read a little over 2 bar on the 951 gauge.

[AaronM]

Originally posted by natey
Yes, it's normal for your boost gauge to read 1.8 bar at full boost for a factory stock setup. Mine certainly does.

I think the confusion might come from what the boost is read in reference to. In the 951, "1 bar" on the boost gauge means that the manifold is at the same pressure as the outside air (about one bar). Some other cars have the boost gauge set up so that 0 is the same as the outside air, less pressure in the manifold is read as vacuum, and more is boost.

I think when AaronM says set the boost for 15 psi, he means 15 psi over atmosphere, which would read a little over 2 bar on the 951 gauge.

Yup, 15 PSI of boost, or about 29.7 PSI absolute pressure.

Boost pressure is almost always referred to using 1 bar (14.7 PSI, atmospheric pressure at sea level) as the "zero point". The 951 is one of the few cars that shows absolute pressure on the boost guage rather than pressure relative to atmospheric pressure at sea level.

[Tapage]

Originally posted by AaronM
Yup, 15 PSI of boost, or about 29.7 PSI absolute pressure.

Boost pressure is almost always referred to using 1 bar (14.7 PSI, atmospheric pressure at sea level) as the "zero point". The 951 is one of the few cars that shows absolute pressure on the boost guage rather than pressure relative to atmospheric pressure at sea level.

woooouuuuu slow please .. I'm not too smart ..

That means, when I see 1.8 bar in my gauge, is really 11.76 PSI of boost .. ?

Or boost is all presure in the intake manifold .. then, when I see 1.8 bar of boost in my gauge, that means, my turbo is was generating 26.46 PSI of boost .. ?

[AaronM]

Originally posted by Tapage
woooouuuuu slow please .. I'm not too smart ..

That means, when I see 1.8 bar in my gauge, is really 11.76 PSI of boost .. ?

Or boost is all presure in the intake manifold .. then, when I see 1.8 bar of boost in my gauge, that means, my turbo is was generating 26.46 PSI of boost .. ?

Turn the key to the "on" position without starting the engine. Notice that the boost guage will read about 1 bar (less if the car is at higher altitude, should read exactly 1 bar at sea level).

When the engine is running there is a suction through the intake which makes the pressure lower than atmospheric, the turbo isn't making boost at idle. Notice that the boost guage reads somewhere around 0.4 bar with the engine idling.

0.0 bar is a complete vacuum, like outer space.

0.4 bar is a _relative_ vacuum since the pressure is lower than the outside air pressure.

At full throttle, a non-turbo car will have an intake pressure roughly equal to atmospheric (1.0 bar). To get the intake pressure above 1.0 bar, a supercharger of some sort is necessary (a turbo is actually a sub-species of supercharger, but that's getting really technical).

Most boost guages show 1.0 bar as "0.0" because it's the normal air pressure and the car can achieve 1.0 bar intake pressure even without a turbo or supercharger. "Boost" is defined as manifold pressure above and beyond atmospheric pressure. So 11.76 PSI (0.8 bar) of "boost" pressure is the same as 1.8 bar of "absolute" pressure.

The guage in the 951 is really a manifold absolute pressure guage and not a "boost" guage because of the way it is scaled.

Aaron

[Tapage]

Thanks for your time and patiend .. I'm still learning. Then .. If I put a usual aftermaket boost gauge, it measurement goes about, 11 PSI aprox.

[nize]

here you go;
http://www.clarks-garage.com/951faq.htm#questions

[Tapage]

Nice and clear .. thanks .. !

P.S. also read about bar, presure, and all terms related !

[nize]

good to hear. welcome to the 951 world!