Correct me if I'm wrong please

[chicagoavenger]

The turbo has to be under a load for it to build boost? I am about to purchase a 91 GSX and the guy selling it was showing me the motor and started it and said he didn't hear the turbo spool. I told him since he was reeving in neutral that it would only build 1-3 psi of boost since it wasn't under a load and thats why he didn't hear it. Is this correct or did I tell him wrong? Thanks

Shant

 

[Warmachine91vr4]

correct

 

[chicagoavenger]

Mucho Gracias!!!!

 

[HighPsi92GST]

yup your right. some cars can build alittle boost in neutral, others not at all. turbos boost off the exhaust heat, in neutral the engine isnt working that hard to make the car move so the exhaust doesnt get hot enough to build up boost.

though if i was looking at the car, id say "yeah the turbo must be shot, brings down the value of the car alot"

 

[97GS-TSpyder]

exhaust gass velocity(exiting the engine) not heat...otherwiase an over would make a turbo spool

 

[Defiant]

Well, before this gets too sideways...

Yes, Chicaga, you mostly got it right. "Boost" is "More air being pumped in than the pistons can let in". So yes, that pretty much boils down to being "under load".

As for the gas velocity vs. heat, the turbine is doing most of its work by taking the heat energy out of the exhaust- more than from simply being pumped by the gas flow. This is why DSMs and other contemporary turbocharged cars have the turbo mounted right on the exhaust manifold, and not like the old Ford which ran the exhaust under the pan and back up to the turbo. It's also why the thing of having the turbo back at the end of the tailpipe is such a bizarre idea.