Backpressure vs Cylinder Pressure

[PSDEng]

Bad joke I guess...

That's gettin up there though.

LOL

 

[lincolnlocker]

messed with the wg today and it gates at 32 lbs and doesnt get any higher then 35lbs. boost to bp stays 1:1 until it gets past 33lbs then bp slowly creeps up to 45lbs and egts get up there... the ratio was the same up to 35lbs before i started messing with it... but max boost was 38lbs and bp was 58lbs. so it went from 1:1.52 to 1:1.28 if i did it right. but it was kinda a turd with the gate hooked up compared to not hooked up. at wot that is...

 

[Chvyrkr]

Just because you've pushed a turbo up out of its map doesn't mean it's not making power there.

Generally it just means you'll have higher EGT's and a shorter life on the turbo.

A GT45 or 47 at 38# might make better power though, as it's still efficient.

 

[lincolnlocker]

very true.... i was just curious as to what i have been running for over a year now and flogging the sh!t out of the ol girl at least once or twice a day or even more.. im guessing a 38r is pretty stout? ive never messed with anything until i put the bp gauge in the other day....

 

[Chvyrkr]

38r isn't a whimpy turbo, but I don't know if I'd call I stout.

Lots of people running them with no gate and hybrids, and not that many people wrecking them.

 

[lincolnlocker]

most have the bigger housing too... and no bpv...

 

[Blowby]

If you can, check you increase in charge temps. Going from low or correct map location to high or out of your map will show that the air density is reduced based on temp increase. Low oxygen content per cylinder intake will lead to quite a few results if you think about it. Egt's, smoke and loss of power.

 

[JDub]

If you can, check you increase in charge temps. Going from low or correct map location to high or out of your map will show that the air density is reduced based on temp increase. Low oxygen content per cylinder intake will lead to quite a few results if you think about it. Egt's, smoke and loss of power.

Not many people think about this, thanks for mentioning it Mike. This is why the GQSSB works so well with standard size hybrids when compared to a 38R. Even at 40-psi, the compressor discharge temperatures are surprisingly low.

 

[lincolnlocker]

How would one check charge temps?

 

[JDub]

How would one check charge temps?

You need a temperature probe in the hotside intercooler pipe. closer to the turbo the better.

 

[lincolnlocker]

ok... but why wouldn't you measure the air temp in the spider after the air cools back down from the intercooler?

 

[Blowby]

I measure before and after the IC with a dual probe temp unit / gauge.

 

[Chvyrkr]

You want to note the temp difference between in and out of map.

If it's cooler right outa the turbo, so much the better after the IC.

 

[TARM]

Otherwise you are adding in measuring the efficiency of the intercooler instead of only isolating the effect of the turbo. I would think before and after is ideal.