Compound and Parallel turbos.

compound are your typical twin setup, one turbo feeds the other. parrallel turbos are 2 of the same size typicaly one on each bank (V-8) that Y together at The intake.
 
Compounds will allow you to run higher boost numbers while keeping both chargers in a livable pressure ratio.
 
What kind of twin settup do they MOD sled pullers run? Most of the time I see the big charger right against the grill on the front of the truck and the small charger close to the block in the stock location. Im sure this is for the hood stack correct? is it piped the same as compounds when ran this way?
 
If you want more than 50PSI gauge boost, you need to start shopping for compound twins. Singles are lousy at going past 5:1 Pressure Ratio, which is 60PSI at the gauge.

With compound twins, the first charger builds boost from outside air, then the second charger takes that air and builds it more. It's the only way to go past 70PSI that I know of.

Parallel twins probably has little application in diesel racing other than packaging. Any advantage you get in spoolup is pretty much pointless. You are even more limited with peak boost with small chargers. The big chargers are the ones with good high pressure ratio performance. This is why the Banks truck will not do well without nitrous IMO.
 
McRat said:
If you want more than 50PSI gauge boost, you need to start shopping for compound twins. Singles are lousy at going past 5:1 Pressure Ratio, which is 60PSI at the gauge.

With compound twins, the first charger builds boost from outside air, then the second charger takes that air and builds it more. It's the only way to go past 70PSI that I know of.

Parallel twins probably has little application in diesel racing other than packaging. Any advantage you get in spoolup is pretty much pointless. You are even more limited with peak boost with small chargers. The big chargers are the ones with good high pressure ratio performance. This is why the Banks truck will not do well without nitrous IMO.
Click to expand...
I'm not a turbo genious by any means, but I was told that boost is more a measure of head restriction, than actual airflow. That being said, wouldn't parallel turbos both pushing 50psi(lets say 1000cfm each) perform just as well as a compound setup with a initial boost of 50psi(at 1000cfm again) and a larger pushing it to a total of 100psi? Would double the boost equal double the airflow? I know what chargers you use reflects directly on CFM/boost, but wouldn't parallels spool faster than compounds with the same CFM? Or am I missing something? I realize V-motor vs. Inline motor throws another variable in there too....
 
Bigger wheels are better at higher pressure ratios. It's a centripetal force thing.

Yup. We want oxygen in the cylinder. Boost does not equal oxygen, but if the temp is the same, more boost = more oxygen.

Unless you need throttle response (we don't), spoolup time is not as important as other things.
 
so for pulling a compund would be the gold ticket. but(just throwin it there) but wouldnt a parallel turbo with 3.os be amazing
 
Parallel 3.0 chargers would not touch compounds due to still not operating past about a 5-1 pressure ratio, also would spool very slow with that big of charger.
 
Engine can only swallow so much air. Even if you are pushing 2000 cfm of air, the engine wont take it in. The more boost, the more air you can force in the cylinder. The only advantage parallel turbos have is cooler intake temps since air is only heated once. But like McRat said, when you try to push 60 psi out of a single turbo, you super heat the air.

Parallel turbos pushing 30 psi will make more power than twins pushing 30 because the charge of air will be cooler so you will in fact force more oxygen into the motor. Big power out of a small engine takes a lot of oxygen in a small volume read density ratio. Twins compounds accomplish this by high psi and using the charge air cooler to remove excess heat.
 
You must log in or register to reply here.
Back
Top