Given the same engine, lets say for instance a 2.0 liter mitsu evo engine, why do two different turbos both regestering the same boost/psi make different power. I've noticed that a small turbos pushing say 10 pounds and a large turbo also pushing 10 pounds have different dyno results. So why does a signifigantly larger tubro, although registering the same psi on the boost gauge as the smaller unit, make much more power than the smaller turbo unit?
Thanks for the help.

 

Its simple, a bigger compressor makes more power at that psi. The bigger compressors also run cooler because its not turning as fast plus the cfm of a t78 is much higher than a t3/t4. Its like asking at idle why does a 2.5 4 cylinder produce more exhaust pressure than a 1.5 4cylinder... I hope i helped

 

Isnt the psi a measurement of the pressure reading coming off of the turbo? If this is the case then how do two identical psi measurement produce different power ratings? I do understand the heat thing you mentioned, that makes sense. I still dont get the differential in power output between the two which output identical pressure.

 

Okay if you have a small turbo pushing 10psi the cfm is much lower than a large turbo pushing 10psi. Its like saying a 1000lb car thats going 60mph has the same force as a 10000 lb car going 60mph...

 

thanks peak.

 

Np

 

Whoa. Thank you guys. I've been wondering about that for some time. I appreciate the help. I had an idea that was close to what Peak said, so that just confirmed that.

 

you just have to remember that the smaller turbo makes 10psi at lower rpms and the larger one makes it at higher rpms. less turbo lag on a small one off the jump. that is what was so beautiful about the RX7. the turbos were different sizes so it virtually eliminated turbo lag.

 

Actually the smaller turbo spins faster, the impeller wheel is smaller so it spins much faster and gets much hotter. The turbo lag is caused by your exhaust side of the turbo, if the wheel is too large this will create lag. The A/R ratio also plays a part in lag, the higher the A/R ratio the more lag you will have. The RX7 had a sequential twin turbo setup which means below a certain rpm only one turbo was working, once the engine got to a certain rpm the second would come online and both would work to create great boost at high rpms so the boost doesnt die out by one small turbo. The supras came with the same sequential system, very good system but a lot of guys now make both work at the same time which increases lag but increases power. Turbochargers are awesome!

 

Good analogy

 

That's why they need 3 turbos. lol

 

LoL There was a supra owner that actually had a tri turbo supra. It was around 700hp but the engine bay was filled with intercooler piping, it looked really cool.

check it out http://www.tuningfever.com/displayim...427&fullsize=1