DCAWD.com

surf any Subaru site and you'll see a lot of cars that are built to the same standard. if you want to impress me, do something new or different. otherwise it's just *another* nice STi that I can't afford.

now that custom pained off white STi with the matching cage and HRE wheels that was posted on NASIOC a while back? THAT was an amazingly clean Scooby.

sirwilliam wrote: You are correct in the fact that FMIC causes some lag but if you want big power, you have to go front mount a TMIC is good to about ~20PSI.
Also, FMIC is good that you don't get heat soak. Lag doesn't mean much once the power kicks in. Sure the guy w/ the TMIC is 1.5 car lengths back off the light for about 2 seconds but then the FMIC guy's turbo spools up and jumps about a football field length ahead. But of course you have many variables: power, aerodynamics, weight, traction, tranny, etc...

I'm just a nit-picky nerd. Learned all this stuff in college (automotive engineering, actually got my ASE certs), and so when I see people just throwing parts like FMICs on their cars it makes me twitch. Even extremely highly tuned supras have hard on road courses with FMICs because they can't get enough flow to the radiator. At some point you have to consider water, nitrous, lowering the compression, repositioning the turbo, redesigning the exhaust manifold (or intake manifold), and so much more.

Matter of fact, I'm gonna just recommend the Maximum Boost book by Corky Bell. We had that as a textbook back in the day. Since I was also taking aircraft gas turbine engines, I got this idea in my head that I wanted a car that was essentially turbine powered, with a 4-stroke motor for an air pump. Those diesels with propane injection are almost doing that now. Ah, dreams. What happens when we're not really doing work.

sirwilliam wrote:You are correct in the fact that FMIC causes some lag but if you want big power, you have to go front mount a TMIC is good to about ~20PSI.
Also, FMIC is good that you don't get heat soak. Lag doesn't mean much once the power kicks in. Sure the guy w/ the TMIC is 1.5 car lengths back off the light for about 2 seconds but then the FMIC guy's turbo spools up and jumps about a football field length ahead. But of course you have many variables: power, aerodynamics, weight, traction, tranny, etc...

Having a FMIC is more a function of the volume of air you are moving, not the pressures that it is at. TMIC can be used at 30PSI, but low volumes of air. The thing is, typically when people are upgrading their turbo's, the efficiency range of the turbo is at higher boost pressures. These turbo's also flow a lot more air. My SZ55 flows much more air at 15PSI than a VF39 at 15PSI. The need for a FMIC arrises when the TMIC starts getting overwhelmed from the amount of air that it is trying to cool. Hence, heat soak

sabre wrote:

sirwilliam wrote:You are correct in the fact that FMIC causes some lag but if you want big power, you have to go front mount a TMIC is good to about ~20PSI.
Also, FMIC is good that you don't get heat soak. Lag doesn't mean much once the power kicks in. Sure the guy w/ the TMIC is 1.5 car lengths back off the light for about 2 seconds but then the FMIC guy's turbo spools up and jumps about a football field length ahead. But of course you have many variables: power, aerodynamics, weight, traction, tranny, etc...

Having a FMIC is more a function of the volume of air you are moving, not the pressures that it is at. TMIC can be used at 30PSI, but low volumes of air. The thing is, typically when people are upgrading their turbo's, the efficiency range of the turbo is at higher boost pressures. These turbo's also flow a lot more air. My SZ55 flows much more air at 15PSI than a VF39 at 15PSI. The need for a FMIC arrises when the TMIC starts getting overwhelmed from the amount of air that it is trying to cool. Hence, heat soak

That was in reference to cooling but thanks for "layman"ing it out for us...I guess I wasn't specific enough. And yes, it varies w/ the size of turbo as well for efficiency. Lets just compare it using the same size turbo.

Julian, you know somebody w/ a suby running 30PSI while using a TMIC? Wow, must be a pretty sweet setup.

lol, didn't say I knew someone doing it

Technically, it could be done as long as it was a water to air incooler (hey, it's still top mount!) and they used Meth/Water injection I know of no turbo's that flow low amounts at those boost pressures though. All the ones that can reach those pressures flow huge amounts of air, haha.