how much can the intercooler do?

[bottledbird68]

O.K., this might seem basic, but I'm a little confused and can't seem to find an answer. I was furthering my knowledge by reading tha advanced tuners forum when I happened across "is 13 psi = 13 psi" and I had a question. I understand that a larger turbo will run cooler, thereby giving you more density and therefore make more power but could you run a smaller turbo with a big intercooler and get the same effect? An exaggertated example, 14b with a huge fmic vs. a 20g with a stock smic. Just looking for some theory on the hows and whys of how it works. Bear with me as I'm new to turbo's and efi. I got this car to broaden my horizons and wound up loving to drive it. Only problem is now I'm so full of questions... just curious

 

[RocketBoy]

In short, no. The biggest problem you're going to run into is pressure drop when using a large front mount intercooler. The larger turbos can make up for it as they are efficient in much larger and higher boost ranges, but the smaller ones can't (t-25, 14b). Think of it like this: You have an intercooler with 2psi pressure drop and a 14b. You want to run 16psi. The 14b will have to make that 16psi + 2psi in order for your motor to get to 16psi. That is already 18psi and you are on the verge of inefficiency. That is my understanding, but i'm sure someone will elaborate more eloquently.

 

[redlined_GS-t]

Well I think what you are wondering about , 13psi=13psi, is that a 14b will make the same pressure but will only flow approxiamately 400cfms of air volume. It really does not come down to pressure but the whole thing of cfm volume and density. Yes a FMIC will drop air temps and make the air more dense. I would not try to compare a 20g to a 14b, the air volume that these two turbos push is no where close to one another.

 

[bottledbird68]

I totally understand that 14b and 20g is apples to oranges. My question was that if air temp is equal to air mass could the intercooler make up for some of the ineficiency of the smaller turbo? What I didn't think about was the pressure drop of the larger ic. Any other thoughts or opinions?

 

[bottledbird68]

P.S. I'm not looking to do this, just looking for some theory...

 

[BoostinAWD]

Air is power, the 20g flows around 650cfm? and the 14b flows 405cfm.

So really it comes down to how much air is entering the engine. CFM and PSI are 2 totally different things.


Think about it, say you have a 1inch upper intercooler pipe with a turbo pushing 20psi through it into your intake manifold, and then you take and install a 2 1/2 inch upper intercooler pipe and then push air through it at 20psi.. Which is gonna flow more?

1inch pipe being the 14b
2 1/2 inch pipe being the 20g

So just think of why the 20g would make more power than a 14b. All the intercooler is doing is preventing detonation at those psi's.

If this doesnt make sense oh well I tried

 

[Enigma_Man]

Gaah, not this again Air is power yes, but the engine is what governs how much CFM moves through the system. You can't force CFM through an engine without raising pressure. At a certain pressure, and engine is going to take a certain CFM, even if the turbo can provide more CFM, it won't, because it can't. You just can't push more air into a closed box without raising pressure.

-Jesse

 

[twistedtsi]

then how come u see these big front mounts for sale and say (applys for 14b and up)????

 

[Enigma_Man]

A big frontmount _will_ help out any turbo you have. However, if the frontmount you get is restrictive, then just remember that your turbo is actually producing the boost + the pressure drop from the intercooler.

That's all

-Jesse

 

[kscott]

If the turbo is too small for the job and the intake air coming out of its
compressor is hot because it's getting churned up a lot, the energy to do
that churning had to come from somewhere. Guess where it comes from?
The exhaust has to spin the turbo to provide the energy, both for
compressing the incoming air, as well as for the friction that's making that air
get hotter than it would naturally. That extra work that the exhaust is having
to do means that you've got a larger pressure difference across the exhaust
side of the turbo.

So, you could use a big intercooler to cool off the intake air, but the engine
would still be seeing higher exhaust backpressure than you'd like.

Kevin

 

[bottledbird68]

O.K., this is all making a lot more sense to me now. Thanks guys. Any other thoughts? Just curious...