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Just a thought, but for the distance and resistance that the air needs to travel to a FMIC, it would seem like the IC is doing more harm than good. I would think, with my basic logic that straight-piping the air straight from the turbo to the intake would give more HP than the 1% hp gain per 10 degrees of temperature change in going to a FMIC..

Whats your thoughts:crazy::crazy:
 

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The high temps would lead to detonation. You wouldn't be able to run much boost or as much timing advance. Some sort of cooling to the intake charge is critical. A good front mount or top mount should have minimal resistance and minimal pressure drop. The difference between a good top mount and front mount in spool time usually isn't all that bad especially if you're running a turbo that needs more cooling capacity than a top mount offers, usually less than 500rpm difference in spool.
 

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Just a thought, but for the distance and resistance that the air needs to travel to a FMIC, it would seem like the IC is doing more harm than good. I would think, with my basic logic that straight-piping the air straight from the turbo to the intake would give more HP than the 1% hp gain per 10 degrees of temperature change in going to a FMIC..

Whats your thoughts:crazy::crazy:


funkymonkey1002 said:
The high temps would lead to detonation. You wouldn't be able to run much boost or as much timing advance. Some sort of cooling to the intake charge is critical. A good front mount or top mount should have minimal resistance and minimal pressure drop. The difference between a good top mount and front mount in spool time usually isn't all that bad especially if you're running a turbo that needs more cooling capacity than a top mount offers, usually less than 500rpm difference in spool.
QFT!

sea-scooby said:
Why is Subaru one of the few companies that run intercoolers? A lot of factory turbo cars don't have them.
Because subaru engineers know what they are doing! (most of the time)
 

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Frankly, it comes down to goals.

You are going to make more power with a IC. Period. The best turbos, assuming to squat on the efficency island, are at best 80% efficient. You are going to blow hot air into the intake. Hot air is less dense than cold air.

The limited supply in every properly designed engine is air. So the cooler you make it, the more of it you can get into the cylinder.

Now, if your goal isn't max power production, running IC-less might make sense. But not on pump gas. I'd never go IC-less on pump.

I have thought about going without an IC on my 2.0L with E85, but the intention isn't power. I have more than enough of that. I'm looking for better economy, and I'm looking for ways to heat the ethanol so I get complete vaporization and atomization, which is something that isn't happening with near ambient air.

But for power, considering if you have a good IC, you are seeing less than a .5 psig drop across it, its worth having it.
 

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Why is Subaru one of the few companies that run intercoolers? A lot of factory turbo cars don't have them.
The old Shelby Dodge turbo cars came both ways...

the Turbo I was sans-intercooler and only 150hp, and the Turbo II & III were intercooled and 175hp (plus forged internals)
It really comes down to cost, it works without and would cost a bit more to add it. It makes more sense to have it though since it adds a safety net for more power and reliability.
 

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The Sub kit guy
2005 Forester X & XT VF39
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The old Shelby Dodge turbo cars came both ways...

the Turbo I was sans-intercooler and only 150hp, and the Turbo II & III were intercooled and 175hp (plus forged internals)
It really comes down to cost, it works without and would cost a bit more to add it. It makes more sense to have it though since it adds a safety net for more power and reliability.
My dad had and 1984 Crysler Laser (Daytona twin) that was turboed but did not have an intercooler. I looked it up and it was a whopping 142hp!

I looked around and it seems most turbo cars do have some sort of intercooler, it just isn't as obvious as the TMIC Subaru uses. I guess the no intercooler was an early 80s thing.
 

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Why is Subaru one of the few companies that run intercoolers? A lot of factory turbo cars don't have them.
What modern turbo equipped cars don't have an IC?

The early 90's Legacy EJ22T equipped cars didn't have an intercooler and if I remember correctly they made about 160hp out an engine which later could make 280hp in cars like the 22b. So the Forester XT without an IC would probably turn out a mild but reliable 180-190hp.
 

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I looked around and it seems most turbo cars do have some sort of intercooler, it just isn't as obvious as the TMIC Subaru uses.
Most are now running a front mount behind a grill or dual "side" mounts like the audi, porsche, 3000gt, etc. Subarus odd layout and the turbo location makes a top mount make sense. Oddly, on the new 2010 LGT's with the turbo in the very front, where a front mount would actually reduce the intake piping, they stuck with a top mount for some reason.
 

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Oddly, on the new 2010 LGT's with the turbo in the very front, where a front mount would actually reduce the intake piping, they stuck with a top mount for some reason.
For the Subaru look. Pretty much the same reason NA Subies used to have scoops.
Sucks though, it would make a for a killer FTMIC. The best design IMO.
 

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For the Subaru look. Pretty much the same reason NA Subies used to have scoops.
Sucks though, it would make a for a killer FTMIC. The best design IMO.
Or just engine/transmission assembly packaging to make it easier to install on the assembly line. No hoses to run to a body mounted IC.
 

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What modern turbo equipped cars don't have an IC?

The early 90's Legacy EJ22T equipped cars didn't have an intercooler and if I remember correctly they made about 160hp out an engine which later could make 280hp in cars like the 22b. So the Forester XT without an IC would probably turn out a mild but reliable 180-190hp.
The 22b motor wasn't the same as the EJ22t. Similar blocks, not much else.

Still, the early EJ22T made 160hp/180ft-lbs.

It's all about boost.

Across a turbine, air increases temperature linearly based on a bunch of variables.

As you increase pressure, you increase temperature.

A quality intercooler will have almost no pressure drop even at high boost, but will have efficiency near 95% while moving (if not 98% or more!).

So as air flows past the intercooler (across it, not through it), you are essentially flowing air slightly warmer than ambient at a much higher pressure.

Obviously, as temperature goes down and pressure goes up, density also increases. Thus, per unit work of the turbine you are increasing mass flow.

Power is directly related to air-fuel ratio, which is directly related to air mass. Increase density and you increase mass, increase fuel, increase power.

If you remove the intercooler, you now have a decrease in air density by an increase in temperature. That means a decrease in mass flow rate, and a decrease in power.

You can realize this yourself on a funny day in Colorado. One day it'll be 70 degrees out. The next 30. Your car will make more power on the colder day, than it will on the warmer day.
 

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You can realize this yourself on a funny day in Colorado. One day it'll be 70 degrees out. The next 30. Your car will make more power on the colder day, than it will on the warmer day.
lol up here in rochester its been going between the high 60's to the low 30's. The difference is ridiculous, almost tempts me to go to an AWIC or meth injection (wish there was e85 around here, one station has it but the quality varies way too much to use).
 

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The Grand National was non intercooled and then Buick started cooling it. The power levels went up! Alot of the GN guys were/are converting to ic set ups.

I do remember seeing on Horsepower tv the banks TT kit for the chevy small block with no ic's. Typically and most aall of the time, an ic will add more than it hurts.

We added a fmic set up to my buddies LGT(what a freaking 10+hour job) and his logs showed it spooling quicker than the stock tmic.
 

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my old 88 mitusbishi mirage didnt have an intercooler, straight from the turbo to the throttle body! i added an mitsu eclipse side mount and noticed a slight difference.
 

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Why is Subaru one of the few companies that run intercoolers? A lot of factory turbo cars don't have them.
Every factory turbo car that I can think of, on the market today, uses one. Back in the day (10+ years ago) many didnt, but those cars also ran VERY low boost, in the 3-6PSI range.
 

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Every factory turbo car that I can think of, on the market today, uses one. Back in the day (10+ years ago) many didnt, but those cars also ran VERY low boost, in the 3-6PSI range.
I was thinking of alot of the 80s turbo cars.
 

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my old 88 mitusbishi mirage didnt have an intercooler, straight from the turbo to the throttle body! i added an mitsu eclipse side mount and noticed a slight difference.
That car runs very little boost from the factory. Had you added the intercooler and 3-4PSI (if not 5-8PSI) you would have noticed a lot more of a difference.




Sure, you could take a stock subaru and run no intercooler. Plan on running at the most, 5-6PSI.


I have however, heard of more than one Subie running no intercooler, and stock boost, using water injection. SUPER fast throttle response. But you are severly limited as to how much power you can make.
 

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Just a thought, but for the distance and resistance that the air needs to travel to a FMIC, it would seem like the IC is doing more harm than good. I would think, with my basic logic that straight-piping the air straight from the turbo to the intake would give more HP than the 1% hp gain per 10 degrees of temperature change in going to a FMIC..

Whats your thoughts:crazy::crazy:



A quality FMIC has less restriction than the OEM tmic. Strange but true. Its also a LOT more than 1% per 10 deg. On an STI, you would have to drop from 14.5PSI to around 5PSI, to keep engine breaking detonation away. That 9PSI will cost you somewhere in the area of 90hp. Lowering you to less hp than a WRX.

You are also not understanding just how much of a temp drop there is from the turbo outlet to the outlet of the intercooler core. I have seen cases where a VERY good FMIC dropped the temps to almost equal with the intake air temps. Considering how much the turbocharger heats the air charge up, thats a HUGE drop in temps.



Going to a FMIC allows (typically)

2 or more PSI boost increase
3-4 degrees more timing
.2 to .5 leaner AFRs

without detonation.

That will bring you closer a good 10% over the stock TMIC. On an STI, we are talking 30+hp over the stock TMIC. Without any overly aggressive tuning.



PLEASE dont take this the wrong way, but if FMICs werent worth it, dont you think that out of the hundreds of thousands of people using them, and the billions of dollars in research and development that has gone into them, not counting the decades they have been in common use, dont you think that someone would have figured out by now that running NO intercooler, or just a TMIC, works better, if that was the case? Think about it that way :)
 
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