Ok, now that I have your attention and you are ready to jump on me, allow me to explain...

The device commonly referred to as an intercooler on our trucks is technically an aftercooler. In all other high speed centrifugal compressors, the cooler after the last compressor stage is an aftercooler. The coolers between compressor stages are called intercoolers. I know that in our case the cooler is in-between the compressor and the engine and that’s where it got its name, but its actually incorrect...

So now back to my question.... Why doesnt anyone run an INTERcooler between the primary and secondary turbo? I was scoping it out, and it you move the front bumper forward an inch to inch and a half, and move the grill brackets the same amount forward on the hood, plus a little sheet metal work on the hood, you could have an intercooler AND your aftercooler..

Using this setup, intake air into the secondary turbo would be cooled down to about 110°F or better depending on outside air temp, and assuming 15 to 18 Psi leaving the primary compressor, would put your density about at .14 #/Ft^3. Which by the way, as it pertains to my other question on the forum, would put you smack in the middle of a cute little HX30 compressor for a 450 to 500 HP twins setup...

I notice allot of guys using an HX35 at the secondary compressor, and that’s a good fit if the air is entering at 250°F and the density is down at .105 #/Ft^3 and your shooting for 600 HP. But I do feel that an HX40 is WAY to big as a secondary compressor, for anything less than 700 HP... Subject of another debate at another time I suppose...

In my calcs, I am using mass airflow of 3,700 Lb/Hr for 500 HP if you are wondering. That’s only about 20% excess air, and I know allot of you guys like to run way more excess air than that to overcool your exhaust and waste horsepower and loose efficiency But that’s again another subject for another heated debate....


Kevin

 

There's a lot of extra plumbing, along with the sheetmetal work. Plus you gotta redo the paint, and the truck would look funny with the bumper sticking out. It makes for a much bigger project than twins with an aftercooler, I'd say that's why it isn't done.

 

Theres a pulling truck out there that runs an "Intercooler".

 

Probably because there's no room. Most guys also buy twins that are bigger than what they need so they have room to upgrade in the future. I know that's what I'm gonna end up doing.

 

I have seen setups where they run the air through the stock intercooler inbetween stages. Then run it over the top of the valve cover into the motor. Less likely to burst the stock intercooler by only running the boost from the primary turbo through it. For those having a hard time imagining... they would run the intake pipe up and over the fan, inbetween the fan shroud and front of motor and then feed it into intake on secondary turbo. I think it would probably be a great setup if you ran water meth with it also.

 

Now that sounds like a good idea, just put the "Chemical aftercooling" in the pipe over the top of the engine. If I ever do twins I think that's how I'd like to do it.

 

I dont think I want to try and shoe horn any thing in between mine its tight enough in there.

 

A true intercooler would be a plumbing inghtmare. It's hard enough to even see the oil filter now, I can't imagine how tight it would be with additional piping. The only cooler that may be small enough would be an air/liquid intercooler and those aren't within the rules for any DHRA classes. Then again, there's not a lot of stuff that DHRA considers legal for the street classes.

brandon.

 

There was a pic floating around that what it looked like a water to air intercoolers, after each Turbo.

 

Can you say lag? would be fine for a pull truck or a dragster, but that's a whole lot of air to get moving!

 

One downside to a intercooler vs. a aftercooler is that if the top turbo lets go (generally the weaker of the two) it'll tend to throw big chunks of aluminum right into the motor. Having the intercooler after the turbos keeps the biggest chunks from ever reaching the motor

 

My dad always talked about it not really being an intercooler but an aftercooler.

I got to thinking and after going to a car show this weakend I have an idea.

Take the plumbing from the bigger turbo and go through the stock aftercooler which is now an intercooler plumb back to the smaller turbo and then have a intercooler that goes from the smaller turbo across the top of the motor and them 90s into the intake like the non itercooled first generations. You would have to get a custom hood scoop made but I think it could be done.
The set up on a subaru wrx is where I got the idea.

 

I doubt you'd notice a difference on the street.

Forrest

 

Eskimo, on the contrary. Spool-up is enhanced. Remember, a centrifugal compressor is a density machine.. It works because of the weight of air. Cooler air is more dense, and the top turbo will begin to make pressure sooner with cool dense air. The volume of the system does not have much effect at all, the lag more a function of turbine-compressor spool up and how much energy is available early on in the exhaust gas to drive the turbine and how the area of the turbine is sized relative to the mass exhaust gas flow ( housing size in cm^2)...


Idaho CTD, I am not suggesting the elimination of the aftercooler, I am saying that both the intercooler and aftercooler would be most advantageous.

Kevin

 

I thought the haisley's machine truck ran an A/C evaporator as an intercooler on the pulling truck. Maybe a false rumor. Very dense cool air. laso power. just a cool thought.