Crazy idea: remove intercooler

[Swordsmith]

There's a guy at my local mechanics who owns a little pickup he's modified to be a drag racer. He's put a bigger, turbocharged engine in (I think he said it's a Suzuki with a Subaru engine, but don't quote me on that)... but more interesting to me, he's Removed the intercooler completely. Just hard piped the turbo straight across.

He says there's more power this way, and that he's only running it for a quarter mile, and by the time he gets through the line back to run again, its cool.

I was looking around (for an unrelated project) and saw some selectable gates which could direct air flow into one tube or another, selected by the driver. Think we could put one of those gates on in front of the intercooler, and another at the other end which would let air in from whichever direction the higher pressure is coming from, so we could switch the intercooler out of the loop briefly?

Would it be worth it? Would it be crazy?

Sounds crazy to me.

 

[Natesriv]

Fluid dynamics I suppose. A shorter pipe length means less time for the compressed air from the turbo to hit the cylinders, and eliminates a lot of the in line compression of the intercooler route. Good for short bursts but it's not good for long

 

[Natesriv]

Wait, am I saying that correct? Does the turbo push the air through the intercooler or does the air come from the intercooler and go into the turbo?

 

[Dogz]

Intake to turbo to intercooler to engine.

Lots of drag cars run no intercooler but then lots of drag cars run huge intercoolers. If you ask the guys not running an intercooler it's because they want the shortest intake tract possible. They use extra fuel to cool the intake charge.

 

[Swordsmith]

My vague understanding is that compressing the air with the turbo heats it, and that hot air is less dense than cold air, offsetting some of your gains. So running it through the intercooler chills the compressed air back down, recovering some of the lost density. But if this is the case, then removing the intercooler would result in less oxygen per liter, which would be counterproductive.

I guess the question is, does the reduction of lag time offset the reduced efficiency?

Or else I'm misunderstanding completely.

I was so confused about this idea that I had to ask if he meant he removed the radiator, rather than the intercooler. Which, by the way, leads me to a second crazy idea, similar to the first; could we see some gains by temporarily shutting off the water pump?

 

[Natesriv]

I'm saying yes, it's the lag of air from one side pushing against all the air in the intercooler pathway compared to less in the non-intercooler pathway. Gets to cylinder faster and for the 1/4 mile shot its max boost faster that chilled

 

[Natesriv]

Wonder if during that time the turbo is fed some air and kept at some min boost which is bypassed until go time....

 

[whitesmoke]

None of this makes any sense. Think about it. The turbo pushes the air through the intercooler and into the manifold, the boost is read at the manifold. The boost reading is the pressure of the air pushing against the back of the intake valves which is the end of the line before the air enters the cylinder, if you dont have any loss of boost pressure at wot then there is nothing you are going to do to make any more flow. You could put a 6" diameter pipe from the turbo directly to the intake port and it still has to push it past the tiny little intake valves. if the boost bleeds off as the rpm goes up then you have a flow problem, ours hold 22 psi of boost from the time my foot hits the carpet till the time I lift all the way to 6000rpm. The only thing that will increase cfm into the cylinder is more boost or a bigger intake port and valves. think of it as an air hose on a compressor, if it has a nozzle on the end it doesn't matter if the hose is 3/8 id or 2" id, 2 ft long or 100 feet long, if there is a set psi on the system the same cfm of air is going to come out of the nozzle unless you increase the pressure, or increase the size of the nozzle (in this case the intake valve) at the end of the hose.

 

[Swordsmith]

Air is compressible, unlike hydraulic fluid. So I can imagine that when you add pressure at the beginning of a large tank, that it takes time (not much time, but enough to perhaps matter in a quarter mile race) to get the entire large tank up to pressure, while a much smaller tank would fill faster.

Say you have a fifty gallon tank and a 12.5 gallon tank, you're running 15PSI in both tanks, and have a same-size compressor available for both. You turn the compressors on, won't the fifty gallon tank take 4 times as long to get to 20PSI as the 12.5 gallon tank?

Substitute the intercooler and associated tubing for the large tank, and a shorter and overall smaller volume direct connect tube for the smaller tank. I don't know what the ratio of volumes is, but the principle would be the same.

I'm not saying it -does- work this way, but at least in a thought experiment I can see how it might.

 

[whitesmoke]

I understand your theory but the arrangement is backwards. you have a huge air compressor( the turbo) on a tiny tank( the tubing) that holds not even 2 gallons of volume. the only thing a smaller tubing system would do is allow the pressure to build a nanosecond quicker to start, after that its the same thing. and if my car built any more pressure any sooner there is no way you could get the car to hook up. it explodes into 1st and 2nd gear wheelspin with slicks as it is. we actually killed some of the low end boost so the car would launch harder.

 

[Natesriv]

...only thing I can think of is the time it takes for the air to pressurize the entire tubing-intercooler-manifold volume is more than the time it takes to pressurize just a tubing-manifold arrangement. That very short period of time is everything in drag racing... tenths, hundredth's of seconds...

 

[Gio]

Every pro-mod car in the NHRA with a turbo, has intercoolers. They bring the boost up before launching the car.

 

[ChrisJ]

Removing an intercooler for more power.
All I can say is.

LOL.

 

[brandon1239]

It's called "hot piping" the turbo. When you have gigantic turbos that flow tons of air at a low psi you can hot pipe the turbo and not have as many negative effects. Between no lift shift and anti lag at the line there's not really a reason to hot pipe a turbo. Get an air to water heat exchanger if you want to see big gains on a drag car. Daily drivers and street/strip cars need an intercooler.