[wash]

The biggest problem with air to air is the restriction and pressure drop.

Some of the drop is the ideal gas law: when you cool a gas, density increases and pressure drops (PV=NRT). Another drop is caused by restriction due to pushing air through long, narrow intercooler fins.

That restriction is probably bad for the ST because our core has a long path that air must be pushed through.

Air to water intercoolers can improve on that because the thermal capacity of water is high which allows for a much smaller core which means a shorter path for the air and less restriction.

The down side is you have to pump water through a heat exchanger to cool the system and the weight is higher than air to air.

So far the aftermarket options we have are thicker core air to air but still a long (slightly less) restrictive path.

Looking at a generic air-water intercooler (350 hp rating) with a nice heat exchanger and Bosch Cobra pump, it looks like going air to water might cost less than $600 which is competitive with the thick core air to air upgrades.

For an intercooler which might be more effective with less pressure drop, I'm considering it.

Packaging is a consideration but I'm optimistic. The heat exchanger seems to be the right size with inlet and outlet on the same side, small water hoses and 90° fittings should make the plumbing easy. All I need to do is figure out a place for the intercooler core and the revised, much shorter boost pipes.

So far it seems promising if it can fit but maybe I'm missing something. Let me know.

 

[[email protected]]

The one issue I see is that with the air to water system is that once the water gets hot it's hot and you have to try to cool it down again, the Cobra, GT500, Lightning guys have struggled with this for years and use all sorts of tricks like A/C cooled reservoirs or ice tanks in the trunk.

With air to air that's not an issue, you have a constant supply of ambient temp air passing over the cooler core.

-Steve

 

[wash]

I'll agree and I have heard of heat soak issues with Cobras but I would essentially be using a Cobra sized system on a car with half the power and turbochargers seem to raise intake air temps less than roots and centrifugal blowers.

If I put a heat exchanger where the factory air to air IC goes, I have the same supply of cooling air. I hope I can find a place in the passenger front fender for the intercooler, that would be a pretty straight shot from the turbo (one 90° bend), then I just have to get from there to the throttle body.

 

[moff3tt]

I thought that the water to air systems had a radiator to cool the water down? If so why not get one about the size of the stock inter cooler and put that in its place?

 

[mossdahaus]

Because of heatsoak as described above...

 

[wash]

The intercooler I've looked at has a 350 HP rating, I assume the rating has to do with how far the air travels through the core and how much water can flow through it. The heat exchangers that look like they will fit our front end are rated for 600-1,200 HP, two of the biggest heat exchangers they sell.

With a good pump and air flow over the heat exchanger, it should remove as much or more heat than air to air because an air to air has more than 50% of the area blocked by the path the intake air goes through while the water tubes in a heat exchanger block far less.

There might be more charge temperature hysteresis but that's more good than bad.

If the ratings are fairly accurate it seems oversized enough that heat soak shouldn't be "bad".

On a related note, I got an email from ATP. Their GTX28 turbo has made 305 whp on the stock fuel system. It looks like we have good head room.

If an air to water intercooler can lower the steady state load IATs, that will allow for a safer, more powerful tune and maybe even faster spool due to the smaller intake volume and less restriction.

 

[eRic]

the 1.5L ecoboost that is available in the Ford Fusion has an air-to-water intercooler.

 

[Karl Kutchi]

the cooler for the 1.5l in the fusion in intake manifold mounted, though, correct?
The 6.7L powerstroke had a body mounted air to water setup, about the size of a battery, but probably excessive for the 1.6l application.

 

[wash]

The 1.5 intercooler is intake mounted. For a retrofit, there are aftermarket options in several different configurations, I'm thinking all of them are bigger than the 1.5 intercooler core.

As long as the intercooler has low pressure drop and can transfer enough heat out of the intake charge and in to the water, all you need is a big enough heat exchanger.

 

[jon jalbert]

I had a killer chiller on my 03 kenne bell cobra, nothing like 600rwhp and 60 degree charge temps on a 100 degree day. I have an extra meziere intercooler pump and was thinking of a vortech battery icebox and a air to water intercooler.

 

[[email protected]]

It'll be interesting to see if the weight gain is offset by the performance gain. I always love to see ingenuity.

 

[wash]

I've been reading up on heat exchanger design and I think I found a better but more extreme solution than the heat exchanger that looks like it might fit like our stock intercooler.

I've found a setup with a 12*24*1" core. The thin core means air will flow through it easily, that will keep air flow to the radiator sufficient for cooling. Its got top and bottom tanks, not a double cross flow so the water will flow through it quite freely. More GPH means more cooling capacity.

A side effect of the taller height is that I can make a hole in the radiator cover panel to get to the fill cap rather than run a burp tank somewhere else. That's cheaper and convenient.

As for weight vs. performance, that's a complicated equation. The brand name direct fit Air to Air intercoolers are as much or more expensive. Can they keep intake temps near ambient for long track sessions? Steep mountains? What if your Fiesta has more than 300 whp?

Hopefully the cheap setup I'm looking at is really 600 HP capable like they say. That would make a 350 HP fiesta have nice cool intake air temps in all situations.

How much weight do you have to save if your IATs go over 160° after 2-3 laps?

Maybe ATP will take their Fiesta ST to a race track and find that their Air to Air setup stays nice and cool lap after lap with a GTX28 turbo. If they do, I'll probably go up there and buy one.

Eventually we will start finding which links are weak in a high horsepower Fiesta ST.

As far as I can tell there is exactly one 300+ whp Fiesta ST excluding rally cars (maybe). It will be a while before a 300+ whp Fiesta ST gets an extended track session to see what happens.

I'll keep planning and if air to air intercoolers are the weak link I'll have an alternative. I might do it just to do it too, we will see.

 

[wash]

After more looking, the heat exchanger I'm looking at is well liked by the Mercury Marauder crowd who love putting Cobra 4.6 supercharger setups in their car.

They do well with 500+ HP in a big heavy car, better than similar volume thick core heat exchangers.

The pump is a cobra pump so 2/3 of the setup is the same.

What I've read about the intercooler seems promising. If I can find the room for it, I think it would work well.

I'm thinking a 2JR style cowl induction intake, twin scroll EFR 6258 turbo and a air to water intercooler might be one hell of a setup in a Fiesta ST.