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Water-air intercooler performance

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Old 09-13-2018, 04:10 PM
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TastyBacon
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Default Water-air intercooler performance

I need to post a build thread at some point but I've just been having too much fun driving and tuning, so here's the short story: 5.3L with an old TTi twin T28 kit. I replaced the dual TTi air-air intercoolers mounted in the corners of the front bumper with water-air intercoolers in the same location, plumbed to a ZL1 heat exchanger sandwiched in front of the factory cooling stack, Bosch pump. Running 50/50 water/glycol, no tank/reservoir in the system.

This is the first turbo car I've built/tuned/logged myself, and my first experience with a water-air intercooler system. It seems to work okay, but I don't really have anything to compare it to, so I thought I'd post up a screenshot from my last log and see what you guys think.

This is zoomed in on a pull through 2nd and a little bit of 3rd. The car was pretty well heat-soaked at the time; I had been driving it hard and just spent a few minutes parked going over the tune. Outside temp was 75F, IAT starts at 109F, then drops to 106F as I accelerate. It peaks at 124F after I let off, then 26 seconds later, it's back to 106F. The system has a pretty small heat capacity without a reservoir, so it would probably suck for HPDE/track day use, but I guess the plus side is that it seems to recover quickly. This is just intended to be a street car anyway. I don't know, what do you guys think? Interesting experiment, or waste of time? I'd really like to compare against a big single air-air setup, since that's the other option I considered before deciding to get weird and try water-air.

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Old 09-13-2018, 08:56 PM
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cool test!
not familiar enough with the logging software to really read that, but what i do know is that capacity would be your friend in combating coolant heat-soak.
what orientation is the ZL1 brick in that stack? if it's flat against the rad & condenser, that won't provide as good of cooling as having it perpendicular (flat across the bottom opening) - assuming there's space to do so. i ain't sure how the dimensions compare to my TVS heat exchanger.
another tip i got from an intercooler company is to run a 25:75 mix of glycol:distilled water rather than 50:50 for better heat transfer.

i'm also curious... are they rigged up in series, the corner ones feeding the center, or something else?

shoot, i should have a stock Magnuson reservoir (1gal, give or take) collecting dust in a few weeks - we could maybe work something out if you'd like to try adding that in. it's designed to sit right on top of the battery (if yours is still in the stock spot).
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Old 09-13-2018, 10:39 PM
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Thanks! The heat exchanger is mounted flat against the A/C condenser, separated by 1/2" adhesive foam strips on the end tanks. One of my goals was to avoid screwing up the factory cooling system, so I left it alone as much as possible for now. Engine coolant temps are still great with a stock radiator and the A/C still blows nice and cold. The heat exchanger is just attached to the condenser with those plastic ties that come in cheap trans cooler kits; if I made some brackets for it, I could mount it a little lower and tip it forward to catch all of the airflow. That would mean a little less for the the A/C and radiator, but it seems like it would probably still work.

Yeah, I could definitely run less glycol, could even run straight water now that my garage is heated.

It was plumbed this way just out of convenience for mounting things and for a minimal amount of plumbing:
ZL1 Heat Exchanger Lower Port -> Bosch Pump -> Driver's side Intercooler -> Passenger's side Intercooler -> ZL1 Heat Exchanger Upper Port
Yes, I know the driver's side will always get cooler water, but all the air gets mixed together before it goes into the engine anyway, so who cares?

I like the design of that Magnuson reservoir, but I'm not sure I could fit it. I went with a smaller battery to make room for a Mighty Mouse catch can in the battery tray area. The engine bay is really packed...

I went looking for pictures and this is the best I could find. It's from when I was first test-fitting the heat exchanger. I later moved it down lower so the shroud would fit better; the bottom is flush with the bottom of the A/C condenser. I realize now I didn't take nearly enough pictures of the intercooler setup because it was one of the last things I did and I was in such a hurry to drive the car after working on it for 6 months, but I have a few more I could post.
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Old 09-13-2018, 11:07 PM
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More pictures.

Here's the driver's side from when I was just mocking it up, lots of pieces missing.


Passenger's side with a mounting bracket and a water fitting:
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Old 09-13-2018, 11:23 PM
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This is how TTi originally mounted their dual air-air intercoolers in the bumper.
Even with the brake ducts and fog light shrouds removed, there just wasn't much airflow for them, and based on what I've read, they never worked that well, which is why I decided to try something different.

Last edited by TastyBacon; 09-13-2018 at 11:33 PM.
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Old 09-14-2018, 12:34 AM
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well, that's what hot-rodding's all about!
if you've got something that ain't quite cutting it for your application, you find a way to make it better & rig it up!
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Old 09-14-2018, 01:43 AM
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Nice work!

What cores are are you using for the charge coolers? I’m guessing frozen boost from the looks of them? Once you have the bugs ironed out you could look to upgrade them as I hear there are better / more efficent cores out there (Garrett for example). Also have you considered mounting HEs in front of the chargecoolers? That would give you more capacity and a little more cooling. The flow path would be main HE - pump - drive side charge cooler - drive side HE - pass side HE - pass side charge cooler - main HE. You could maybe use the new ZL1 chin mounted HEs as well then? Just a thought.

have you thought about a trunk mounted water tank? The ZR1 guy sometimes use them. Would also give you the option of running ice in the system as well then. A tank is only going to hold off heat soak, and once it’s fully heated it’s going to take longer to recover. People seem to forget the tanks DONt cool the water they just hold it!

ace work thougb and nice to see someone trying something different!
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Old 09-14-2018, 10:01 AM
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I like the idea, I've been toying with the idea of running a large A2W intercooler with a remote ice/water tank in the trunk. Pretty interested to see how this works out long term as you continue tuning/modifying the system to reach max efficiency.
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Old 09-14-2018, 12:58 PM
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Thanks! Yeah, they're the generic Chinese water-air coolers, same ones Frozen Boost sells. Typical Chinese stuff, seems like there's one manufacturer cranking them out and lots of people putting their names on them. I got them on eBay, GPI Racing brand, $118 each. The ones on eBay seem to show up and disappear sporadically, so I was lucky to catch a deal. They're a couple bucks more at Frozen Boost but they are always in stock there. With a $100 ZL1 heat exchanger and a $90 Bosch pump, the whole setup is in the same price range as a decent quality large single air-air like a Treadstone. I was pleased to see that they're actually water-air cores; the water passages are half the size of the air passages. The only complaint I can think of is that they're pretty heavy for their size; the cast end tanks are very thick and the end plates for the water fittings are 3/4" billet. They don't leak, so I'm happy.

Interesting idea about adding additional heat exchanger(s). I haven't seen the ZL1 "chin mounted" units anywhere; got a picture of them? Now that I think of it, I have a hose running across the car, right under the radiator, from the driver's side intercooler to the passenger's side intercooler--why not put a heat exchanger in that path too? The flow would then be:
Main Heat Exchanger Lower Port -> Bosch Pump -> Driver's side Intercooler -> Intermediate Heat Exchanger -> Passenger's side Intercooler -> Main Heat Exchanger Upper Port
Seems like I might need a second pump or a better pump to supply two intercoolers and two heat exchangers?

I could go with two shorter, thicker heat exchangers like this, instead of the ZL1. For $100, I think the ZL1 is pretty good price/performance, but I don't think I have room to sandwich two of them together.


Yeah, my drag racing friends don't understand why I didn't just go straight to a big ice-water tank, but this is not a drag car. (Why would anyone build anything other than a turbo LS drag car? Does not compute.) It would be fun to be able to toss a bunch of ice in the system and make some passes with low IATs, or see how long it would last at a HPDE. If I could get a 20-30 minute track session out of an ice-water setup, that would be pretty sweet, but based on what I've seen from drag guys I don't think it would last that long. I don't want to haul a big water tank around or run water hoses the length of the car when it's going to spend 95% of its time on the street, so I never really considered the big ice-water tank option too much.
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Old 09-14-2018, 03:31 PM
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I was thinking a similar thing about a second HE like you mentioned! It could work and it’s similar to what the C7s use as an aux rad. Only concern would be it impacting airflow to the rad... who knows but worth a go!

the chin coolers are from the gen 6 ZL1s so might be expensive still.if you could squeeze them in there though the would definitely help and not impact the air to the rad.

You wont get an ice tank to last 20, I bet it wouldn’t last a lap! Lol

alsp how much power and boost are you making?

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Old 09-14-2018, 04:49 PM
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It's just running off the wastegate springs right now. There's a manual boost controller in there but it's turned down to like 1psi, so not really doing anything, maybe helping spool a little. I am seeing 8 psi in 2nd, tapering to 7 near redline. I see 9-9.5 psi in higher gears. I guess it's making 500ish crank, doesn't have enough injector for a whole lot more than that as shown in the log. I'll get it to a dyno eventually, probably not until next year though.
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Old 09-15-2018, 09:18 AM
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Following. I would love to do another A2W setup, just trying to keep the weight down. Those aren't bad IAT's either. I think once you get a proper reservoir to add capacity it'll work even better.
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Old 09-15-2018, 03:26 PM
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i ultimately deciding to just add a KillerChiller setup that uses the a/c compressor & freon to cool my intercooler water down.
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Old 09-15-2018, 03:47 PM
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Yeah, the weight starts to add up quickly with a water-air setup. I don't want to know how much I added, but when you're building a race car, it does matter.

I really like the KillerChiller concept. The goal is just to move heat from one place to another--the car already comes with a powerful and efficient heat pump system installed, why not use it?
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Old 09-15-2018, 04:06 PM
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The more I think about it, the fact that my IATs started at 30F over ambient bothers me. Yeah, the car was hot, the water-air system was a little heat-soaked, but come on, it was 75F out! I should be able to do better than that. My filters are on long (and definitely restrictive, but that's another can of worms) snorkel-like pipes that go up and over the radiator. With intact fog light shrouds and a factory radiator shroud, there's barely any flow of cold air in that area. I'm pretty much just sucking engine bay air. I think I'm going to cut some rectangular holes in the radiator shroud below the filters, and maybe even angle the filters down into the holes a bit--that should allow them to draw off the cold (and slightly pressurized, at speed) air in front of the radiator. I don't think it will affect the cooling system too much.



Last edited by TastyBacon; 09-15-2018 at 04:07 PM. Reason: added blurry photo
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Old 09-16-2018, 03:31 AM
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Originally Posted by TastyBacon View Post
Yeah, the weight starts to add up quickly with a water-air setup. I don't want to know how much I added, but when you're building a race car, it does matter.

I really like the KillerChiller concept. The goal is just to move heat from one place to another--the car already comes with a powerful and efficient heat pump system installed, why not use it?
you cant argue that the AC chillers donít work, they clearly do! However they arenít the cure for all A2W issues! They take a decent amount of time to reject the heat from the water. And where is all that heat going? Right in front of the radiator!

i think they could work great for track or street cars when you have time to pull you water temps down. They are basically like running iced water but that you can refill on the move.
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Old 09-16-2018, 03:37 AM
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Originally Posted by TastyBacon View Post
The more I think about it, the fact that my IATs started at 30F over ambient bothers me. Yeah, the car was hot, the water-air system was a little heat-soaked, but come on, it was 75F out! I should be able to do better than that. My filters are on long (and definitely restrictive, but that's another can of worms) snorkel-like pipes that go up and over the radiator. With intact fog light shrouds and a factory radiator shroud, there's barely any flow of cold air in that area. I'm pretty much just sucking engine bay air. I think I'm going to cut some rectangular holes in the radiator shroud below the filters, and maybe even angle the filters down into the holes a bit--that should allow them to draw off the cold (and slightly pressurized, at speed) air in front of the radiator. I don't think it will affect the cooling system too much.
Good idea! Canít hurt pulling colder air from in front of the rad! It would be interesting to see the air temps at the inlet to the turbos. How close do the inlets run to the manifolds? Maybe use some exhaust wrap or something on the inlet pipes to try and slow down the heat transfer?

Do you have the core core size for the coolers used?
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Old 09-17-2018, 12:38 PM
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I agree, it would be interesting to see pre-turbo air temps. Maybe I'll find a way to stick a sensor there so I can get a before/after. The inlet snorkel pipes run pretty close to the exhaust manifolds, especially on the passenger's side. I am planning to remove them, rework them for better hood clearance, and paint them black to match the car at some point; I'll look into adding some heat shielding then.

The intercooler cores are about 9.25" long by 3.5" square.
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