Air to air, or air to water intercooler? 4A-GE race engine

[Chris Wilson]

I have asked five people, and had five different responses, so am now asking a wider audience .

I have a sports GT race car (Zeus) that currently has a Toyota 1600 4A-GE Formula Atlantic engine in it, making about 210 BHP. I am turbo charging it with the hope of seeing about 350 to 380 BHP at the flywheel. The turbo is a Garrett GT3071R, with integral wastegate. The management will be Motec M800. The current pair of twin choke Weber 48DCOE carb are removed and a plenum with a single 65 mm throttle body made. I am dropping the CR to about 8.5 to 1 and fitting milder cams, of about 270 to 280 degrees duration.

My indecision rests on how to intercool it. Anyone with nothing better to do is welcome to look at some photos of the car I link below. I won't muddy the water with my own, or currently suggested ideas, except to say I need to keep the current water radiator set up, I can't get away with less. I don't mind scoops on the rear body work, but don't want any heat exchange at the front of the car.

I will consider air to water, but ONLY if I can get information from people with first hand experience of this of this running a similar power output from a small engine, in circuit RACE trim. My fear is an air to water will work fine on the road, or even tack days, but may heat soak in full long distance circuit race usage.

Photos of the ongoing project at http://www.gatesgarth.com/intercooli...ercooling.html


Thanks for looking.

[NME308]

+ rep for a really nice use of a toyota engine!
That thing looks like it would turn corners too

I'll keep my opions on your current dilemma to myself cos my turbo experience is limited to short duration runs only. With such a tight engine bay my crystal ball does however show a trip to the fiberglass shop before this is all finished though!

Good luck!

[big_zop]

What an amazing looking car you have there. I love it!

The problem you are going to face is integrating something that wasnt designed to be there in the first place. Mechanically, there shouldnt be a problem but i think you are going to have to modify the body work a little to accomodate the IC. Now, i have never had experience with what you are dealing with but in my FSAE team, they had a very nifty solution for intercooling which might be able to be adapted to suit yours (though the engine is east-west configuration). It does place the core high which isnt favourable for CoG but at least its an option that you can consider against others. As always, there are compromises to be made and i believe that the reduced intake length won out over better CoG as the tracks used are very tight and twisty and throttle response won out over CoG.

The first iteration had the IC on top of the engine with a single side inlet and four outlets into each intake port. The scoop cought air from either side of the drivers headrest and fed it down onto the top of the core (much like an F1 intake).

1st Iteration - no scoop


1st Iteration - with scoop


The second iteration had a similar layout for the IC but altered the ducting. This time the intakes were on either side of the cockpit and fed air under the IC.

2nd Iteration - no scoop


2nd Iteration - with scoop


I believe the second iteration would be easier to incorporate into your vehicle due to it being mode compact. if you can do some pressure tests and palce the IC in a low pressure region, then that would help evacuate the air.

If you want any more information about these setups, then please let me know.

There is a thread on the Laminova, a very different water to air cooler which looks very compact and probably what you are after if it can be proved in a race situation.

Good luck with your endeavours and look forward to seeing the results of the new engine package.

[Roundy]

I would say air to air for 2 reasons

Less weight

Likely to give lower inlet temps.

Water to air gives another potential reliability problem in the pump and wiring, water hoses splitting. However fitting the intercooler is likely easier as it can be smaller than an Air to Air

To make it work on a circuit racer you also need to get a suitably sized heat exchanger to shed all the heat from the turbo, on street cars it is possible to get away with a smaller heat exchanger, simply because once the car is off boost the air going into the engine is also cooling the water in the intercooler.

[MattMc]

You need to look at one of these Air to water

Cooling a GT3082R Turbo off road racing I'm afraid thought not circuit.

Mine's in Red



Pre and Post intercooler temp

Pre and post intercooler MAP


Minimal pressure drop minimal lag minimal heat rise

Heat soak is only an issue if your heat exchanger is not up to the job.

http://www.toymods.net/forums/showthread.php?t=43226

[love ke70]

watching this one with interest

[Chris Wilson]

Wow, excellent replies, thank you all for your trouble. OK, I think air to air is going to be the best solution. I spoke with Docking and Co Engineering, (Silverstone), who have done some intercooler work for me before, and they too were strongly in favour of air to air.. The people who have run air to water all seem to be using it in road cars, or drag / sprint cars, where, no matter how much of a lunatic you think you are, it's all but impossible to maintain the sort of engine loadings you'd see in a 25 lap race situation on a road race circuit. Therefore I remain sceptical of the seemingly very small heat exchangers they get away with. For sure, I am in no doubt that air to water can and does work, I am just uneasy about the cost of sizing a set up incorrectly, and having to re-engineer a lot of stuff, plus the added complexity and weight. I feel they may be more suited to other situations than this specific one.

So, now I am set on air to air here is a truly dreadful rendition of two locations I consider feasible for an air to air charge cooler. The original oval aperture in the rear body work is where a carbon air box, F3 style, stuck out. I have now removed the twin side draught Webers and am in the process of fitting the existing short manifold with an alloy plenum and a single throttle body. It shoudn't stick out laterally from the head too much, hopefully allowing a maybe 50 mm core intercooler to fit semi vertically behind the side of the bodywork, roughly where the existing air box was. The aperture could be enlarged and a simple carbon or glass fibre scoop made to feed the outer face of the I/C with air. I could probably seal it to the bodywork with foam or a simple rubber seal strip. I reckon the rear engine bay is a low pressure area, to a pressure differential should exist.

The other idea is to cut out a rectangular section of the passenger (LH) side of the rear bodywork upper surface, fit the I/C above the exhaust manifold, and make a scoop to bring the rear bodywork on the LH side level with that on the RH side. The scoop would see clean air, and would be higher than than the dashboard line. Downside to that is the I/C would be quite lose to the exhaust manifolding and heat soak would occur. I could make some heat shielding though. I am unsure which area would be best for picking up the best flow of clean high pressure air. Despite a plethora of photos of the car in one piece I don't seem to be able to find anything very suitable from a rearward angle. I have added the best one I can find, you can see how the LH rear bodywork top panel is lower on that side, compared to behind the drivers head. The broken white lines badly reflect where I would envisage making the actual apertures for the I/C, in each case.

Please bounce more opinions and ideas about Thanks and a very happy, healthy and prosperous New Year to all.

[MattMc]

Your 1st post does not say what boost you intend to run?

Also I take it you have calculated your turbo maps going with the GT3071R, do you have an idea of your pre intercooler intake temps, have you calculated them at various boost levels?

Also what are your desired post intercooler temps, how close to ambient do you expect to get with air to air.


Turbo Calculator

Regards Matt

[kassma]

Don't mean to be a stick in the mud... but wouldnt' it be cheaper to just pull the engine, sell it as a seperate entity, as I think you could get a fair amount of $$$ for it, and then just buy a stock 4agze engine, wack on a turbo, and get an instant 300HP?

Realistically, the Atlantic engine is build for NA purposes, and sticking on a turbo, will just kill this engine, as it's not designed for Turbo application. I don't think you will get 350Hp out of this engine even with a turbo, because of detonation issues... you will never be able to cool the air enough to run in a 12:1 comp ratios. But why do you want to ruine a perfect NA specimen, for turbo application, where you can get a cheaper engine for turbo application, which have better potention for turbo.

Also... Air to air is the best setup, and if you have a enough air flowing on the side of the body, the definitly use air-to-air, as it's the best you can get... but if you dont' have the flow, then use Water to air. Intercooler is a tradeoff between air flowing across it, and the amount of air within the system... IE: If you have a big a$$ intercooler in the front, but no air going across it, then it's pointless.... It's better to have a small intercooler (less lag) with lots of airflow across it (Cooling) than to have a big intercooler (with lots of piping) and less airflow (Interheater).

But love your setup...

MIKE.

[soulfire]

i'd hate to say it Mike, but it sounds like this is a fairly serious race motor...

And he did say in his first post (if you even read it) that he was going to drop the CR down to 8 - 8.5:1

It's his motor and he can do whatever he likes with it at the end of the day?
Perfect N/A specimen? Not even going to justify a response to that one...

Not trying to flame, but maybe read the post and think about the application before you start trying to give some "sound" advice.

Adam

[abently]

Slightly off topic, but I wouldn't drop the CR down that much. 9.0-9.5:1 is more sensible given you have unlimited control over the Fueling and Ignition.

On topic, I agree with big-zop's recommendation for the postioning and cooling method.

[KARNAGE]

it all depends on how much boost he plans on running whether or not the lower comp will work well. if he wants to run high boost then the lower compression will be fine.

[Joshstix]

I would have said it depends on the fuel he is planning on running and how effective his intercooling is more so than how much boost he wants to run. To get 350BHP from the 4A wouldn't need more than 18-20 psi of boost at the most I reckon and I get away with more that on my daily driven 3S with 9.1:1 compression on BP ultimate. If he's happy to run race fuel (100+ MON not RON) and he can get within 20-30 degrees of ambient I don't see why he wouldn't be able to get away with 10:1 or even more.

Whether it is needed or worth running closer to the edge than absolutely necessary is another matter though and I guess that would be determined by what the car is used for. I'd assume it's a track day car rather than an out and out race car running in a series with other equivalent vehicles so the lower stressed lower maintenance option is probably the more logical.

On the topic of water to air or air to air intercooling though my main comment would be aimed at a comment by the original poster where there is concern shown about the sizing of the heat exchanger to shed heat from the setup and getting heat soak. My answer to this would be that the air to air setup needs constant air flow to keep it cool and if you use a radiator for water to air setup the same surface area and with the same air flow through the radiator as you can get away with for the air to air there will be absolutely no problems with heat sink. The radiator will shed heat more efficiently to the air stream than the air to air intercooler, which really works more like a short term heatsink that is then cooled by the air flow through it while under low load.

There are definately issues with water to air but heat soaking would be at the bottom of my list of concerns in this situation. Much more important I feel would be weight, bulk of the multiple components, electrical requirement of the pump, additional failure points.

If you can get a good air stream to an air to air cooler then it's the answer, just try not to compromise the aero of the car too much or the extra weight etc of the water to air may have been a better compromise.

[deviant]

I seem to remember turbo F1 cars ran with an air-to-air intercooler in the sidepods in front of the radiators? Simple to build and uses existing air flow and vents.

Also what kind of rules and regulations are you having to work to? Are you allowed water / methanol injection?