Air-to-Air or Water-to-Air??? Opinions please

i'm going water/air on my next engine swap, partly due to space but also i think it's a much better setup.
be aware you will need to fit a small front mounted radiator for the water part of the water/air cooler. also will need a pump, and swirl pot type thing to fill it up.
good thing is you won't need to run large bore intake pipes to and from a front mounted air/air intercooler.

What's it being used for?

If it's for drag racing or for off road then I'd consider a charge cooler. Drag racing only last a few seconds so may as well just have a charge cooler with cold water in their, but off roading won't have the air speed to cool down an intercooler so a charge cooler with a large water volume and a rad with a fan may be a better route.

If it's for the open fast road then an intercooler is easiest

You might be able to find it cheaper, but this has been about the going rate on eBay for the past few years at least....actually not too bad when you think this is the complete set-up and all you'll need is probably some different pipework to get everything located on you Landy. Pipework is dead easy because it's just to route the water.

cgi.ebay.co.uk/Gt4-complete-chargecooler-setup-Mr2-turbo-Celica-St205-/130539253410?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item1e64beeea2

This was the system I had in my MR2 and it's pretty darn effective. The pump is quite powerful and the only thing I had different was the pipework and rad (mine was a Cinquecento rad for even better cooling)

A number of Subaru's also had chargecoolers (most seemed to have intercoolers), so did Citroen XM TD's so there might be a few avenues to explore there, but I can vouch for the Celica GT4 set-up being a good system to have and easy to adapt.

Robin its the mk1 RS IIRC that uses the W2A system, but most ditch it in favour of a FMIC due to charge air temps increasing dramatically when they start tuning them, so there are always a couple on ebay for sale.

Chargecooler and fit air con....


Drop the cold bit of the air con in the chargecooler tank...


Then when normally driving you have the air con off and a normal chargecooler setup but when expecting 'heavy work' turn the air con on before hand and chill the chargecoler water right down, turn it off and enjoy a tempoary boost in power until it warms up again.

I wonder how much BHP air con would require vs how much cold intake temps boost BHP?
It's not like it's 'free' energy as colder intake air allows more fuel to be added so that is where the gains come from...

As above the chargecooler is heavier but easier to plumb in, intercooelr is physically larger and probably cheaper too.

This is the water/air setup in my Saab 99. You can see the core mounted behind the radiator.




The core I've got is the XS-Power branded core which comes from China. I think there are other people importing it as well and you can probably buy direct from China if you search worldwide eBay. I've nothing against China stuff if it's simple like this. Heard too many horror stories about China turbos though!




I used a radiator from a MINI as the cooling for the water. It was a big radiator so I didn't bother with a tank but I might add a tank later. The radiator has a fan on the back of it.

The advantage of a water/air setup is that you need an air/air core x4 the size of the water/air core to get the same conversion rate. You can also have a shorter intake tract. Some manufactures like Mercedes actually build the core into the intake plenum. The water/air units made by PWR are pipe shaped so they fit inline with the charge hose. A good water/air setup basically has a straight pipe from the turbo to the throttle body with just a small diversion into the water core.

Mine needs tweaking still. For the next revision I'm going to mount the core on the side of the engine block under the intake manifold. You can get a different Saab manifold with a centre mounted throttle body and I will butt the chargecooler exit straight up to that. A pipe straight from the turbo will go into the intake side of the core.

Reason I used the air/water method was down to space. The 16v turbo engine only just fits into the 99 engine bay. The old 99 radiator does not cool that well either. Having something in front of it would be silly.

I'm going to move my MINI radiator down and outside the engine bay and redesign the front bumper to include a duct to drive air into the radiator.

I don't have any evidence to suggest my current setup does not work but I'm not happy that I did the best job with the original setup. No such thing as 'too good' where chargecooling is concerned. The better the chargecooling the more boost you can run.

I think I'm going to put a water temp sensor into the core so I can see if I get heatsoak or not. I already have an intake air temp sensor but that is a relatively new addition so not had a chance to monitor air temps yet.

The downsides of an air/water setup is the complexity, chances of failure, weight, cost, what to do about heatsoak.

Cooling wise, if both setups are working properly then there is no difference between the two. Both are just as effective, assuming you are not dumping ice into the water.

The other thing people have done in the past is added water injection. That works but you have to keep an eye on the water level in your tank. Make sure you have some sort of warning system to let you know when the tank needs filling.

Water injection hurts power but having it working means you aren't going to wreck the engine. You can increase the boost a lot when you are running the water injection but because you are adding water to the mixture it is effectively damping the flame and reducing efficiency. To work around this people sometimes use methanol in the water to counteract the effect of the water. I don't know how much it costs for methanol but I bet its not as cheap as straight water.

Some cars have intercoolers mounted on top of the engine (with a bonnet duct) but the downside is the heat from the engine rising and affecting efficiency.

Subaru used a water spray bar to increase cooling by spraying a mist of water over the intercooler. Very effetive but only if there is a good flow of air to force evaporation.

This could also be an effective way of increasing cooling on a water to air rad (on the rad, not the cooler) to bring the water temp right down. The downside is having to use yet another water tank (washer bottle)

I found the water temp in the chargecooler system on my MR2 never got above tepid at worst. Even after lots of spirited driving with the turbo working hard, the Cinquecento rad did a really good job of keeping things very cool. After having it in the MR2, I am a complete convert and would prefer it over an intercooler any day.

Thanks for all the replies lads, it does seem that the chargecooler is the prefered option!

The original idea with this project was gonna be a sub-12 second drag landy just cos as far as I'm aware there isnt one on the scene here in England, but that would kind of make it of limited use on the road (which is where its likely to spend most of its time ) so might reel it in a bit and look at the easiest option in terms of cost and practicality which comes back to the Intercooler

I don't know if the extra few (possible) ponies are worth the extra weight and complexity of the Chargecooler.......might just say sod it and put a full height/width Intercooler hanging out the front and just paint it to match the bodywork ;D

What can i say........i cant decide what "it" is I'm building!!

Steve

cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=360373693358&ssPageName=STRK:MEWAX:IT

about the biggest you can get for the money, tis what i will be purchasing for mine