Water/air intercooler in 930, need input...
 

Hey guys, reading all these posts about placing of intercoolers on 930's and looking at pictures on thise gargantuan and expensive devices covering everything in the engine-bay made me think about another option:

Why not use air/water intercoolers just like they did on 935's and Mercedes is currently using on their supercharged models? Air-flow and packaging problems would dissapear. Also, it could be done pretty cheap. Water has excellent thermal coeficient, and those devices run wery efficient.

It would look something like this:

1. Welded box containing water/air heat-exchanger, situated between turbo and throttle plate. Essentially nothing else but a row of coolers with serialized water plumbing.

2. Water radiator bolted onto engine-lid where air intake is, with flexible coolant hoses connecting them to heat-exchanger (so you could pop the hood and still have everything attached). There are no air-flow issues here so those hoses can be pretty long, as long as they are flowing coolant it's OK.

3. Small 12V water pump circulating coolant around, and maybe thermostat-equipped electric fan on a cooler to keep it cool during slow driving (if you really want to do it nice).


This approach would solve many problems:

- As water has very high specific temperature coeficient, it would mean efficient intercooling even from a dead-stop (until it gets heat-soaked, can be rectified with addition of small fan on a radiator)

- Engine bay would be much cleaner as you don't need to care about air-flow over intercooler or install gigantic inercooler that would keep everything covered.

- "Flexible plumbing" would transfer coolant and not air and is practically doable (compared to Jockes idea of flexible air-hoses piping air to lid-mounted intercooler) allowing radiator to be positioned at best possible place (right behind air-openings in the Whale-tail), and keep engine bay clean from obstacles.



Cons?

...introducing more parts in the loop that could go wrong, (but i think basic idea is pretty sound, no?)

Worst case scenario is plumbing developing a leak, but air/water heat exchangers are welded pretty tight and there is nothing going trough them but filtered air, so chance of them failing and spraying coolant into intake is minimal. Only thing that could happend is external plumbing-leak covering engine with few liters of coolant which isn't so catastrophic. Also, there is possibility of coolant-pump seizure, which would render intercooler inoperative after a while (heat soak). No big fuss.

So, what do you guys think?

Cheers!

I like the idea!

'Your' intercooler would be very effective, and is an interesting approach to the problem. In traffic, when my air-to-air intercooler begins to soak up engine heat, your intercooler would remain 'cool' - a good thing!

On the other hand, I think an aftermarket intercooler would be less expensive, less complex, and less maintenance over the long run...

Go for it! :D

You could also spray the intercooler. Seine makes a great system. You can activate it with a pressure switch or or just flip a switch when in traffic and ready to race. Decreases temps by 10 degrees and more. Fans work great also. Spal makes the best. Their little 7.5 inch fan pulls 450 cfm.

Spraying the intercooler is good idea in short term, but i don't see it as long-term solution. Small fan would probably solve it, altough i believe than air engine would be drawing trough radiator would be plenty enough even in stop/go traffic.

To put it this way, you don't use boost more than few seconds (if at all) in stop/go traffic, so electrical fan is probably overkill and one more thing that can fail.

Know very little about intercoolers, but the engine lid may not be a good place for the radiator. More weight, high up and in the back, just where you don't want it. You also run the risk of increasing the temp of the intake air, same reason you don't want an oil cooler there. How big a deal this would be, I have no idea.

Tom

Hey BeeBeep, are their many modified saabs in your neck of the woods? Just wondering since I have one. Thanks.
I have no idea how the mods I mentioned would work on a porsche But, they work like a gem on my saab. Actually the reason why I mentioned the waterspray is because i saw one on a porsche 2 weeks ago. He had it hooked up to a small cooler mounted in the rear seat. It held ice cold water. 750hp twin turbo monster!
http://www.seinesystems.com/MPC-Intercool.htm

Hey Beep, if Juan isn't too offended with your "ricer" comment on the other post (hehe), he would be the one to comment on this. I recall him saying he is a marine diesel mechanic. Marine applications typically have a high ambient air intake temp (hot engine room). Also typically have a great deal of water flow for cooling. He would probably be able to give you a good workable system. Although your system sounds feasible. I was helping my friend on his boat yesterday, it has turbo charged caterpillar engines with an aftercooler. Aside from the flow thru sea water system, the cooler was a pretty compact unit. Cooling the air after the air filter. For a large engine, the aftercooler was around 12"x10"x10" (or so).
I will admit to not being an engineer. I just drive the dang things. And I realize that diesels run better at higher temps.
I have also thought about an air-water intercooler system. Would looking at a schematic from a newer water cooled (993/996) system be compatible? The price issue would negate any savings if using the same parts I suppose. But that might give a good idea of how to plumb everything.

http://www.pelicanparts.com/support/smileys/pc2.gif [imhttp://www.turboneticsinc.com/spearco/dragrace.htmg]httphttp://www.kennedysdynotune.com/water_injection.htm://www.phttp://www.panhandleperformance.com/intercooler/intercooler2.htmlelicanparts.com/support/smileys/cut.gif[/img]


http://www.pelicanparts.com/support/...oilet_claw.gif

This is what you want,

http://www.vortechsuperchargers.com/aftercoolers/

I've seen the Mondo listed on the bottom of the page used on 1000+HP drag cars. In effect the tank, pump and radiator could be moved to the front of the car. Most of these are Mustang specific but it wouldn't take much to make them work on a P-car.

http://www.turboneticsinc.com/spearco/dragrace.htm

http://www.kennedysdynotune.com/water_injection.htm

http://www.panhandleperformance.com/intercooler/intercooler2.html

http://www.pelicanparts.com/support/smileys/wat5.gif

My thoughts exactly. I would consider under the car as a good place for the water lines to loose the heat. (Water is heavy)
Aside from that, keep in mind, the boost side still needs to see lots of surface area, to cool well. . .thee problem with air/water.

Thanx Juan, i found exactly what i was looking for:
http://forums.pelicanparts.com/uploads/core.jpg http://forums.pelicanparts.com/uploads/cores-5.jpg


Now is there a good place to look for nice small radiator or hould i visit nearest junkyard? What about water-pump? My own guess is that you don't need exceptional flow rates as water absorbs heat really well.

I'll try to do some calculations on needed coolant flow tomorow. (based on PV=nRT / Ideal Gas Law). I'll do it for worst case scenario: engine @ 1-bar of boost turning at 6000RPM, plus some additional margin for heat-exchanger inefficiency, heating from engine bay, IR-absorption etc.

My uneducated guess is that <10L/min. would be plenty even for sustained high boost driving.

Thank you for all your input, creative criticism is good thing! ;)

Yes, it will increase temperature of air going trough engine lid, but that's not different from ordinary air/air intercooler. The better intercooler the more heat-exchange. Considering amounts of air being drawn by engine-fan, i don't think it's something to consider. (930 engines run cold to begin with and i never went past 9 o'clock on temp guage)

And no, i don't think that additional weight of coolant and a radiator is something that one needs to worry about. This would be very effective solution and i bet that air/air intercooler with that kind of efficieny would weight little more as well.

Just a suggestion.....there may be better options. This is most likely what I would go with, as it is what I'm familiar with.

http://www.westmarine.com/webapp/commerce/command/ProductDisplay?prmenbr=201&prrfnbr=117607&outlet=

Not sure what kind of water/coolant tank you would use, but I would think you could put one of these submersible bilge pumps in it.

Don't know about mounting options other than vertical or close to it but VW Scirroco radiators are commonly used on big inch drag motors due to their lightweight and excellent efficency. Along the same lines a large oilcooler could probably be made to work as well. Whatever you decide make sure to use a water/antifreeze blend since antifreeze helps thermal efficency (an of course prevents freezing)

One possible radiator location would be in the front side of the rear wheelwell. I have my transmission cooler there (it's a 951 oil cooler). You can easily add a scoop to keep it flooded with ambient air.

Another idea would be to plumb the water all the way to the front driver's side fender, moving the weight forward.

I want to see somebody put this together with a Protomotive turbo kit to fit under a stock decklid. Talk about a sleeper.

As far as the concern that the intercooler would preheat the intake air - I've chewed on this issue myself.

First, what's the difference if it's water cooled or air-to-air? You're still putting the air that's warmed as you draw it through the intercooler into the engine compartment.

The question I have is, on one of these monster air-to-air intercooler is the intake air from the tail directed through the intercooler and into the engine fan intake (is it shrouded so that all the air goes this path)? If not, then your air-to-air intercooler is making big trouble as it is definitely warming the air the engine intake picks up.

Heck, even if it IS ducted through the engine fan, it's pre-heating your engine cooling air! Is that better?

It seems to me:

1. You could figure a way to duct outside air to the engine intake, solving that problem,

2. You could duct the water-to-air radiator cooling air through the engine fan,

3. You could duct outside air in and / or duct the heated water-to-air radiator waste air out under the engine with a hose and your fan,

4. Or, as someone mentioned already, you could run the plumbing up to the front valence and put your radiator there,

5. Hey - (if this is patentable, I want my name on the application too :D !) - but, how about running your A/C refrigerant through an air-to-freon intercooler? Then you get ACTIVE cooling of the charge air. If it does a good enough job, it should more than make up for the power you lose by rinning the A/C ;) .

beepbeep - let me know what you wind up with, as I've got to do this to my car too.

Larry

you're not going to need an actual radiator, since this won't we as highly pressurized as a normal radiator you will be able to get away with using an oil cooler per say. there are tons of universal ones on the market that could work better than a radiator, since you will be useing some sort of electric pump (alot of scca rally guys use these pumps for power steering/coolant) you'll be able to make very nice custom setup.
i've been looking into this for my turbo dodge for some time and with the exception of the added weight it's a great performance mod. the spearco coolers are very nice quality but these things can be kinda pricey, you should be able to find a nice used one somewhere.

Yepp, coolant is only going to circulate there, so it won't be so pressurized that it needs some special radiator. I'm thinking about two junkyard Saab-oilcoolers connected in series.


I identified only one problem:

Overflow-tank is going to overflow (pun intended) when i lift the lid... :rolleyes: Only way to fix that is to place overflow-tank on the lid itself (higher than a radiator) or to do some sort of "dry-sump" -solution that will allow for raised coolant level when i lift the lid and coolant starts to drain down from the radiator.

P.S. I don't think pre-heating engine cooling air is a issue to consider. Routing coolant to front fender would be cool, but it's too much plumbing involved for a cheap / bolt on installation i'm considering. Extra plumbing also means more pipes, more weight and more things that can leak.

No, this is old idea/myth. Laws of thermodynamics will make sure you loose more energy to compress all that than you gain by further intercooling.

P.S. You can always run cool-colar around coolant catchtank. :)

Routing coolant to front fender would be cool, but it's too much plumbing...

But the advantage of a front-radiator system would be that you don't have the weight of an intercooler (or a pair of radiators) that far back and up high, which compromises the car's handling.