Ive been thinking about it, why not just get an air to water intercooler and use the hugmongous ac condenser as a radiator for the intercooler? all you have to do is run a small flow pump and antifreeze. What do you guys think?

Its been done here before by a forum member.

It was what I was going to do before going with air-air.

Why not use a radiator designed for water? I used one from a Honda goldwing, but the junkyards are full of small cars with tiny radiators that would be perfect.

Why not use a radiator designed for water? I used one from a Honda goldwing, but the junkyards are full of small cars with tiny radiators that would be perfect. for one this one is much larger than any other radiator you could fit into the mercedes. And its before the engine radiator as well, Killing two birds with one stone? and if you have innopperable a/c (wich most of us do) It may be the best way to go.

It's worth a shot, but I think you would get better efficiency with a real radiator. Little Toyotas have radiators that are about 1" thick and about 1.5'x1.5', they seem like they would be perfect to me.

Size is only part of the puzzle, you need one with the hose fittings in the right locations. It won't be much use to get a radiator with hose fittings that are pointing straight into your coolant radiator.

If you are up to the job, you can buy a custom radiator and have the tank ends split to have part for coolant and part for the intercooler. International does its trucks kind of like that with the radiator and intercooler side by side instead of one in front of the other.

I like the idea of an air-air if possible, but the water-air makes sense for packaging. I've looked at a bunch of them and discussed the applications for them at length with other Engineers and Sales Engineers at the SAE conference/show, and have these concerns:

By the time you get a water-air aftercooler small enough to package in the 124/603 compartment, will there be enough airflow through it to not restrict full-boost full-rpm operation significantly? Also, will there be enough contact time with one pass for the water to really pull much heat out of the air? If the answers aren't both yes, then the water-air solution won't work for the 124/603 application. Anyone have any pressure and temp delta numbers?

I am not familiar with the W124, and I don't have any numbers off hand, but an air/water intercooler unit will always be way smaller and have way less of a pressure drop through it than an air/air unit that provides the same amount of cooling. This is due to the higher thermal conductivity of water vs air. The intercooler I am using is WAY oversized for my engine, it is roughly 1' by 1' by6" including the end tanks. The core is approx 1'x 6"x 6".

Dont forget the down side of AWIC, heat soak.

Heat soaking should not be an issue if you have designed a system with a proper volume of water in it.

Volume of water doesn't do it, area of radiator is what's needed to maintain acceptable water temperature.

I'm still not convinced that the A/W has enough contact time with the air to reduce the temp adequately, but it is the easiest system to package, and I'm only hoping for ~230hp (engine/SAE) so the area necessary should be fairly easy to calculate.

Anyone with an aftercooled 124 here?

I'm still not convinced that the A/W has enough contact time with the air to reduce the temp adequately

Thats why the flow rate is important, Too slow and you heat soak the water, too fast and the heat transfer rate will be low.

1.5-2gpm is the target range, IIRC.

The reason heat soak is not an issue boils down to this:


The turbo produces the most heat when under "heavy" boost
The turbo is only producing "heavy boost" during hard, full load acceleration
bursts of full load acceleration do not last very long
If you have an adequate water tank and flow rate of water through your system your acceleration burst will be well over by the time all of the water begins to heat up


This is why it important to have a proper water flow rate and water volume in the system.

To quote Corky Bell "The front cooler is the least important part of the IC system, as it is doing most of its work when the vehicle is not operating under boost. At the start of a boost run, the entire system will be at approximately ambient temperature. As boost rises, heating the water in the main core, this heated water must get to the front core before it has any temperature difference with which to drive the heat out This time delay can be as longs as 7-8 seconds, depending on the size of the reservoir. That amount of time is typical of a boost application, It is clear, then, that the front cooler will do most if its work after the boost run... The font core does not need to be as big as it may seem at first glance, because the relative cfm rates through the two cores (IC and Radiator) will usually be heavily biased toward the front cooler. For example a forward velocity of just 60 MPH could potentially pit 5280 cfm through a cooler of 1 sq. ft, of area."

I remember the lesson that the Whittington Brothers taught the rest of the field in their 935 K2 cars around 1979. The rest of the turboed Porsches in IMSA were running water/air, the Whittington Brothers air/air, so they pushed the field until the water/air cars were heat soaked and had to back down, slaughtered them.

But I digress.

Water/air might be the ticket, since I have no space for an air/air aftercooler in front of the radiator with the condensor there. Plumbing is easier for water lines than for hot air also.

Will a spare aux-pump work for a circ. pump? I've got a spare from a VR6 Vanagon-Syncro project.

I am using a MB Aux water pump.

Thanks. I figured that out after I posted, clicked on your links, duh. The VR6 and Audi 200 pumps are basically the same with different plugs, so I guess it'll work.

Do you know what you're putting out for peak HP? I haven't followed your project (sorry), what's your max boost set to?

How about an integrated intercooler? Cummins has done it on many of their engines using the engine's cooling system.

Something in place of the stock intake with the head ports welded as part of the cooler would be very compact and space efficient.

http://i13.ebayimg.com/04/i/000/f3/9b/ebb0_1.JPG
http://i20.ebayimg.com/01/i/000/f3/9b/dbb0_1.JPG
http://i6.ebayimg.com/01/i/000/f3/d3/d753_1.JPG

How about an integrated intercooler? Cummins has done it on many of their engines using the engine's cooling system.

Something in place of the stock intake with the head ports welded as part of the cooler would be very compact and space efficient.



What engine models were these used on?

4BTA, 6BTA (Non-Dodge) and their larger Big Cam engines.

their larger Big Cam engines.

Was it ever used on any of the NT855 Big Cam engines to your knowledge?

One of the things about big-truck parts vs car and light truck, is the big-truck stuff is designed to take full rated hp (or close) continuously. The air-to-air aftercooler on a 300hp CAT I had was HUGE, big enough to dissipate the heat for a long mountain grade at full throttle (which I did regularly), wouldn't even come close to fitting the front of a pickup truck. The one on my 500hp Detroit was rediculous.

If it's truck rated, it's probably overkill.

If it's truck rated, it's probably overkill.

Overkill becomes moot IMO, if the price is right and it will fit w/o extensive mods. The unit that FI pictured is quite compact and looks easily modified to fit.

We have a large inventory of parts (dating back to the 50’s) where I work. If I know what applications these were used in I may have a chance of finding it buried on the shelf under 6” of dirt. My company will sell me parts they no longer use for scrap price or if the boss is in a good mood he’ll say “take and give it a good home.” :cool:

Not worried about overkill at those prices.:D

How about an integrated intercooler? Cummins has done it on many of their engines using the engine's cooling system.

Something in place of the stock intake with the head ports welded as part of the cooler would be very compact and space efficient.



How much does this one weight?

Thanks. I figured that out after I posted, clicked on your links, duh. The VR6 and Audi 200 pumps are basically the same with different plugs, so I guess it'll work.

Do you know what you're putting out for peak HP? I haven't followed your project (sorry), what's your max boost set to?

I still have not added any fuel yet, so power is still stock. Also my VNT still needs some twaking (mostly a new, lower pressure actuator) so I will hit 25 psi sometimes. I am shooting for a max of 13 psi or so.

I remember the lesson that the Whittington Brothers taught the rest of the field in their 935 K2 cars around 1979. The rest of the turboed Porsches in IMSA were running water/air, the Whittington Brothers air/air, so they pushed the field until the water/air cars were heat soaked and had to back down, slaughtered them.
They're road racing... totally different scenario. If you were daily driving/autocrossing/etc you wouldn't have that problem with an A/W. :)

Since you're running more boost, and cooled charge, in theory you wouldn't get more power unless there's more fuel, so does the ALDA respond to the higher boost with any more fuel or was it pretty much finished at stock boost?

I still have not added any fuel yet, so power is still stock. Also my VNT still needs some twaking (mostly a new, lower pressure actuator) so I will hit 25 psi sometimes. I am shooting for a max of 13 psi or so.

Yes, just trivia, it happens when you get old, the stuff just rolls out (like flatulence) whether you intend it to or not.

They're road racing... totally different scenario. If you were daily driving/autocrossing/etc you wouldn't have that problem with an A/W. :)

so does the ALDA respond to the higher boost with any more fuel or was it pretty much finished at stock boost?

The ALDA has returned all it has taken by 12psi.

The ALDA has returned all it has taken by 12psi.


I guess I do have a bit more power now as my T3 was only putting out 8 psi or so. :)

Was it ever used on any of the NT855 Big Cam engines to your knowledge?
yes, it was used on the 855s, small & big cam versions

I guess I do have a bit more power now as my T3 was only putting out 8 psi or so. :)

An unmolested ALDA that is. If you have adjusted it in the past then it may be a higher or lower boost psi that returns full fuel.

So I can start by adjusting my wastegate rod to increase max. boost, since the overboost protection valve (if working) will limit to 15.6psi and wastegate (603) is supposed to limit to 10.5psi.? Hopefully the 603 ALDA also has a little headroom to provide more fuel for mid-range boost.

The gauges will tell.

BTW, I noticed that the wastegate actuator rod is adjusbable (factory) on both the turbo from the 603.960 and the .970, only a single thread and lock-nut though, not a turnbuckle type. Not sure how much length is available.

Where did that 12psi number come from? Was that something someone measured or is in some documentation somewhere?

Where did that 12psi number come from? Was that something someone measured or is in some documentation somewhere?

0.7-0.8bar = 10.15-11.6psi.

Going higher than 12psi on stock internal fuel settings only wastes energy by making the turbo and engine work harder to pump extra air that doesn't do anything.

Understood. Just curious where that number came from.

So I can start by adjusting my wastegate rod to increase max. boost, since the overboost protection valve (if working) will limit to 15.6psi and wastegate (603) is supposed to limit to 10.5psi.? Hopefully the 603 ALDA also has a little headroom to provide more fuel for mid-range boost.

The gauges will tell.

BTW, I noticed that the wastegate actuator rod is adjusbable (factory) on both the turbo from the 603.960 and the .970, only a single thread and lock-nut though, not a turnbuckle type. Not sure how much length is available.

I think the 603 might run quite a bit more boost than the 10 psi of the 617. I had a wastegate actuator off of a 603 T3 and it had a cracking pressure of 10 psi. Max boost was probably about 14 psi. There is about 2" of threads on the actuator rod, so there is plenty of adjustment.

My 603 actuator is on ebay BTW: http://cgi.ebay.com/ebaymotors/Garrett-Adjustable-Wastegate-Actuator-15psi-Large-body_W0QQcmdZViewItemQQ_trkparmsZ72Q3a635Q7c39Q3a1Q7c65Q3a12QQ_trksidZp3286Q2ec0Q2em14QQhashZitem120 271008403QQitemZ120271008403

The FSM says 10.5psi is wastegate pressure, 15.6 or 16.5 (can't remember) is overboost protection trip on the 603.960.

Weird, I wonder what was up with the actuator I have.