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Cedric · Joined: 27 Aug 2004 Posts: 2610 Location: Sweden

Im not saying he is wrong, but his assumption is that you only squirt on boost from time to time. Which is a very narrow way of usage, and is more or less using the thermal inertia. I wouldnt put my money on a very expensive charge cooler to have such limited use, but every one do as they want

To have low temps in repeated use the radiator will have to be big, or it will heats soak fairly quickly. Look at the BMW m cars for example, the primary radiatior is almost as big as the engine radiatior, and it has an additional radiatior on the side in series. Ive not worked on massive amounts of charge cooled engines at work, but I have some experience from them, though they where a bit larger

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1980 924 Turbo
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Carrera RSR · Joined: 08 Jan 2010 Posts: 2309 Location: Somerset, UK

On boost air temps post turbo at 1bar will over 100degC. I saw 125degC with a 2660 compressor. Even at cruise at 70mph can see 40-50degC post turbo temps.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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Fasteddie313 · Joined: 29 Sep 2013 Posts: 2596 Location: MI

Very interesting to hear the insinuation that cruising air could help cool the l2a ic bank while not on boost..
I have never even considered that but it totally makes sense.. Hmmm..

Thinking of this also a large “bank” would also be advantageous, as in a lot of volume of water storage, to soak up a lot of heat... But then nose weight..

I’d just put a cooler in front of the rad as big as it will fit and call it a day..

Just go big, as big as you can fit.. IMO..

PS: Be sure to put antifreeze in it just like your engine.. 50/50
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80 Turbo - Slightly Modified

Cedric · Joined: 27 Aug 2004 Posts: 2610 Location: Sweden

Carrera RSR · Joined: 08 Jan 2010 Posts: 2309 Location: Somerset, UK

Am I missing something with charge coolers versus air to air intercoolers? I've never got my head around the hauling of added weight of water, pumps for a charge coooler. Once heat soaked its often harder to cool. I cannot see the benefits only the pitfalls. Happy to be educated.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
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chuck21401 · Joined: 20 Feb 2005 Posts: 530 Location: Annapolis, MD

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2596 Location: MI

I think the top mount l2a cooler is better than the top mount a2a cooler..

I’m not a big fan of a top mount a2a intercooler right above the exhaust/turbo on 931s..
Maybe good/decent at constant speed but it looks like a time bomb in stop and go traffic (top mount a2a)..

I think the l2a there will be better, but I would consider wrapping/insulating it no matter how pretty it is, to shield it from those under good temps..

If you boost a bunch and then have to stop and idle for a bit, it’s super hot there.. My naca duct area is progressively loosing paint.. Exhaust glows at night after some hard boosting then Immediately stopping and popping the hood..

The gts/gtr intercoolers are amazing, but in attempting to keep things relatively stock, I hate saying it, but I think my ic setup is.... I love it and would do it again in an instant..

Chuck.. Just staying at 9psi, just adding the intercooler, you are going to feel a bunch of power just from the lower intake temps, and when you pop the hood your intake manifold will go from frying eggs hot to surprisingly cool to the touch..
Just the IC will make such a huge difference..
I was amazed at the change it made on my car just adding an IC, and I was only at stock boost..

Add the lower temp thermostat and lower temp rad fan operation to that mix, and you are in for a much healthier engine overall..
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80 Turbo - Slightly Modified

jazz guy · Joined: 26 Nov 2002 Posts: 434 Location: Colorado

I think the top mount water to air IC concept is cool, no pun intended. I like the advantage of having a shorter intake path and I like the way it looks. I'm sure you can make it work, especially on a street car. Worst case, you throw a bigger IC radiator in front. Without AC, there should be enough room.

It'll be interesting to see how it does when you're driving sustained highway speeds where the car is right at boost. With inclines and traffic, it's easy to be in boost for pretty long periods. Maybe the increased air flow will offset the it. Looking forward to hearing more about your progress!

Cheers! Brian
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'81/'81/'82

Carrera RSR · Joined: 08 Jan 2010 Posts: 2309 Location: Somerset, UK

chuck21401 · Joined: 20 Feb 2005 Posts: 530 Location: Annapolis, MD

Yesterday I connected the silicone couplers and the aluminum elbow running from the turbo to the intercooler. Had to trim each coupler about 1 inch. I wasn't able to install as one assembly...had to install the coupler to the turbo first, tighten it down, then add the other parts. Next step will be to run the coolant lines.

One of these would be more elegant.

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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler

Mike9311 · Joined: 14 Dec 2004 Posts: 1678 Location: Chicago-ish

So far there is only one of those elbows. Need to make a few since I have been asked and need one myself for the CS.

I too am interested to see the real data in all this and hope to get deep into it this coming summer. I have had the luxury of driving a GT twice and was expecting it to be strange with the intercooler/interheater, like there would be some sort of lag of oncoming power at every stop. Yet power was always there. So far with the top mount water cooled unit I have been impressed but alas without data both in the CS and the '82. I am all too curious. Both the CS and '82 will be producing data after this winter break. I also like that they are Bell intercoolers. At least we have that storied history behind them

Of course I am super curious how a front mount would be with a 931. Steve's numbers are phenomenal and there is more to be had from that 951 IC with mods and drop-in replacement upgrades from the likes of Broadfoot and others. I have paused my front mount install for the moment on the red car so I can concentrate on having some Spring rides ready. Steve working on his GTS after his CS was sorted is "pro thinking"

Love the pump install BTW. The '82 is getting some cheap horn replacements this winter. $3-5 ebay buys. Lightweight and noisy.

I think you will be pleased with the 10-12psi use case you are setting up
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car

chuck21401 · Joined: 20 Feb 2005 Posts: 530 Location: Annapolis, MD

I started routing the coolant hoses today. With the heat exchanger mounted up front, I didn't have enough hose to get it all connected. Had to order another 8' of 3/4" hose to run from the filler to the heat exchanger.

But I was able to run the line from the cool side of the heat exchanger to the pump and up to the intercooler inlet.

Over to the pump. The Ford performance sticker is just for fun.

I ran the hose up under the headlight motor and the expansion tank. The blue cable ties (representing cool) are to help me keep the hoses straight.

And here is the connection to the cool side of the intercooler.

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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler

Carrera RSR · Joined: 08 Jan 2010 Posts: 2309 Location: Somerset, UK

safe · Joined: 18 Mar 2017 Posts: 588 Location: Sweden