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Gregarious
Joined: 13 Sep 2003
Posts: 86
Location: Los Angeles
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 Posted: Mon Feb 27, 2006 12:31 pm Post subject: Cooling... |
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You know, everyone wants to do some work on their engines that they can tell how great their work does now. How about not doing ANYTHING but using improved modern innovations on coolant and oil? Simply switch to 100% Synthetic oil, and get synthetic coolant additive (it's pink, but it still works great). After switching, I could drive the bumper to bumper with my A/C on, and not overheat. Being in Los Angeles, I used no regular antifreeze, so the coolant worked better, but even if you add it...
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924RACR
Joined: 29 Jul 2001
Posts: 9072
Location: Royal Oak, MI, USA
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| Posted: Mon Feb 27, 2006 11:01 pm Post subject: |
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You mean Redline's Water Wetter. Yes, the stock cooling system does work great when using synthetic, as you suggest, and when properly maintained. All the same, as power goes up, so does heat output. The problem here is that it's so easy to make so much more power in a turbo that you can easily overtax the stock system (if you use all that extra power a lot)... and we've already established what the extra heat and higher temps do to these motors, NA or turbo... increasing the longevity and robustness is a Good Thing...
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Vaughan Scott
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'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype |
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numbbers
Joined: 05 Nov 2002
Posts: 1910
Location: Highlands Ranch, Colorado
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| Posted: Tue Feb 28, 2006 10:25 am Post subject: |
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Yep, I always used water wetter even with my recorred performance products radiator. And, I have always used Mobil-1. But, with my boost at 17 PSI, those items were not enough. But, the 951 radiator solved my heating problems.
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1980 924 Turbo |
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Gregarious
Joined: 13 Sep 2003
Posts: 86
Location: Los Angeles
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| Posted: Tue Feb 28, 2006 4:21 pm Post subject: Apology |
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I guess I stand corrected. I use those, stock, and my engine has a hard time coming up to standard operating temp. I have had no problems. And the synthetic brake fluid is another; never takes on water, use indefinately. ;D
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Smoothie
Joined: 01 Jan 2003
Posts: 8032
Location: DE (the one near MD, PA, NJ)
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| Posted: Wed Mar 01, 2006 2:54 am Post subject: Re: Apology |
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| Gregarious wrote: | | synthetic brake fluid is another; never takes on water, use indefinately. |
The fact that that type of fluid doen't mix with water, also has a downside - water can still enter the system, but instead of it dispersing throughout the fluid, it will stay in one spot, causing rust and also boiling (it'll tend to settle at the hottest areas - wheel cylinders and calipers).
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'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox |
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Gregarious
Joined: 13 Sep 2003
Posts: 86
Location: Los Angeles
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| Posted: Thu Mar 02, 2006 6:33 pm Post subject: Syn Brake Fluid |
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| Smoothie, how often would you suggest flushing and refilling on the brake fluid, either standard or racing? I understand regular brake fluid attracts and retains water, but this does not. Only because it is not water soluble? ;D |
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Smoothie
Joined: 01 Jan 2003
Posts: 8032
Location: DE (the one near MD, PA, NJ)
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| Posted: Fri Mar 03, 2006 5:47 am Post subject: |
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The service interval for DOT3/4 is generally 2 years. DOT 5.1 can be 5-10 years - http://www.synlube.com/brake.htm I haven't seen a number given for Dot5 silicone, but it would depend on miles driven (which by brake use would increase the air taken up by the fluid) and on how many puddles it gets driven through.
| http://www.advancepetro.com/differentbrakefluid.htm wrote: | DOT 5: This brake fluid is based upon silicone. Its dry boiling point (ERBP) is 260°C minimum and wet boiling point is (Wet ERBP) 180°C. It is used in applications, like for weekend, antique, collector cars that sit for long periods and for some military vehicles. Some car manufacturers are also used in their road driven vehicles. This brake fluid does not mix with DOT 3, DOT 4 or DOT 5.1. It will not absorb water and will not damage the paint on a vehicle. It is also compatible with most rubber formulations. It absorbs more air and giving poor pedal feeling. It is unsuitable for racing due to more compressibility under high temperatures. If as little as one drop of water enters the fluid, severe localized corrosion, freezing or gassing may occur. This can happen because water is heavier and not mixable with silicone fluids thus it is unsuitable for ABS.
DOT 5 fluid is highly compressible due to aeration and foaming under normal braking conditions, providing a spongy brake feel. Poly glycol type fluids are 2 times less compressible than silicone type fluids, even when heated.
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http://www.belray.com/consumer/Q&A%20pages/q&abf.html
http://www.advancepetro.com/faq.htm
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"..it's made in Germany. You know the Germans always make good stuff."
'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox |
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Tigger937
Joined: 11 Apr 2004
Posts: 919
Location: PCA Milwaukee Region
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| Posted: Fri Mar 03, 2006 6:31 pm Post subject: |
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Great collection of ideas.
| numbbers wrote: | | First and easy mod, is to go to the lower temp fan temp sensor. I tried the recorred radiator from Performance Products ($400) with little to no improvement. Then I picked up a 951 aluminum radiator and fans off of Ebay for $100. Big Improvement. |
Numbbers, you got a great deal on the 951 radiator setup and I have little doubt that what you and Emoore924 have done will handle anything the 931 motor throws at it, especially since it was designed to provide cooling for the turbo too. I like the 6 blade fans for added airflow too. But it seems now they are more difficult to come by and those that are available, are quite pricey. Still might have to consider it though. A lower temp fan switch, like both of you suggested, has already made a big difference.
| simsport wrote: | | I fitted a davies craig elec water pump. It gives better cooling flow than the stock pump plus saves weight and uses less power. |
| bass gt wrote: | Guy's,
I have the same set up. It's eay peasy. The Pump sits in the lower pipe that runs from the rad to the original water pump. You then remove the impeller from the pump and weld over the shaft hole which mounts the pulley wheel. Then you wire the pump up and hey presto. One MAJOR advantage over the mech pump is that above 3k rpm, mech pumps tend to lose efficiency, ie they start cavitating. So what you get is lots of bubbles being forced around. With the electric pump, there is a constant feed of water, regardless of engine speed. There is also a variable contrlooer available, which fine tunes the pumps operation. As the sensor measures the water temp, the pump is sped up or slowed down accordingly.
Oh, and try turning your water pump pulley by hand. You are saving that power staright away. Probably 2-3hp in lost energy.
Regards,
Steve |
Simsport and Bass gt, I really like the idea of going to an electric pump, better control, more efficient, less drag on the engine.................sounds great and makes good sense for racing application! But, it is a little pricey for my situation and I'm a little concerned about the rated motor life, 3-4 years @ 2 hrs/day. Smoothie also makes a good point about the coolant flow which I think could be worked out.
| 924RACR wrote: | | I haven't played with the turbo in this way, but rather with my NA racecar - oil cooling is huge. Of course, the 931 already includes... my first upgrade would be a bigger oil cooler swapped in for stock. The stock one isn't exactly huge. |
I'm initially leaning this way as this sounds the most economical at this point. It seems this is where most of the heat is concentrated and therefore sounds like the most logical place to begin removing from the engine without taxing other systems, ie., coolant water. Also, as Dans931 suggested, improving air flow behind the oil cooler by reducing the size of the washer bottle can improve efficiency.
My radiator definitely needs a good cleaning/reconditioning as I don't think it's ever been done before. Then seal up gaps and edges around the radiator and perhaps a change to more efficient/lighter fans too. Then, if this still isn't enough, maybe give more consideration to a 951 radiator setup. What do y'all think?
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1982 931 (Daily Driver)
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