Quote:
Originally Posted by Stielow
The Mule had a oil to water oil cooler built into the end tank of a Griffin rad. It held the oil temp down to under 250F for 3-5 laps. The turbos drive a lot of heat into the oil. One issue I have found is some of the older gauges don’t read high enough for synthetic oils. Redline has told me there engine oils are good to 325F. The Mule gauge pegged at 250F so we were shutting off early. Jackass has a relatively stock LS9 in it and it has no cooling issues on track with its Ron Davis rad with an oil to water oil cooler built into it. Red Devil runs a stock LS9 oil to water oil cooler mounted to the side of the engine. Once we had that car fully tuned up it would over temp the oil and the water in 5 laps on a 90 degree day. On Mayhem I upped the rad and moved the trans and diff coolers to the back of the car. In a 5 lap session the water temp was great and the oil temp is getting marginal. That oil cooler is built into the rad as a oil to water cooler.
On Camaro XV we upper the rad size even more with a custom core from Dewitt. I met with C&R rad at SEMA and they steered me to a larger 13 plate oil to water oil cooler that should keep my oil temp good. I have opened up the front of the car with the new Anvil front clip. I’m using my vented hood again to help move air through the rad. Dewitt is also making me a one off intercooler heat exchanger that will nest into the cooling stack to maximize core face and air flow. On Red Devil, Mayhem and Camaro XV I’ve ran a very large powerful cooling fan. It is a 20 inch dia Caddy SRX Turbo fan what pulls 850W. I like oil to water coolers because it heat the oil then cools the oil. It also makes a very clean installation. Dewitt is finishing the cooling stack next week and I hope to have some photos to post.
On a side note the LS9 based engines have oil squirters that shoot oil on the bottom of the piston to cool the pistons. Thomson modifies the LS7 block to add the piston squirters. He did a lot of testing to sort out the size and the location of these squirters. This does drive oil temp. Also as the power goes up so do the heat rejection requirements.
On your question on oil line sizes. I’ve been running -10 AN for cooling lines. I have run 12 AN but the 10 AN seems fine. I don’t have the sizes of all of the different coolers, sometimes it is hard to get the heat rejection rates or to know what you need without just testing it.
Hope that helps
Mark
|
Have you considered making a portion of the radiator into an air to air oil cooler? The reasoning is that on some of the endurance race engines I produced used only half the original radiator area for coolant and the same amount of area as an oil cooler. What we found is that we were still able to keep cylinder head temps under control while dramatically increasing engine life and reliability while allowing for tighter ring side clearance and using narrower rings with no loss in reliability. Valvesprings that would fail after 3-4 races would last all season with oil temps at 180-190° instead of 250-260°, and they would only get freshened up because the engine got torn down in the off season. We no longer had problems with rocker shaft or pin seizures, or hydrodynamic issues running a considerably lighter oil.
The original thinking on my part was that synthetic oil was good to X° so as long as it stayed below that....... That was wrong thinking. Turns out that when it comes to metallurgical strength of piston and valvespring materials, cooler is way better. Keep in mind that 5w20 at 190° has the same viscosity as 15w50 at 270° and the protection is not better with heavier oil when it comes to the EP package. I know that you have enough of a grasp on tribology to deduce all the other advantages. The same held true for differentials and transmissions....... less/lighter oil always equaled more power and lower temps improved durability. I found that 180° was sufficient for moisture evaporation in the crankcase, and 140-ish was awesome for clutch plate life in auto trans and clutch posi units. Just some food for thought