DragBikeMike
Serious Thumper
Offline
SuzukiSavage.com Rocks!
Posts: 4406
Honolulu
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Early on, I figured this thing could use an oil cooler, but after a lot of mods and tests, it looks like a cooler would be overkill.
The DRs use a cooler with Suzukis Advanced Cooling System (ACS). That system has two pumps. One circulates oil for lubrication, the other circulates oil for cooling. I figured the LS needs a cooler too.
I installed a pressure gage, CHT gage, and an oil temp gage in order to collect baseline data for a cooler project. The hotest I have seen the oil is about 242 degrees with a Wiseco pop-top and ignition timing retarded 2 degrees. The ignition timing plays a significant role. It runs cooler when the timing is set to 30 degrees.
With the flat-top Wiseco, I generally run between 200 to 210 (usually closer to 200). The ambient over here is usually around 70 to 88 degrees. It takes about 30 minutes to get the thing all the way up to temperature.
Generally, an oil cooler should be installed downstream of the oil filter. You want the oil hot going into the filter. On the Savage, the only reasonable provision for cooler installation is on the inlet to the filter. I don't think that's good.
At normal operating temp, my oil pressure at 4K is usually about 8 psi, and at idle it is usually about 2 psi. My bike idles at 1400. Those pressures are with a DR cam, no holes in the lobes. With a stock cam (holes in the lobes), it runs 6 psi at 4K and zero at idle. These pressures are achieved using 20W-50 oil. If you use 10W-40, the pressure will be significantly lower.
Most of the literature I have seen recommends 200 to 230 degree normal oil temp with a maximum permissible of 250 degrees. Synthetic oil is supposed to tolerate max temps up to 300 degrees. Seems to me I'm running well within the limits.
One problem I see with an oil cooler is air in the system. If you mount the cooler higher than the crankcase, when you shut down the engine, the contents of the cooler will drain back into the sump. That's a lot of oil. When you start back up, the pump will have to fill the cooler before you start to feed oil to the top end. My bike, without a cooler, takes 3 to 5 seconds to develop pressure at the gage. The gage is connected to the head cover. Filling the cooler will add a significant amount of time to dry operation at startup.
Installing a pressure gage and an oil temp gage is easy. If I lived in a hot climate (AZ, NM, NV, SoCal), and I was interested in modifying my engine, I would find those instruments invaluable. I would install the instruments rather than the cooler. Then, if warranted, I would install a cooler. Make sure it's rated for at least 30 psi. This thing buries my pressure gage when I start it cold.
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