Oil temps vs. Power output

I

ITSRX7

New member
Has anyone observed increased power output when oil temps (13B in my case) exceed 200 deg F?

We have heard rumors that this is true. So if it is, is it simply because reciprocating mass is getting pushed through thinner oil thus reducing internal drag and allowing quicker increases in RPM?

I want to increase power anyway I can but I also want to extend the life of the motor - and high oil temps can have some serious issues there.

Thanks,

AB
 
Originally posted by ITSRX7:
Has anyone observed increased power output when oil temps (13B in my case) exceed 200 deg F?

We have heard rumors that this is true. So if it is, is it simply because reciprocating mass is getting pushed through thinner oil thus reducing internal drag and allowing quicker increases in RPM?

I want to increase power anyway I can but I also want to extend the life of the motor - and high oil temps can have some serious issues there.

Since no one responded, so please allow me :

Increase of H.P. is negligible.
Your optimal oil temps on a 13B should be between 200 - 230 degrees. Continuous operation at high RPM over 240 degrees will shorten your engine life. I know the SpeedSource guys all run at 250 degrees but they rebuild their motors every year anyway.
My question is : how do you run oil temps under 200 ? Down here in SEDIV we struggle to keep our water temps under 200 !
Click to expand...
 
The only correlation I can think of in relation to 200+ oil temps and increased power output is this. The rotors are cooled by engine oil only. One of the problems with combustion efficeincy in rotarys is the large surface area of the rotors and housings. They act as heat sinks to combustion heat. This heat loss to these surfaces cools down the combustion and slows the flame front down as it travels through the fuel charge. This results in incomplete combustion and loss of potential power. 200+ oil temps would mean higher rotor surface temps and reduced heat sink capacity.Maybe some improvement in combustion efficiency? I'm not sure if this would be very significant at 200 degs though!How about 210-220 degs? But!
According to your dyno tests, you found that power dropped off with oil temps above 200 degs. This may be due to increased frictional losses due to the oil film thinning at these temps. Oils with a wide viscosity range like a 5w50 Mobil 1 are prone to this(check the Redline oil site out for an explanation). A 30W or 40W Redline race oil would provide excellent oil film thickness at 200+ temps with very low friction losses.
So maybe there is some power(better combustion?) to be gained if the higher oil temps are not allowing higher friction losses or increased wear!Water temps may become a problem though!
I've been running 30W redline race oil(with premix) in my 13B for the last 2 years.
BB

[This message has been edited by BrianB (edited May 04, 2002).]
 
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