Guys Thanks for sharing what you found on the dyno!
Originally Posted by Cab_Burge

I've done a lot of engine dyno testing and found out that the oil temps can have a direct affect on HP, 30 W oil at 130F would not have as much power as it would at 170+ F oil temps, 8 HP gain with hotter oil up I then tried 10W30 wt and saw 5 HP differences between 130 F and 160F, the next test was with straight 20W and I saw no HP gain from 70F up to 210F shruggy work
That is why I use that weight oil now in all my street motors and low (below 750HP) HP bracket motors up


Thank you both for sharing!
The termperature relationship makes sense.

Viscosity for a straight 30 at
130 F is around 45 cSt
175 F is around 20 cSt
8 Hp

For a 10W-30
130 F is around 35 cSt
160 F is around 25 cSt
5 Hp

I don;'t have info from straight 20 plotted.
But to your findings on that engine it seems that viscosity above 20 or 25 cSt was costing power.

Originally Posted by Dave_J
we did a Dyno run on a 513 BBM years ago using 20W50 racing oil. All tests were at 180 degrees F. We then replaced the HV oil pump with a standard one and gained 10 HP. Then we dumped the 20W50 and ran 5W30 and gained 15 Horsepower. So a gain of 25 Horses. .


@ 180 F
20W-50 has viscosity around 34 cSt
_5W-30 has viscosity around 18 cSt.
15 Hp




Last edited by Mattax; 02/29/20 11:51 PM.