caddyman one member I think it was fast 355 said he had a oil temp gauge and when he added timming or adjusted fuel ratio he could see the differents in his oil temp going up or down he said the oil is what cools the pistons,that is why I ask it might help you decide how much less timming on less octane you apply.
Before I installed the factory in-radiator style oil cooler I could see an effect on oil temperature when lean cruise/advanced timing was used. Now going down the highway with the 454 radiator, Duramax fan, factory oil cooler it runs with a very stable temperature.Originally Posted by ony
What kind of temp spikes would you see and what was lean?
Oil temp is what we use when dyno tuning or tuning in the desert to know where we are. 90% of what we do isn't concerned about lean cruise.
Steady state cruise at 2,200 rpm running no EGR, 16.5-16:1 afr, 42-44° of timing, 40-60 kpa map reading, I saw a 10-20° hike in temps compared to 14.7:1 and stock 38-40° advance. Dropped back to 15.5:1 and 42° and saw oil temps drop 5-10° Turned EGR on running at 42° timing and the engine fell on its face power wise, afr stayed about the same and oil temps dropped about 5-10°F (back to stock). I bumped the cruise timing map a bit to make the engine a little more responsive with the super slow burning egr diluted mixture. Running 46-48° timing, map was in the 60-70 kpa range and MPG was pretty good on flatland with up to 21 mpg showing (instantaneous fuel economy on a datalog) at 70 mph where 17-18 is the normal. EGTs without EGR get a bit warm above 15.5:1 afr and escalate rapidly at 16:1 and above to the point I would worry about exhaust valve and seat durability for ordinary heads. Gaseous fuel heads on the other hand would probably live fine. EGR dropped the EGTs nearly 200°F.
Last edited by Fast355; 08-08-2015 at 08:18 AM.
Oil temp is a great source of information. As you're working up to optimum advance the oil temp will generally rise very slightly. Quite often as you continue to advance timing you can add several degrees of advance which doesn't add power and may not cause knock. What it does do is put additional pressure on the oil which can cause a noticeably fast increase in oil temp. Keep advancing timing and oil temp will continue to rise while knock will begin. These are very general rules and there are many configurations where oil temp is not as useful for tuning but if you have it I'd say learn to use it.
Hey guys thanks for the info... Looks like I was worrying for nothing, there was super all the way across US 50 and US 6. Made it here to CA just fine in the caddy. Man does she love the air down here at sea level. Thanks again guys!
glad you got where you was headed, did your milage veary as you started heading down towards sea level?
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