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oil viscosity on wet sump systems

10K views 21 replies 13 participants last post by  557MAV 
#1 ·
Jon

what is your opinion of oil viscosity of a mountain motor,500" prostock motor or a 520" motor for super comp. also what do you think the surrounding area temperatures would do to affect this. I'm sure you done some research over the years on the dyno.

Ace
 
#2 ·
Hey Ace... I know Jon will weigh in on this ;)

But to give you some basic info... Most competition engines in those catagories are running a very light weight oil. We for instance run Royal Purple 11 Lite which is a 0-5 weight. I have run that in everything from a 397 inch wet sump N/A Hot Street engine to our Mountain Motor 825 Pro Stock stuff. Of course all built by Jon.

We do see the pressures go down a little quicker in extreme heat. However keep this in mind. If our operating temperature is 130-140 it takes the engine a little bit of time to reach that point even on a Hot July day when it is 105. Therefore the surrounding air temperature doesn't effect the oil, other than how quickly the engine will reach a hotter temperature. At a hotter temperature the viscosity of course will drop as will your pressure ;)
 
#4 ·
4-5 runs is the average. Some change it more some less. Which reminds me... I need to change mine ;)
 
#6 ·
Thanks Cale....I just wanted to put some context to the oil deal. I have a buddy that runs a very fast rear engine dragster....in 2008 he ran a 3 day show at Gateway in St Louis...35 hits on the engine that weekend. Having said that, most sportsman racers do not need to have a pro-stock oil package. He'd have to change oil twice a day.
 
#10 ·
George... your right! I actually myself usually go like all weekend ;) but most guys think it is horsepower... lol!

Kinda like spark plugs.... LOL!
 
#8 ·
George, do you think it would matter if it was a 638" engine that was driven to the line and driven back to the pits rather than a "pamper" unit that did not get hot laped like the sportsman stuff ? If a guy is winning aint no 45 minutes till the next round.
 
#9 ·
Just from what I have witnessed, the lite oil gets aerated VERY quickly and changing the oil also gets rid of the trapped air.
NOW, the oil you've drained can simply sit for 48 hours to rid itself of that air and be used again if you need to save money on the cost of the oil.
 
#11 ·
Ace, we run a light oil in the big engines. It pours like kerosene. Royal Purple, Synergyn, Lucas, and Joe Gibbs. It helps the big engines a bunch over 15-W-40 Rotella-T used for break in. We run the engines cold and the oil is cold as the engine. At normal operating temp. these oils may not have enough oil perssure. In a race engine that runs at a higher temp., almost any name brand race oil, 20W40 or 20W50 will work good. It needs to be warmed up a little.

Strange thing is, in our 825" engines the real thin oils help 30-35 HP sometimes. But every year I've tried those oils in my Enginemasters entry, with no power increase at all. At $14 a quart, you want to be sure it helps. ... Jon
 
#13 ·
Just wanted to add my .02 My 588 is not in the same league with most of the engines mentioned in the this thread.

I use Royal Purple 41 (10W-40) Racing Synthetic. Not cheap, but I'm getting really good life out of it. The engine is alky injected which normally makes a mess of the oil. Using an electric vac pump to pull vapors out of the engine (while running and 3-4 minutes after shutdown) and a gas primer system to get heat in the engine really helps.

I'm running the RP 41 around 70-75 passes between changes. It still looks like it came out of the bottle. I change it just because I feel guilty. I have also run conventional Valvoline VR1 10W30 and saw no difference in et/mph vs the RP, but the conventional oil looked terrible after 12-15 passes with the same vac pump/gas primer heat routine.
 
#15 ·
Take an oil analysis instead of a change, usually a engine in 100% mechanical shape will need one oil change a season maybe two if you monitor the engine/filters, etc if you dont you really dont have a clue and your money goes with your feelings...

I have run a 10w40 100% synthetic over 5 years with no change with excellent results, finally last week the block split after ten years of abuse.

Block broke OEM cast crank still in one piece! Drove the car home! no noises! and no oil pressure! http://www.ranchopower.com/wp-content/uploads/2009/11/Picture-0113.jpg

http://www.ranchopower.com/wp-content/uploads/2009/11/Picture-039.jpg

In ten years I did one oil change with this engine, last 1.5 years I race it fri nights, driven to and from the track best ET 6.770 at 101.76 mph

Never had a lubricant related issue in ten years...

Javier
 
#14 ·
You gotta love a guy who changes the oil in his engine because he feels guilty! I love that!
 
#16 ·
i use brad penn 20-50.i got 12 passes on the oil and now my psi is 70.when it was fresh it was 80,both cold.
003 on mains,2.5 thou on rods,block is filled.

when engine is 160 deg h20 oil is 35-40lbs or less

can the extra heat in the bottom end break down the oil faster?no cooling down there.

motor has 18 passes on it, all checks out well
 
#17 ·
That is normal for fresh oil to breakdown viscosity the first few heat cycles.
A 50 weight oil has a viscosity grade @100*C the minimum is 16.3 and max is 21.9

Brad Penn also has a very high HTHS "High temp high shear", so this means the oil will last alot longer than most would think!

always pull and cut oil filters open and inspect for metal to verify if your oil brand or machine shop brand is up to the task.
If you have metal in the filter somebody has robbed you, up to you to figure which one, or maybe both?

Javier
 
#19 ·
Well so-long as you're not comparing it to Red Line, Motul, (maybe Amz-oil), but of the Mega companies that produce syn-oil it's damn hard to beat...particularly for the price.

At SEMA on year I was sitting down eating lunch and a guy with a Motul shirt sat at the same table he gave me the " everything you ever wanted to learn about syn oil in 20 minutes or less" lesson. I should have written everything down on a note pad when I got home.

G-
 
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