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Author Topic:   oil pressure
aligater
Dirt Roller

Total posts: 10
posted September 27, 2005 09:20 PM  
had a oil pump failure during the last race.
saved the engine but needed to replace the pump and bearings. the pressure was @45# at idle/cold, now it is at @60# at idle cold.
it goes down to 50# at 190 degrees. this is prob. due to only having a h. vol. pump on hand on sunday. is this going to be a prob. on the track , using 20-50 could go to 15-40.
when reving it in the driveway had @ 65# at roughly 3000 rpm when hot(190). anyone not like the h. vol. pump?

ss99
Dirt Maniac

Total posts: 120
posted September 28, 2005 06:54 AM  
You'll be fine. Been using the HV pump for years with no problems with 20-50 synthetic. It's good to have good oil drainback in the lifter valley and a 7 or 8 quart pan.

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted September 28, 2005 07:20 AM  
hig volume is good as long as you dont have excessive high pressure. what you have sounds good. Our mod at 2000 idle cold will have about 65-70# and will carry about 50 when hot at 1500 and pulls about 65# on the track.

alibaba
Dirt Roller

Total posts: 7
posted September 28, 2005 07:37 AM  
has a factory pan on it now. have a 300 lapper this weekend
aligater

BrianW
Dirt Freak

Total posts: 385
posted September 28, 2005 07:44 AM  
Run the thinner oil - with that pressure and the stock pan I'd run a synthetic 5W30 or so to get the pressure down and it should free up a little HP...

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted September 28, 2005 08:18 AM  
did you say 300 lapper? Or did you mean 30 lapper.

I would stick with the 20w50 oil. With a stock pan you donít have a lot of oil capacity anyway and your oil is really going to heat up prob 300+. When it gets really hot you need an oil that can still support the loads and I donít think a 5w30 will do that even if it is synthetic, its still going to thin down to much. If you had a 8qt or more pan and oil cooler and could keep oil temps around 220 and your engine was clearanced right then 5w30 might work. Even then I would think several times before doing it.

I wouldnít worry about the pressure, just make sure you have good drain back and your valve cover breathers are clean and open and the oil can get back to the pan fast otherwise you could starve the pump. The pressures you listed are good, now if you had 85# hot then that would be a little much.

alibaba
Dirt Roller

Total posts: 7
posted September 28, 2005 10:20 AM  
yes a 300 lapper. car only runs 190 - 210 coolant temp at the worst. what about bearing wash at that pressure. should i go to 15-40 to be safe?

juliaferrell
Dirt Freak

Total posts: 370
posted September 28, 2005 11:01 AM  
Your fine. Drain the oil out of the wife's car and git r done.........

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted September 28, 2005 11:20 AM  
There is a difference between coolant temp and oil temp. If your running a stock 5 qt pan your oil is well over 300degrees . Thats where the problem comes in. Teh hotter the oil is the less load carryingn ability it has. Thats why you need the heavier oil because of the higher temps. With an 8qt pan and oil cooler ours will run 240-250 in a 25 lap feature.

Your not going to wash the bearings out at 65psi. if you have 85+ when its hot and your running down the front stretch then you have too much. 65-70 is about right.

If you are that worried about it go to the 15w40 but I wouldnt go any lighter than that.

aligater
Dirt Roller

Total posts: 10
posted September 29, 2005 05:05 PM  
i havent had the car up to speed yet, usually run 55-5800 rpm, so i will wait till i get to the track and see i guess. will bring the 15-40 with me, just in case. we over fill the oil slightly.

str8racing
Dirt Full Roller

Total posts: 65
posted September 29, 2005 05:20 PM  
why would you overfill the oil, won't it blow seals?

James Ott
Dirt Maniac

Total posts: 131
posted September 29, 2005 05:40 PM  
All oils thin as they heat up Synthetic or not. The rule of thumb is 10psi per thousand RPM. 5W-30 is alittle on the lite side, you may experiance scuffed pistons. 15W-40 is better and while youre at it try some synthetics like Amsoil. You will be happy! nuff said

B.K.ENG45
Dirt Full Roller

Total posts: 31
posted October 03, 2005 06:16 PM  
I AGREE W/ JAMES OTT 10lbs PER 1000 R.P.M.s' WE RUN STRAIGHT 50 wt valvoline racing oil

[This message has been edited by B.K.ENG45 (edited October 03, 2005).]

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