Race engine oil viscosity
#3130677
03/19/23 09:35 PM
03/19/23 09:35 PM
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Joined: Jun 2003
Posts: 2,423 Weatherford, Texas
RapidusMaximus
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Not to start a keyboard war but I’m curious as to what viscosity everyone runs in their race car and why. I’ve been involved in some discussions related to rpm, engine water temp, fuel preferences, 1/8 mile vs 1/4 mile, cold starts, outside air temp and so on. The discussion started relating to cold starts and how hard it may be on the engine with a 20/50 oil and oil system components, also gas vs alcohol related to water temp, and of course the hp differences related to viscosity…what say the masses…
1968 Plymouth GTX 1974 Dodge P/U Long Bed Stepside 318 2019 Ram 2500 6.4, auto, 4WD
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Re: Race engine oil viscosity
[Re: RapidusMaximus]
#3130694
03/19/23 10:47 PM
03/19/23 10:47 PM
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AndyF
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[quote=RapidusMaximus]Not to start a keyboard war but I’m curious as to what viscosity everyone runs in their race car and why. I’ve been involved in some discussions related to rpm, engine water temp, fuel preferences, 1/8 mile vs 1/4 mile, cold starts, outside air temp and so on. The discussion started relating to cold starts and how hard it may be on the engine with a 20/50 oil and oil system components, also gas vs alcohol related to water temp, and of course the hp differences related to viscosity…what say the masses… [/quot About the only thing that matters in terms of viscosity for race engines is bearing clearance. Typically race engines only operate in warmer temps and the engines are usually up to temp before max power is applied so that leaves bearing clearances as the primary issue. Modern engine design has trended towards tighter clearances and lighter oil for awhile now. Lots of "high tech" motors are using 0 weight oils. Old school guys still go with wider clearances and heavy oils.
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Re: Race engine oil viscosity
[Re: RapidusMaximus]
#3130742
03/20/23 08:34 AM
03/20/23 08:34 AM
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Joined: Jan 2003
Posts: 13,492 Marion, South Carolina [><]
an8sec70cuda
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I still go w/ the old school train of thought b/c it's served me well. I use 20w50 in my hemi b/c the clearances are on the loose side. Same w/ my 440. My BB chevy is a little tighter, so it gets 10w30. All using Valvoline VR1 conventional race oil.
CHIP '70 hemicuda, 575" Hemi, 727, Dana 60 '69 road runner, 440-6, 4 speed, Dana 60 '71 Demon 340, no drivetrain, on blocks behind the barn '73 Chrysler New Yorker, 440, 727, 8.75 '90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt '06 GMC 2500HD LBZ Duramax
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Re: Race engine oil viscosity
[Re: wheelsup68dart]
#3130762
03/20/23 10:14 AM
03/20/23 10:14 AM
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Joined: Jun 2003
Posts: 2,423 Weatherford, Texas
RapidusMaximus
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Been running 10w30 for some time on Methanol and double entry. As stated before bearing clearance should dictate this. No reason to sling molasses when near water can do the trick. Interesting, any concerns about methanol thinning the 10/30 too much? Do you run a vacuum pump? How much water/oil/ methanol do you get into your catch tank? Thanks
1968 Plymouth GTX 1974 Dodge P/U Long Bed Stepside 318 2019 Ram 2500 6.4, auto, 4WD
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Re: Race engine oil viscosity
[Re: 440Jim]
#3130771
03/20/23 10:40 AM
03/20/23 10:40 AM
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Posts: 4,203 Shelby Twp. Mi
HardcoreB
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In my drag race engine, I started using 10W-30 maybe 15 years ago. That engine had an oil temperature sensor in the pan, and it was hard to get heat in the oil. Even once the water temp was 170, the oil temp was cold. It did heat up some during the run, but never got "hot" and since it was shut off and waiting for the next round, the oil in the pan got cold again. Water temp and oil temp were very different in an engine that does not run for long. Street driven was a completely different story.
I found that 10W-30 produced less ET variation in the later rounds when there was less time between rounds. Compared to the 10W-40 I used to run. Spot on! it's hard to get the oil at a good operating temp in a drag engine application. And nearly impossible to 'overtemp' the oil unless something is going wrong.
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Re: Race engine oil viscosity
[Re: RapidusMaximus]
#3130795
03/20/23 12:14 PM
03/20/23 12:14 PM
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polyspheric
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A joke: the 1st number in a multi-viscosity, or the only number in single viscosity is the time in seconds it takes when cranking a cold engine for oil pressure to reach the last connecting rod. 20W50: 20 seconds.
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Re: Race engine oil viscosity
[Re: AndyF]
#3130802
03/20/23 12:26 PM
03/20/23 12:26 PM
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moparacer
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GM recommends Mobil 1 0w-50 for their 632 crate engines. The owner is used to running 20w-50 in his race engines. I tell the guy to run what the GM engineers tell him to run but he isn't super comfortable with it. That's what I have been running for a few years now. I run alky. If a lot of racers installed oil temp gauges and actually seen how hot the oil really gets they wouldn't be running syrup for oil.
67 Barracuda street/bracket car 11.27-119 68 Dart 502 BB 8.70s-152 414 cid SB Dragster 7.65-174
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Re: Race engine oil viscosity
[Re: AndyF]
#3130837
03/20/23 01:59 PM
03/20/23 01:59 PM
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madscientist
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I ran an oil temp sensor in my Duster. It takes a long time for oil to heat up. Usually takes about 10 miles of driving before oil is up to temp. Oil doesn't get warm in the pits or driving to the staging lanes. What was the oil temp when it finally came up and stabilized?
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: Race engine oil viscosity
[Re: madscientist]
#3130868
03/20/23 03:00 PM
03/20/23 03:00 PM
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Posts: 31,200 Oregon
AndyF
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I ran an oil temp sensor in my Duster. It takes a long time for oil to heat up. Usually takes about 10 miles of driving before oil is up to temp. Oil doesn't get warm in the pits or driving to the staging lanes. What was the oil temp when it finally came up and stabilized? Depends on the load and ambient. Driving around town oil temp is 150 to 180 depending on air temp. Freeway usually 180. Climbing a long hill or hammering on the engine for more than a minute spikes the oil temp pretty quickly.
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Re: Race engine oil viscosity
[Re: an8sec70cuda]
#3130875
03/20/23 03:08 PM
03/20/23 03:08 PM
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Posts: 26,470 Rio Linda, CA
John_Kunkel
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I still go w/ the old school train of thought b/c it's served me well. I use 20w50 in my hemi b/c the clearances are on the loose side. Clearances weren't mentioned in the OP and that'd critical in the decision making.
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Re: Race engine oil viscosity
[Re: John_Kunkel]
#3130904
03/20/23 04:52 PM
03/20/23 04:52 PM
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Joined: Jun 2003
Posts: 2,423 Weatherford, Texas
RapidusMaximus
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I still go w/ the old school train of thought b/c it's served me well. I use 20w50 in my hemi b/c the clearances are on the loose side. Clearances weren't mentioned in the OP and that'd critical in the decision making. Yeah, didn’t mention clearances mainly because I figured most race engine builders shoot for close to the relatively same clearances .002-.004 but I may be off base, I kinda assumed that anyway , it’s a really good point, I’m not smart enough to go down the rabbit hole of bearing clearances and viscosity relationships…lol
1968 Plymouth GTX 1974 Dodge P/U Long Bed Stepside 318 2019 Ram 2500 6.4, auto, 4WD
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Re: Race engine oil viscosity
[Re: AndyF]
#3130923
03/20/23 07:27 PM
03/20/23 07:27 PM
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I ran an oil temp sensor in my Duster. It takes a long time for oil to heat up. Usually takes about 10 miles of driving before oil is up to temp. Oil doesn't get warm in the pits or driving to the staging lanes. What was the oil temp when it finally came up and stabilized? Depends on the load and ambient. Driving around town oil temp is 150 to 180 depending on air temp. Freeway usually 180. Climbing a long hill or hammering on the engine for more than a minute spikes the oil temp pretty quickly. Thank you. One more if you don’t mind. When the temp went up with load, did it come back down to where it was or did it stay up where it was when the load was the greatest? Also, if it came down about how long did it take? I snuck two in there. TIA
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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