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496 Mag HO Oil weight/power gain

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Old 04-02-2013, 04:08 AM
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Default 496 Mag HO Oil weight/power gain

We dynoed a 496 yesterday but unfortunately we didn't have enough time to test different oils.

Is there anyone that has done this? I have been using Royal Purple 20W50 but would like to go down in viscosity to gain some power - but still want to keep the reliability of course!

The 496 is in my 24 Pantera that I use purely for racing and I'm looking for all gains I can find. I run it 99% at WOT except for warmup.
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Old 04-02-2013, 05:19 AM
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Originally Posted by tomas_wallin View Post
We dynoed a 496 yesterday but unfortunately we didn't have enough time to test different oils.

Is there anyone that has done this? I have been using Royal Purple 20W50 but would like to go down in viscosity to gain some power - but still want to keep the reliability of course!

The 496 is in my 24 Pantera that I use purely for racing and I'm looking for all gains I can find. I run it 99% at WOT except for warmup.

there is more to it than that. yes. lighter oil will buy a bit of overall power and better acceleration BUT if you are going to use that approach, the bearing clearences through out will have had to have been done as a function of the thinner oils you would be running. big clearences with thin oil will result in low oil pressure and no film to support the shock load.

and unless you are racing at the extreme limits, the benefits will not be noticeable in any way at all. at 230 degrees , where your oil temp should be, the viscosity will be so thin that drag from that will be a meaningless number . a properly designed oil system that reduces windage will be far more effective. the bottom line here is that the clearences that are in your motor NOW define what oil you need to run. unless you are planning to change those, you really have no choice as what to run.
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Old 04-02-2013, 05:40 AM
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there is more to it than that. yes. lighter oil will buy a bit of overall power and better acceleration BUT if you are going to use that approach, the bearing clearences through out will have had to have been done as a function of the thinner oils you would be running. big clearences with thin oil will result in low oil pressure and no film to support the shock load.

and unless you are racing at the extreme limits, the benefits will not be noticeable in any way at all. at 230 degrees , where your oil temp should be, the viscosity will be so thin that drag from that will be a meaningless number . a properly designed oil system that reduces windage will be far more effective. the bottom line here is that the clearences that are in your motor NOW define what oil you need to run. unless you are planning to change those, you really have no choice as what to run.
Thanks Steve,

What viscosities work with the 496 Mag HO then? Is it 50 and nothing less?
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Old 04-02-2013, 07:11 AM
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Just had a local race engine builder test Joe Gibbs and Spectro Motorgard and Rotella T, all viscosities, 10w40, 20w50, 10w30.

Warmed the oil to 230 F and started his pulls. after a day on the dyno, no difference in power. The JG rep was shocked and sent home with his tail between his legs.

Ken
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Old 04-02-2013, 07:33 AM
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I ran Rotella 15-40 for a while and liked it. I never saw any WOT speed gains in thinner oils. I ended up using Amsoil dominator 15-50 with 1 QT of 60 wt racing(during mid summer/hot) oil during every change to keep consistent oil pressures..

Here is what I have gathered over 8 years with a 496 mag, a 496 HO and a Raylar 496/600:
1. According to Raylar "dont run anything 5 or 10" its too thin. And he was right, my engines were noisier on startup when I did...
2. What you think you are gaining at WOT you are losing when you come back to idle. (On both my stock engines) after a hard run with anything but 20-50 they would run really low oil pressure when coming back to idle for a no wake. Oil pressure would always drop down around 30-35. The 15-50 or 20-50 seemed to stop that. A K&N or similar good filter seemed to help as well.
3. After 30 hours on an oil change, the idle oil pressure always became an issue.
4. For what its worth, my 600's have -10AN lines, high volume pump and cleaned up oil ports and its better at idle.
5. The "good" synthetics are your answer. I picked up more speed with an oil change in the engines and drives than messing with viscosity. My boat is always a hair faster with new oil in both.
6. If you want +1 mph, thin down the screens on your stock flame arrestors. Taking off the top 3 layers gave me speed on all 3 sets of 496's.

Last edited by Keith Atlanta; 04-02-2013 at 07:38 AM.
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Old 04-02-2013, 07:43 AM
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Originally Posted by Keith Atlanta View Post
I ran Rotella 15-40 for a while and liked it. I never saw any WOT speed gains in thinner oils. I ended up using Amsoil dominator 15-50 with 1 QT of 60 wt racing(during mid summer/hot) oil during every change to keep consistent oil pressures..

Here is what I have gathered over 8 years with a 496 mag, a 496 HO and a Raylar 496/600:
1. According to Raylar "dont run anything 5 or 10" its too thin. And he was right, my engines were noisier on startup when I did...
2. What you think you are gaining at WOT you are losing when you come back to idle. (On both my stock engines) after a hard run with anything but 20-50 they would run really low oil pressure when coming back to idle for a no wake. Oil pressure would always drop down around 30-35. The 15-50 or 20-50 seemed to stop that. A K&N or similar good filter seemed to help as well.
3. After 30 hours on an oil change, the idle oil pressure always became an issue.
4. For what its worth, my 600's have -10AN lines, high volume pump and cleaned up oil ports and its better at idle.
5. The "good" synthetics are your answer. I picked up more speed with an oil change in the engines and drives than messing with viscosity. My boat is always a hair faster with new oil in both.
6. If you want +1 mph, thin down the screens on your stock flame arrestors. Taking off the top 3 layers gave me speed on all 3 sets of 496's.
Thank you Keith!!!
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Old 04-02-2013, 11:03 AM
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I have run Mercruiser 25W-40 dino until the Mercruiser 25W-40 semi syn became available a few years ago. Changed every 25 hrs on the high perf and 50 hrs on the low perf engines.

I had:
1986 350MAG in 21' Formula 350 hrs, sold with no engine work or issues ever.
1987 350MAG in 24' Formula over 400 hrs, sold with no engine work or issues ever.
2004 Baja 33' twin 496HO, sold with 275 hrs, no engine work or issues ever.
2005 42' Fountain twin 525's have 325 hrs, no engine work or issues ever.
2007 23' Sea Ray 350MAG ski boat 150 hrs, no engine work or issues ever.
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Old 04-02-2013, 11:49 AM
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i have used the rotella for 3 years now, no issues to speak of. But unless you are going for milliseconds in a race setting I dont think worrying about oil in speed would be the tops on my list.
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Old 04-02-2013, 12:43 PM
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Originally Posted by soldier4402 View Post
i have used the rotella for 3 years now, no issues to speak of. But unless you are going for milliseconds in a race setting I dont think worrying about oil in speed would be the tops on my list.
The "problem" is that we're racing stock motors and can't change anything but the exhaust. So oil, and spark plugs, is more or less the only other thing I can look into.


Has anyone had any luck with other brands of replacement spark plugs?
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Old 04-02-2013, 12:53 PM
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Originally Posted by tomas_wallin View Post
The "problem" is that we're racing stock motors and can't change anything but the exhaust. So oil, and spark plugs, is more or less the only other thing I can look into.


Has anyone had any luck with other brands of replacement spark plugs?
I guess thats something to look into. You may also look into weight savings.
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