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Small block Chevy endurance racing failures.

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Engine: 15w40 dino Rotella change every race

Trans: Amalie universal synthetic ATF change it when it doesn't look new

Diff: Mobile one 75w90 change it every year or 2

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35 minutes ago, Team Infiniti said:

Engine: 15w40 dino Rotella change every race

Trans: Amalie universal synthetic ATF change it when it doesn't look new

Diff: Mobile one 75w90 change it every year or 2

 

Ok, so that is a pretty good sanity check... I'm not too far off in thought process/action, I assumed I might be a little on the conservative side. 

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8 hours ago, mcoppola said:

Aren't oil viscosity requirements determined by the main and rod bearing clearances for a given engine?

Yes. The engine that I used for a year then sold to someone else (who ran it another two years, then sold it to a guy who put it in his truck) had unknown bearing clearances because I patched it together. Dirt cheap in this case meant that I didn't have an engine stand so I rebuilt it by rolling it around on the garage floor, doing my best to keep the dirt out of the important places. Apparently, I was successful. :)

 

The engines that I build for endurance racing now have precise bearing clearances and I typically use Redline 40 wt racing oil, changed after each weekend or about 15 hours.

 

The downside of running too heavy an oil is a slight loss of hp; the downside of running too light an oil is the possible loss of the engine.

Edited by mender
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On 8/22/2019 at 9:37 PM, wd6681 said:

What weight oil do most of you guys run in your smallblocks for endurance racing?

 

15/40 full syntho.. 7 qts. We used to run more but got rid of the oil cooler and remote filter. K&N makes a nice deep filter for a SBC. We check it after a weekend. Get a magnetic drain plug. Easy way to tell if something bad is going to happen. 

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Better yet is to buy one of these:

Image result for oil filter cutter

 

I cut apart every filter that comes off the engine. I then use a knife to cut the filter element at the top and bottom then slit the ends and pull out the section in one piece. I squeeze out the residual oil then carefully extend the section like an accordian so I can see what the filter trapped inside the folds.

 

Bearing material isn't magnetic unless you get well past the surface layer on the tri-metal (Clevitte 77) bearings, and some other ones are aluminum alloy (Federal Mogul) so this is the best way to get an early warning.

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I also check to see what is sitting in the bottom of the metal canister by slowly pouring out the oil and watching for sparklies. 

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We had every sbc failure that's possible...

 

I hate those engines....

 

Spun bearings, broken pistons, wiped lobes, broken rockers, head haskets, etc...  it was never the same failure.

 

However, this was back in the early days of champcar and lemons.  We made it work with what we could.

 

I have seen more v8s fail in this type of racing than rotaries.

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On 8/23/2019 at 9:06 PM, mender said:

Yes. The engine that I used for a year then sold to someone else (who ran it another two years, then sold it to a guy who put it in his truck) had unknown bearing clearances because I patched it together. Dirt cheap in this case meant that I didn't have an engine stand so I rebuilt it by rolling it around on the garage floor, doing my best to keep the dirt out of the important places. Apparently, I was successful. :)

 

The engines that I build for endurance racing now have precise bearing clearances and I typically use Redline 40 wt racing oil, changed after each weekend or about 15 hours.

 

The downside of running too heavy an oil is a slight loss of hp; the downside of running too light an oil is the possible loss of the engine.

 

Do you shoot for looser than std clearance or tight end?

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For SBC I use 0.0021-2" on the rods and 0.0026-7" on the mains. Old school but very few issues, has about the right combination of load bearing and oil flow for proper cooling.

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We've vented one lt1 after about 7 races. Biggest thing to save these motors is short shifting. Torque is lower and you'll be faster shifting <6k rpm; DON'T wind out the motor. We also have a Canton baffled pan on for good measure. 

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