Who knew? NASCAR engines run at way over 300F.......

[machoneman]

https://www.msn.com/en-us/autos/enthusiasts/the-fascinating-reason-why-nascar-engines-run-so-hot/ar-AAC6gnC?li=BBnbfcL&ocid=wispr

[WConley]

They also run with the rocker covers filled to the top with oil.  It's the only way to keep the valve springs cool enough to live at 9,500 rpm!

[gregaba]

By running their engines so hot they can be more efficient and use less fuel.
If you can light all the fuel in the chamber you can run a A/F ratio of 20 to 40 to 1.
With the right ignition and FI you can control the burn and increase your fuel mileage not to mention your engine is more efficient.   
Greg

[FrozenMerc]

Put a thermocouple or temp gun on your favorite air cooled lawn mower / tiller / snow blower engine the next time you are working it at full tilt.  You would be surprised how hot those Briggs / Kohlers / Techumsha's run.  The NASCAR deal is not much different.  Lots of advantages to running that hot, with very little downside. 

[C8OZ]

Interesting read...stressed me out imagining that cool-down unit coming in.
Had no idea they were risking/sacrificing parts and HP in that way for the aerodynamic edge.

[RustyCrankshaft]

Put a thermocouple or temp gun on your favorite air cooled lawn mower / tiller / snow blower engine the next time you are working it at full tilt.  You would be surprised how hot those Briggs / Kohlers / Techumsha's run.  The NASCAR deal is not much different.  Lots of advantages to running that hot, with very little downside.

I run a lot of ported chainsaws and I watch cyl temps before and after porting and it's one of the tools used to help dial in the porting. My Stihl 461 after a few minutes of "warmup" cuts will be 325 on an average temperature day (60-75*). 32" bar with full comp chain in 4 feet of fir and it'll be 380 at the end of a cut. Good oil helps.

On F1 engines they run hot water thru them because when the engines are cold the clearances are so tight they're basically "stuck" until they warm up and everything expands enough to turn over freely. No the same architecture as a NASCAR obviously, but interesting to see the different strategies and affects on the cooling systems/engine design it has.

I bet they use a lot of ceramic coatings to help stuff live. I digress, however, I used to think they were sort of a gimmick until I was racing some 2 stroke diesel at Bonneville. We'd get 2 passes out of a set of pistons and the crowns would melted off them. We couldn't shut the truck off after the first pass or we ran the risk of not being able to re-start it. I had a local place coat the crowns with a ceramic thermal barrier and after a dozen passes you could wipe the crowns with brake clean on a rag and they looked just like I put them in.

[machoneman]

I had thought even before I posted the article that after a quick read, the high temps were solely for qualifying (lots of tape fpr max speed). But, after a more careful read, it's apparent that these high temps are for the entire race. And yes, they must use various coating on lots of engine parts.

Funny, but when NASCAR says they want to keep the costs down, they might want to limit top temps to say 220F with some kind of pop-off valve and let the teams skip all the fancy and very pricey coatings. Don't hold your breath! 

[gt350hr]

   The higher temps also require higher water pressure ( as mentioned) to keep the water from forming steam around the cylinders . that leads to pins in the impeller and the drive flange to keep them from spinning on the shaft. This was another reason they went to serpentine drive belts for more "traction". High temps are another reason why internals are "cycled out" after a few thousand miles of racing. Pistons , rings , bearings , valves , springs etc. are all one race items. Heads "can'' go two races , rarely more , cranks a few more and blocks until they reach their wear limit unless they have the nikasil liners.
  Randy

[Katz427]

We know that the rules were changed to even the "field", by limiting the pressure to 33 lbs. A 33 psi cap and 14.7 psi atmosphere limits them to about 280F if all are using plain water.

[machoneman]

We know that the rules were changed to even the "field", by limiting the pressure to 33 lbs. A 33 psi cap and 14.7 psi atmosphere limits them to about 280F if all are using plain water.

Got it. Didn't know of the already established limits. I do think they are mandated to run clear water to avoid slow track drying after a big accident. But, I don't know if so water wetter type of fluids can be added to that water to further raise the boiling point.

[gt350hr]

    Yes Bob , plain water , no additives.