UghThatMemeGuy wrote: ↑05 Dec 2022, 23:38
I was looking for an answer on why it is that there are often times no air filters on racing engines. Someone correct me if i am wrong, but in NASCAR, aren’t the cars (and engines?) disassembled after each race to validate no cheating has occurred?
That said, for F1, if the teams get 3 engines to use per season and the primary engine of those three is supposed to be used all season where possible, then it would suffoce to say that at an average of about 100 min per race, w/ 7 races per season, that the engine needs to last 700 min or about 11.6hrs. Let’s say the avg speed is 161 mph and the engine puts on a total of about 1,878 miles per season. For grins, I would double or triple that mileage for practice sessions and qualifying etc. That said, if the oil is changed after every single use, then essentially, the engine only has to last for roughly 6,000 miles making an air filter of fairly little concerned… Yes there will be where on the engine and it won’t last as long, but aren’t they likely to rebuild the engine, Hon, bore, etc. after every season to prep for the following season?
If you get into NHRA they tear engines down after each race… So it seems relatively fruitless to worry about air filtration when tear downs and oil changes are so frequent... *shrug*
Thoughts?
NASCAR engines use air filters. The engines have to last one race weekend, so figure 700-800 miles. They're torn down after each weekend and rebuilt. Hard parts are re-used; crank, heads, block, etc. Other stuff checked for wear (camshafts), but springs / rings, etc. are one and done. The blocks go about 8000-9000 miles between cycling out. Heads would be less. One thing to keep in mind, and part of rebuilding / swapping engines out every race, is to set the engines up for different track types, you're going to have different porting / camshafts / exhaust headers, etc. It's not exactly like taking an engine like a F1 engine where you have MORE than enough air and you can just tune it via other means (variable geometry turbo inlets, wastegate, MGU-H, MGU-K, variable length intake runners, etc.). You have plenty of tools at your disposable to shape the torque curve. On a naturally aspirated engine, you literally have to change parts out.
The Ilmor LS prodution based ARCA engines go about 1800 miles between rebuilds. The LS based IMSA engines go about 3000-3500 miles between rebuilds. RPM is a big factor. I know Ilmor has tested some of these LS based platforms to 10,000 miles on the test cells, but there is a tradeoff in power.
The DTM engines run about 3000 miles before rebuilds.
Again, everything has a cycle life and when you are pushing the limits of the rules in terms of tolerances, weight, tune, etc. You run it right up to your margin of safety. What might be junk to a NASCAR builder will be just fine on your average hot street or even drag strip engine. They just don't feel comfortable with it going another 700 miles at those rpm at those temperatures. There are a lot of wasted costs to a DNF.