600 Miles and Engine Building

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19USMC69

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Undoubtedly, and all through this weekend's race, the subject of engine failure will arise. For good reason, to be sure. So, are engines (torerances, I suppose) built any different for 600 miles. If so, it would seem logical that a Charlotte/600 mile engine might be down a bit on HP. Or, if a 600 mile engine isn't any different, does it come down to the driver to be a bit less aggressive during the course of the race?
 
Not really, the engines are sooooooo much more reliable , while engine failure is always possible, its less these days , even for the 600 mile race.
 
19USMC69 said:
Undoubtedly, and all through this weekend's race, the subject of engine failure will arise. For good reason, to be sure. So, are engines (torerances, I suppose) built any different for 600 miles. If so, it would seem logical that a Charlotte/600 mile engine might be down a bit on HP. Or, if a 600 mile engine isn't any different, does it come down to the driver to be a bit less aggressive during the course of the race?
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Caution laps are easy on engines ;)
 
Every year, around the 500 mile mark, DW likes to point out that these engines are going farther than they have or will for the rest of the season.

And every year they just keep on going to the finish.
 
In the past, builders used different valve-train geometry (less severe angles) and a little less valve spring pressure for improved reliability.

The current race engines all have their camshafts located much higher in the block ... the pushrods are a lot shorter and the geometry angles are a lot less extreme. With practice and qualifying laps the engines have to live for 800 -850 miles plus a margin. I would guess that some teams (those that need to finish in order to pay their tire bill) choose the safest rear gear ratio on the permitted list in order to reduce maximum engine speed by 200 or so rpm.
 
Not that long ago it was common to see cars pushing water and overheating and seeing engines expire was common. In fact it was one of the reasons you were on the edge of your seat back in the old days as even if the leader was on a lap of his own you never knew if he was going to blow up. These days the engine designers and builders do a great job and engine failures are not that common even in 600 miles races.
 
They blow up pretty quick when they miss a shift, or hot dog wrappers clog up the works, but engine mechanical failure all by itself is all but gone from today's engines. Probably have a backmarker or two blow up before it is all over.
 
I have always wondered if teams practice a little less to t compensate for the extra 100 miles on the engine. A neutral set up is probably not bad anyhow, long race and an expected temperature drop between 6pm to 10 pm. Being the rocket from 6 to 9pm will be neutralized as well by some hot dog wrappers.
 
I loved the old days seeing the c reasons why someone was out of the race

Rear end
Shifter
Gears
Engine
Transmission
 
aunty dive said:
In the past, builders used different valve-train geometry (less severe angles) and a little less valve spring pressure for improved reliability.

The current race engines all have their camshafts located much higher in the block ... the pushrods are a lot shorter and the geometry angles are a lot less extreme. With practice and qualifying laps the engines have to live for 800 -850 miles plus a margin. I would guess that some teams (those that need to finish in order to pay their tire bill) choose the safest rear gear ratio on the permitted list in order to reduce maximum engine speed by 200 or so rpm.
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Greg said:
I have always wondered if teams practice a little less to t compensate for the extra 100 miles on the engine.
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Good stuff, Aunty, thanks for posting that. I recall discussion from the broadcast crew a few years ago, that each builder recommended a mileage limit. I could be wrong, but I think the numbers were 720 to 750 miles. They said this meant that practice miles were carefully monitored and somewhat reduced, IIRC.

I looked at practice and qualifying sheets from the 2016 race. (These numbers ignore roughly 12 to 15 out laps, which are as hard on a motor as any timed lap.)
Car 48 = 7+3+40+54=104 laps=156 miles.
Car 4 = 7+3+35+31=76 laps=114 miles.
Car 31 = 7+2+26+34=69 laps=104 miles.
Car 3 = 8+3+28+34=73 laps=110 miles.
Car 18 = 25+4+31+41=101 laps=152 miles.
Car 78 = 9+3+31+27=70 laps=105 miles.
Car 2 = 7+3+36+42=88 laps=132 miles.
Car 22 = 9+4+31+38=82 laps=123 miles.
 
This topic was mentioned by Fox during practice for the 600. Manufacturer recommended mileage limits for practice and qualifying:
- 100 laps Ford
- 115 laps Toyota
- 125 laps Chevy

Also Fox reported, in the 57 year history of the 600, only three times has the race not had an engine failure. That is now 58 years. Two blown motors this year.
 
They took a lot of hp from these engines a couple years ago. They also moved to a roller cam. The engine failures have really went away after that
 
The Chevy, Ford, and Toyota motors did a lot better over 600 miles than the Honda motors did over 500 miles yesterday.
 
ToyYoda said:
The Chevy, Ford, and Toyota motors did a lot better over 600 miles than the Honda motors did over 500 miles yesterday.
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Well turbocharging surely makes a difference, plus those things are essentially running full throttle the entire time
 
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