Stress on engine during autocross.
Stress on engine during autocross.
Poll inspired by dumb thread on NASIOC. Guys car blew up (stock STi) because the 08's had a tuning problem, causing them to run lean sometimes. Subaru rebuilt engine under warranty, idiots on NASIOC are blaming autocross.
Do you think that autocross is any harder on a stock engine than what could conceivably occur on the street?
I say no for a variety of reasons.
Do you think that autocross is any harder on a stock engine than what could conceivably occur on the street?
I say no for a variety of reasons.
Chris Harp
2009 Mazda RX-8 | 2018 Toyota Tundra | 2011 BMW M3
2009 Mazda RX-8 | 2018 Toyota Tundra | 2011 BMW M3
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Nope. There's a red line on the tach for a reason. That's with a margin of safety so they don't end up with tons of warranty claims. Everything you do to the engine autocrossing is well within the designed tolerance.
David Guffey
97 Miata - STS #40
99 Miata - Nicest beater I've ever had
88 4Runner - Trusty, rusty trail-sled
97 Miata - STS #40
99 Miata - Nicest beater I've ever had
88 4Runner - Trusty, rusty trail-sled
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But during an average autocross run of ~45 seconds, how long are you going to be at or near redline?Budman wrote:I think yes, but only due to the engine rpms being higher than normal and for longer periods time. Higher rpms puts more stress on moving parts and also could cause decreased lubrication.
I would venture to say that taking a car to redline in gears 1-3 while getting on the freeway would net you an average higher maintained RMP than your average autocross run.
eidt: and of course the service guy would say yes *WARRANTY DENIED*
Chris Harp
2009 Mazda RX-8 | 2018 Toyota Tundra | 2011 BMW M3
2009 Mazda RX-8 | 2018 Toyota Tundra | 2011 BMW M3
I voted yes for the following reasons:
a) I assume you mean over period of time although short instead of instantanious. There would be no difference if instantanious.
b) Just to keep up my contrarian role
Seriously, there is probably a little more time at max rpm under load in autoX, but it is a small amount and driver controlled. This is probably more true of us that run lower torque, high rpm cars such as Miata's, Mini's, S2000's, etc. that use 1st gear more than say a WRX. Rarely on the street will I go from full load at max rpm to no throttle without depressing the clutch to change grears. This is common in autocross.
If one were to short shift staying away from max rpm, and drive very smoothly, the extra stress would be negible IMHO.
a) I assume you mean over period of time although short instead of instantanious. There would be no difference if instantanious.
b) Just to keep up my contrarian role
Seriously, there is probably a little more time at max rpm under load in autoX, but it is a small amount and driver controlled. This is probably more true of us that run lower torque, high rpm cars such as Miata's, Mini's, S2000's, etc. that use 1st gear more than say a WRX. Rarely on the street will I go from full load at max rpm to no throttle without depressing the clutch to change grears. This is common in autocross.
If one were to short shift staying away from max rpm, and drive very smoothly, the extra stress would be negible IMHO.
Old men can still dream!
Scott Gibson
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I wonder what effect heat cycling and short on-off cycles might have. Turn the car on, let it warm up to op-temp, flog car for 35-60s, idle car for a minute, turn off for 5-10 minutes, then repeat 3-7 times.
That said, I voted no, because I'm sure stop & go city driving and traffic idling is probably still worse.
Roadracing would be a different story obviously.
That said, I voted no, because I'm sure stop & go city driving and traffic idling is probably still worse.
Roadracing would be a different story obviously.
engine != ecuthrdeye wrote:I said stock engine. Read noob.steverife wrote:I would tend to say yes.
I bought an eBay knockoff Mugen chip for the CRX and it didn't have a rev limiter.
"Everyone is going to third and I'm not even hitting the limiter. WTF?"
...but seriously, I'd say yes. How much harder? Eh, who knows?
'16 FRS - PSTX 97
My Gtech recorded all my runs the day I blew my car up, I never even got into the rev limiter.
And before you all point out my motor wasn't stock:
1) The cam had a GM part number.
2) You could get an engine from GM in that specification.
3) It was running a rich tune. (Verfied by my dyno pull with wideband the week before).
4) The engines bottom end was untouched, as were the heads, and it was running stock compression.
And before you all point out my motor wasn't stock:
1) The cam had a GM part number.
2) You could get an engine from GM in that specification.
3) It was running a rich tune. (Verfied by my dyno pull with wideband the week before).
4) The engines bottom end was untouched, as were the heads, and it was running stock compression.