im having this discussion with someone and i wonder what you folks have to say about it. which do u think is harder on an engine. autox or track days. i have my own opinion, but i'm leaving that out.
-spenc

edited for spelling. college much?


[Modified by SOLOef, 1:34 PM 12/18/2002]

 

road racing by far.....my friend who runs a C prepared 1979 Mustang is basically building a drag motor for his car....only needs to run hard for ~1minute 3-6 times twice a month....just my opinion

 

definitely road racing/track days.

 

As he said "Track Use" and not "Road-Racing"... I almost think that Competitive Auto-Xing is a little harder on the engine/clutch/tranny, than HPDEs are. Just my opinion.. but think about it... drag race launching starts... No moving air to cool the engine... more gear changing... ON/OFF brake use with not much cooling... More use of Low gears means faster time to RedLine... well, just my $.02

 

on average, drivetrain parts wear out more during time trialing/roadrace/hard hpde. but, i think that autocross wears out tires minute for minute compared to the track. i shred through fronts at autocrosses.

 

Count the sustained RPM's at an autocross, and at a single session on track.
Wear is the result of the engine spinning, and it spins much, much more over a 20 minute session than it does on a 40 second autocross course.

 

if its a standing start in a race, you launch just the same.
no moving air?????
more gear changing?? 99% of the time i shift once into second gear and stay there for the duration of the course.
as you progress in autocrossing, you arent on the brake all that much. even so, 60 seconds is HARDLY enough time to heat up the brakes to where cooling becomes a huge issue.
true, low gears = fast to redline, however you stay near redline for a second or two at most, and then its time to turn. and thats only when the autox course has a decent straight.

jhmo

 

Minute for minute, they're about equally hard on engine and drivetrain. But there are a TON more minutes in a weekend of club racing or HPDE than a typical weekend of autocross.

 

This "flok" (lol) thinks that a track day is way more abusive on an engine than an autocross event. At a track day you would be watching your water temp's and oil temp/pressure/idiot light closely - at least I would. In autocrossing your main concern is making sure the car is actually up to temp before the run... and after a run I let the engine run for a few minutes with the heater on and hood up, and I leave the hood up until it's time to run again.

BTW, what do tires, brakes, drivetrains, and transmissions have to do with engines... engines was the question.

And I normally only shift once for an autocross run, maybe twice if the course requires 3rd gear. Thats whats nice about having nearly as much torque as a GSR has horsepower....


[Modified by Vracer111, 8:34 AM 12/18/2002]

 

AutoX = 3 or 4 runs of 1min in length.
Track Days = about 3 20min sesions.

U do the math

 

Like Crack Monkey Said.... I was speaking about a minute to minute comparison... but quite frankly, excluding engine wear from extended high rpms, I felt like my previous car(Autocross/Solo1/HPDEs) took more of a beating in other areas(tranny/clutch) in a day of autocross(3 runs) than a day of an HPDE.

Re-read my first post.... He said Track Days... not Road-Racing. There is a difference.



[Modified by XR4racer, 10:23 AM 12/18/2002]

 

Tire wear aside, the only thing in autocross that might cause more engine wear than tracking a car would be the extended use of the rev limiter.

There are pitfalls to bouncing off the limiter, and at track events, you typically will shift.

So, my vote is for track events being a bit harder on the car.

Scott

 

I'm with Rob and the Crackster. Wear/unit time is probably the same. I might even give the nod to auto-x. But obviously, you spend more time on track than on an auto-x course, so per event, a day at the track is harder than a day auto-xing.

IMO, of course.

 

A minute-to-minute comparison?

IMO it's a wash. Fact is, I'm running the at 110% the whole time in either discipline. There will be course sections that are easier on the drivetrain and others that are harder. But in the end I'm extracting every bit of power I possibly can. There are too many variables to make a blanket statement in either direction.

I'm not sure this is a logical issue in the first place. When was the last time any of us did a 20 minute autox run, or a HPDE run for no more 65 seconds? A *track day* is obviously harder on the motor than an *autox day*. Isn't that a better comparison?

 

This question has been asked about as much as:

"Which takes more skill?"
"Which is more fun?"

Questions that can be debated forever...........

 

Autox and track time are hard on an engine?

How about choice "c" -- street driving in rush-hour traffic?

Seriously though, I think that opentracking will be harder on an engine than autocross. Someone mentioned that the revs at an autocross are a bigger deal than on the track, but my experience differs. At an autocross, I shift once, and leave it in second, except in the case of really crappy courses (1st gear) or courses that are too fast (3rd gear). At Summit Point, I'm in fifth coming into turn 1, then down to 2rd, then up to 3rd and 4th, coming out, third in turn 5, back into 4th, then into 5th just before the starter stand (my car has 6 gears, remember). There is a lot more potential for a missed shift resulting in over-revs. There is also a lot more potential for lateral g's to cause oil starvation if you aren't savvy enough to check fluid levels before every session.

Karen
242K, no rebuilds, still running strong....who says autox is "hard" on a car???

 

i'm glad to see the majority feels the way i do about this.
-spenc

 

This depends on your car. My car goes to 3rd at around 47mph... Ive shifted as many at 9 times during an autocross run. At our event this past weekend, i went through the lights in 4th...

Also, as you progress, you MAY infact be on the brakes more. If you develop your skills as a left-foot braker, you may actually be on the brakes quite a bit.

Second for second, id say autocross, simply because the engine is either accelerating or decelerating more often, and faster. Also, as someone mentioned, people use the rev limiter quite a bit more.

 

depends on your aggression level. i still tend to think that rush hour traffic is worse on your engine then a day of autocrossing.

nate-who's car has 183k miles

 

I thought the point of a rev limiter was to protect the engine, but if you stuff it into a lower gear that it shouldn't be in (like going 2->1 instead of 2->3), you could overrev the engine past the limiter, causing catastrophic failure.

Karen

 

i've heard of some cars that have oil starve issues when banging against the limiter, and cars like saturns can wipe out main bearings if you do it too much. on a honda i don't see much of an issue. not to mention i know of at least 2 other hondas that have well over 225k on the original motor and have no problems at all.

 

You can't really give one definitive answer on this issue. The true answer is "it depends".

As one guy stated, rush-hour traffic/daily driving is the the worst and this is why all the auto companies perform extensive testing with mule vehicles on the streets. Why? Because frequent stops and starts are the hardest on an engine. First of all, the operating temperature fluctuates wildly. The causes areas of high localized stress since some parts are getting hotter than others. The effect is multiplied because the air flowing into the cooling equipment also stops. Also, just starting your car in the morning causes more wear than a half day at the track due to no oil pressure for the first several seconds.

So, the answer is that running on a open track like Daytona at 150MPH is actually much easier on your engine than autocross (or daily driving for that matter) because the engine is allowed to normalize its temperature among the internal components. Generally, autocross will be a little harder because the courses are smaller and the turns are sharper (which causes a huge fluctuation in engine temps). However a twisty track course can easily punish the engine far more than any autocross track.

It all depends...

 

Typically a factory rev limiter cuts fuel (this seems OK unless you are running high boost), bt a lot of aftermarket ignitions will cut the spark (even the simple ones, Crane, MSD, etc.)

If you start cutting teh spark for extended periods 9like you often can see in an autocross) all that unburned fuel can wash the oil off the cylinder walls and suddenly you have accelerated wear and cracked piston rings.

I know a Street Mod autocrosser rebuilding his engine right now for what is probably this very reason.

Scott

 

From personal experience daily-driving and tracking the celica.

The coolant rarely hits and never exceeds 215°F and oil 250°F during daily driving. Hottest temp usually occur during Summer where ambient temp is close 100°F and with stop & go (LA) traffic. Mind you, the fan properly turns on at 199°F and verified by an aftermarket gauge. Still, the water pump isn't doing much at idle.

I've managed to run up coolant temp at 240°F last summer at Big Willow. I got the oil up to 290°F further backed by 10psi drop of oil presure at peak rev.

If you solely factor engine thermal stress, I would have to say track use puts the worst toll.

 

City traffic.