WOT Good?

[Millermagic]

A few people told me that having the pedal to the floor is a good thing on occasion. Is this true? Now maybe because of the high rpms and carbon build up, if I want to get rid of the carbon build up, I'll just put the gear selector in 1 and reach 4000 rpm for a few seconds and that should help to get rid of the carbon. But I always thought it was bad for the transaxle and other fwd drivetrain components.

[abaird]

As long as you don't exceed the redline you shouldn't hurt anything. Todays vehicles can handle some pretty hard abuse without falling apart.

[AlmostStock]

It is hard on any drive train, not just FWD. If a vehicle is in good overall condition occasional pedal to the metal episodes are not going to hurt anything. If you do it a lot something will eventually give. Higher horse power and sticky tires add to the stress. This is why race cars have built up drive trains to handle the abuse.

I think the carbon build up was more common with the old carburetors. Newer FI and ignition systems monitor the fuel to the point where carbon build up is minimal. At least this is what I have noticed on my cars. Old timers would spray water into the intake of a running engine to remove carbon. Rev it up a little as you spray to keep it from stalling. Use a spray bottle not a garden hose!

[mazdatech177]

FI engines buildup carbon just as bad as the old carbureted ones do. so the occasional top engine clean and flogging of the throttle is not a bad thing at all.

[curtis73]

The internal engine parts see forces that are proportional to throttle position and RPM. The greatest forces occurring in an engine are at redline with your foot to the floor. So, as far as engine wear is concerned, WOT and redline is the place where the most wear and fatigue happens. That's not to say its bad, but an engine that spends more time at WOT will typically not last as long before failure than an engine that's driven more calmly with an occasional WOT.

[SaabJohan]

Originally Posted by curtis73

The internal engine parts see forces that are proportional to throttle position and RPM. The greatest forces occurring in an engine are at redline with your foot to the floor. So, as far as engine wear is concerned, WOT and redline is the place where the most wear and fatigue happens. That's not to say its bad, but an engine that spends more time at WOT will typically not last as long before failure than an engine that's driven more calmly with an occasional WOT.

In a car engine most wear is caused during start up, especially cold starts. Wear on bearings is usually highest when the engine is driven by the start motor or directly thereafter.

As for load on the engine, there are different loads. Inertia forces are highest during max rpm but forces caused by combustion pressure are higher at around maximum torque with WOT while inertia forces aren't affected by throttle position. Anyway, stock engines does usually have very large margins against fatigue so using an engine hard should not cause any problems as long you stay away from the engine speed limiter.

As for carbon build up. Carbon or soot is formed during rich incomplete combustions, such as WOT.

[AlmostStock]

Originally Posted by mazdatech177

FI engines buildup carbon just as bad as the old carbureted ones do.

Since carbon is a byproduct of burning (or the incomplete burning of) gasoline, I don't see how something that allows the use of less fuel (like FI and modern OB management systems) could produce the same amount of carbon as an older, less fuel efficient, system.

Originally Posted by SaabJohan

In a car engine most wear is caused during start up, especially cold starts. Wear on bearings is usually highest when the engine is driven by the start motor or directly thereafter.

True, but dry start up wear and high rpm stress are two completely different things and will eventually cause different failures.

[beef_bourito]

the use of fi does not necessarily increase the a/f ratio. if you add boost and don't add fuel, you'll have a dangerous engine but that's beside the point, you'll have complete combustion. if you do increase the fuel to the same a/f ratio as before fi you will most likely have the same ammount of carbon buildup as before.