Fishey

Sounds cool... Best of luck!

Z-man

It's your call, but brake pads and rotors are still cheaper than clutches and trannies, so why put unneccessary wear and tear on a more expensive item?

-Z.

gleamingred944

My 2c worth is that downshifting to the gear you need to best accelerate after a turn then using it to slow the car down is smooth but definitely not as good for lap times as using brakes.

One of our local drivers put it this way: a clutch job on a 944 costs 5 times as much as a brake job!

Another 2c worth is: when I got my braking calibrated at a local track: from 200 km/hr to stop, my brakes soak up just over 2000 hp (two thousand!). The best I could do with engine braking was 50.

Porsche brakes are a dream. Use them!

mpw

I've found the opposite. I don't use the engine to slow the car, but the times I've botched a heel-toe and put it in gear at the wrong RPM, it sure doesn't feel smooth.

Chris Moon

OK, let me know if this is too much of a change in direction for the engine braking point. You'll have to excuse me if I jump around on topics, too. Anyway, I would say that using the throttle to balance the car most definitely is a good tool to use.

Clayton said,

"I cannot see how there is any time when compression braking <edit: I mean engine braking, not that truck thing that happens down steep hills> could be used even if it were to have some positive effect in terms of stability (which I doubt completely since any increase in retardation at the rear of the car versus the front will encourage a pendular moment that will try to spin you).

You should be either accelerating HARD or braking HARD. There is no in between, save for the minimum time wasted trying to make the transition as smooth as you can."

First, let me say that I'm talking about track driving, not street driving. Having said that, while I would agree with the general consensus that using the engine soley (sp?) for the purpose of slowing the car is wrong, I think most would agree that using the throttle to balance the car is often useful. For instance, using trailing throttle (like trail braking) to put weight on the nose to help the car turn in. Most of the PCA time-trialers I know advocate this in the proper situation.

So, if by saying "You should be either accelerating HARD or braking HARD." you mean that the throttle is an on/off switch , I would disagree. Two examples. First, have you ever been in a long corner and found yourself drifting to the outside (understeering)? Lifting the throttle will tuck the nose in every time. Too much, too fast in an older 911 can be very "exciting". Second, for those of us without limited slip, it's the rare corner that I can use even all of my stock torque on exit. It just ends up as lots of inside wheel spin. It may be just my perception, but it does seem like stiffer springs/torsion bars and reduced body roll have helped cut down on how much corner exit wheel spin I get.

The second point leads me to another topic. There's been a lot of discussion about whether engine braking "settles" the car when braking for a corner. An article on the Guard Transmission site (http://www.guardtransmission.com/velocity.htm) talks about the effect of the amount of differential lock-up on deceleration. I won't go through the whole article, but it does talk about what is going on when you're off-throttle as an aid braking and cornering speeds. At least in cars using this style differential. Maybe this is what people are talking about as "settling" the car.

Cool thread, keep it going.


CM

Z-man

Chris: good point about throttle steering: I would say that "either on the GAS HARD or BRAKES HARD -- there is no in-between" only applies to the straights! There are several corners on the tracks I drive where throttle steering can be very helpful: Big Bend at Lime Rock and the Carousel (Outer Loop) at The Glen come to mind.

Also: HARD on the GAS doesn't mean that you use the throttle like an on-off switch: one must smoothly dial in the throttle until it is wide open.

My additional $0.42,
-Zoltan.

Rich Sandor

ESPECIALLY when you have no LSD like me!

Also I find it extremely helpfull never to go immediately WOT on exiting a tight corner until the car is 90% pointed straight in the new direction.

WOT too early after apexing usually equates to loopdy loop city.

Of course the delay I'm talking about is very very small - but you still have to wait a few milliseconds for the car to settle before you gas it. For some people it seems like more time than for other people.

Z-man

Rich:
Actually, if you approach a 'classic' late apex turn spot on, you should be at WOT just before you hit the apex.

-Z.

Rich Sandor

Zoltan: You're absolutley correct.

What I SHOULD have said was: "WOT too early (ie. while still cornering with weight on front of car) usually equates to loopdy loop city."

but our point still stands: Quick, but smooth on the gas.

gleamingred944

"the times I've botched a heel-toe and put it in gear at the wrong RPM, it sure doesn't feel smooth."

Of course when we goof it doesn't feel smooth! But, engine braking is smooth if you do it right. My point is that on the track it's inadequate.

gnosis

I need to clarify this HARD business.

When I say on the throttle HARD, I mean as hard as you can get away with at that point in the circuit. My point is that you shouldn't muck around. If you can accelerate more or brake harder than you are now, then you should do it.

I had a co-driver in an endurance race once who was a lot slower than me and couldn't figure out why. We sat down and compared data from our laps. You could see clearly that when he approached a corner, he slowly came off the throttle, and then slowly applied the brakes, whereas my data showed me coming up to the point where I needed to slow down, but doing so as fast as I could. HARD, as you will. Then at this point, my transition to braking was equally as HARD. I don't mean I slammed them on without a care in the world, but the transition was swift and as smooth as I could make it, and the braking was as HARD as I could do it without locking wheels. Did I slam the throttle to 100% open as soon as I stopped braking? No, but my transition to full throttle was a lot quicker than my co-driver. Another example was in a sweeping turn. I could at best use 3/4 throttle as I drifted through this corner. This was as HARD as I could go. My co-driver was on and off the throttle. Not just unbalancing the car, but also losing time simply because he wasn't powering the car down the road as much as he could.

I hope that makes my position clearer. I think we're all in agreeance on this issue.

Clayton

FSAEracer03

Hey Chris,

could you explain what you were trying to say about "trail throttle"? The way I'm reading it, you're saying to keep more on the throttle then necessary.. which would take grip from the front tires. I'm assuming I'm misreading or something, please explain.

And you're def right about the thread... it's blossoming into a real winner

-Kevin

Viva la throttle-steer! lol

Luis de Prat

Sorry to interrupt this "real winner" of a thread, but while you front-engine Porsche guys are at it, please consider registering your cars in the new Rennlist Registry.

You can register here:

http://registry.rennlist.com

Thanks for your input!

Chris Moon

Clayton,

Yes, that makes your position very clear and yes, I'd say we are in total agreement on throttle use.

Kevin,

I'll try to use Clayton's example above about a corner where 3/4 throttle is the most he can use. If he were using 100% throttle and the car was understeering, lifting (slightly) off the throttle would (dare I say it) transfer some weight to the front of the car. This gives the front tires better grip and should put the car back on his desired line. I guess a better example of what I'm calling "trailing throttle" (am I making up a term here?) would be a corner where braking wasn't required, but you still have to lift. Again, in this case full on the gas might cause a push, but a slight lift would help the nose of the car turn in. The reason I say "trailing throttle" is that just like "trail braking", the goal is to get the front to stick better. All of this comes down to using throttle and brakes not only to go and stop, but to help balance the car in a turn.


CM

FSAEracer03

...ohh, so you were just refering to throttle-steer?? Well why didn't ya just say so!?