8 replies to this topic

[NMAv]

A while ago I recall reading about an after market product that keeps the engine RPMs up so when you are racing you do not have to do that toe/heel roll to get the RPMs on the engine up to the transmission.  Or at least that is my recollection. Being as I have big, fat feet the toe/heel process is difficult me and I thought this would be a great mod for my car.  Can someone point me in the correct direction?  Or am I just dreaming?

[Boidster]

Are you thinking of a WOT Box? Doesn't quite do what you're suggesting, though - it allows you to stay on WOT while shifting.

Are the synchros too slow to keep up when racing, so you need a throttle blip? Curious, since I don't race (yet).

[NMAv]

I'm thinking when you downshift coming into a corner and you need to roll your foot from the brake to the gas peddle to get the engine RPMs up, then release the clutch and engine the trasnmission smoothly.  The stock pedals dn't make this very easy for someone with fat feet like myself. The WOT sorta sounds like it but it seems like it could be harsh on your transmission and such.  But this is a great starting point forfurther research, at least I have some key search terms.

[Torched10]

ive been to several road racing training schools and they always advise letting the rpms drop in a corner---actually shift into neutral for a micr second to allow them to drop. The reason is that if you downshift and have high rpms its possible to cause the rear end to twist out of control with all the torque and the car turning.If your in a straghtaway, keeping the rpms up is fine,like in drag racing,but not on a turn

[Boidster]

NMAv, on 13 April 2012 - 07:47 PM, said:

I'm thinking when you downshift coming into a corner and you need to roll your foot from the brake to the gas peddle to get the engine RPMs up, then release the clutch and engine the trasnmission smoothly.

Ah, gotcha. Definitely not the WOT box. I don't race (yet?), but I had read about the WOT box in a couple of drag-racing threads. It's been long enough since I regularly drove a clutch that I get crappy downshifts on the highway. And then there's the 1-2 grind...>sigh<

[Torched10]

Yes--in drag racing you want to maintain high rpms..Hers a true story i saw with my own eyes--- a rich guy i know had just bought a new Ferrari--we were at open track day at Road Atlanta.One of his buddies (not me) begged him to let him drive--he gave in. The guy goes flying out of the pits,w/o any traing, goes into the first turn which is a 90 degree sloped up turn, downshifts to 1st gear--the clutch grabs, the rear end swings all the way left crashes the car into the wall  -- brand new Ferrari.  My friend says to me thats it for the ferrari, you cant sell a repaired Ferrari thats been wrecked on a track--the insurance company wouldnt pay since it was a racing event--the car was sold as is for scrap to the dealer

[twobjshelbys]

Torched10, on 14 April 2012 - 06:18 AM, said:

The reason is that if you downshift and have high rpms its possible to cause the rear end to twist out of control with all the torque and the car turning.If your in a straghtaway, keeping the rpms up is fine,like in drag racing,but not on a turn

The idea is to match the speed and RPM of the old gear to the RPM of the new gear. If you don't match then indeed the car will attempt to find the speed of the new gear.  The result is the rear end slows down to the tire speed of the previous RPM and gear and the engine tries to slow down to match.  The result is what is called compression braking.   The result is called trailing throttle oversteer, or simply put, exchanging the rear end and front end at high speed.  Results is much pucker.

We spent a 1/2 day or so practicing heel-toe downshifting at Bondurant.  It was fairly difficult giving the spacing and offset in the Corvette.  It was a piece of cake on the Formula Mazdas given the pedal arrangement.  It was impossible given the pedal height difference between the throttle and brake on the Cobra.   The Ford GT is close to the Formula cars.  In most cars you have to keep your big toe side half of the foot on the brake and roll your ankle to the throttle.  Note also that you do not have to pricely match the RPM to the new gear - anything over where it would be is OK since the engine braking will bring it to the correct place to begin accelerating again.

[twobjshelbys]

Torched10, on 15 April 2012 - 05:50 AM, said:

The guy goes flying out of the pits,w/o any traing, goes into the first turn which is a 90 degree sloped up turn, downshifts to 1st gear--the clutch grabs, the rear end swings all the way left crashes the car into the wall  -- brand new Ferrari.

Yep, that's what happens if you don't speed match.

I've seen that some of the newer cars (I think the GTR) actually has it built into the paddle shifting program.

[Boidster]

twobjshelbys, on 15 April 2012 - 07:37 AM, said:

The idea is to match the speed and RPM of the old gear to the RPM of the new gear. If you don't match then indeed the car will attempt to find the speed of the new gear.  The result is the rear end slows down to the tire speed of the previous RPM and gear and the engine tries to slow down to match.

I think you mean the engine tries to speed up to match. You're describing normal downshift deceleration, but in a racing context, right? So if I'm moving along at 4,000 RPM in 3rd and downshift to 2nd, the speed of the car might require 7,000 RPM in 2nd, but the engine is only doing 4,000 so if I let the clutch out the car is going to try to slow down to the proper speed for 4,000 RPM, and the engine is going to try to speed up to 7,000 RPM, resulting in significant engine braking (and quite sudden, if you just dump the clutch.)

I can see how that would be...exciting...in a racing context, while cornering. Like pulling the e-brake. I did not realize, though, that when racing the car should remain in gear essentially throughout the turn. Makes sense, for quick acceleration on exit; I just hadn't really thought it through. So when braking at the entrance of the turn, you're using that time to get into the correct gear - RPM matched - to be ready for the exit, correct?
I'm not sure my feet would have the proper coordination. Maybe somebody would lend me their Ferrari for my first try.