Engine Braking in F1
Discussion
Engine braking, and therefore changing down thru. gears is quick, as you carry speed later into the bend, and that in a nutshell is it.
However, you do sometimes see (today for example) the driver locking a brake and spinning, which is the (slight) danger if you try it a bit too keenly on the road in something like a TVR.
As a passing "did you know" ...
F1 cars are not aerodynamic to "cut through the air" like a road car, instead all the air flow pushes the car down to gain grip, at high speed, this downforce is greater than the weight of the car, so technically, an F1 car could drive upside down in a tunnel. Further, at high speed (like 180-200 mph) there is a lot of drag if the driver lifts off, and therefore an F1 car will "brake" (initially anyway) at over 1G, just by lifting off the gas, before the driver has touched the brakes. This is a force greater than some road cars could generate in an emergency stop.
Martin
However, you do sometimes see (today for example) the driver locking a brake and spinning, which is the (slight) danger if you try it a bit too keenly on the road in something like a TVR.
As a passing "did you know" ...
F1 cars are not aerodynamic to "cut through the air" like a road car, instead all the air flow pushes the car down to gain grip, at high speed, this downforce is greater than the weight of the car, so technically, an F1 car could drive upside down in a tunnel. Further, at high speed (like 180-200 mph) there is a lot of drag if the driver lifts off, and therefore an F1 car will "brake" (initially anyway) at over 1G, just by lifting off the gas, before the driver has touched the brakes. This is a force greater than some road cars could generate in an emergency stop.
Martin
It's all about balance. Engine braking in a rwd car reduces the car's stability, which is generally a bad thing. But you can use this to your advantage for example if you're approaching a very tight corner and want to prevent the car from pushing on into understeer. F1 cars are rather more sophisticated than your average TVR and you can be certain that the brake balance has been set up to reflect the amount of engine braking applied, probably (for all I know) calculated separately for each corner and gear change and for different fuel loads and tyre conditions etc. As far as mere mortal roadgoing TVRs are concerned, engine braking is a bad thing and clutch braking is a very bad thing. 
Platinum said:
Could you explain clutch braking please?
Is it this that induces 'clutch bite oversteer'?
Engaging the clutch with the revs too low for the road speed for the selected gear, so that the clutch brings the engine revs up. It can produce a lot of engine braking very suddenly and is a good way to spin the car under braking.
It's not really an F1 thing. All race drivers use a different technique to the prescribed advanced road techniques. Ie they change gear at the same time as braking. If you are using a sequential box such as in F1, WRC or Touring cars, you have to go through the gears in sequence. Other race cars that use an H pattern box, will block change.
The mechanism that stops the spin is blipping the throttle with heal and toe'ing in 'mortals' race cars. F1 cars do it for you (as do many paddle-shift boxes these days on road cars).
Race drivers are not too bothered about taking a hand off the wheel when braking during the gear change. It's done toward the end of the deceleration stage, but still usually under max deceleration before the turn in.
Graham
The mechanism that stops the spin is blipping the throttle with heal and toe'ing in 'mortals' race cars. F1 cars do it for you (as do many paddle-shift boxes these days on road cars).
Race drivers are not too bothered about taking a hand off the wheel when braking during the gear change. It's done toward the end of the deceleration stage, but still usually under max deceleration before the turn in.
Graham
ngr said:
Some teams have played about with maped partial throttle under breaking so they can have a more rearward brake balance without locking the rear wheels(due to the slight push from the engine) which can give a greater overall braking before they flat spot tyres.
Can you explain how that works? Is it something to do with varying the effective brake balance with speed to account for aerodynamic effects?
Yes I understand what it means to have more braking available, but I don't understand how this system achieves it compared to an ordinary passive balanced brake system. Is it using the engine management to produce some crafty form of ABS, or varying the brake balance with speed, or what?
makes sense in the case of F1 with very high revving engines with low moments of inertia where the engine braking will be (relatively) quite extreme. In the general case there are mapping questions of what to do with fuel cut on closed throttle. For the road car the decisions are often emissions based. With a race car, they are more often about getting the best response to WOT, which normally happens after hard braking!
Graham
Graham
My understanding, from reading Carrol Smith's Race to Win, is that there is no such thing as engine braking only frictional loss retardation.
I did not watch the GP but it would be very surprising to see these drivers not using brakes as the only way to loose speed.
More likely they are modulating the throttle to tansfer dynamic weight to trim in and out of understeer.
I did not watch the GP but it would be very surprising to see these drivers not using brakes as the only way to loose speed.
More likely they are modulating the throttle to tansfer dynamic weight to trim in and out of understeer.
way of saying engine braking 
GreenV8S said:
Yes I understand what it means to have more braking available, but I don't understand how this system achieves it compared to an ordinary passive balanced brake system. Is it using the engine management to produce some crafty form of ABS, or varying the brake balance with speed, or what?
In a way you could call it "a crafty form of ABS" The brake balance is static and adjusted with a more rear bias this would normally cause the rear tyres to lock first but due to a slight input of engine power on the rear wheels they keep rotating. The amount of push is then adjustable via a control on the steering wheel. The bar front diff worked in a similar way causing a rotating force on the inside wheel to stop it locking.
not sure if the "clutch" is re-engaged between each gear downshifted in F1. With the sequential box in my Radical, you have to re-engage the clutch else the box gets its knickers in a twist (to use the techy term).
Whichever way in F1, the time take to downshift is very small so the engine is engaged with the back wheels for most of the braking.
Re frictional retardation, a lot of engine braking is the fact that with a closed throttle the bang part of suck-squeeze-bang-blow doesnt do any banging! So the engine braking comes from the squeezing bit as well as frictional retardation.
Graham
Whichever way in F1, the time take to downshift is very small so the engine is engaged with the back wheels for most of the braking.
Re frictional retardation, a lot of engine braking is the fact that with a closed throttle the bang part of suck-squeeze-bang-blow doesnt do any banging! So the engine braking comes from the squeezing bit as well as frictional retardation.
Graham
Gassing Station | Advanced Driving | Top of Page | What's New | My Stuff