Engine braking to reduce strain on brakes

[ELS]

Why haven't race cars, at least back when brake materials weren't so good. Why haven't race teams used engine braking to reduce the strain on the brake system? like adding a block-off valve on the exhaust to close when needed.

It would take some time for the engine to transition back into power making state but if you just push some pins out in the rocker arms of the exhaust valves it should be a short time to do that. And you could also make it so the exhaust opens up right before you need to accelerate again, perhaps by some driver input.

I'd guess it would be especially beneficial in drag racing.

[hoffman900]

Why haven't race cars, at least back when brake materials weren't so good. Why haven't race teams used engine braking to reduce the strain on the brake system? like adding a block-off valve on the exhaust to close when needed.

It would take some time for the engine to transition back into power making state but if you just push some pins out in the rocker arms of the exhaust valves it should be a short time to do that. And you could also make it so the exhaust opens up right before you need to accelerate again, perhaps by some driver input.

I'd guess it would be especially beneficial in drag racing.

Brakes aren’t a limiting factor in motorsports and haven’t been for a while. Drag racers having a brake problem is just people not allocating their money properly. I don’t think brakes are a problem in the pro classes because those builders understand it’s about the complete package.

As for engine braking, in road racing (cars and bikes) where you have throttle by wire, the engine braking is highly tuneable and has a big effect on how the car or bike handles into the corner. The MotoGP guys even use an exhaust valve to add engine braking at the apex to help rotate the bike, but generally bike guys run very little engine braking. Cars it depends. If circle track classes every went to electronic controlled throttle bodies, other than Indy (as they have it), you’d see a lot playing with this.

The amount of engine braking in those classes however is highly tuneable, and driver / rider preferences play a roll.

[gunt]

The race bike builder i often mention , had 3 riders , and had 2 different weight cranks between them due to completely different riding styles , but yes , 2 were also completely different on brakes and had completely different cams compression due to 1 having to have engine braking to match his style , all with in a controlled 1.0cc rules , any yet there would be side by side , on track , when dyno charts , engine specks and gearing was looked at this was spectacular to see the guys neck and neck