I dont have a turbo car right now so i cant figure this one out myself, but how do you brake boost? You apply the brakes while giving more gas to build up boost while staying at the same speed right. Is it hard to do, does it easily warp your rotors or thing that it can damage? O and how hard is it to get good at and how much boost can u really get off of it?

 

nobody can help, come on

 

You answered your own question. Left foot on the break while the right is on the gas, and then release break pressure when ready to go. Obviously people use this technique when racing from a roll to avoid turbo lag. It takes some practice to get good at though.

 

I do a similar technique while autocrossing, but I'm not sure we're talking about the same thing. I'll use it when making tight turns where you have to slow considerably, and are looking to accelerate rapidly once you're out of the turn. I've never used it, or felt it was needed, in any other situation. Our local courses are small and tight, and thus I'm typically doing almost all of the course in 1st gear - i.e., no shifting.

You're basically left foot braking while giving the engine some gas to keep the revs up, while simultaneously leaving the car in gear and slowing the car for a tight turn. What can be tricky is getting your left foot practiced enough so that you can feather the braking. When I first tried it the braking was a bit herky-jerky because my left foot didn't have a lot of finesse. What I found myself changing to was using more of an ankle pivot on the brake pedal in that situation rather than the leg extension you'd normally use on the clutch.

Since I'm not doing this on the track, the brake temps, brake pressures, and duration of braking are nowhere near sufficient to causing warping. I'm not sure if this really is building boost as much as it is keeping the revs up, but obviously revs are needed for boost, so one does lead to the other.

 

^I think you're talking about heal-toe downshifting no?

 

No - heel-toe is for downshifting. As I said, I'm not shifting. I'm simply depressing both the brake and gas pedal simultaneously.

 

not too hard. floor the gas and press the brake to mantain the same speed. Wants the boost builds takes foot off brake and keep flooring the gas

 

heel--toe or AKA REV MATCHING is for downshifting to equal your RPM to speed threwout your gears.

Brake Boosting is holding the brake while accel so that the engine spool the turbo without moving. This is alot easier using the Ebrake btw. But why are you running a AWD car from a roll thats gay.

 

yeah i know an evo/awd car is for digs but u know... i wanna know how to use it for all it can, brake boosting being a cool way to build boost.

So now all i gotta ask is how much boost can u build from 40mph with stock turbo. My guess is like 15 psi, i think i heard that somewhere. but i know it all depends on how high the rpms are at 40mph. But since im guessing 40 is the beginning of 2nd gear, there shouldnt be too much boost.

 

left foot on brake while right foot on gas while revving above 4 k rpm. let go of brake and WOT. basically knda like a "slingshot".

 

In 2nd gear I can hit 20lbs of boost pretty easily by brake boosting and im running right around 22-23 lbs

 

break boosting is one of the best techniques to use when street racing. Cuz most ricers and people with other boosted cars have no clue what the hell it is. I'v even tought a few of the older members on the forum how to do it. I do brake and WOT at the same time. First gear feels like an olympic situp hahaha. But thats how you get the jump on cars with blowers on them.

 

In race cars it is very common to fit oversized turbochargers in order to be able to produce enough boost pressure and assure a sufficient engine output. Big turbochargers display significant amounts of lag due to their increased rotational inertia. In such cases the dump valve is insufficient to allow the turbocharger not to loose too much speed when the driver lifts off. Additionally rally cars hold a turbo restrictor, which is regulated by the FIA. One of the restrictor' effects is to increase lag time. This is why in racing cars, and more specifically in rally cars, where torque and engine availability are critical factors, most applications use anti-lag systems.

To counter the effect of the turbocharger's lag time drivers used to anticipate the engine's reactions by accelerating well before they would have done in a non-turbo car. Others have used a technique, introduced by the German driver Walter Röhrl, known as "left foot braking" where the driver uses his left foot to brake the car while his right foot accelerates to keep the turbocharger in optimal load.

Source: http://www.rallycars.com/Cars/bangbang.html

Left foot braking is very hard on the brakes which are put into extreme stress but is very efficient in keeping the turbo spinning.

BONUS VIDEO: Walter Rohrl / Audi Quattro. <-- Watch, learn, and enjoy. Nevermind the antiquated music.

Left foot braking is employed to slow the car, or to balance the car in corners (transfering weight forward to rotate, etc). Ok, so it's not a video of boost braking.. but it's still pretty darn cool and you get the point. Brake in the turn while keeping the engine revved up while in gear.

 

bringin back an old thread

can i brake boost? or does the ECU over ride it?? (it did in my audi ,havnt tried it on the evo)

 

Don't see why not. It's hard on the brakes though.