[AAHTT]

Originally Posted by vbb

I understand the concept of brake boosting, but like a few others in this thread have already stated, I don't see much of an advantage of doing this in the 335i with it's extremely low boost levels, small turbos, lack of lag, and early onset of maximum torque.

You might be right, but torque braking from standstill is what makes the 997TT tiptronic faster than the manual form 0-60. Without torque braking to at least 3000 rpm, the manual is faster. The 997TT also develops most of its torque at low rpms, so the same technique might be beneficial for the 335 although I would not do it on my car.

[asdflkijd]

Originally Posted by homerunball

What do you think turbo "spooling" is?? You say that it "spools" at 3-4k rpm; that doesn't mean anything. The turbo's in our 335i's reach full boost at 1500k rpm. From that point on, the boost, more or less, pretty much stay the same, with slight peaking at high rpms due to additional fuel. You are not gaining anything extra by going up a few k's in rpm.

Yes, slight brake boosting is necessary for a good launch but your explanation is wrong. Its not to make the turbo's "spool" its to reach full pressure in the engine. You can dump the clutch at 4k or 5k or whatever but if its steady state (ie. not on its way up the rpm band), your engine is not under boost and it would be an incorrect way to launch a turbo car. In summary you have to launch it while loading the engine to create boost, and you can provide that load by braking or by launching while the engine is going up on the rpm band. The engine is only boosting (pressurized) when it is under load, or accelerating (engine not the car). If you are cruising at 95mph at 3k rpm, its at a lower boost than if you slammed on the gas in 6th gear going 30 mph even though you are going slow and accelerating like a turtle. Boost is all load dependant and you can provide that load in a variety of ways.

You can only brake boost with auto's. I would not even attempt something that dumb with a manual tranny.

you can only brake boost with autos on a stop, but on a roll i.e. highway, track you can brake boost with both manual and auto

[asdflkijd]

Originally Posted by vbb

I understand the concept of brake boosting, but like a few others in this thread have already stated, I don't see much of an advantage of doing this in the 335i with it's extremely low boost levels, small turbos, lack of lag, and early onset of maximum torque.

max torque doesn't necessarily mean max boost.. get a boost gauge if you don't believe me

[hl0m4n]

never heard of this "brake boost" but if i am correct are you speaking of something this porsche is doing here?

slow down, drop a gear, spool, and on go floor it?

[asdflkijd]

Originally Posted by hl0m4n

never heard of this "brake boost" but if i am correct are you speaking of something this porsche is doing here?

slow down, drop a gear, spool, and on go floor it?

good vid, looks like it.. you should check out the vid on my first post at the beg. of this threat its more clear that the car is braking in this one because it is at night. btw its a white STI if you decide to watch it.

[gfrnk69]

Originally Posted by hl0m4n

never heard of this "brake boost" but if i am correct are you speaking of something this porsche is doing here?

slow down, drop a gear, spool, and on go floor it?

The vid just seems more like turbo lag, once the boost kicked it, that turbo was gonzo.

Didnt seem like the Turbo was brake boosting or else u wouldve heard the turbos spooling while the m6 was honking.

-Frank

[hl0m4n]

Originally Posted by gfrnk69

The vid just seems more like turbo lag, once the boost kicked it, that turbo was gonzo.

Didnt seem like the Turbo was brake boosting or else u wouldve heard the turbos spooling while the m6 was honking.

-Frank

hell yea turbo lag. insanely big lag. but you got a turbo and the outcome of the huge lag is that strong damn who cares lol. friggin thing pulls SOO damn hard.

[533ogetnom]

oh god who moved this to the track forum

[Getagrip]

Never heard of this procedure by the term brake boosting, I called it left foot braking. I found it very useful while autocrossing WRXs, but never used it on the street as I don't street race or drag.

[Dascamel]

change gears if need be...., small turbos don't need that much love to spool.

[smellthebeans]

Originally Posted by 533ogetnom

wow, you like, missed the WHOLE point of the thread

I got the point...breaking while applying throttle = break boosting...Got it...

yes I have auto crossed (not die hard ie eat,sleep,cone). Its fun and almost necessary to toss the car around to set yourself up for your next turn/straight what have you. I'm not competitive...its purely enjoyable!

I am trying to understand the logic as applied to a road course. The idea of applying steady and hard pressure to the breaks through a turn in order to maintain boost.

I guess... breaking, setting the nose down, down shifting (the purpose of which is to move the engine into the rev band) entering your turn not late or early, applying steady throttle across the apex and beyond?

I must have missed something during the last DE
perhaps to much the night before

[hl0m4n]

Originally Posted by hl0m4n

never heard of this "brake boost" but if i am correct are you speaking of something this porsche is doing here?

slow down, drop a gear, spool, and on go floor it?

can this be done in a 335i auto? can the turbos even be heard when spooling? would sound so sick. maybe with the procede and extra boost?

PS: 335xi coupe is on bmw na now

[Miami Bimmer06]

Wow That Car Took Off

[asdflkijd]

Originally Posted by hl0m4n

can this be done in a 335i auto? can the turbos even be heard when spooling? would sound so sick. maybe with the procede and extra boost?

PS: 335xi coupe is on bmw na now

If you read the thread... brake boosting can be done on both autos and manuals.. autos have the advantage because you can brake boost from a stand and a roll, unlike manual you can only brake boost from a roll.

[hl0m4n]

yea i did read the thread. question is for the autos at what gear and rpm do the turbos spool? did you see the video i posted? i know stock turbos won't sound that loud but maybe with a procede or xede.

[hl0m4n]

nobody knows what speed and rpm the turbo spools?

[Walked U]

Originally Posted by homerunball

You can only brake boost with auto's. I would not even attempt something that dumb with a manual tranny.

Huh? Who told you that?

[ulises 335i]

instead of brake can u use handbrake?

[asdflkijd]

Originally Posted by hl0m4n

yea i did read the thread. question is for the autos at what gear and rpm do the turbos spool? did you see the video i posted? i know stock turbos won't sound that loud but maybe with a procede or xede.

i dont know if youd be able to hear the turbos spool but you will defiantly feel it once you let go of the brake, and im not too sure if procede or xede or tt or jb or any other chip will help with the sound

[asdflkijd]

Originally Posted by ulises 335i

instead of brake can u use handbrake?

probably not... but if you do, youd have to get a new handbrake.. the amount of stress it puts on the brakes itself is enough, cant even imagine how the handbrake would hold up