[Wicked69]

On my set up I usually run grudge racing stuff with a bump box and transbrake. I leave around 3300rpms, make 4-5lbs of boost and ramp it in to 20 at a rate of 20 using the boost leash. I have disc brakes all the way around but not duel rear brakes. Our local track runs footbrake and I gave it a try at the end of the year just for fun and actually had a blast. Car ran only 6.50 but at a 121mph. lol I can hold the footbrake to the same 3300rpms but won't build any boost. I use the holley boost builder and pull 9 degrees of timing while on the transbrake to build boost. I am curious if I just manually pull the same amount of timing in the individual cells will it build boost like it does on the transbrake or not? I can set a limiter on the footbrake but we are not allowed to in this class.

Just curious....thanks. It seemed like the footbrake would allow me to have some fun throughout the year and still be able to grudge race with the bump box and transbrake. Car is two different animals on footbrake and transbrake. Trying to not go duel calipers if I don't need to. Just wanting to get 2-3lbs on the footbrake.

6.0 Holley EFI, 4.11 gears, PTC 9.5, Powerglide, 1.80 straight cuts, twin On3 61's.

 

[Chuckles]

" I can hold the footbrake to the same 3300rpms but won't build any boost.
Look at the tps, when on the T-brake, vs on the foot brake.

 

[ken6881]

" I can hold the footbrake to the same 3300rpms but won't build any boost.
Look at the tps, when on the T-brake, vs on the foot brake.

My car builds more on the foot vs transbrake at the same rpm.

He could hook his transbrake button up to his brake light switch and make it pull timing so he can open the throttle more and see the manifold pressure go up.

Op post a data log zoomed into the first sixty feet and you can probably tell a lot about what the car wants/ needs.

 

[boostedbowtie]

Yes , you can disconnect input from trans brake and connect to brake switch .

Have you tried running MORE timing instead ?

 

[Wicked69]

I am at full timing until I hit the transbrake. I am at 36 degrees.

 

[Screwblower]

What fuel?

 

[Screwblower]

Are you opposed to changing rear gears ?

 

[brianj5600]

Can you run a 2 step rev limiter? I put one on a button and could make 6 psi at 2700 rpm foot braking. Launching was similar to transbrake, tps 100%, foot brake, and 2 step on a button. Initial hit isn't as hard as TB, but power comes in very fast when the limiter turns off.

 

[Dustin87]

Yes , you can disconnect input from trans brake and connect to brake switch .

Have you tried running MORE timing instead ?

Do it like this instead of the base map. Trigger a timing retard with the footbrake. Or do the dual calipers out back and you can have rpm, boost and timing.

 

[Wicked69]

Do it like this instead of the base map. Trigger a timing retard with the footbrake. Or do the dual calipers out back and you can have rpm, boost and timing.

Okay, kind of what I thought. My footbrake has a 2 step I can use but we are not allowed for the class. Don't want to change gears or anything crazy. We will just do the duel calipers.

 

[brianj5600]

How about dropping timing to zero or even after tdc?

 

[ken6881]

Okay, kind of what I thought. My footbrake has a 2 step I can use but we are not allowed for the class. Don't want to change gears or anything crazy. We will just do the duel calipers.

My two step just pulls timing doesn't cut events so you can't hear it no one will ever know your using it and the car will sit at your desired rpm until you let off the brake and the timing will come on and you can still make timing and boost timers work.

What Ecu do you have

On meagasquirt there is a way to do it based off tps sensor that works very well. At 80% throttle or less two step is active above that no two step.

 

[3 window]

My two step just pulls timing doesn't cut events so you can't hear it no one will ever know your using it and the car will sit at your desired rpm until you let off the brake and the timing will come on and you can still make timing and boost timers work.

What Ecu do you have

On meagasquirt there is a way to do it based off tps sensor that works very well. At 80% throttle or less two step is active above that no two step.

How much boost do you build like that?

 

[ken6881]

How much boost do you build like that?

Wastegate 5lbs on my car. It wil make more.

It's the combo if it will make it on the trans brake it will make it on the foot brake if you can hold the brakes. But you already said you can at your leave rpm so you should be close with any of the methods I suggested.

We use the last method on a car without a bump box so he can stage with boost then grab the brake and flat foot it.

 

[Wicked69]

I have the Holley EFI Hp. I am able to engage a two step on the footbrake which isn't allowed. I am not sure if Holley has a way to just pull timing while on that two step unless it will still do it in boost builder, which it probably would but the two step would be engaged. Not sure.

 

[boostedbowtie]

just disconnect the trans brake solenoid wire .

Now when you hit the button it will enable the boost builder without engaging the trans brake .

Or set the "manual enable" in boost builer settings and use a different button to enable it .

Disable the 2-step limiter

 

[boostedbowtie]

Just thinking though , Ive only heard of pulling timing on the 2-step because it causes backfires that help spool the turbo .

If you pull timing without cutting spark , wouldnt it just make it lazy ????

 

[434chevelle]

just disconnect the trans brake solenoid wire .

Now when you hit the button it will enable the boost builder without engaging the trans brake .

Or set the "manual enable" in boost builer settings and use a different button to enable it .

Disable the 2-step limiter

I just found out the hard way not to have Fixed Timing or Fixed Fuel checked without transbrake or manual enable checked. I spent a lot of time chasing a problem that I didn’t have. I didn’t realize boost builder was automatically active that way. What a nightmare. Lol

 

[Wicked69]

Just thinking though , Ive only heard of pulling timing on the 2-step because it causes backfires that help spool the turbo .

If you pull timing without cutting spark , wouldnt it just make it lazy ????

Good point. Not sure.

 

[S_M_I_D_D_Y]

Just set the 2step like normal but set the rpm to redline. Wont sit on 2step but boost builder will still work