LBZ: Will making a variable vane turbo brake in efi harm anything?

[Jasondt2001]

Hi guys; and Kat,

I've made a 'turbo brake' with efilive by closing the vane tables to 99.5 at 0-15mm3.

It's worked GREAT holding back my trailer going down a windy grade.

I do have a few questions though :baby:

The maximum boost was 10 psi on the descent but averaged about 7 psi. It didn't chug or lurch, it was a very smooth controllable easy descent down that horrid hill.

1. When i come to a stop and the torque converter unlocks as your approach a stop sign or signal it makes a weird noise... It SOUNDS like the engine fan spinning but I'm wondering if it's something turbo related. There's still boost pressure when the tq converter unlocks and I'm kind of wondering if that's the turbo trying to deal with the air....

To fix this I've smoothed out the cells from 800 - 1200 RPM where as they used to be 99.5 vane position they're now smoothed up from 80 to 95 percent and anything above that is 99.5 vane position. Any ideas?
I haven't been able to try this though...

2. This is the most important to me.... Longevity...
By doing this, am I creating some extreme cylinder pressure or more turbine speed than my stock turbo can handle? Am I going to life the heads? In other words... by doing this am I risking blowing something up?

3. I've heard of turbo-bark - If I'm slowing and the light changes and i put my foot back down to accelerate - is this going to create an issue?

Thank you all!!

 

[JoshH]

Hi guys; and Kat,

I've made a 'turbo brake' with efilive by closing the vane tables to 99.5 at 0-15mm3.

It's worked GREAT holding back my trailer going down a windy grade.

I do have a few questions though :baby:

The maximum boost was 10 psi on the descent but averaged about 7 psi. It didn't chug or lurch, it was a very smooth controllable easy descent down that horrid hill.

1. When i come to a stop and the torque converter unlocks as your approach a stop sign or signal it makes a weird noise... It SOUNDS like the engine fan spinning but I'm wondering if it's something turbo related. There's still boost pressure when the tq converter unlocks and I'm kind of wondering if that's the turbo trying to deal with the air....

To fix this I've smoothed out the cells from 800 - 1200 RPM where as they used to be 99.5 vane position they're now smoothed up from 80 to 95 percent and anything above that is 99.5 vane position. Any ideas?
I haven't been able to try this though...

2. This is the most important to me.... Longevity...
By doing this, am I creating some extreme cylinder pressure or more turbine speed than my stock turbo can handle? Am I going to life the heads? In other words... by doing this am I risking blowing something up?

3. I've heard of turbo-bark - If I'm slowing and the light changes and i put my foot back down to accelerate - is this going to create an issue?

Thank you all!!

1. Kinda hard to tell you what you're hearing. Nothing comes to my mind based on what you're describing. The only thing I can come up with is maybe a boost leak?

2. You aren't hurting anything. You're causing no more stress (and probably a lot less) than WOT conditions. I've been doing this on various tunes for over a year for my truck and several friends' trucks. No problems yet.

3. I can't see how you could bark the turbo by doing this. What I would suggest is you make the turbo brake function inactive below 2k RPM. That would allow you to drive normally without knowing it is even there (without a trailer, everyday driving, you can still coast to a light or a turn), and then if you need the turbo brake you can bump it down into manual mode and downshift to get into the turbo brake's active range. Something else I sometimes do is raise the downshifts at 0% throttle in T/H mode so that when you take your foot off the throttle in T/H mode it automatically raises the RPMs into the range of the brake and starts slowing you down. It works pretty well. You might have to play with your shift speeds to get it where you want it.

 

[MMLMM]

are you getting a loud buzzing type sound?

 

[Jasondt2001]

1. Kinda hard to tell you what you're hearing. Nothing comes to my mind based on what you're describing. The only thing I can come up with is maybe a boost leak?

2. You aren't hurting anything. You're causing no more stress (and probably a lot less) than WOT conditions. I've been doing this on various tunes for over a year for my truck and several friends' trucks. No problems yet.

3. I can't see how you could bark the turbo by doing this. What I would suggest is you make the turbo brake function inactive below 2k RPM. That would allow you to drive normally without knowing it is even there (without a trailer, everyday driving, you can still coast to a light or a turn), and then if you need the turbo brake you can bump it down into manual mode and downshift to get into the turbo brake's active range. Something else I sometimes do is raise the downshifts at 0% throttle in T/H mode so that when you take your foot off the throttle in T/H mode it automatically raises the RPMs into the range of the brake and starts slowing you down. It works pretty well. You might have to play with your shift speeds to get it where you want it.

Thanks Josh!!!!

The only thing I can think of as describing this sound is you know when your truck gets heated up? The engine fan comes on blaring... Then when it turns off the fan rpms slow and then all of a sudden you get that 'rolling' noise from the engine fan... that's EXACTLY what this sounds like but quieter...

I really appreciate your feedback on the longevity, I REALLY like it and want to keep it! I'm SHOCKED it helped so much!

I think I'm going to kick it up in the RPM engagement area like you suggested. I really do like that idea because then the brake would be even better at the upper RPM's.

Thanks alot, Josh :hug:

are you getting a loud buzzing type sound?

No I went through that already
I set all my vane positions at 100% even at 0-300 RPM and it gave me that horrid vane buzz. A couple guys on this forum helped me through that thankfully!
Thank you though!

 

[Drholliday]

One thing I have done on my turbo brake tune is I only change the vane positions in the 0mm3 cubed column. That way as soon as you touch the go peddle the turbo brake shuts off.

As far as driving around unloaded with the t-brake on I don't notice any issues. When your slowing down with the trans in normal mode the TC isn't locked so its not really putting a load on the engine to make the turbo brake function.

 

[Drholliday]

One thing I have done on my turbo brake tune is I only change the vane positions in the 0mm3 cubed column. That way as soon as you touch the go peddle the turbo brake shuts off.

As far as driving around unloaded with the t-brake on I don't notice any issues. When your slowing down with the trans in normal mode the TC isn't locked so its not really putting a load on the engine to make the turbo brake function.

 

[Jasondt2001]

I didn't notice it very much until I hit the freeway. Even in normal mode when you hit the freeway and the tq locks up it'll turn itself on. It was just a bit much so I upped the RPMs to 2000 @ 99.5% and blended it from 2000 RPM to 1700 RPM (I dont know if that helps - I just don't want to stress or shock the turbo vanes).

I started out doing the 0mm3 but for some reason I noticed it lurching with the brake at decent. When it downshifted if i remember correctly and even on some long braking the mm3 went to 5 and even a spot in the 10 position with NO fuel as i logged... so I bumped it up there and have had NO issues with it.
Even on take offjust VERY easy on the throttle you can't feel that I've made a change.
I REALLY like it! :angel:

 

[Jasondt2001]

Re: the noise I hear when the tq unlocks.... I am REALLY starting to think it's the engine fan...
that's the only thing it can be... it sounds exactly like that.

 

[LBZ]

Re: the noise I hear when the tq unlocks.... I am REALLY starting to think it's the engine fan...
that's the only thing it can be... it sounds exactly like that.

Could be-especially if your A/C is on.

 

[othrgrl]

I have alot of guys running around with turbo-brake features on their tow tunes with no issues. I have a few guys that like it so much they had me put it on all of their tunes.

 

[TIM Z]

Dont know what your talkin bout Dustin

 

[stacks04]

guys sorry to resurrect this but is there a way to do this in a dsp tune when the town tune is one of the dsp tunes. i ask because i fear i know the answer and i would have to adjust the min vain table in the main tune to make it work. then i would have a turbo brake anytime the converter is locked on the highway, destroying any mileage i get now.

 

[Jasondt2001]

I don't have DSP (not YET ) but, I think you mean adjust your maximum vane position tables, right?
I would see no problem with that in the main tune, I mean, just because it has the ability it wouldnt call it to max position unless your vane table position calls for it...
Another thing, you have an 04 - do you have a VVT ??? (Sorry I know dumb question!)

 

[LBZ]

I don't have DSP (not YET ) but, I think you mean adjust your maximum vane position tables, right?
I would see no problem with that in the main tune, I mean, just because it has the ability it wouldnt call it to max position unless your vane table position calls for it...
Another thing, you have an 04 - do you have a VVT ??? (Sorry I know dumb question!)

04 has the lly vvt.

I've done the vvt brake thing as well and love it-especially towing!! With the trans braking thing in the ally and this, I hardly use the brakes on the highway towing #8000lbs!!

 

[FIREFIGHTER 503]

I put a turbo brake function in nearly every VVT tune I build and have yet to see any type of failure from it, have not had a complaint yet from any customers, they don't know what it does but they like the way it spools up when they slow down.........sounds good with a Cheetah too

 

[Jasondt2001]

04 has the lly vvt.

Thank you!

Stacks, if you want, I'll send you my stock and tow brake tune over and you can compare and see exactly what I have changed. :hug:

 

[Kat]

04 has the lly vvt.

I've done the vvt brake thing as well and love it-especially towing!! With the trans braking thing in the ally and this, I hardly use the brakes on the highway towing #8000lbs!!

Thank you!

Stacks, if you want, I'll send you my stock and tow brake tune over and you can compare and see exactly what I have changed. :hug:

Just an FYI there is an 04 LB7 and an 04 LLY that most call 4.5 so it is a legitimate question

 

[LBZ]

Ah yes-I forgot about the 04.5 thing.

Thanks Kat!!:hug:

 

[The Neens]

Ah yes-I forgot about the 04.5 thing.

It's extremely difficult for me to bite my tongue right now

 

[LBZ]

It's extremely difficult for me to bite my tongue right now

Shut it!!:toetap::redneck:

Actually, my buddy's driller has an 04 and it IS an LB7 now that I think of it.