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Discussion Starter #1
I have a garret gtx55 91 mm with 1.15Turbine Housings with terrible spool, approx 10 sec. engine v6 4.3l wonder how big difference you can expect if I switcj it to 1.00 af? Thanks!
 

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It will be tune and or Converter related.

I have a Promod88 with 1.15ar on a 3.8L 6 cylinder and can spool from idle to 5500rpm and 25psi of boost in 5sec without any nitrous and around 3secs with a 40shot of nitrous
 

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Discussion Starter #5
It will be tune and or Converter related.

I have a Promod88 with 1.15ar on a 3.8L 6 cylinder and can spool from idle to 5500rpm and 25psi of boost in 5sec without any nitrous and around 3secs with a 40shot of nitrous
yes converter is to tight and the can't make loser....
 

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What engine management system?? What converter including stator specs??
 

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Sounds like you need some tune-up work and possibly a converter dump if it's ok down track especially shift extension rpm. The 1.00 A/R would help but as above it will not get you there alone.
 

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Discussion Starter #8
Sounds like you need some tune-up work and possibly a converter dump if it's ok down track especially shift extension rpm. The 1.00 A/R would help but as above it will not get you there alone.
Stator is 19-35 , engine management system FAST XFI and a don't fink the make any dump system for 4L80e =( the problem is 3600-4000 rpm i tried timing and fuel
 

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You cannot be in closed loop on the transbrake. I tune that area with the 2-step set high so it doesn't activate during tuning. Tune it by making logs on the transbrake and get a good lean and mean fuel/timing map in those areas to give it the most chance of making maximum torque to get up on the converter. If its rich or timing too soft it will never get up on the converter. On something sensitive like that the air Density from day to day can have a lot of effect on it spooling. Generally speaking if its rich it from one day to the next it will sound kind of blubbery and labor to get up on the converter.

What fuel??

What compression??

Timing on transbrake??

AFR in the area up to launch rpm/boost??
 
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Discussion Starter #10
You cannot be in closed loop on the transbrake. I tune that area with the 2-step set high so it doesn't activate during tuning. Tune it by making logs on the transbrake and get a good lean and mean fuel/timing map in those areas to give it the most chance of making maximum torque to get up on the converter. If its rich or timing too soft it will never get up on the converter. On something sensitive like that the air Density from day to day can have a lot of effect on it spooling. Generally speaking if its rich it from one day to the next it will sound kind of blubbery and labor to get up on the converter.

What fuel??

What compression??

Timing on transbrake??

AFR in the area up to launch rpm/boost??
E85, Compression 9, timing on TB 28 degree ....Appreciate your time to me ;)

if I do not get the spool , I will change the house
 

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19-35 should spool no issues with 4.3litres.
You will want a lot more then 28 degrees on the TB below boost, Once it starts making some boost you can back it down. Im up around 38 - 40 degrees before it starts making boost.
 

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Discussion Starter #12
19-35 should spool no issues with 4.3litres.
You will want a lot more then 28 degrees on the TB below boost, Once it starts making some boost you can back it down. Im up around 38 - 40 degrees before it starts making boost.
Miss understanding i have apox 38 degrees under build up and ON TB 28 degrees
 

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Exhaust side wrapped/coated for heat retention?
Can you try full timing up to the limiter and then slowly pull some as boost comes in? Once its up to the chip, taking some timing out slowly will help heat build up to drive turbine. As a lb or two builds, drop more timing, it will stay at the limiter and put more heat into exhaust. Leaner is meaner here too.

not the same but i have a remote mounted twin setup that i went from 1.32 ar to 1.15 and it seems to have gained 200 rpm. Roughly. From what i could tell. Defbetter on the brake but the tune changes helped alot more i feel
 
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