Turbo Lag
Jan 30, 2007 | 01:50 PM
#1
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From: Cleburne, Tx.
Turbo Lag
Anyone out there running a T-70 on a 408? Was hoping to get by for a little while with the T-60 which I ran on the stock 6.0L but fear I've got a little too much backpressure for the new 6.7L...Anyway, gonna "nut up" and buy a new T-70 or 76 and just curious as to what kind of lag you were experiencing.. Also, what kind of HP are the 70 and 76 capable of with that kind of displacement?
Jan 30, 2007 | 01:57 PM
#2
Jan 30, 2007 | 01:57 PM
#3
with a eninge that size, I would think that you would see very little lag at all. I am going to be running a bi s-85mm on my 408 and I am not anticipating much lag at all.
As for power, I think you will deffinitally max the turbo out early (5000ish). I would step up even more to a 80mm with a big housing
As for power, I think you will deffinitally max the turbo out early (5000ish). I would step up even more to a 80mm with a big housing
Jan 31, 2007 | 12:24 AM
#6
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From: Odessa, Texas
If you are getting lag from a 408cu engine... Here's a list of things to double tap.
Wastegate, Stuck open? Vaccum Leak? Stall Converter too low? Exhaust Leaks pre Turbo?
Most laggy spools are caused by problems like the above. I know a GN and an SS vary, but the concept is the same. I have had vaccum lines break on my GN which would cause the turbo to lag badly, an easy way to make sure your system is sealed is to monitor vaccum pressures at idle. They should remain steady and not fluxuate.
Depending on the wastegate and setup, if the wastegate sticks open then it will obviously take forever for it to spool if it does to begin with. If your stall is frelled up, then you will have to make high RPMs to get the Turbo to spool and the tranny to begin transfering power. Another possibility... Your mixture may be too rich or to lean to effectively generate enough heat for the turbine to spool rapidly enough. I doubt that though. Look for little problems first. If you have access to an EGT guage, make sure your EGTs are stable etc. Good luck, and sorry for the generalized answers but maybe it helps some.
Wastegate, Stuck open? Vaccum Leak? Stall Converter too low? Exhaust Leaks pre Turbo?
Most laggy spools are caused by problems like the above. I know a GN and an SS vary, but the concept is the same. I have had vaccum lines break on my GN which would cause the turbo to lag badly, an easy way to make sure your system is sealed is to monitor vaccum pressures at idle. They should remain steady and not fluxuate.
Depending on the wastegate and setup, if the wastegate sticks open then it will obviously take forever for it to spool if it does to begin with. If your stall is frelled up, then you will have to make high RPMs to get the Turbo to spool and the tranny to begin transfering power. Another possibility... Your mixture may be too rich or to lean to effectively generate enough heat for the turbine to spool rapidly enough. I doubt that though. Look for little problems first. If you have access to an EGT guage, make sure your EGTs are stable etc. Good luck, and sorry for the generalized answers but maybe it helps some.
Jan 31, 2007 | 05:21 AM
#7
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From: Newark, Tx.
I dont think he means he has lag now. He is worried about the bigger turbo creating some lag because of the size. I know because we installed the motor, trans, turbo, gauges, tuned it, wrapped the exhaust, & custom made the intercooler. His truck will stall to 6psi and hold it w/o a problem.
We left the tune very conservative and the boost at just 6psi until he is ready to do the bigger turbo.
His truck will hang with his buddies Viper
We left the tune very conservative and the boost at just 6psi until he is ready to do the bigger turbo.
His truck will hang with his buddies Viper
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Feb 2, 2007 | 04:04 AM
#9
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From: Here and sometimes there too.
Originally Posted by Orion231
If you are getting lag from a 408cu engine... Here's a list of things to double tap.
Wastegate, Stuck open? Vaccum Leak? Stall Converter too low? Exhaust Leaks pre Turbo?
Most laggy spools are caused by problems like the above. I know a GN and an SS vary, but the concept is the same. I have had vaccum lines break on my GN which would cause the turbo to lag badly, an easy way to make sure your system is sealed is to monitor vaccum pressures at idle. They should remain steady and not fluxuate.
Depending on the wastegate and setup, if the wastegate sticks open then it will obviously take forever for it to spool if it does to begin with. If your stall is frelled up, then you will have to make high RPMs to get the Turbo to spool and the tranny to begin transfering power. Another possibility... Your mixture may be too rich or to lean to effectively generate enough heat for the turbine to spool rapidly enough. I doubt that though. Look for little problems first. If you have access to an EGT guage, make sure your EGTs are stable etc. Good luck, and sorry for the generalized answers but maybe it helps some.
Wastegate, Stuck open? Vaccum Leak? Stall Converter too low? Exhaust Leaks pre Turbo?
Most laggy spools are caused by problems like the above. I know a GN and an SS vary, but the concept is the same. I have had vaccum lines break on my GN which would cause the turbo to lag badly, an easy way to make sure your system is sealed is to monitor vaccum pressures at idle. They should remain steady and not fluxuate.
Depending on the wastegate and setup, if the wastegate sticks open then it will obviously take forever for it to spool if it does to begin with. If your stall is frelled up, then you will have to make high RPMs to get the Turbo to spool and the tranny to begin transfering power. Another possibility... Your mixture may be too rich or to lean to effectively generate enough heat for the turbine to spool rapidly enough. I doubt that though. Look for little problems first. If you have access to an EGT guage, make sure your EGTs are stable etc. Good luck, and sorry for the generalized answers but maybe it helps some.
Feb 3, 2007 | 04:08 AM
#10
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From: Odessa, Texas
Thanks Spoolin, I have alot of experience when it comes to trying to diagnose turbocharged engines, most of it from long hours researching then poking and prying at my own GN. I honestly only read the first line of his post then went straight into a "quick help" reply lol. I think he will be ok though with his upgrade.