turbo spool vs AFR & Timing
Thread Starter
TECH Resident
Joined: Aug 2008
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From: Dubai
turbo spool vs AFR & Timing Is there any relation at all between how fast a turbo spools compared to AFR and timing.
With all else equal, will a turbo motor with more timing and a leaner fuel mixture build boost earlier.
This might sound stupid, but I never hesitate to ask
With all else equal, will a turbo motor with more timing and a leaner fuel mixture build boost earlier.
This might sound stupid, but I never hesitate to ask
8 Second Club
Joined: May 2004
Posts: 371
Likes: 0
From: Savannah, TN
Put the timing to it . As for the afr some where in the middle. Some say rich and retard others say lean. It depends on trans type. and with an auto alot to do with how tight the convertor is and the cam duration . if you run a tight convertor it will take all you can make to get you over the hump. If you run one on the loser side seems like a rich with lots of timing seams to spool fast. One thing that most dont consider is spark duration and how hot the spark is . hotter and longer
Thread i did back in '07, lots of good info here
https://ls1tech.com/forums/forced-in...me-tuning.html
https://ls1tech.com/forums/forced-in...me-tuning.html
8 Second Club
Joined: May 2004
Posts: 371
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From: Savannah, TN
Thread i did back in '07, lots of good info here
https://ls1tech.com/forums/forced-in...me-tuning.html
https://ls1tech.com/forums/forced-in...me-tuning.html
What is the reason you would change timing & fueling depending on the trans? Not trying to argue the fact with you, I assume you are correct, I just don't understand why.
I would also think you would always want to be rich - more fuel = denser exhaust gases. I guess leaner could = hotter exhaust gasses, but varying advance depending on trans type doesn't make sense to me.
To the OP - if you don't have an LPE 2-step - get one. I can make 5 psi on the foot brake at 2700 rpm's with mine. I've just started playing with it. Hopefully I can make 7 or so at 3000 if the brakes hold. With a t-brake I'm sure it could make a lot more. Thing is bad ***.
I would also think you would always want to be rich - more fuel = denser exhaust gases. I guess leaner could = hotter exhaust gasses, but varying advance depending on trans type doesn't make sense to me.
To the OP - if you don't have an LPE 2-step - get one. I can make 5 psi on the foot brake at 2700 rpm's with mine. I've just started playing with it. Hopefully I can make 7 or so at 3000 if the brakes hold. With a t-brake I'm sure it could make a lot more. Thing is bad ***.
Thread Starter
TECH Resident
Joined: Aug 2008
Posts: 910
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From: Dubai
Well let me make my question clearer, not asking for boost off the line, just building up boost from a roll. Car is a stick, its running very rich, AFR in the 9's (not tuned yet) and boost wasnt kicking in as I expected it to be.
I know this has a little to do with the boost controller too, but I was wondering if the tune had anything to do with this.
I know this has a little to do with the boost controller too, but I was wondering if the tune had anything to do with this.
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Brett Foote 8 Second Club
Joined: May 2004
Posts: 371
Likes: 0
From: Savannah, TN
What is the reason you would change timing & fueling depending on the trans? Not trying to argue the fact with you, I assume you are correct, I just don't understand why.
I would also think you would always want to be rich - more fuel = denser exhaust gases. I guess leaner could = hotter exhaust gasses, but varying advance depending on trans type doesn't make sense to me.
To the OP - if you don't have an LPE 2-step - get one. I can make 5 psi on the foot brake at 2700 rpm's with mine. I've just started playing with it. Hopefully I can make 7 or so at 3000 if the brakes hold. With a t-brake I'm sure it could make a lot more. Thing is bad ***.
I would also think you would always want to be rich - more fuel = denser exhaust gases. I guess leaner could = hotter exhaust gasses, but varying advance depending on trans type doesn't make sense to me.
To the OP - if you don't have an LPE 2-step - get one. I can make 5 psi on the foot brake at 2700 rpm's with mine. I've just started playing with it. Hopefully I can make 7 or so at 3000 if the brakes hold. With a t-brake I'm sure it could make a lot more. Thing is bad ***.
You basically want to optimize engine performance across the board. Lets take a normal ls1 with a mild turbo setup at about 800hp.
2000rpm 10inhg, 38-40 degress and a afr of 14-15:1
2000rpm 0psi 24-28 degress and afr of 13:1
3000rpm 0-3psi 23-25 degrees and afr of 12.5:1
3500rpm 5-8psi 19-20 degrees and afr of 12-12.2:1
4000+ 10+psi 11.4-11.8:1 and 14-18 degrees................
Just a really crude example but you get the idea.
Then of coarse there is a lot of tricks like dumping timing on the 2-step to bang the turbo, but that all comes after a good understanding of how to get a turbo engine running correctly.
2000rpm 10inhg, 38-40 degress and a afr of 14-15:1
2000rpm 0psi 24-28 degress and afr of 13:1
3000rpm 0-3psi 23-25 degrees and afr of 12.5:1
3500rpm 5-8psi 19-20 degrees and afr of 12-12.2:1
4000+ 10+psi 11.4-11.8:1 and 14-18 degrees................
Just a really crude example but you get the idea.
Then of coarse there is a lot of tricks like dumping timing on the 2-step to bang the turbo, but that all comes after a good understanding of how to get a turbo engine running correctly.
TECH Regular
Joined: Nov 2006
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Whith an auto you will need to make as much torque that a motor can make down low before boost. So it will have to be a little on the lean side every engine is different and all the timing you can put to it and once again all engines are differnt so there is no magic numers. ( coming up on boost mine is like 36 to 38 degrees). and as sone as boost comes in it will fall way back. I also use a 7531 MSD and it has spool up option . And for a stick like you said a engine with out load will not make boost so throw the fuel to pull timing and you have a dense burning exhaust gas in the pipe so boost at the drop of the clutch. just somthing to think of all set ups are different I run a 98mm with a 1.0AR with a T6 flange and heck my cam dont clear out untile 3000 to 4000.
TECH Apprentice
Joined: Mar 2006
Posts: 361
Likes: 1
From: australia
it has 3 rd rpm limiter, than can be controlled by electrical signal , to help spool the turbo before you go into full stage, AND will not activate the trans break , and stop the car from rolling into full stage...
go to msd web site amd down load the instructions...
TECH Apprentice
Joined: Mar 2006
Posts: 361
Likes: 1
From: australia
Whith an auto you will need to make as much torque that a motor can make down low before boost. So it will have to be a little on the lean side every engine is different and all the timing you can put to it and once again all engines are differnt so there is no magic numers. ( coming up on boost mine is like 36 to 38 degrees). and as sone as boost comes in it will fall way back. I also use a 7531 MSD and it has spool up option . And for a stick like you said a engine with out load will not make boost so throw the fuel to pull timing and you have a dense burning exhaust gas in the pipe so boost at the drop of the clutch. just somthing to think of all set ups are different I run a 98mm with a 1.0AR with a T6 flange and heck my cam dont clear out untile 3000 to 4000.
You basically want to optimize engine performance across the board. Lets take a normal ls1 with a mild turbo setup at about 800hp.
2000rpm 10inhg, 38-40 degress and a afr of 14-15:1
2000rpm 0psi 24-28 degress and afr of 13:1
3000rpm 0-3psi 23-25 degrees and afr of 12.5:1
3500rpm 5-8psi 19-20 degrees and afr of 12-12.2:1
4000+ 10+psi 11.4-11.8:1 and 14-18 degrees................
Just a really crude example but you get the idea.
Then of coarse there is a lot of tricks like dumping timing on the 2-step to bang the turbo, but that all comes after a good understanding of how to get a turbo engine running correctly.
2000rpm 10inhg, 38-40 degress and a afr of 14-15:1
2000rpm 0psi 24-28 degress and afr of 13:1
3000rpm 0-3psi 23-25 degrees and afr of 12.5:1
3500rpm 5-8psi 19-20 degrees and afr of 12-12.2:1
4000+ 10+psi 11.4-11.8:1 and 14-18 degrees................
Just a really crude example but you get the idea.
Then of coarse there is a lot of tricks like dumping timing on the 2-step to bang the turbo, but that all comes after a good understanding of how to get a turbo engine running correctly.
Going to try something to this effect. This has been my thinking as well to get on boost sooner. I will be trying this as soon as my trans gets finished this next week.
