What's your timing Retard curve like?
09-20-2015, 04:06 PM
#1
Supreme Member
Thread Starter
What's your timing Retard curve like?
Blown/pump gas setups, what are you guys doing with timing? just playing around with my digital 7, and curious what other people are running for retard on pump gas these days.
09-23-2015, 01:00 PM
#2
Re: What's your timing Retard curve like?
Your blower comes in pretty linear with rpm correct?
Last d1sc blown car i tuned. I had air fuel slowly dip down from 13:1 at wot at the hit before any boost and as it comes in, it dips to 11.8 at 5500-5800 rpm where its at 8-9 psi
Timing curve does something similar. However it doesnt pull much timing until 4-5 psi. First few psi dont require any timing pulled. At peak psi and rpm, its down about 9-10 deg, which is about 1 deg per lb maybe alittle more. Afr heads on it so fairly quick burn chamber. Doesnt need or want alot of timing.
Last d1sc blown car i tuned. I had air fuel slowly dip down from 13:1 at wot at the hit before any boost and as it comes in, it dips to 11.8 at 5500-5800 rpm where its at 8-9 psi
Timing curve does something similar. However it doesnt pull much timing until 4-5 psi. First few psi dont require any timing pulled. At peak psi and rpm, its down about 9-10 deg, which is about 1 deg per lb maybe alittle more. Afr heads on it so fairly quick burn chamber. Doesnt need or want alot of timing.
09-25-2015, 11:31 AM
#3
Supreme Member
Thread Starter
Re: What's your timing Retard curve like?
Cool ... I'm doing something similar. Right now I have full timing (locked out at 36deg) up to 7psi, then it's pulling about 1deg per PSI.
I need more time at the track to dial it in up top, because I'm not going to pull 20deg out of it haha ... I also have AFR heads, but even with conservative timing (20-22 deg total) on the engine dyno, adding a degree picked up about 100hp ... but we never had time to really lean on it.
At the moment I'm chasing down what seemed like a low timing, or lean pop on the hit. I'm not convinced that the cam just doesn't want to run at "pedestrian RPM" though, and it might never go away in street driving. It's always run decent down the track at decent RPM. The carb has 50cc squirters and bigger nozzles (can't remember the exact size at the moment) so I'm doubtful there isn't enough gas getting in there.
I need more time at the track to dial it in up top, because I'm not going to pull 20deg out of it haha ... I also have AFR heads, but even with conservative timing (20-22 deg total) on the engine dyno, adding a degree picked up about 100hp ... but we never had time to really lean on it.
At the moment I'm chasing down what seemed like a low timing, or lean pop on the hit. I'm not convinced that the cam just doesn't want to run at "pedestrian RPM" though, and it might never go away in street driving. It's always run decent down the track at decent RPM. The carb has 50cc squirters and bigger nozzles (can't remember the exact size at the moment) so I'm doubtful there isn't enough gas getting in there.
Last edited by 383backinblack; 09-25-2015 at 11:35 AM.
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