I'm heading into the final stages of my build, intending to run bottom 10's to high 9's at somewhere between 135 and 140. I've found some impressive runs with the 120's, but they seem to be limited to the 8th mile presumably to stay within the limits of the fuel pump and or injectors. I'm wondering where the duty cycle typically hits the ceiling in relation to mph in a full weight GN.
Highest MPH on E85 and 120 lb injectors. (Quarter mile)
- Thread starter Deebar
- Start date
Thanks Steve. I assume you're using a double pumper. Did you raise your base pressure, or just burying the needle on the boost gauge? Nice job either way. I vaguely remember reading somewhere that lowering the base fuel pressure could preserve some fuel volume as you run higher boost.
- Joined
- May 26, 2001
My car will run high 9's, 136-7 with 120# injectors on e-85 and the duty cycle is under 70%. I only need 18 psi boost to run a 9.80
I run an external pump, and would never consider running a 600+ RWHP with 2 in-tank pumps?
My fuel pressure is set the same as when I was using 116 octane race gas.
I run an external pump, and would never consider running a 600+ RWHP with 2 in-tank pumps?
My fuel pressure is set the same as when I was using 116 octane race gas.
- Joined
- May 26, 2001
The turbo is a HPQ-70 MM, 270 cu. in. production 4.1 block, and about 9:1 compression.
With a big bore and awesome TA heads, it has LOTS of low-end torque and increases all the way through the traps!
With a big bore and awesome TA heads, it has LOTS of low-end torque and increases all the way through the traps!
TurboBuick86
Active Member
- Joined
- Sep 24, 2008
Love E85!
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Last edited:
Ok here we go i hope this information can help. This is on E85 with ethanol content of about 83-85%
On my iron headed 3.8 about 3650lb with me in it FP at 50psi base with 30-31psi of boost my 120s were done with dual walbros "with reliefe valves pushed in" at right under 110mph through the 1/8th mile when easing my car out of the gate and it finally turning on a good 30ft or so out which causes me to lose about 2-3mph as my 60ft was a terrible 1.56... inj duty on that pass went to high 120s at the end of the track... but i did run it out to 120 mph per log before i shut it down.... I stay in it as long as i can to get as much data as i can Once i went into 3rd on this pass im sure the pumps were getting drained... looking through the log i was at 105% inj duty right before the 2-3 shift. On my car the boost comes up a little in 3rd gear as well so once it got into 3rd it started slowly going leaner the more rpm i turned it. Was still 11.6 AFR when i let off when my target was 11.3 but at this point the injector was compensating a lot to hold this AFR. I have since went to a magna fuel 4303 pump and sumped my tank. I've had inj duty in the 90s% out on the street playing around. The magnafuel 4303 did give me some more fuel without a doubt but the injectors seem to be about done or as far as i want to push them anyways. Of course i am going by the inj duty on the powerlogger which i dont find to be 100% accurate and when i say that i mean 100% duty my injectors are not done.. Ive ran 80s and my 120s at over 100% duty cycle and found i had fuel up to around 115% per logger. All that said i think the 120s are good on my setup to about 140ish mph depending on how well the car will 60ft and produce the momentum it needs out of the hole. The quicker i 60ft the more momentum i have and obviously the faster both my ET and MPH are EVERY time.
You are going to need more fuel per HP with an iron head due to them being less effecient then a good set of aftermarket heads. Setup is a major role in all this from head intake combo to cam, CI, RPM you are turning etc... So simply saying an injector is good for X mph is not a very accurate way to judge how far you can go on X injector. Way too many variables there... But above is an example of how my car reacts with my variables i guess you could say. I hope this helps some of you all on injector selection!
Here is a video of the pass i was talking about to give u a better idea of how the car was acting outof the gate etc. The first pass on this video was 6.5 at 108.7mph and Injector duty stayed around 98-100% on that pass. 2nd out of car pass is the 6.40 at 109.7 And honestly if i could have got the car out of the hole on a good 1.40 60ft id say i would be looking at 6.teens to 6.20 @ 112-113mph. I was happy with it for leaky stock headers and a small 3 inch restrictive exhaust with an also VERY restrictive internal gate. Back pressure city here folks!!! haha
On my iron headed 3.8 about 3650lb with me in it FP at 50psi base with 30-31psi of boost my 120s were done with dual walbros "with reliefe valves pushed in" at right under 110mph through the 1/8th mile when easing my car out of the gate and it finally turning on a good 30ft or so out which causes me to lose about 2-3mph as my 60ft was a terrible 1.56... inj duty on that pass went to high 120s at the end of the track... but i did run it out to 120 mph per log before i shut it down.... I stay in it as long as i can to get as much data as i can
Once i went into 3rd on this pass im sure the pumps were getting drained... looking through the log i was at 105% inj duty right before the 2-3 shift. On my car the boost comes up a little in 3rd gear as well so once it got into 3rd it started slowly going leaner the more rpm i turned it. Was still 11.6 AFR when i let off when my target was 11.3 but at this point the injector was compensating a lot to hold this AFR. I have since went to a magna fuel 4303 pump and sumped my tank. I've had inj duty in the 90s% out on the street playing around. The magnafuel 4303 did give me some more fuel without a doubt but the injectors seem to be about done or as far as i want to push them anyways. Of course i am going by the inj duty on the powerlogger which i dont find to be 100% accurate and when i say that i mean 100% duty my injectors are not done.. Ive ran 80s and my 120s at over 100% duty cycle and found i had fuel up to around 115% per logger. All that said i think the 120s are good on my setup to about 140ish mph depending on how well the car will 60ft and produce the momentum it needs out of the hole. The quicker i 60ft the more momentum i have and obviously the faster both my ET and MPH are EVERY time. You are going to need more fuel per HP with an iron head due to them being less effecient then a good set of aftermarket heads. Setup is a major role in all this from head intake combo to cam, CI, RPM you are turning etc... So simply saying an injector is good for X mph is not a very accurate way to judge how far you can go on X injector. Way too many variables there... But above is an example of how my car reacts with my variables i guess you could say. I hope this helps some of you all on injector selection!
Here is a video of the pass i was talking about to give u a better idea of how the car was acting outof the gate etc. The first pass on this video was 6.5 at 108.7mph and Injector duty stayed around 98-100% on that pass. 2nd out of car pass is the 6.40 at 109.7 And honestly if i could have got the car out of the hole on a good 1.40 60ft id say i would be looking at 6.teens to 6.20 @ 112-113mph. I was happy with it for leaky stock headers and a small 3 inch restrictive exhaust with an also VERY restrictive internal gate. Back pressure city here folks!!! haha
Rafs-T-Type
Not so Senior Member
- Joined
- Mar 8, 2009
Your IDC went to high 120's?!? That's nuts! I thought it pretty much ended around 105.
That's nuts! I thought it pretty much ended around 105.Oh they did or thats what the PL was reading anyways. Ive always been able to fuel the car to about 110-115% going by the powerlogger. I have seen this with MANY other systems used to tune and log stock ECUs on many different cars not just the buicks. Now the stand alone systems i use to tune other cars with are usually pretty on such as AEM stand alone system for example.
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