Seem about right for 80 lb injectors?

[MNwe4]

Curious to see if people think this is about right for using 80 lb injectors of if something is a bit off. Combo is as shown below in sig. On E85 with -8 feed line, -6 return line, stock fuel rail. I'm hitting 98% duty cycle at 21 psi boost around 5300 rpm. Air temp that day at the track was around 75* F. AFR on the gas scale was 11.0-11.2. Base FP set at 43 psi and during the runs it stayed steady at 60 psi. I know it should have been 64, so either the FPR isn't the greatest or the gauge is off. It's a digital unit.

Since the motor is a stroker I realize that at the same boost level it would be using more air than a stock stroke thereby requiring more fuel. However, it's not like it's that many extra cubes. Best et was 11.29 and best mph was 124. Couldn't get a 60' below 1.73 though due to my 255 et streets and terrible track conditions.

What do you all think? Should I try ditching the raw aluminum style FP reg for an Accufab unit or is there something else I should be looking at?

 

[Flyin Brian]

I'm no expert but that sounds pretty close to me. I leaned out and blew a head gasket at 25 psi boost with my 80's. I would recommend turning up the base fuel pressure and re-tuning to try and get your duty cycle down. I would also look at the regulator and make sure you are getting 1:1 rise with boost. Make sure the boost reference line on the regulator is nice and tight. Lots of people run the base pressure way up on 80's with E85. That is a nice MPH by the way!

 

[Boost231]

Data log fuel pressure, that will tell you what's going on. What fuel pump setup? Sounds about right to me. You could bump up the base pressure like stated above but that will tax the pump more. If you have a good pump that will work and make the injectors act larger

 

[MNwe4]

I'm no expert but that sounds pretty close to me. I leaned out and blew a head gasket at 25 psi boost with my 80's. I would recommend turning up the base fuel pressure and re-tuning to try and get your duty cycle down. I would also look at the regulator and make sure you are getting 1:1 rise with boost. Make sure the boost reference line on the regulator is nice and tight. Lots of people run the base pressure way up on 80's with E85. That is a nice MPH by the way!

Thanks for the response. I think I'll for sure get a new Accufab unit. This billet style has been on the car since 2003. Maybe the diaphragm is starting to give up. At the same time it would probably be a good idea to purchase a mechanical gauge and tape it to the windshield to compare to the electronic gauge. Getting a video of that is easy too. The whole thing just had me curious though since people have said 80's can get down to the mid-high 10's. I'm a long way from that.

 

[Flyin Brian]

I forgot about the pump. I am not familiar with the Walbro 430 but if it is not enough pump that will show up on the windshield mounted mechanical gauge as the needle fluttering wildly at full boost. You are not far from a high 10 with that mph and 60'. Get more fuel in it and more boost with a really good 60' and you should be there.

 

[MNwe4]

Data log fuel pressure, that will tell you what's going on. What fuel pump setup? Sounds about right to me. You could bump up the base pressure like stated above but that will tax the pump more. If you have a good pump that will work and make the injectors act larger

Thanks for joining in. You bring up good points. I am logging fuel pressure, the line stays constant, but is not at 60 psi like my gauge says. It oscillates at good frequency between 55-59. I think there's some offset issues with the powerlogger because the AFR on my gauge says 11.0-11.2 during a run while the PL bounces around 10.7. Everything is consistent though so I just keep the offset in mind.

Fuel pump is the 430 lph Walbro setup from Racetronix on the new hangar with -8 feed and -6 return line. Stock fuel rail. I'm also running a TPS based volt booster and during a run the PL reports 15.1 volts. Have good wire running to the pump as well, so I think it's possible to assume the pump is getting 13.5 volts. From the MFG's data that pump fully supports 80's and I've calculated that it'll support 100's to 95% duty cycle at that voltage. This of course assumes no other losses, but I'm confident it'll cover 80's without issue. I'll try to attach my spreadsheet later. It's having issues right now.

Any idea what kind of base fuel pressures people are cranking them up to? For regular drivability I don't think I'd want to go above 50 psi. I'd like to keep the car tuned the same for track and street.

 

[MNwe4]

Wouldn't let me upload an Excel file, but PDF screenshot worked.

 

[Flyin Brian]

I had my base pressure at 50. Many people go higher than that. You will have to do some tuning with the higher base pressures to get it to run right everywhere else though.

 

[dynoman]

Did you upgrade the grounds from the pump ? Your system may read 15+ volts , but the pump will not run to its full potential if the circuit doesn't have wires large enough to support the current draw that pump will put on the circuit . Hotwire kits are pretty common now but the grounds are often overlooked . 10 gauge or larger ground wire from the battery to the back of the car is the best way to go . Sam

 

[MNwe4]

Yes, I believe the grounds are are upgraded. I know we did the best we could with the wiring. Extra grounds going to tank as well. Going to try a new FP reg in the spring and give everything another look. Went out for a last run with the club this weekend and the transmission let go. Time to ship the other trans out and put the car away for the winter unfortunately.

 

[Terbro]

Did you upgrade the grounds from the pump ? Your system may read 15+ volts , but the pump will not run to its full potential if the circuit doesn't have wires large enough to support the current draw that pump will put on the circuit . Hotwire kits are pretty common now but the grounds are often overlooked . 10 gauge or larger ground wire from the battery to the back of the car is the best way to go . Sam

I need to get in on this thread (I'll try not to hijack it though!). I've currently got 60# injectors, but will be upgraded to 80#ers (injectors have arrived, just waiting on TT chip) because it's losing power around the top of 2nd and through 3rd gear (and won't hit the full 20#'s boost I've got it set at in 1st). My FP was low, and I just set the base pressure to 50 psi (line off). Helped a bit, but still lagging around midway thru 3rd. TT chip is already programmed for 100% duty cycle.

Nick Micale built my motor and recommended I ground the pump, just as you have dynoman. Well, he recommends grounding it to the unused threaded hole on the alternator. I'm seeing typically 13.8-13.9 volts on the Scanmaster at the start of a run (before getting on it), and by the time I'm into 3rd gear, I've seen it drop to 13.1 and 12.6 volts. I need to get volt booster as well.

I'm anxious to get the TT chip and install the 80#er's. But I'm reading that even higher base fuel pressure than 50 psi? I'm pretty excited, actually. My TR is making mad power at 20 psi boost for the first gear and a half. Bigger injectors, fuel pump ground, volt booster and, that's right...more boost (say up to 23 psi), should have me rockin' hard!

 

[LSTTYPE]

My buddy went 10.60 @ 127 with 80s. Deatchwerks dw300, hot wired with a volt booster. His 60 ft was a 1.60 or worse.

 

[Terbro]

My buddy went 10.60 @ 127 with 80s. Deatchwerks dw300, hot wired with a volt booster. His 60 ft was a 1.60 or worse.

Come on. On E85? What was his build, do you know. I'm guessing GN1 heads...and close to 30 psi boost. Wow.

 

[LSTTYPE]

Of course it was on e85 and not 30 psi but 25. It has stock iron heads with a little bowl work done by I believe dls. Roller cam. Stock crank with billet mains. His wideband never showed lean either. Precision 6262 with a ptc non lu. Look up the time slip thread of the guy with the cutlass that went 132 mph on 83 lb injectors and e85.

 

[Terbro]

Of course it was on e85 and not 30 psi but 25. It has stock iron heads with a little bowl work done by I believe dls. Roller cam. Stock crank with billet mains. His wideband never showed lean either. Precision 6262 with a ptc non lu. Look up the time slip thread of the guy with the cutlass that went 132 mph on 83 lb injectors and e85.

Well, that's encouraging.