Guess I should have looked at the FAQ at the top of the page. I am going to guess and say I have at least 300 hp, so it looks like I need about 16 pounds of fuel pressure. We shall see what happens.
Guess I should have looked at the FAQ at the top of the page. I am going to guess and say I have at least 300 hp, so it looks like I need about 16 pounds of fuel pressure. We shall see what happens.
-1999 Hugger Orange SS, LS2 402 T56, 9 inch Ford 3.90 gears, Tuned with HP Tuners
-2002 Cavalier, Tuned with HP Tuners
-1994 Full Size Blazer ,383 TBI 4L60E, 4.10's, Tuned with Tunerpro RT (Where it all began)
Ooofff....60 PSI on 80lb injectors. Yikes. The 94-95 TBI 454 was the only one to use a high pressure pump, regulated to 30psi, but it used 40pph(@13psi) injectors, which ended up being 75pph, with the higher pressure.
What supply pressure are those 80pph injectors rated?
Sorry, I meant 60 pound per hour injectors, not 60 pounds of fuel pressure. I am running stock 13 psi fuel pressure with 80 PPH injectors right now. I am going back to the 55's and raising the fuel pressure.Originally Posted by jameslleary
-1999 Hugger Orange SS, LS2 402 T56, 9 inch Ford 3.90 gears, Tuned with HP Tuners
-2002 Cavalier, Tuned with HP Tuners
-1994 Full Size Blazer ,383 TBI 4L60E, 4.10's, Tuned with Tunerpro RT (Where it all began)
Did you find the Injector Sizing Spreadsheet? You can enter fuel pressure, injector size engine displacement and see if it will support estimated HP. One big thing to factor in and included in spreadsheet is BPW to all this or your screwed...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Yes I found the spread sheet, thanks. I will take a look at the Base Pulse Width.
-1999 Hugger Orange SS, LS2 402 T56, 9 inch Ford 3.90 gears, Tuned with HP Tuners
-2002 Cavalier, Tuned with HP Tuners
-1994 Full Size Blazer ,383 TBI 4L60E, 4.10's, Tuned with Tunerpro RT (Where it all began)
Which spreadsheet calculates base pulse width? I must have downloaded the wrong one?
Nevermind, downloaded them all and found it, man this site is sweet...like a kid in a candy store...LOL
Last edited by 96lt4c4; 07-06-2012 at 03:25 PM.
-1999 Hugger Orange SS, LS2 402 T56, 9 inch Ford 3.90 gears, Tuned with HP Tuners
-2002 Cavalier, Tuned with HP Tuners
-1994 Full Size Blazer ,383 TBI 4L60E, 4.10's, Tuned with Tunerpro RT (Where it all began)
I do have another question though, why is it the stock tune shows the injectors as 60 PPH and they are known as 55 PPH? I always called them 60's because thats what the stock tune shows.
I just recalculated using one of the other sheets and it shows I need to run the 60's at 25 psi.
Last edited by 96lt4c4; 07-06-2012 at 03:35 PM.
-1999 Hugger Orange SS, LS2 402 T56, 9 inch Ford 3.90 gears, Tuned with HP Tuners
-2002 Cavalier, Tuned with HP Tuners
-1994 Full Size Blazer ,383 TBI 4L60E, 4.10's, Tuned with Tunerpro RT (Where it all began)
Once an internet rumor is started it can never be taken back!
Your 55PPH and 60 PPH are 61PPH...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
I was waiting for that!I just recalculated using one of the other sheets and it shows I need to run the 60's at 25 psi.
This also brings on many more tuning issues as the pressure is way outside of what the injector was designed for, can be done but way to much work.
But your 80PPH injectors, at 85% Duty Cycle and .5 BSFC and 17 PSI (more realistic) will support 311 HP, now the key to get a good tune with this spreadsheet is the BPW is 102. Or at 16 PSI = 302 HP and BPW 105.5. I er to a little bigger, easy to take away fuel in tune, hard to add if it was never there... VE numbers can come down but can only go to 100 and should really never pass 95, but having WOT only need 85 is sweet....
This is really KEY to tuning a modified engine with old 160 Baud ECM.
Now you probably have a newer 16197427 and it can be fudged a little after this calculation by changing injector size, smaller = more fuel and larger = less fuel, but you still need enough fuel to feed the beast at WOT or all your idle and drive ability tuning has been a waste of time. This fudging will only work so far and you'll be able to tune in low end or high end, usually you end up short at high end and injector duty cycle goes 100% or static... so only fudge a little after calibration.
I like to calibrate a tune correctly to start. If it does not have enough fuel to support WOT High RPM, then why start?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Yes, its a 94 Truck so it has the 7427 in it. I have done what you are talking about, fudging the the injector constant while datalogging, and emulating. I watch the BLMs and fudge the consant to get it close in real time. Seems to work OK most of the time. So it looks like I may be keeping the 80;s in there and just doing some more tuning.I was waiting for that!
This also brings on many more tuning issues as the pressure is way outside of what the injector was designed for, can be done but way to much work.
But your 80PPH injectors, at 85% Duty Cycle and .5 BSFC and 17 PSI (more realistic) will support 311 HP, now the key to get a good tune with this spreadsheet is the BPW is 102. Or at 16 PSI = 302 HP and BPW 105.5. I er to a little bigger, easy to take away fuel in tune, hard to add if it was never there... VE numbers can come down but can only go to 100 and should really never pass 95, but having WOT only need 85 is sweet....
This is really KEY to tuning a modified engine with old 160 Baud ECM.
Now you probably have a newer 16197427 and it can be fudged a little after this calculation by changing injector size, smaller = more fuel and larger = less fuel, but you still need enough fuel to feed the beast at WOT or all your idle and drive ability tuning has been a waste of time. This fudging will only work so far and you'll be able to tune in low end or high end, usually you end up short at high end and injector duty cycle goes 100% or static... so only fudge a little after calibration.
I like to calibrate a tune correctly to start. If it does not have enough fuel to support WOT High RPM, then why start?
-1999 Hugger Orange SS, LS2 402 T56, 9 inch Ford 3.90 gears, Tuned with HP Tuners
-2002 Cavalier, Tuned with HP Tuners
-1994 Full Size Blazer ,383 TBI 4L60E, 4.10's, Tuned with Tunerpro RT (Where it all began)
If you get the injector size correct then no BPW in that PCM... so it's a matter of building a smooth VE table to work with. Like 85 at WOT stuff down to little lower then stock at idle area with cam.
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
So instead of starting a new thread I'm digging this one up because this is an issue I'm faced with at the moment. I have two sets of injectors (61&80pph) and need to decide which to use. Either set I'll need to run at higher than stock pressure and I will be sending the injectors off to be cleaned and flow rated as well as having witch hunter measure latency.I was waiting for that!
This also brings on many more tuning issues as the pressure is way outside of what the injector was designed for, can be done but way to much work.
But your 80PPH injectors, at 85% Duty Cycle and .5 BSFC and 17 PSI (more realistic) will support 311 HP, now the key to get a good tune with this spreadsheet is the BPW is 102. Or at 16 PSI = 302 HP and BPW 105.5. I er to a little bigger, easy to take away fuel in tune, hard to add if it was never there... VE numbers can come down but can only go to 100 and should really never pass 95, but having WOT only need 85 is sweet....
This is really KEY to tuning a modified engine with old 160 Baud ECM.
Now you probably have a newer 16197427 and it can be fudged a little after this calculation by changing injector size, smaller = more fuel and larger = less fuel, but you still need enough fuel to feed the beast at WOT or all your idle and drive ability tuning has been a waste of time. This fudging will only work so far and you'll be able to tune in low end or high end, usually you end up short at high end and injector duty cycle goes 100% or static... so only fudge a little after calibration.
I like to calibrate a tune correctly to start. If it does not have enough fuel to support WOT High RPM, then why start?
My engine setup should hopefully be close to 400 hp and assuming 0.45 BSFC and at 85% DC I'd need to run the 61pph and 80pph injectors at 35 psi and 21 psi respectively to give the engine the required fuel. So larger injectors/lower pressure or smaller injectors/higher pressure? What are the pros and cons of each?
I'm running a vortec EP281 pump so higher fuel pressure is not an issue with respect to fuel supply.
Whatcha guys think?
95 ecsb vortec 357 10.44:1 scr LT4 hot cam single plane TBI 7427 $0D
Bigger injectors at lower pressure! Pro is they work fine at that pressure, Con at higher pressure is they open slow and casue issues, no need for latency on TBI injectors, just a service.
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
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