383 injector sizing with mild-ish blower
Thread Starter
Registered User
Joined: Sep 1998
Posts: 561
From: Vancouver, BC, Canada
383 injector sizing with mild-ish blower
I've got a 9.5:1 Compression MTI head/383 motor going in my car next week. I'm not blowing it right away, but plan to in the semi-near future. The question I have is, say 8-12 pounds of boost, 383... what size injectors am I going to need?
I've just found out Ford stopped making the 36# SVO injectors, so it's a toss up between 30# and 42#. Unless anyone can suggest a different injector type that's half decent and around 36#'s.
I've just found out Ford stopped making the 36# SVO injectors, so it's a toss up between 30# and 42#. Unless anyone can suggest a different injector type that's half decent and around 36#'s.
Registered User
Joined: Jun 1999
Posts: 329
From: TEXAS
Well I just got my car done. Its 9.1:1 and a D1SC pullied for 15psi. I ran out of gas with my combo and I was running MSD 50# injectors at 50psi base pressure and a racetronix fuel system. It held fine til around 560rwhp on a Mustang dyno so depends on if you are thinking the motor is going to be going over that. Someone said that equates roughly to 620-635rwhp on a DynoJett. Also I was not running a FMU, only a 1:1 boost referenced regulator.
Anyway...heres a litte more infor for ya.
http://web.camaross.com/forums/showt...hreadid=166552
Anyway...heres a litte more infor for ya.
http://web.camaross.com/forums/showt...hreadid=166552
Registered User
Joined: Nov 2001
Posts: 1,751
From: Surrey, BC, Can
Hi Jason
I had a 15 # pulley on an ATI D1, 383 with moderately worked heads.
I had 50# injectors and a Walbro 255 in tank and ran out of fuel at about 4600 rpms at 10 - 12#'s of boost. I THINK the injectors would perhaps have been OK but the fuel pump sysytem needed to be upgraded and went with a Racetronic dual intank (great piece
)
I also went to a FAST and decided to get some 75# Delphi injectors. I think the 50's are borderline but perhaps try upgrading the fuel delivery before having to get the bigger injectors.
I had a 15 # pulley on an ATI D1, 383 with moderately worked heads.
I had 50# injectors and a Walbro 255 in tank and ran out of fuel at about 4600 rpms at 10 - 12#'s of boost. I THINK the injectors would perhaps have been OK but the fuel pump sysytem needed to be upgraded and went with a Racetronic dual intank (great piece
)I also went to a FAST and decided to get some 75# Delphi injectors. I think the 50's are borderline but perhaps try upgrading the fuel delivery before having to get the bigger injectors.
Registered User
Joined: Aug 2003
Posts: 267
Registered User
Joined: Aug 2003
Posts: 267
I was checking with T Byrne Motorsports about ATI procharger for my 355 LT1 and was told that I should be able to run 30# injectors with my mods. That amounts to 527 RWHP (620FWHP). Off course, the kit comes with a Pro Pump from ATI.
I know the stock 24# injectors will support upto 450FWHP with PCM programming.
I know the stock 24# injectors will support upto 450FWHP with PCM programming.
Thread Starter
Registered User
Joined: Sep 1998
Posts: 561
From: Vancouver, BC, Canada
Before I do the blower, I will definitely be replacing the fuel pump with something better (I'm still running the stocker).
I think I'll toss in my 24# SVO's for the time being (like I said currently un-boosted). And pansy it for a while... because right now I'm car-less. I want a good break-in period before the boost goes on. So sometime later this year or early next year I'll pick up a set of those 50#ers and a new fuel setup... After that I'll start looking at blowers.
Actually Shawn, do you still have those 50#ers or did you sell them already?
Is MSD-2013 (summit) the part # that we're talking about? And are those a direct fit, or am I going to have to do something else with them?
I think I'll toss in my 24# SVO's for the time being (like I said currently un-boosted). And pansy it for a while... because right now I'm car-less. I want a good break-in period before the boost goes on. So sometime later this year or early next year I'll pick up a set of those 50#ers and a new fuel setup... After that I'll start looking at blowers.
Actually Shawn, do you still have those 50#ers or did you sell them already?
Is MSD-2013 (summit) the part # that we're talking about? And are those a direct fit, or am I going to have to do something else with them?
Registered User
Joined: Nov 2001
Posts: 1,751
From: Surrey, BC, Can
Originally posted by Jason Dove
Actually Shawn, do you still have those 50#ers or did you sell them already?
Is MSD-2013 (summit) the part # that we're talking about? And are those a direct fit, or am I going to have to do something else with them?
Actually Shawn, do you still have those 50#ers or did you sell them already?
Is MSD-2013 (summit) the part # that we're talking about? And are those a direct fit, or am I going to have to do something else with them?
Not sure what you mean.
If I were you, check Racetronic if you buy new for the injectors and the pump. No PST (although you will have GST) and JAcks prices are good, although you may find a dollar or too chaeaper elsewhere.
Registered User
Joined: Oct 2001
Posts: 784
Delphi 50's (same part as MSD / Holley, but Racetronix are flow matched sets):
http://www.racetronix.com/Racetronix..._Sale-50s.html
Siemens 57's (high impedance):
http://www.racetronix.com/Racetronix..._Sale-55h.html
In-tank fuel system good for apx. 550RWHP (add a pump booster as a PnP option for an additional 100-150RWHP support)
http://www.racetronix.com/Racetronix..._Pump_Kit.html
http://www.racetronix.com/Racetronix..._Sale-50s.html
Siemens 57's (high impedance):
http://www.racetronix.com/Racetronix..._Sale-55h.html
In-tank fuel system good for apx. 550RWHP (add a pump booster as a PnP option for an additional 100-150RWHP support)
http://www.racetronix.com/Racetronix..._Pump_Kit.html
Registered User
Joined: Aug 2003
Posts: 267
For those who say 50# injectors are the correct size for a supercharged Z28, 355 or 383, did you count the additional fuel that the supercharger kit will add (boost).
Isn't 50# injectors size going to run rich at idle. 50# injectors will feed 600+FWHP. You won't have that power at idle or near 1000-2000RPM.
Isn't 50# injectors size going to run rich at idle. 50# injectors will feed 600+FWHP. You won't have that power at idle or near 1000-2000RPM.
Last edited by BlueCamaroZ28; Sep 11, 2003 at 07:51 AM.
Registered User
Joined: Dec 1969
Posts: 324
From: Calgary, Alberta, Canada
Re: 383 injector sizing with mild-ish blower
Originally posted by Jason Dove
I've got a 9.5:1 Compression MTI head/383 motor going in my car next week. I'm not blowing it right away, but plan to in the semi-near future. The question I have is, say 8-12 pounds of boost, 383... what size injectors am I going to need?
I've just found out Ford stopped making the 36# SVO injectors, so it's a toss up between 30# and 42#. Unless anyone can suggest a different injector type that's half decent and around 36#'s.
I've got a 9.5:1 Compression MTI head/383 motor going in my car next week. I'm not blowing it right away, but plan to in the semi-near future. The question I have is, say 8-12 pounds of boost, 383... what size injectors am I going to need?
I've just found out Ford stopped making the 36# SVO injectors, so it's a toss up between 30# and 42#. Unless anyone can suggest a different injector type that's half decent and around 36#'s.
The 42# SVO injectors can be set up easily with the LT1 editor program.
The guys recommending the larger, in excess of 50# are going without an FMU. That works well also, I just don't see whats so bad about an FMU.
Hope this helps
LWM
Registered User
Joined: Jun 1999
Posts: 329
From: TEXAS
BlueCamaro-
How is the supercharger going to add fuel? Its job is to pump in a lot more air not fuel. Now since most use (and the correct way to do it) a boost referenced FPR it does add about 1psi of fuel pressure per 1 psi of boost. So that does add a little bit. The kits do come with a FMU that is at a 4:1 ratio on most of them. The only problem with a FMU is that it makes it a PITA to tune with and most of the don't work exactly like they should. So to make the car easier to work with just go with a bigger injector and tune it. A FMU just like a Boost-A-Pump is just a bandaid used to patch something up instead of getting parts that actualy do what they are suppose to do.
Another thing you have to think about using a really small injector with a FMU or similar device is that you are going to be running longer pulse widths with can burn injectors up (you don't want to go over 80% duty cycle) and not only that when really high fuel pressures are involved some injectors just can not over come that and lock open or shut depending on how they work.
Lastly...yes 50s are somewhat of a pain to tune with at idle and low rpms but once you get the tune worked out you can drive around town just fine. Hell if you stay out of boost mine just seems like a stock Z28, just with a little more pep. Once you put your foot down past 1/4 throttle then traction is just over. But yes you can get cars to idle with big injectors. From what I have heard low impedance injectors (bigger than 50/57) like the 72 and 96lbers are even easier to work with and sort out for driveablity just due to how they work. Most turbo imports use injectors like these.
How is the supercharger going to add fuel? Its job is to pump in a lot more air not fuel. Now since most use (and the correct way to do it) a boost referenced FPR it does add about 1psi of fuel pressure per 1 psi of boost. So that does add a little bit. The kits do come with a FMU that is at a 4:1 ratio on most of them. The only problem with a FMU is that it makes it a PITA to tune with and most of the don't work exactly like they should. So to make the car easier to work with just go with a bigger injector and tune it. A FMU just like a Boost-A-Pump is just a bandaid used to patch something up instead of getting parts that actualy do what they are suppose to do.
Another thing you have to think about using a really small injector with a FMU or similar device is that you are going to be running longer pulse widths with can burn injectors up (you don't want to go over 80% duty cycle) and not only that when really high fuel pressures are involved some injectors just can not over come that and lock open or shut depending on how they work.
Lastly...yes 50s are somewhat of a pain to tune with at idle and low rpms but once you get the tune worked out you can drive around town just fine. Hell if you stay out of boost mine just seems like a stock Z28, just with a little more pep. Once you put your foot down past 1/4 throttle then traction is just over. But yes you can get cars to idle with big injectors. From what I have heard low impedance injectors (bigger than 50/57) like the 72 and 96lbers are even easier to work with and sort out for driveablity just due to how they work. Most turbo imports use injectors like these.