Clarification on injector sizing
Clarification on injector sizing I'm using the search function but most of the threads call the injectors 36#, 42#, 60#, etc.
Are those "values" the rated values for the injectors or the values the injectors will have at the LS1 fuel pressures?
Background is that my friend needs new injectors for his supercharged Mallett 435. He will likely have about 550Rwhp when tuned. Will a 60# injector be too big? (since it flows about 72 at LS1 pressures) Or should he get a 48-50# one that will flow about 60?
Just a little confused and don't want to go too big. It won't ever be sprayed if that comes up.
Thanks,
George
Are those "values" the rated values for the injectors or the values the injectors will have at the LS1 fuel pressures?
Background is that my friend needs new injectors for his supercharged Mallett 435. He will likely have about 550Rwhp when tuned. Will a 60# injector be too big? (since it flows about 72 at LS1 pressures) Or should he get a 48-50# one that will flow about 60?
Just a little confused and don't want to go too big. It won't ever be sprayed if that comes up.
Thanks,
George
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From: Perth, Australia
Different injector manufacturers use different pressures as their "standard" rated pressure. Many injectors can be used in different makes of vehicle so the manufacturers sizing and labelling will be xx.x lb/hr @ some "standard" pressure.
eg
A Ford Racing / FMS / SVO #42 is rated at 42lb/hr @ 40psi differential pressure.
You'd have to convert the flowrate if you used a different fuel rail pressure.
Try this
http://users.erols.com/srweiss/calcpchg.htm
In case you just aren't confused enough.....here is a massive chart of different injectors,flowrates and pressures.
http://users.erols.com/srweiss/tableifc.htm
eg
A Ford Racing / FMS / SVO #42 is rated at 42lb/hr @ 40psi differential pressure.
You'd have to convert the flowrate if you used a different fuel rail pressure.
Try this
http://users.erols.com/srweiss/calcpchg.htm
In case you just aren't confused enough.....here is a massive chart of different injectors,flowrates and pressures.
http://users.erols.com/srweiss/tableifc.htm
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Joined: May 2005
Posts: 689
Likes: 0
From: Perth, Australia
As to what size injectors your friend needs.
550rwhp = about 690 fwhp (erring on the high side)
= 86.25 fwhp/cyl
Erring on the safe side again, lets assume 80% duty cycle and a supercharged street engine @ .57 BSFC
Look at this chart, 6th column from the left.......go down until you find a number higher than 86.25. http://users.erols.com/srweiss/tableifc.htm#ITABLE
87 fwhp/cyl needs 62lb/hr
550rwhp = about 690 fwhp (erring on the high side)
= 86.25 fwhp/cyl
Erring on the safe side again, lets assume 80% duty cycle and a supercharged street engine @ .57 BSFC
Look at this chart, 6th column from the left.......go down until you find a number higher than 86.25. http://users.erols.com/srweiss/tableifc.htm#ITABLE
87 fwhp/cyl needs 62lb/hr
Last edited by HSV-GTS-300; Sep 1, 2006 at 07:09 AM. Reason: fixed a mistake
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Joined: May 2005
Posts: 689
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From: Perth, Australia
