40#vs.42# injectors

[t-typex1]

Whats the difference between 40# & 42# injectors? Iwas always under the impression these were the same injectors.

 

[SS_Sean]

If I do my math correctly, it looks like two pounds pressure. :biggrin:

 

[22lbChevelle]

Not pressure, but volume flow. (Lb/hour).. These numbers are the maximum flow when the injector is held open. These flow measurements are usually made with fuel pressure around 45PSI [Lb/(inch)(inch)]. These two injectors do not have a big difference in their max flow, or horsepower potential; a difference may exist between their minimum flow, which can affect idle characteristics.

 

[salvageV6]

Kenne-Bell and other vendors in the older days sold a ton of red stripe or red top 40lb. injectors, don't know who made those but with a good chip they work fine, just might have some age to them if bought used.

The popular 42lb. injectors were the 009's that were a bit non-linear in flow and require a good chip also to work well, most are used also out there.

Bosch 42 or 42.5 Ford Lightning injectors are the other version of the 42's and are green top injectors.

 

[t-typex1]

Thanks for the info, sounds as if there are no big differences in performance, that they will both deliver almost identical results.

 

[onslow]

Not pressure, but volume flow. (Lb/hour).. These numbers are the maximum flow when the injector is held open. These flow measurements are usually made with fuel pressure around 45PSI [Lb/(inch)(inch)]. These two injectors do not have a big difference in their max flow, or horsepower potential; a difference may exist between their minimum flow, which can affect idle characteristics.

Re HP potential...I agree.

Somewhere, I picked up a formula for normally aspirated engines that relates potential HP to injector flow:

HP Potential = 6 x .85 x (Injector lbs. x 2).

Using this formula, the 40s can support up to about 408 HP and the 42s up to about 428 HP.

With the turbo...a Kenne Bell project GN got just over 400 HP with stock injectors and bolt ons only.

I recommend Eric at turbotweak.com for a chip matched to your injectors.

Steve