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Discussion Starter #1
For the last couple of years, stroker owners have been using srt4 injectors for the fuel requirements. These injectors are a little large for a 600hp motor, but they worked and so thats what we have been using. With the new 6.4 coming out, we decided to buy a set of injectors and have them flow-tested. What we found is that the 6.4 injectors is as close to perfect as it gets for a 600hp NA stroker. They are the correct size, they flow just the right amount to enjoy an 80% duty cycle, and they have the extended tip like the stock 6.1 injector.

I took a pic to demonstrate the physical differences in the 3 injectors.

Yellow Stripe: OEM 6.1 Injector
Red Stripe: OEM SRT4 Injector
Blue Stripe: OEM 6.4 Injector

As you can see, the OEM 6.1 injector has a longer tip which is probably designed that way for a reason. With the srt4 injector, you have a short tip which could potentially be a negative if the fuel is not atomizing properly. We have not seen any negative side affects of using this injector, I am only pointing out the physical differences. The 6.4 injector is 100% identical to the 6.1 injector in every way. The only difference is in the flow numbers.

6.1: 34 lbs/hr
6.4: 44 lbs/hr
srt4: 55 lbs/hr

Assuming a .50 BSFC, the 6.4 injector is right at 80% duty cycle in a 600hp NA stroker. The srt4 injector is still the preferred injector for anything over 600hp, but I thought this might be useful info for others.

 

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Discussion Starter #7
Crank. For cars between 475-540rwhp this is what I would use. You could go either way with yours. I would do the 6.4 just because of the longer tip.
 

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How does the SRT4 injector compare to the other two as it doesn't extend nearly as far down the head before it sprays? I was curious about this as my milled blue giants look like the other two.
 
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