sr20det injector upgrade or not with my set up? is it worth it?
i have a s13 redtop with the following set up….should i buy 440cc injectors or not?
headers, 4inc down pipe, 3 1/2 cat-back k and n intake greddy pullies boost controller side mount stock turbo.
i have been looking on ebay and i have found the 440cc injectors off a 96 s14. should i buy them? is it worth it? will i even see a difference in power?how much if any? please help
Right now you are running 370cc/min. It does depend on what kind of horsepower you are going to make. You can use any larger injector as long as the ecu is tuned to that specific size.
But here is a general formula
(Horsepower * B.S.F.C) / ( # or injectors * Duty Cycle)= injector flow (lb/hr)
this is the conversion from lb/hr to cc/min ( cc/min = lb/hr * 10.5)
BSFC means brake specific fuel consuption which is how much fuel your engine takes to make power. Since it is turbo, and turbos run richer then na’s to prevent detonation and, the bsfc is about .6 to .65 on the rich side( factory will use a little less then .6 because of conservative tuning from factory). NA’s run .5 pounds of fuel per horsepower. Duty cycle is .8 and you have 4 injecors and the horsepower is what you want to run or how much horsepower you have now.
Lets say you want to run 250hp at the crank (do not use wheel horsepower) (250*.60)/(.8*4)=46.9lb/hr =490cc/min If you are going to run 250-260 the blacktop’s s15 480cc/min would work great.
You will only see an increase in power if you have tuned very conservatively (ie retarded timing) because you are running a little lean. But if you run bigger injectors you can now get more fuel to the cylinders, and retune the a/f mixture and ignition timing to get the most from your set up. If you are already on the rich side then bigger injectors will not help. If you plan on making more hp in the future then you will need bigger injectors.
Mike’s Si with Greddy Turbo – outside car