I did some searching and didn't really come to a conclusion on what size injector I should run. The car makes roughly 380rwhp (might go up some when I get it tweaked on a dyno), it is a M6 so I figured it is rougly making 440fwhp or so. I'm going to purchase the delphi injectors from racetronix but should I use 32lb or 36lb? I really have no future plans to upgrade the motor. If I need a horsepower fix I would probably install a wet nitrous kit.

 

Go with the 36 lb injectors. If you ever plan on changing things, you will be covered. I always said that I was finished when I completed a project. Guess what... I was upgrading cams or heads a year later. You can always buy bigger and tune down. To go smaller and have to buy larger injectors later would be rediculous. Plan for the future even if you think you're finished now. Most likely you won't be...

I would suggest the Ford SVO injectors, I have had a ton of success with those compared to delphi and I believe they are less money; not sure about that though...

 

36lb is where I was leaning but was concerned about having too much injector. The SVO and racetronix are similar in pricing. Just looking for the best injector.

 

Considering that the stock injectors are good for upwards of 400 rwhp, if you're only at 380rwhp, the 24# SVO is all you need. 30# if you plan on doing anything else.

Mike

 

I had the SVO 30# injectors in my 95 Z, and did 425 at the wheels with absolutly no problems what so ever. 30# injectors will also support more than I put down. As long as the tune is sound, and everything is where it should be, you shouldn't need more than that for the HP range you are looking at.

 

I think the SVO 30#'s are a little underated too. That should be plenty for your setup and any tweaks you plan on doing.

Benji

 

Too big = no problem
Too small = problems

You want to keep the injectors under 80% duty cycle.
As they reach 90%, the spray pattern gets all scrwed up.

 

Here's a worksheet to figure sizing.

http://www.rceng.com/technical.htm#WORKSHEET

I would go with the 36#.

 

Also, I used the 30# SVO injectors on my 471rwhp heads/cam Vette with room to spare.

 

Not true to a certain degree. Ex., you can have 60# injectors on a bolt on car, and even have it tuned, but it will never run as good as a smaller injector which would be more appropriate for the bolt on application. You want a correct size for the application, not just go big and think you'll be all set with no problems.

 

What effect does running a higher fuel pressure do to the injector? Is it always best to run it at it's rated number? It seems like everyone who has posted is using SVO injectors, has anybody compared them to the racetronix delphi injectors?

 

I have heard that 42# injectors is where idle issues come into play, but if you don't need larger the 42#, a little larger then you think will be fine(36# instead of 30#)


as for fuel pressure, increasing it will increase the flow, but most injectors, after a certian pressure, will "lock", open or closed, so, it is a fix, lots of people are doing it, but there are times where larger injectors are needed, and FP will not help

 

IMHO, 30# are plenty. They can be tuned to handle more horsepower than he plans on putting down. Running the nitrous has nothing to do with the injectors, since he plans on using a wet kit. If you are still worried, go with the 36# injectors. You'll be fine with either. The 36#'ers are a little more expensive.

Benji

 

Again, for the power you are looking for, and if you are going to do a wet Nitrous system, the 30# SVO's are going to work the best for you. Comparisons have been made only by preference, and it is a general consensus that the SVO's are a great injector. As for going for a bigger injector size again, yes you can do it, however your OPTIMAL performance will be from getting the appropriate size for your application. Bigger is not necissarily always the best way to go. You don't want to go too small either, YOU WANT THE RIGHT SIZE!

 

30# injectors are fine given the current power level.