Coach62

I currently put out 420 RWHP, getting ready to replace the heads, cam and intake, will probably put out in the 470-480 RWHP after these mods.

I'm figuring about 45lb injectors by my math,sound about right?

Lothar34

What injectors do you have now and what's your duty cycle?

And you may want to consider a higher-capacity fuel pump when you upgrade.

Coach62

I believe they're stock, but I plan on checking. I figured these injectors at 80% duty cycle.

the guy I bought the car from had almost no information on it. He bought it and it sat in his garage, the previous owner to him did all the mods.

Lothar34

Are you doing the tuning or is someone else doing it?

Last C5

42 lb matched flow injectors are going to work fine, and I agree with the other post that you may need to upgrade your fuel pump. Lingenfelter has an intank upgrade that works well.

Vicarious.

42lb Bosch / Ford green injectors are actually 48lb or so when used on an LS engine.

tblu92

LS injectors are rated at 4 bar ( 54 PSI) however most aftermarket injectors and most other stock injectors are rated at 3 bar ( 43 PSI) make sure you address this correctly
As an example a popular mod is to install FORD 30 lb injectors on an LS engine--These are rated at 3 bar --so on a LS application they are actually apprx. 34 lb !!!
Here is a great site with multiple injector calculations---
It uses BRAKE HP rather than RWHP which would make your engine (after mods) with a 6 speed apprx 540 brake HP
Chart shows to get 80% duty cylcles you would need only approx 38 lb injectors rated at 3 bar in order to end up with the desired 42 lbs
Running injectors that are larger then needed---does NOT make more HP !!!
Also too large of an injector will most always create idle/issues--surging/dying etc.
This can be fixed with tuning somewhat but the injector rate is so large the ECM can't command a small enough pulse -that's where the problems arise from--

http://www.witchhunter.com/injectorcalc1.php4

Coach62

Thanks, all good info.

Someone else is doing the tuning.

I know I'll have to do something with the fuel pump, I was thinking a boost a pump, but I'll look into the lingenfelter. I was going to buy one of their 2 stage launch controllers anyway.

I noticed that about the aftermarket injectors being rated at 3 bar. I'm aware that going too large with the injectors causes driveability issues, but too small causes short life and potentially running lean. I'm guessing just a few lbs oversized is ok - example would be 42lb injectors when the calculation shows 38lb. Or 45lb vs 42lb. I'm not off base here, am I?

Coach62

I see a good deal on a set of those - stupid question, is there any adapter or anything that has to be used with those - like the wiring harness or clips?

tlove32

They are a direct fit. I used them when I was NA at 460rwhp

Last C5

I'm using them now and I am NA at 460 rwhp. I also had to go to the Lingenfelter pump upgrade.

Vicarious.

Look into FAST 36# injectors....the sets I've seen online are white plastic bosch, and are rated 36lb @ 43psi ...which will be closest to your target number.

Otherwise use the bosch green injectors, they are 48lb injectors.

Coach62

There is a REALLY good deal on the Bosch 48 lb injectors on one site I found, they're rebuilt, but really cheap.

So a boost a pump isn't a good alternative?

tblu92

Cheapest and best way to get larger injectors is to send YOURS off to someone who can port the nozzles with a C&C machine--Usually costs around $150 and you know you won't have any fitment issues cause you are usuing your same ones !!--I know a great company that I have used in the past to do them if interested---

crainholio

I have a set of Ford/SVO red 30# (34# at 58psi) flow-matched injectors from New Era Performance just removed to go back to stock, PM if interested.

WKMCD

FWIW: I ran Ford Red Tops with my 460RWHP build and they had some room left and were easy to tune.

Coach62

Modifying mine is a great idea, but I'll probably go back to stock some day (like you are) so that's not a great option.

As far as the Ford, thanks but I think I'll probably need a bit bigger.

WKMCD, you ran 34 lb injectors with 460 WHP? that seems small by the tables. I believe you of course, but according to the math that just doesn't work out. What am I missing????

WKMCD

I run Ford Green Tops in my 577RWHP 427. Still good.

Here's a good site.

http://www.rceng.com/technical.aspx

nyelectrify

If those red tops are available IDE be interested in them. I'm putting on a ls6 intake soon and would like to upgrade to the red tops