I have a turbo 420a and am trying to figure out what size injectors to get along with what type and size to get. I am using SFMU and was reading about several people using 440's? What size would you guys recommend and what brand should i go with? Also where should i get them? Thanks...Jeff

RC Engineering 440cc injectors are the largest you can run with the SFMU and the 420a motor.

Check Ebay...

2016 WRX STi Limited (current)
2001 A4 1.8tqms (donated)
1991 GVR4 #1933 (sold)
old.dsmregistry.com/detail.php?carid=218 (dismantled)

Blue/black top 450cc (off turbo 4g63's) are the largest w/ a SFMU only. I know, that's what I use, and they only me cost $40 off eBay.

Joel Baldridge, ASE Certified Master Technician, Audi Certified Expert Technician

I just installed bosch(mustang) injectors on mine and I'm having trouble tuning with them. I'm using ONLY SFMU. I want to run 15psi for now until I get an ignition. My bleed valve will be here thursday(the day i'm leaving for the shootout w 0 0 t!) but it looks like 2.72 + dark spring + bleed valve will be perfect. Right now I've got my idle pressure at 20psi(lowest i can get it with sfmu) which runs rich at idle -25 LTFT, STFT is not maxed tho. With the 2.72 disc I was getting around 55~60psi @ 10psi of boost. I was getting .94~.98 o2 readings and EGTs were topping out at 1475ish (too low?). With the next smallest disc I was getting 45~50psi @ 10psi, that gave me .90~.94 o2 readings and high egts(over 1575). Any suggestions? For now I'm going to keep in the 2nd smallest disc. I know stock o2 sensor isnt much to tune by, but what are unsafe numbers?

I do have an SAFC II also on my car but with the stock injectors that are on it now I've left it zero'd out and been depending on the SFMU mostly. RC Engineering 440's will work with my stock fuel rail right? Thanks guys...I appreciate the help.

Also, Any of you guys know of a good website that I can order RC injectors from? Basically the same as Delphi or what? Also, how many lbs. are 440's? As in 42lb. or 38lb. or what? Thanks

I forgot to mention the bosch injectors I just installed are 440cc/m. Anyway I decided to go back to the 2.72" disc for now just to be safe.

So RC's and Bosch's will both work with the stock fuel rail or what?....Thanks

Well if you're motor is not built with forged parts, you will be just fine with the stock fuel system + sfmu. Yes the bosch injectors work as well as Accel/RC. No need for AFC or bigger injectors really. I have a set Accel 335cc/m injectors if you want them tho. They are definetally better than stock, but not necessary. $75 shipped for the injectors if you want them.

hmm....I might do that....how long did you use the injectors? Also, how can I get in contact with you?...thanks

I used them for about 10,000miles. They're still in great working and visual condition.