Anybody out there know what the M2 Stage 3 ECU fuel maps set the maximum duty cycle at? I've heard 85%, but I've also heard that it sprays the injectors "full open" after 13psi???????

Wanting to confirm with anyone who knows.

Quick fuel calculations show that with a stock fuel pressure of 37psi, BSFC 0.62, and 85% duty cycle, the max horsepower that the fuel system could support would be 288 RWHP. Now since M2 is very conservative in their nature, and their stage 3 kit is good for around 320rwhp, this doesn't sound right.

 

This is true no matter what ecu you are running. At 15psi, which is what some people (foolishly) run sometimes w/ the stock fuel system your at a full spray not a pulse on your injector. All it takes is a tiny piece of dirt or debris and your motor is done. But running 13psi, w/ all the bolt ones, you can get as much as 348rwhp. I did when I had stock twins and stock motor. Even if you don't invest in bigger secondary injectors, at the very least get an upgraded fuel pump.

 

I was one of those "foolish" people to run 15 psi at the track with the stock fuel system. It worked great, but I prayed to the rotary gods everytime I went down the track. Ernie is right. You want to upgrade your fuel system at anything over 12-13 psi. Brian (M2) told me a few years ago that my M2 ecu was setup to run at 90% duty cycle at 13 psi. He also strongly recommended I stick with the main cat.

 

The setup that I have is pushing the duty cycle a little bit. I'm hitting around 92% duty cycle and this is with an upgraded fuel pump. At 13psi I hit 100% duty cycle, which is extremely bad. Anyone that has the M2 stage 3 setup should definitely upgrade the injectors. It is not worth taking the chance on blowing your motor just for a simple mod.

 

this is my next hurdle...i am looking into injectors right now
my question is this. i have the pettit ecu. and dont want to sell it to buy the apexpfc. i dont think i have to right now. i wanted to go to the larger secondaries. BUT i dont know that it will work right with the ecu i have. actually i am 99% sure it wont. what i want to do is get the haltech f5 additional inj. controller and the greddy elbo fitted for the 2 inj's or just plumb them into the plenum. i aready have many injectors around. i think it should work just as good. i think i can use the stock 460's from a n/a and acuire 1310's between the 2. if this is not enough, i always have 2 550's(to get 1400's) and 2 850's(to get 1700's). the other part of this is that i am going to run these injectors with its own fuel system (dedicated line, pump, and filter) what are your opinions on this "route" for extra fuel? please let me know.

 

whatever....I've been running the totally stock fuel system with a midpipe and 13-14 psi and Pettit ECU for at least a year, and I drive WFO all the time...all the paranoia about an upgraded fuel pump/ injectors for a stock engine with stock turbos is just that, paranoia....I think people just love to blow cash on new parts just for this car just for the heck of it...the stock radiator works just fine as well, for the street

I may replace the fuel pump at 60k-80k with a Walbro just to be safe, but I've heard these 5,000 psi pumps can make the the engine run rich, so then again I may just go with a new stock pump

I am **** about keeping my relocated K&N fuel filter clean, I think quite a few engine failures are due to clogged stock POS filters and/or crap gas....the stock fuel filter is such a pain in the *** to change that nobody changes it, or not frequently enough

 

If you go with larger injectors, you are going to have to get your ECU repogrammed. If not, you are going to run like a super rich ****. The ECU will be running the same injector duty control on the larger injector.

Getting a larger pump is a big plus since it WILL ensure that the required fuel will be delivered.

 

if you have a pettit or m2 ecu. you can always put in bigger injectors and run a s-afc and tune it for the bigger secondaries

an upgraded fuel pump is cheap insurance. my car spiked to 15psi several times (when it ran) in cold weather on tear down of my engine i had ZERO signs the engine had ever detonated. apex seals still had in spec compression too bad i no longer had coolant or oil seals

 

Some of us don't like having 3 dozen little electronic boxes running in our car.....

 

apparently some do. i'm not one of them either

 

That's what I don't get. If you do your fuel calclutations, with only a 90% duty cycle, 37psi stock fuel pressure, and say a conservative 0.62 BSFC, you'll find that it's good for a max of 310rwhp. Now Brian at M2 being very conservative, would NOT sell a stage 3 kit with stage 3 ecu rated for 315rwhp, without having his stage 3 ecu and stock fuel sytem good for more than that. I'd have to guess that the M2 stage 3 should be supporting at least 330 rwhp in terms of fuel maps with stock fuel system, to be on the safe side of things.

 

anybody?