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Hello all.. in the old days of adding a carb intake and cam you would always jet up the carb.... well in my eng swap ive added a VS cam had the heads ported a bit will have custom exhaust headers, run a 3.25/3.1 pulley and also ported the throttle body. I got a good deal on some #42.5 injectors, with these mods will I need them now or wait and make some runs on the new engine and see what the duty cycle of the injecors... what is max value they should be before I should consider them full open and need bigger injectors to slow down the duty cycle???
 

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With a third gen M90 supercharger, stock L67 injectors (36.5 pounds/hour) are usually maxed out right around the 3.0" supercharger pulley size.

With a fifth gen M90 supercharger, stock L67 injectors (36.5 pounds/hour) are usually maxed out right around the 3.2" supercharger pulley size.

And with a fifth gen M90 supercharger, stock L32 injectors (31.0 pounds/hour) are usually maxed out right around the 3.4" supercharger pulley size.

It seems strange that the L32-powered cars come stock with blowers that make two more pounds of boost and injectors that flow 15% less, but it's true.

The above numbers are guidelines only, and depend on many factors like air/fuel ratio, belt slippage, altitude, engine speed, etc.
 

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I scan with a LS1M and can see IPW's.

I have heard that the stock injectors are getting close to being maxed out at somewhere between 20-22, depending on who you're asking.

FWIW, with a 3.4, DHP, SLP's, and a custom Ported/Pollished gen3 SC, I am seeing a max of about 19 on the IPWs with 16-17 degrees timming... thats at around 100 mph.

I can go to a 3.1 pulley and 18 deg timming, but only when I use my alky injection (extra fuel). :D

I would guess that you will be very close to maxing out your injectors when you get in the higher mph/rpm.
 

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firemangtp said:
I have heard that the stock injectors are getting close to being maxed out at somewhere between 20-22, depending on who you're asking.
Mine seemed to max out at 21ish. They never went static but my KR increased in the upper RPM's as the car went lean due to not enough fuel.

firemangtp said:
I can go to a 3.1 pulley and 18 deg timming, but only when I use my alky injection (extra fuel). :D
Recent Dyno testing has shown that while alcohol/water injection may eliminate KR it seems to produce less HP then without it. My theory is that the water/alcohol is displacing the fuel providing less power and the reason KR drops is because their isnt as much volatile gas in the cylinder to be touched off by hotspots.
 

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I have heard that the stock injectors are getting close to being maxed out at somewhere between 20-22, depending on who you're asking.
Dan, no flame intended towards you at all, but I see this statement all the time and it drives me nuts. Stop listening to the wrong people. ;) Going static depends on your RPMs, and not when your IPW reaches a constant value.

Your injectors are static when your actual* IPW = 120/RPM. For example, if your motor was spinning at 6000 RPM, and your IPW was 20 ms, you would be static. If your RPMs were 6500 and your IPW was 18.5 ms, etc.

* - Please note that I used the word actual. OBDII scan tools report commanded IPW. Once you go static, you may see that the IPW as reported by your scan tool may exceed the static value for that particular RPM. Obviously that cannot be since your injectors can't possibly stay open longer than 100% of the time. That's just reported that way for simplicity as the PCM is attempting to get more fuel. When the reported value is greater than the calculated static value, just know that you're already static and it's a sign that your PCM is calling for more fuel.

John
 

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Great info John. Its quite possible my injectors were static then. My assumption was that as long as the IPW's were changing then they weren't static.

See, isnt this site great, you learn stuff all the time... :)
 

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That is definitely not true Todd. The reported IPW value will always vary. I remember one time last year when I had a fueling problem, I saw my reported IPW go from 22 to 24 to 28 to 35 to 42 all the way to about 50 until I lifted off. Yikes!

John
 

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With a third gen M90 supercharger, stock L67 injectors (36.5 pounds/hour) are usually maxed out right around the 3.0" supercharger pulley size.

With a fifth gen M90 supercharger, stock L67 injectors (36.5 pounds/hour) are usually maxed out right around the 3.2" supercharger pulley size.

And with a fifth gen M90 supercharger, stock L32 injectors (31.0 pounds/hour) are usually maxed out right around the 3.4" supercharger pulley size.

It seems strange that the L32-powered cars come stock with blowers that make two more pounds of boost and injectors that flow 15% less, but it's true.

The above numbers are guidelines only, and depend on many factors like air/fuel ratio, belt slippage, altitude, engine speed, etc.
I wish you guys and other vendors would start directing the 04+ owners to start with a 3.5 pulley instead of a 3.4.

I got a good deal on some #42.5 injectors
Yeah, I was way static with those, 25ms at 6K rpms.
I think I would still be static if I used the 3.0 pulley on the 60lb injectors.
 

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I think I would still be static if I used the 3.0 pulley on the 60lb injectors.
Not a chance. We're still running those same injectors in our Bad SSEi and Turbo Car, and neither is static (yet). These 60 pounders are incredible!
 

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johnt said:
Dan, no flame intended towards you at all, but I see this statement all the time and it drives me nuts. Stop listening to the wrong people. ;) Going static depends on your RPMs, and not when your IPW reaches a constant value.

Your injectors are static when your actual* IPW = 120/RPM. For example, if your motor was spinning at 6000 RPM, and your IPW was 20 ms, you would be static. If your RPMs were 6500 and your IPW was 18.5 ms, etc.

* - Please note that I used the word actual. OBDII scan tools report commanded IPW. Once you go static, you may see that the IPW as reported by your scan tool may exceed the static value for that particular RPM. Obviously that cannot be since your injectors can't possibly stay open longer than 100% of the time. That's just reported that way for simplicity as the PCM is attempting to get more fuel. When the reported value is greater than the calculated static value, just know that you're already static and it's a sign that your PCM is calling for more fuel.

John
Great info John, thanks for the heads up :)
Thats why I said, "ive heard", I was kinda confussed about it myself, but you definatly cleared it up. :D
 

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I just changed to the 42.5 injectors. Obviously now im running pig rich. Im using the HP tuner suite to lean it out. (gotta make sure i don'tgo too far or boom) anyone out there with the same?
 

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Chris,

How are you planning on changing it? If you're not overrunning your MAF table, you should probably just increase your IFR by a fixed percentage until your LTFTs look good. Start by multiplying it by 1.15 as a start and work from there. Once you get your LTFTs low, if you find that your LTFTs are varying by too much then you'll need to change the slope somewhat.

John
 

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today we ran at Byron Ill with the Chicago grand prix club. I set PB after PB. Im currently running [email protected] with a 1.903 60'!!!!!!!!! We really got to use the HP tuner suite today. Anyone thinking about this for any application I would higly recommend it. One of the things we did to tune for the injectors was the flow rate vs KPA table. worked great. took a few times, but we got the LTFT very close to where we want them. However we saw some good know throughout the whole run. (going to up 5* at one point) so thats the next step, but were not worried, were just getting started.
 

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Recent Dyno testing has shown that while alcohol/water injection may eliminate KR it seems to produce less HP then without it. My theory is that the water/alcohol is displacing the fuel providing less power and the reason KR drops is because their isnt as much volatile gas in the cylinder to be touched off by hotspots
Gee, i wonder how much power and how fast i'd be if i didn't use water injection??? :eek: I think it's faster on 93 + w/i vs straight 110 race fuel
 

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so my IPW of 18.64 at 6237 RPM is pretty much static and I should go for a new injector? Im only running a 3.25 pulley and seeing those numbers on an 02.
 
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