At what HP rating is our stock injectors maxxed out at i looked at a calculator deal and it said 24# injectors are only good to 334 hp does that sound right???i had did a search and could not find a definate answer

 

The online calculators are a bit conservative. They typically use a brake specific fuel consumption (BSFC) of 0.500 #/HR/HP. And they limit injector duty cycle to 80%.

Actual BSFC should be below 0.48 on a factory tune, and you could push them to 90% DC. That would tell you the stockers (actually programmed at 24.89 #/HR in the PCM) are good for 373 flywheel HP. Put a really good tune on it (0.46), and run them to 100% DC (not recommended) and you could argue that they should support as much as 433 flywheel HP. There are people here who have done that.

All of the above assumes you are running the injectors at the stock 43.5psi.

 

Roughly what they can do at 85% DC and .47 BSFC. It's basically what Injuneer just said.

http://www.geocities.com/scwizzo/graph.jpg

 

Well maybe im in trouble then because i did a datalog when i was on the dyno and it peaked at 103% DC my A/F ratio was a tad rich do you think "Injuneer" that im getting injector lockup it was 103% DC @5900 rpm then the power dropped off substantially i have a 355 P&P heads 11:1 CR and a CC503 i threw down 350 RWHP and 334 RWTQ through an M6 i thought the #'s were a little low and i am running 43.5 psi of fuel pressure

 

What software are you using? I've seen some sort of irrational numbers come out of TTS DataMaster for "BPW", which is what the program uses to calculate the duty cycle.

Screwing around with more numbers, your 350rwHP works out to about 405-410 flyweel. That would certainly tax the stock injectors if you were running 0.48- 0.50 BSFC. Are you running a dyno tune or a mail-order tune?

As the injectors approach 100% DC, the flow capacity can drop and the spray pattern becomes erratic. You may be throwing enough fuel in, or you may not. But if its not spraying properly, its not likely you will make as much power as you could with the correct injectors size.

A couple of things that need to be clarified....

Even though your dyno results show 350 rwHP, your engine may not have actually made that much power on the dyno. If you ran under conditions like high air temps, low barometer, high altitude or high humidity, your dyno "correction factor" can get pretty large. Let's say the correction factor was 1.05.... that means your actual HP on the dyno was only 333rwHP. You may not even have pushed the injectors to 350rwHP. And if you run on a day with mineshaft conditions - cold, dry air and a high barometer - you will make way more than 350rwHP..... think about the risk of running an injector that is too small.

Then there is the issue of how long during a simple dyno pull that the engine is actually at peak fuel demand..... it might be less than 1 second. Injectors might be able to approach 100% DC without immediate problems, but if you tried to hold it at peak HP for a longer period of time, the injector might become unstable.

 

Yes it was TTS datamaster another thing is i was getting 4-7 degrees of retard with no knock counts i was just reading the tech write ups you wrote lots of good info havent finished yet to try to determine where my retard is coming from and yes it is an E-mail tune thanks Injuneer!!And i might as well upgrade my stock injectors


And as far as if they corrected the dyno #'s or not i dont know