Injector Question: Some easier to tune than others?

[Goldfinger911]

I am almost done doing my AutoVE on my LS1 stroker. I am running SVO 30# injectors.

I was wondering, since I see several posts here and on LS1Tech.com asking how to make 30# SVO's idle or decel better....

Are there other injectors, larger even, that seem to easier to tune on an LS1? Or, do things get harder the larger the injector, period?

Just curious is anyone has gone up in injector size and found tuning easier, or the engine run smoother.

THanks guys and girls.

-GF

[vatman02]

i had 60's and 42's and i had the same issue with both. just a little worse for the 60's. when i would let off the gas peddle they just start dumping fuel. i found a post stating because these injectors are more efficient you need to adjust/reduce the (injector pulde width voltage) table {B3701} by 12% for the 42's. i had been fighting it so long that i sold the 60's for half price for the 42's, in an attempt to solve the problem, to no avail. now it turns out i need the 60's or bigger. but changing this table fixed the decel problem of running rich ie.. 10:1 give it a try it may work. if not put it back and try something else. good luck :cheers:

edit: 30's seem a bit small for a stroker. i started with just heads and cam and was seeing injector duty cycles over 100% on the stockers. 85% is the max you should go. you should probably go with 42's, IMO

[mr.prick]

are you matching you IFR table to your fuel pressure?
i had mine set for 60PSI and for some strange reason
i ended up with 70PSI and that threw thing way off.
check your pressure at the rail.

[dfe1]

I got a set of 36-pounders from Cody Motorsports, adjusted the IFR table and had absolutely no problems. Keep in mind that the flow of most injectors is rated at a pressure of 3 bar (43.5 psi) and LS systems run at 4 bar (58 psi) so the injector flow table has to be changed accordingly. That is, a 36-pound injector rated at 3-bar converters to a flow of 41.5+/- pounds per hour at 4-bar. For what it's worth, I found that the conversion formulas floating around aren't as accurate as you might think. When I took the numbers generated by the formula and plugged them into the IFR table, AFRs were off across the board. I altered the flow rate data and that corrected the problem.

[Goldfinger911]

Cool, thanks guys. Good info.
I dont seem to be running out of fuel and never hit more than 85-88% duty cycle. I run 62psi of fuel pressure. The car put 497hp/452tq to the rear wheels on motor at Cartek, and that was with a shitty tune. The tune is getting better and better every day so we'll see what she'll do now.

If I go bigger, 42's will definitely be inline next.

[eboggs_jkvl]

Cool, thanks guys. Good info.
I dont seem to be running out of fuel and never hit more than 85-88% duty cycle. I run 62psi of fuel pressure. The car put 497hp/452tq to the rear wheels on motor at Cartek, and that was with a shitty tune. The tune is getting better and better every day so we'll see what she'll do now.

If I go bigger, 42's will definitely be inline next.


That RWHP will kill the 42s, you might need 60s. My 42s went 100% around 460 RWHP.

Use this to size: http://www.rceng.com/technical.htm

My $.02

Elmer

[Goldfinger911]

42# injectors ran out of fuel at 460whp? Something is wrong there.

Even with the RCEng calc, which is very conservative, my 30lb injectors, which at 58psi of pressure are between 36 and 37#, are enough for 548 crank hp at 80% duty. Increase the fuel pressure to 62 psi like mine and the results are right in line.