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Thread: Injector Duty Cycle Analyzing..Help Requested

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Posts: 1-10 of 10
2011-05-08 02:04:18
#1
Injector Duty Cycle Analyzing..Help Requested
Hey,

So, I decided it was time to up the boost to 17psi but I took Consult along w/me so I can catch my injector duty cycles because I knew I was getting close to maxing out my injectors.

What I saw at 17psi was 92% duty cycle at 7265RPM(highest I took the car).

My question is, how high should you take the duty cycle of the injectors before it starts to get a little dangerous. I know I should allow room for overboosting but how high can you take it and what's considered safe?

I also adjusted my fuel pressure down a few psi because the JWT tune was running a little too rich for me. I see about 11.5 A/F now w/my adjustments.

Any advice/help would be appreciated.

Set up is:

W10 DET
S4 Cams
STI Injectors @ 4 bar (520cc)
JWT ECU
Z32 MAF
GT2871R

Thanks!
-G
Last edited by gomba on 2011-05-08 at 02-18-55.
2011-05-08 05:40:42
#2
on a turbo car you should not exceed 80-85% even though i my self have been up to 90% or a little more. Depending on the injector they will start to go static in the high 90% range but to be safe keep it under 90
2011-05-08 05:49:27
#3
I've always heard and followed the 80% rule too.

How much power do you think you were making? STI's at 3 bar, 520ish cc, are good for 350whp. You are running them at 4 bar, that's close to 600cc (just a quick estimate), which is 400whp.

Referance
2011-05-08 06:08:12
#4
Originally Posted by Vadim
I've always heard and followed the 80% rule too.

How much power do you think you were making? STI's at 3 bar, 520ish cc, are good for 350whp. You are running them at 4 bar, that's close to 600cc (just a quick estimate), which is 400whp.

Referance


I have no idea. I want to get the car dyno'd. I'd guess around 350whp based on other setups.

Well, I don't really want to get a retune and new injectors so 17psi may be it for me :/ I guess no crazy race-gas 22psi runs for me lol The stock bottom end would probably blow up anyways

-G
Last edited by gomba on 2011-05-08 at 06-18-36.
2011-05-08 14:23:45
#5
I have a very similar setup det/2871R/Z32 maf I'm getting ready to buy S4's and I will need to run 4 bar at that point. I'm running nistune though, is there a way I could run your map since its for jwt instead of a bin like nistune or are they both bin's?? I'm still reading/learning about nistune.
2011-05-15 04:49:26
#6
bump, any other advice/thoughts?
2011-05-15 04:59:16
#7
It's always been said you're on borrowed time anywhere above 80% duty cycle. Above that and you're really dealing with a lot of heat. If you keep the bursts to redline few and far between then 90% might not be the end of the world.

Some serious business OEM's run their injectors at 100% from the factory, but they are built to handle the heat. Subaru is not one of those manufacturers. =]
2011-05-15 05:44:20
#8
Originally Posted by BenFenner
It's always been said you're on borrowed time anywhere above 80% duty cycle. Above that and you're really dealing with a lot of heat. If you keep the bursts to redline few and far between then 90% might not be the end of the world.

Some serious business OEM's run their injectors at 100% from the factory, but they are built to handle the heat. Subaru is not one of those manufacturers. =]


Ya, I wish I realized this before I settled on the STI injectors. I wanted an injector that would take me to 400whp, but at the time I didn't realize that's at 100% and wouldn't make much sense lol Looking back on it I should have went with 740's from the start..oh well :/

-G
2011-05-19 14:11:56
#9
@ I fastR: why do you say you'll need 4 bar once you acquire cams?
2011-05-20 06:40:21
#10
Originally Posted by 93specv
@ I fastR: why do you say you'll need 4 bar once you acquire cams?


at 3 bar with my mods I'll be running out of injector with the addition of cams....
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