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Old 03-30-2010, 07:41 PM   #1
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Default Injector duty cyles -> Would like input

At 10.5 psi @11:1afr I'm seing 89% duty cycles which is getting a bit high. I suppose my stock fuel pump could also just be getting tired, but it seems like I should have more headroom than that using 450cc injectors...Any thoughts on whether or not inline resistors effect IDC %s?

What kind of duty cycles are other people seeing at similar boost levels?

Edit: after doing a quick search, I'm going to just assume that my fuel pump is eating **** and change it out for my 190 + re-wire it. I guess I was just being overly hopeful in my expectations for the sad old stocker.
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Old 03-30-2010, 07:59 PM   #2
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Yeah, fuel pump must be suckin' *****.

You're running a lot richer than I am, but I'm running another pound, and my duty cycles hardly get over 60%.
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Old 03-30-2010, 08:02 PM   #3
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Originally Posted by gospeed81 View Post
Yeah, fuel pump must be suckin' *****.

You're running a lot richer than I am, but I'm running another pound, and my duty cycles hardly get over 60%.
Thanks for the input. I'm heading to a dyno day on the 10th and I'd really like to turn this ****** up a little more and hit 250. I guess its going to be a late friday/early saturday for me next week :/
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Old 03-30-2010, 08:04 PM   #4
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Originally Posted by Jeff_Ciesielski View Post
Thanks for the input. I'm heading to a dyno day on the 10th and I'd really like to turn this ****** up a little more and hit 250. I guess its going to be a late friday/early saturday for me next week :/
Yeah, sorry, forgot details.

That was with RX7 460s, and 11.5-12psi on a little RHB5. Stock 1.6L

Now that I've got the 550s in my duty cycles are ridiculously low. Needs moar boostz.
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Old 03-30-2010, 08:06 PM   #5
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Originally Posted by gospeed81 View Post
Yeah, sorry, forgot details.

That was with RX7 460s, and 11.5-12psi on a little RHB5. Stock 1.6L

Now that I've got the 550s in my duty cycles are ridiculously low. Needs moar boostz.
Well, I'm using a *slightly* bigger turbo, but either way, shouldn't be hitting 98%. I should probably change my fuel filter as well, its been a while...
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Old 03-30-2010, 08:18 PM   #6
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11.5:1 afr
12psi
7000rpm
86% duty
460cc injectors
stock pump
1.8
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Old 03-30-2010, 08:23 PM   #7
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I must just have a bitch *** little turbo....
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Old 03-30-2010, 08:26 PM   #8
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Here's a 3rd gear pull from my car:



That's with a Walbro 190 and 465cc injectors. AFR was in the low 12s for most of it, and then dipped into the mid 11s there at the end. (Not sure what's up with that...)

As you can see, that's 198 kPa, which is 14.something PSI of boost. IAT peaked at 100F, from 69F ambient.
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