How much boost on stock 1.8 injectors??? - Miata Turbo Forum - Boost cars, acquire cats.

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Old 10-01-2007, 10:05 PM   #1
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Default How much boost on stock 1.8 injectors???

So as you may know I have been having many problems with my low z injectors and have a track day on wednesday, leaving tomorrow. How much boost can I run if I put the stock 1.8l injectors back in, SAFELY???
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Old 10-01-2007, 10:50 PM   #2
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the '94 stock injectors?
Probably around 5 psi on most turbos. I run 7 on mine but they're the bigger 1.8 being a '99. We're also using the same turbo. .80 A/R compressor?
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Old 10-01-2007, 11:33 PM   #3
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I was running 7psi on my 305s and seeing 100% DC.
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Old 10-02-2007, 12:46 AM   #4
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How could I limit the boost to 4-5psi without cutting the engine spark/fuel with the MegaSquirt? I need to be able to rev it up with the 5 psi?
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Old 10-02-2007, 01:30 AM   #5
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Looks like i'm seeing about 55% at ~6psi or 145 kpa. No idea if this is an accurate reading for the injectors though.
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Old 10-02-2007, 03:00 AM   #6
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Kyle, what time are you leaving tomorrow? I know a couple of people who may have some spare injectors that will work. No guarantees.

Edit: Found you a set of 680cc PnPs in Los Gatos. Let me know if you want them. It won't idle great, but they will work.

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Old 10-02-2007, 04:12 AM   #7
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Yeah, if I can run them then I will definately go get them. I am trying to leave at 3 or 4, getting off work at 1:30 or 2pm. Please call me or email ASAP to let me know how to get them. Thanks!!
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Old 10-02-2007, 04:46 AM   #8
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Another option is to use a rising rate fpr. When I first hooked up megasquirt and had not picked up 550cc injectors yet, i ran the 1.6 injectors with an aux. fpr around 5-7psi. I had some trouble getting consistant AFRs, but I think that had much to do with my ineptitude with megasquirt at that point (its still a learning experience at this point) rather than mechanical FPR though. 305cc injectors at 60-70psi may get you to 10 to 12psi ... just a thought, and they would idle a bit better as well.
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Old 10-02-2007, 09:56 AM   #9
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nothing wrong with an fmu and MS with smaller injectors....you'd just want to swap them out eventually.
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Old 10-02-2007, 09:59 AM   #10
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Ok, thanks for the good ideas....I think I am going to run the 680's and see what happens
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Old 10-02-2007, 10:01 AM   #11
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about 400hp is what's going to happen
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Old 10-02-2007, 11:24 PM   #12
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Looks like I lied. Something weird about that datalog for some reason. Here is one from today. Considering it's saying 110% dutycycle i'm thinking they're maxed out.
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Old 10-02-2007, 11:38 PM   #13
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you're done at 7.5 psi it looks like. but you're also running 11.2:1 at 7.5 psi, so you could stand to trim some fuel back which will lower duty cycle
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Old 10-04-2007, 02:38 PM   #14
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heh, yeah, i hit 111% the other night with mine around 7psi. i don't quite get how that's even possible...

same deal, though, pig rich at that point...
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