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85 Fuel and Turbo Upgrade


mrvwbug
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I want to go down the road to an upgrade upgrade my stock 1985.5 injectors. I want more fuel to justify a little bigger turbo. I want to shelve my rare original parts and go with something will a little extra performance. What size injectors to support a BIG 16g or a 17C turbo. Please advise or give me your thoughts! Thanks-Jim
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Unless I'm badly mistaken, your 85.5 should have plain 'ol 850cc injectors. Nothing rare about them. Came in all 84-86 cars prior to Mitsu going primary/secondary route in late 86. I run the dual 850's in a couple of my cars and actually prefer them to the later primary/secondary configuration. 850x2 is more fuel than 550+1050 too. You have the best Mitsu TBI injectors for a bigger turbo (unless you decided to run dual secondaries at 1050 each and a Translator or other piggyback...and not an easy wiring job in an 85.5).

 

Plenty of guys running dual 850's with pretty much all the Mitsu turbos. Problem with your 85.5 (if you want to retain stock TBI) is wiring in a MAF Translator, SAFC, etc for fuel control. I'm sure someone has figured out how, but I never had much luck. Just went straight to Megasquirt and called it a day. My Raider is running MS with dual 850's currently (but still on a 12a). I can't recall a percentage off the top of my head, but back in the day I was pushing dual 850's hard with a Super16g and Megasquirt and my duty cycles never got into a "dangerzone"...IE stayed under 90%. That car runs a pretty decent Garrett turbo now and as far as I know still off dual 850's.

Edited by jonboyb
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And I almost forgot....my 84 flatty has a non-intercooled turbo still but with a 16G wheel and it's running a BONE STOCK setup with 850's at 7psi. However, it will hit fuel cut if you hammer the throttle too fast (need a BCC to overcome that). Previous owner let a speed shop talk him into rebuilding the non-IC 12a into a 16g....not a good idea but it is what it is. At 7 psi, not a big deal. Runs acceptable AFR's and plugs always look good. Edited by jonboyb
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O.K. Gents Thank you for the guidance as always. So can I go to a big 16g for a little more pep in my step? I am going with a stage 2 clutch, I've gutted the precat (probably need a true DP) and put on a perf. magnoflow muffler and a hot coil. I have those "J" injectors sorry I was mistaken I thought they were hard to come by?

 

ANyhoo what's next? I want about 220-250 hp? I love the reliability so I don't want to trade this in. Please let me know.

 

Thank you.

 

Jim

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Gotta have a way to know your AFR's and a way to control your fuel. To get to your 220-250 hp range (wheel) with a S16g, you will need to up your fuel trim under boost. Unless someone has determined a way to install a MAFT in a pre-87 car (very likely someone has....been a long time since I watched those threads), a piggyback like an SAFC is needed if you want to keep your stock wiring and ecu. Or you could always go standalone :D
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I know I have run my HX35W up to 15psi on two "J" injectors with safe AFRs. One thing my car has a problem with is wanting to run off the MAP system instead of the MAFT. I had to unplug the MAP box on the firewall to get the car to run on the MAFT and allow me to tune the fuel curve.
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i've tried every way to make a 85.5 (aka 86 ) set up run fast without having headaches. why d*** around with the mitsu BS ? been there done that til i opened my eyes and contacted Scott for a MS set up. keep all of your 85.5 stuff BUT go MS and run two secondary injectors or 1000cc delphi's and get a wide band. Scott can utilize boost control, fan relay's, etc. in the ecu and if you ever ( you won't :lol: ) want to go back to stock you can with ease. also get a real exhaust system 3" from the turbo back with a hooker aero chamber, you will be VERY happy with how it runs and sounds ;) jmo -_-

...but what the hellz do i know, i have a V8 :P

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