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Old 04-24-2011, 08:11 AM   #1
87hilux7mge
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Default High or Low impedance injectors?

aight so i need a lil advice. i have been doing TONS of research on injectors recently, cuz i have a few options for my application.

it will begin as an N/A 7mge, bored .50mm over, balance rotating assembly using N/A pistons, HKS 1.2mm MHG, street ported/polished cylinder head with polished valves, stock cams, adjustable cam gears, 9.48:1 compression, full header and 2.5 inch exhaust with some sort of muffler, all running off Megasquirt 2 v3.0, map based.

then after the motor is broken in properly, i will be aquiring parts for a supercharger addition, particularly an eaton m90, ported, polished and rebuilt. i will run through a FMIC, and also be running water/methanol injection (found a company that makes an adapter if anyones wondering how), probably around 5-7psi max.

i have 3 sets of injectors right now: stock GE injectors (too small for the boost probably), LS1 style 36#lb hr injectors from the S/C motor, or a set of flow-matched 440cc GTE injectors. the GE and GTE injectors are LOW impedance, and the LS1 style injectors are HIGH impedance.

so, for my application, what would you all do? use stock GE injectors, then swap in the higher flowing ones when i S/C, or just throw in the higher flowing ones? at that point, would you go high, or low impedance?

after reading, id say high impedance are the "less efficient" in terms of power consumption and possibility of slower pintle opening and response time, but they also create less heat and dont require a resistor pack. low impedance would be great, but they need a resistor pack. i should be able to over come this since ill be running MS, but i have yet to call the MS guys and confirm, so im looking for a lil bit of feedback.

LEMME KNOW!
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Old 04-24-2011, 09:01 AM   #2
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I haven't set up a MS system myself yet, but I do know low impedance will work just fine. My personal preference is low impedance for the reasons you list and quite simply because in the circles I work within they're easier to come by. The resistor pack is not a big deal at all and isn't anything which would affect my choice.

You're not going to need any larger than stock GTE injectors either... Could buy a set with a couple extra get them all serviced and blue printed and have a set of matched injectors for a lot less than new if you're looking for reliable but inexpensive.

I hope you're at least using NEW and moly coated pistons if you're using cast, GE spec pistons.... I've see a large number of pelted 7M-GE pistons all based on the whole "I'll only be running Xpsi". I happen to have one sitting on my desk which was ONLY running 8psi on a very well tuned engine. Water/methanol injection will help a little, but it has it's downsides too...
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Old 04-24-2011, 09:32 AM   #3
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Default

good news on the injectors then, ill use that flowmatched set of gte's. hes only put about 2k on them, and has all the paperwork from them. traded him a trick fuel rail for them so im not actually out any money.

as for the pistons, they are stock type cast, i had them teflon coated just the other day, pulled the block back apart to do it, but they all went back in just fine as well. so hopefully that will help a lil. i had it done by a buddy of mine and they all looked really good. unfortunately i didnt get any pics! fail..

i plan on building a boost ready block with forged pistons while i have the truck runnin so im not terribly worried about this lasting like 100k miles. prolly be lucky to get 5k out of it with a good tune and low boost. but as soon as the boost spec engine goes in, that boost will prolly be cranked to about 14-15 if the m90 can handle it. ill also use the time to get a transmission sourced for it cuz that w56 is gonna self destruct for sure.

out of curiosity what are the disadvantages to water/meth injection?
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