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Can you run injectors that are to large?

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Old 05-19-14, 01:28 PM   #1
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Default Can you run injectors that are to large?

Can you run injectors that are to large for your application?

Lets say this... this summer im looking for ~350-400 hp on 93 oct. That would tell me I would need 550cc injectors or so.

But this upcoming winter, I plan on doing a e85 build, which would require 1200cc injectors.

Would their be a downfall to just getting the 1200cc injectors now?
Would it cause the gas to overheat?
Would it cause the car to run rich?
Would it be difficult to tune idle?

Any insights would be helpful. Tried googling but couldn't find anything useful.
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Old 05-19-14, 01:41 PM   #2
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it will not cause any difference to gas temperature, it will only run rich if you don't tune for injector size, but for regular running i ran 880cc in my 240sx and it was fine. cold/warm starts was the trickiest thing to tune in but otherwise my car idled just fine, even cruising and idling in closed loop was fine.

there will eventually be some threshold where your minimum injection time is going to cause you issues though, i don't know where that is.
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Old 05-19-14, 01:43 PM   #3
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depends on the ecu. I see you have AEM v2 listed in your signature.
If you have an aem box, then you can tune for whatever injectors, and you should just get the 1000-1200cc now before you tune. that way you just have to tune for e85 later.
Make sure to get EV14 Bosch style injectors like the ID brand sells. those have low response times so you can get larger injectors and still have a good idle and part throttle. lots of manufacturers sell these types of injectors not just ID.

If you were on a more stock sort of ecu you would not want to do that, but with the standalone most people go straight to EV14 1000-2000cc injectors.

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Old 05-29-14, 09:26 AM   #4
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Alisc3 is right. If you already have a standalone, it shouldn't be much of an issue to run the 1000-1200cc injectors you plan to use. Idle-ing bigger injectors is the trick like ali said, and he is right again regarding the low response time making big CC injectors idle best or like stock. ID'S and Bosch are examples. Save your money and purchase the injectors needed for you e85 goal.
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Old 05-29-14, 02:10 PM   #5
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what kind of power are you hoping to get from the e85?

just for comparison -
380cc 1jz injectors on stock twins - No issue what so ever running 10.0:1 up to 20psi then the ratios start to go up to 10.1 10.2 10.3 up to about 10.7 at 25psi

now - at 17psi - and 80% duty cycle.. u can hit 11.5 to 12:1 air fuel ratio.
which pumps 320rwhp on my soarer..

so why is that the case?? its the size of the turbos and the amount of air flow..

so you have a borg warner s360 you can easily get away with 550s - from the supra... inexpensive and easy to obtain. the resolution is good. and no need for a topmount feed -

however you did mention e85... to each their own but I think its just too much hastle. Make sure you upgrade the fuel system - some ppl have noticed an issue with inaccuracies of their gastank levels with the e85 in it.

E85 requires the use of 40 to 50 percent larger fuel injectors, to compensate for its 40-45 percent increase in fuel demand. The change in stoichiometric AFR from 14.7:1 with gasoline to 9.76:1 with E85 is 66 percent, but the resulting flow needed is only 40 percent greater, due to E85's higher density than gasoline (which can cause inaccurate gas tank readings).
thus - in effect, you actually use MORE gas, to achieve the same results.. and yes you can gain more power. but you can easily obtain it without the use of e85.. and without using such large injectors - and make sure if you switch and tune for e85.. you have a map to switch to for regular fuel as not every place in the us has e85, if you ever drive your car outside your area.

550cc @ 150% is 825 so you can get away with 800-1000 easily.
and ofcourse you can do the 1200s.. the problem with larger injectors as someone mentioned is the idle/low rpm which most tuning can account for...

which do you think will have a better time spraying one gallon of water .. a garden hose or a massive firehose.. at the same initial burst of pressure.. (your fuel pressure)

the garden hose as the pressure will actually be useful even at low volume.. where as the fire hose.. water will trickle out and fall to your feet..
same amount of water, same pressure but too big of a hose. however for Higher volumes they both can be manageable..
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Old 05-30-14, 07:39 AM   #6
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Originally Posted by soarer93 View Post
what kind of power are you hoping to get from the e85?

just for comparison -
380cc 1jz injectors on stock twins - No issue what so ever running 10.0:1 up to 20psi then the ratios start to go up to 10.1 10.2 10.3 up to about 10.7 at 25psi

now - at 17psi - and 80% duty cycle.. u can hit 11.5 to 12:1 air fuel ratio.
which pumps 320rwhp on my soarer..
I don't quite understand anything you said.

E85 lets you run much higher psi on 'pump' gas. Regular premium gas limits you to about 20psi. E85 can be treated like race fuel to 30psi+ on the same turbo. That's the advantage.

To answer the question, modern EV14 cores make any size easy to tune especially on a standalone. Injector Clinic is also another brand to consider that uses those same EV14 cores

I say go 1000cc. I don't know what turbo you plan to run specifically, but with a pump goal of 400rwhp they should be just fine for when you do e85.
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Last edited by INTIMAZY; 05-30-14 at 08:01 AM..
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Old 05-30-14, 07:39 AM

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