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Too big of injectors, is it possible?

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Old 06-15-2012, 06:52 PM
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Default Too big of injectors, is it possible?

Trying to pick and choose cheap parts as I see them, and someone local has some huge bosch 1650cc low impedance injectors.
I could pick them up dirt cheap ( maybe $250 brand new. ) They were going to be going in a big turbo e85 SR20.

I am guessing even with standalone I would have to run resistors on these becasue they are low impedance?
= Me with tuning anything electronic.

I plan on going MSpnp soon ( Deciding options I want still )
Would sequential injection be enough to keep the car idling nicely on stock motor, and at lower-mid boost levels. ( I am going to learn to tune n/a while I gather/make all the boosty parts. )

I like the philosphy "buy it once" instead of out running small injectors and buying the next size.
I don't have huge power dreams, maybe 220hp, then gather forged parts ( 2 year goal? )
And if I ever get a gas station that has e85 close enough.... that might be an option that would need huge injectors.
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Old 06-15-2012, 06:54 PM
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There's no way you will be able to properly idle low-imp 1650s.
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Old 06-15-2012, 07:15 PM
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Originally Posted by AkaZero

I like the philosphy "buy it once" .
yet you don't live by it.
buy ID1000's and be done.
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Old 06-15-2012, 10:15 PM
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Well currently, I haven't bought anything due to low funds.
But I am selling off other hobbies to add some power to the miata.

I'll skip the 1650s and get some 1000s then.
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Old 06-16-2012, 09:09 AM
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also the MSPNP can't natively do low impedance injectors. you'll need either a relatively expensive add-on driver or a resistor pack. just get high impedance.
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Old 06-16-2012, 11:15 AM
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Originally Posted by AkaZero
I'll skip the 1650s and get some 1000s then.
Just to be clear, we did not suggest some 1000s, we suggested a specific kind.
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Old 06-16-2012, 11:29 AM
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1650 for a 220 hp is a headache.. trust me i'm running 820cc dws and i'm having issues getting them to idle smoothly because they just dont open little enough. 800 but they flow 820 per testing.
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Old 06-16-2012, 12:00 PM
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also dw = ev6 and sucks

you want Injector Dynamics or Fuel Injector Clinic ev14
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Old 06-16-2012, 02:52 PM
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Just a question, but I think a good one for the OP: Do you understand why running very large injectors (without the need for them) is a bad idea?

Just trying to gauge if this is something we can help you understand.
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Old 06-16-2012, 03:44 PM
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because the minimum injector time is probably going to be way more fuel than you want at idle.

and the injectors are less linear at very low pulsewidths

and you probably don't have the real dead times for them which makes it worse.
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Old 06-16-2012, 03:49 PM
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Y8S bsing u... miatas idle epically at 9:1 afr.

How about a 5th injector setup but only with 1 injector :P
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Old 06-16-2012, 04:06 PM
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Originally Posted by triple88a
Y8S bsing u... miatas idle epically at 9:1 afr.

How about a 5th injector setup but only with 1 injector :P
I think that's called TBI, lol.
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Old 06-17-2012, 10:39 PM
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I am trying to read as much into megasquirt in general, and more miata specific stuff as well. And ask questions when I don't find and obvious or specific answer I am looking for.

I understand the theory behind this, but I have not hand my hand into any actual tuning.
I just don't know how big injectors is too big, so I asked.
Seen a lot of "I need bigger injectors" but have never seen someone "I need smaller injectors"

Basically too big of injector can't cycle short enough, to get low enough fuel for correct fuel/air ratio at low rpm.
And each % adjustment is a larger amount of fuel than a smaller injector.
So 1% duty cycle out of a 1650 is is 16.5cc
While a 500cc it is only 5cc a much finer adjustment, better control etc...

I am just on the lookout for deals since I am just starting to piece stuff together.
And $250 for 1650cc, and the cost of resistors ( low imp injectors ) looked appealing to the wallet.

The injector dynamics 1000 are double the cost of these, but some research on them proved it is money well spent.
With the money I save buying a china charger I might as well get all the best electronics.
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Old 06-17-2012, 10:47 PM
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2 of the top things not to cheap out on: injectors and engine management.
Right up there with exhaust manifold for a 1.8

just keep that in mind
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Old 06-17-2012, 11:03 PM
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I plan on going MegaSquirt ( not built by me.... ) Probably will be the most expensive part of the build, then injectors.

And I plan on building my own manifold out of mild steel. I have plenty of time to get it right before I have all the pieces assembled to go turbo.
Plan on doing thin steel tubing for the IC tubing also. If I have the tools, I will try to make as many parts of the build myself. I have time, tools, and not a lot of money.
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Old 06-18-2012, 12:39 AM
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Originally Posted by 18psi
Right up there with exhaust manifold for a 1.8
I hear ebay manifolds are top notch.
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Old 06-18-2012, 03:05 AM
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I know everyone sips the ID kool-aid, but check out FIC. They sell ev14 injectors for about 1/2 of what ID does. And they are very good to work with.

Also OP, understand that the technology behind ev14 injectors allows the pintle to be much lighter, this allows it to be modulated more effectively. This translates to injectors that are stable down to extremely low pulsewidths, as well as injectors that can function with very high base-fuel pressure.

We would not be telling you to run an ev1 style injector that was 1000cc, it would probably be rough. I have a set of ev14 injectors on my VW and I think they are stable down to like 1.0ms. It lets you run absurdly large injecotors smoothly.
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Old 06-18-2012, 03:48 AM
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yes ID injectors are worth every penny. Yes, I tried buying cheaper EV14's from fiveomotorsports, etc. and have been disappointed. ID injectors are everything they say they are and I wish I had not wasted money (shipping, reselling, etc.) and just gone straight to Injector Dynamic ID1000's from the get go
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Old 06-18-2012, 07:38 AM
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Originally Posted by y8s
also the MSPNP can't natively do low impedance injectors. you'll need either a relatively expensive add-on driver or a resistor pack. just get high impedance.
Yes it can, you just need to not use the high_res code.
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Old 06-18-2012, 08:02 AM
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Originally Posted by tasty danish
I know everyone sips the ID kool-aid, but check out FIC. They sell ev14 injectors for about 1/2 of what ID does. And they are very good to work with.
no one said fic was bad. they're just as good. nowhere near 1/2 price tho.
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