Fuel Injector Recommendations?

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nogoodwithusernames
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Fuel Injector Recommendations?

Post by nogoodwithusernames » Thu Oct 29, 2015 6:21 pm

Hello all, I am working on a 1745cc engine to put into my squareback currently and am converting to MS FI and ignition.
As I said it will be 1745cc with a 76mm crank, 85.5mm cylinders, Eagle 2231 cam, stock rockers, stock valves, and the VW Speed Shop "Throttle Manifolds".
I would like to know some injector recommendations based on this size motor. I know that there are different pulse lengths and such I just don't know what would be good for this application and I don't really wanna buy more injectors than necessary!
Thanks!

Clonebug
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Re: Fuel Injector Recommendations?

Post by Clonebug » Thu Oct 29, 2015 7:37 pm

You install Fuel injectors based on your hp estimates or goals.

I use 32# Bosch injectors from a 1994 Volvo 940 Turbo and they are 336cc's and good for 230 plus hp on my 1679.
You also have to decide whether you will run Low-Impedence or Hi-Impedence injectors. It will depend on how your MS ECU is set up.

Pick an injector that will service the hp you have now and what you think you will need in the future.
Stripped66 wrote:The point wasn't to argue air temps with the current world record holder, but to dispel the claim that the K03 is wrapped up at 150 HP. It's not.

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Max Welton
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Re: Fuel Injector Recommendations?

Post by Max Welton » Fri Oct 30, 2015 7:11 pm

Yes. Pick injectors that are spec for any 4 cylinder engine that puts out about the same HP as your engine will generate. As long as you are in the ballpark, you will be fine.

Max

nogoodwithusernames
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Re: Fuel Injector Recommendations?

Post by nogoodwithusernames » Mon Nov 02, 2015 12:42 pm

Thanks for the replies, should help me out in my decision.
I assume that I could also pull injectors from any size engine so long as I do the math and the per cylinder HP is the same?

Clonebug
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Re: Fuel Injector Recommendations?

Post by Clonebug » Tue Nov 03, 2015 9:28 am

There are different physical sizes with injectors also.

You will want to get the style that fits your intakes.

Don't forget to check on the Low-Z and Hi-Z also.

There are plenty of sites listing injectors and flows that you can narrow down your search on.

Post your hp estimates and someone will recommend a size.

I just checked my logs and I am at 94% Duty Cycle with my injector flows.......it's time to look for bigger ones.
Stripped66 wrote:The point wasn't to argue air temps with the current world record holder, but to dispel the claim that the K03 is wrapped up at 150 HP. It's not.

nogoodwithusernames
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Re: Fuel Injector Recommendations?

Post by nogoodwithusernames » Tue Nov 03, 2015 5:04 pm

Yep, my manifolds/fuel rails will need 14mm IIRC, I can check that again though before I finalize anything.

I plan on running Hi-z (based on reading through the MSextra manual the Hi-z seems easier to setup since they don't require any inline resistors or such.)

Got a link for one? I wouldn't even know where to begin looking to find a site like that :?

As far as HP I'm hoping to get 70-80, although with this being my first build that may be a bit optimistic. It will be a balanced 1745 stroker with stock heads and approx 9:1 compression.

Clonebug
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Re: Fuel Injector Recommendations?

Post by Clonebug » Tue Nov 03, 2015 8:09 pm

Here is a calculator for you to figure your size.

http://fuelinjectorclinic.com/flow-calculator

Just plug in your data....using 80 hp at crank I came up with a 14 lb. per hour injector. A 19 lb. per hour injector would work fine for you but You could easily run 32# per hour and have room if you ever want to increase size or turbo it....

Here is a list of lots of injectors and their flow rates.

http://www.autospeed.com/cms/article.ht ... ows&A=0102

Like I said before......don't get too small of an injector....you want a little headroom.

I have a 1679 and it runs great with a 3.3% duty cycle at idle all the way up to the 94.5% at 22 lbs. boost on the 32# injectors I am using.
Stripped66 wrote:The point wasn't to argue air temps with the current world record holder, but to dispel the claim that the K03 is wrapped up at 150 HP. It's not.

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Chip Birks
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Re: Fuel Injector Recommendations?

Post by Chip Birks » Tue Nov 03, 2015 9:47 pm

I bought from injector.com once. Prices are decent. Just remember, you are buying new parts, not junkyard stuff. Nothing wrong with hitting the junkyard either. I haven't ever used used injectors since my power goals have generally been higher than most oems offer, at least cars that are in the typical junk yard here.

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