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Injector/pump sizing for bolt-on car

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Old 04-22-2009, 07:32 AM
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Default Injector/pump sizing for bolt-on car

Well I will never put a cage in my car so 11.5 is my cut-off. Car is full... I do mean full bolt-ons right now and goes 12.1. I see Ford has a sale on 42's for $200 shipped so I was thinking about it. Will my stock pump supply enough for them? Is this upgrade worth doing for my car? I don't know what duty cycle I am currently running but if I don't get close to the 11.5 mark I may slap on a set of heads and want to have enough fuel to do it.
Old 04-22-2009, 10:18 AM
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You should be fine for the stock pump and inj. If you wanted to get the inj. for future use they will need a tune to work. A good upgrade pump would be the Racetronix/Walbro 255 direct fit.

Nate
Old 04-22-2009, 10:26 AM
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If you do heads and cam, you'll need to upgrade most likely, or you'll be at least very close to overwhelming your stock fuel system. With the bolt-ons you're 100% okay with the stock setup.

Personally, I wouldn't upgrade the fuel system until you need to. You never know when your plans might change and those 42lb injectors will become useless because suddenly you're going forced induction and need 60lb injectors.
Old 04-22-2009, 10:41 AM
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I bought the 42's. I guess maybe I don't need them now but the price is helluvagood so why not. What DC do you think I am running full bolt-ons? Maybe I can wait until next year when I do the heads before putting them in. Stock fuel pump will keep up with them?
Old 04-22-2009, 06:52 PM
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Can I plop these in and make a drive 25 miles for a tune? If not what can I use to adjust things to get it there?
Old 04-22-2009, 07:19 PM
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Originally Posted by Intercooler2
Can I plop these in and make a drive 25 miles for a tune? If not what can I use to adjust things to get it there?

NO!

I had 42s in my car with the Injector Flow Rate changed correctly and it still wouldn't idle. Although the Ford SVOs are better about that, but still you are pretty much doubling the injector size from 28 to 50. (42 is rated at 3bar, LS1 is 4bar.)

I am using Ford SVO 30# injectors on my bolt-on + dry nitrous car. And I still have room for more power, they are not maxed yet.

I bought mine used from a Mustang guy for $100..hah
Old 04-22-2009, 07:23 PM
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Oh. Guess it will have to be done there then
Old 04-24-2009, 07:08 PM
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Like Nate said, with all the bolt-ons 42s should be about right. And yes, I'd upgrade even if you have to buy bigger ones later. Much cheaper than a motor after you go WOT with too little gas. I started with SVO 30s, then went to 42s, then to 60s, now I'm on 80s. You can always sell the old injectors.....

And a single Walbro will feed up to 60s if you do it right. I run twins now (Nasty Stg 2? system) can't have TOO much fuel.
Old 05-25-2009, 07:24 PM
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Thanks for asking this question, I have been wondering this myself.

I have yet to install my 243 Stage 2 TEA heads and my new cam. I am going to run a 150 shot of nitrous with a NO plate system. Do I need to upgrade my injectors or should I be alright with stock.

I've been gathering up parts to do the swap and I didn't even think of the injectors, the last thing I want to do is run it lean.

If I have to change them, are the Thunder Racing Racetronix 37# OK for my use?
And Will my stock fuel pump supply 37# injectors?

Thanks for any input.
Old 05-25-2009, 07:34 PM
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I'm running the SVO 42 Green tops on a bolt on car. Plenty of fuel to go with what I have (cam, 243's, Nitrous, etc.) I'm still running the stock fuel pump.

Buy some 42's. drive to wherever you get your stuff tuned and slap on the new injectors its an easy 5 minute change.




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