Hey guys. Was hoping someone could give me a suggestion on what size injectors to run onmy slant I've decided to drop in a stock slant to get my car running and get experience with the Megasquirt system. I'm running an injector in each runner and I found a nice throttle body(is probably to big it flows 1000 cfm) from force and I've found everything else I need, just have no idea what to run ofr injector size? I'm assuming the basic standard 60-70?

A lot depends on what your going to be doing with the build and if you plan to upgrade latter on. Dont worry about the 1000cfm throttlebody it will work just fine as long as its a 4 barrel progressive version.


I would probably go with a set of 60lb injectors. You can get them in high ohms type at a good price, this would work good with the MS. They make the 60lb high ohms injectors for the Buick GN is why they have such a good deal on them. A 60lb injector will carry you upto around 600 to 650hp if you was going to run a turbo or blower.


If your not going to run a power adder then you dont need anything near that big. You can get a set out of a Mustang V8 or Explorer that will work just fine. I think some of the Mustang injectors are 32lb and these would carry you to around 320 hp. What ever pound (lbs) the size of the injector is just add a zero and that will be real close to the HP level it will carry. You can find Mustang injectors ranging from 28lb to 42lb from the factory ( I believe the green tops are 42 lbs injectors) on Ebay all the time. To get the 60lb Buick GN injectors go to Turbo Buicks "Dot" com and look in the forsale section.

Although this will not be exact, if they are marked in CC then something like a 440cc injector is around a 44lb injector ( closer to 42lbs I believe but it gets you close).



You want to try and run a size that is not much bigger than the amount of HP you will be making. But you do want a little bigger so you dont have to run the injectors over 86% duty cycle. If your going to be upgrading on performance latter you can run the bigger ones now even though you dont need them, it will just take a little bit to get them tuned in and the MS can handle that pretty easy with no problems.


Jess

Are you going to be turbocharging in? My Dart is running 440 cc/min injectors off a Supra, close to 42 lb/hr. If you're running a force fed motor, that's a pretty good size. You don't need that big for a naturally aspirated motor, though. A stocker could run 14 lb/hr injectors if you were trying a primarily fuel economy buildup. 24 lb/hr would probably be good for a mild NA buildup.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

How much power will you be making? Normally aspirated or forced induction? The later 4-hole injectors work better than single pintle type.

Mitch

I'm going to go with just a stock N/A motor maybe I'll buy the cam I plan on using in my turbo motor and throw it in to gain a bit of juice from the motor.

I am running 6 @36 lb injectors with a turbo, and have not run out of fuel at 9 pounds of boost. If you are running six injectors and an NA slant, then 24 or 28 would likely be big enough. But, I think you can find a calculator for that on line, and you should use a calulator to figure that rather than rely on someone's guess. . There might be one in the Mega Manual found at Megamanual.com

Sam

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According to the Megamanual for my slant(I plan on upping the flow through the motor and maybe changing the cam maybe around 200 hp?) and it suggests a 20 lb injector if I run 6 for my slant. I was thinking of upping that to a 25lb just so I'm not working the injector to hard?

I'm fairly confident that calculator includes the rule of thumb that you shouldn't run an injector past 80% pulse width so its figures should have enough padding in it already.

http://fiveomotorsport.com/ for new injectors. Can find used all over the place on ebay if you want. I believe one of the EFI articles on here and the megamanual gives you a how-to clean injectors procedure.

I bought some cheap new Delphi 24lb injectors on ebay about 5yrs ago and they are running strong in my 68 Dart with MP-EFI. Almost stock motor, and I doubt the duty cycle has been over 50%.

Lou

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Home of Slant6-powered fun machines since 1988

there are some cheap injectors available thru this company; http://www.racetronix.com

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