howdy 2nd gen forum people. i'm going to be picking up an engien at the end of the month from an '86 to put into my '84. will be using a stand-alone fuel computer to run the injectors. and i was curious about injector sizes.

would i stand to gain performance by running a stock port S4 NA motor with bigger injectors? 'cause i'll have a pair of GSL-SE injectors left over from my dead motor and i'm deciding whether to sell them off or keep 'em to use.

i plan on making about 150hp from this engine.

 

I've seen the limits of the stock 460cc secondary injectors on my street ported S4 NA engine. Its only exhaust mod is a header, and it has a mild ported intake manifold / cold air intake. I followed the path of forum member Wozoom and added a pair of TII 550cc secondary injectors, which are about perfect for the engine's current state of mods, and only require slight (+ or - 5%) fuel correction on the SAFC to work to my liking.

If you have a standalone ecu, I don't see any problem with using a pair of GSL-SE injectors in lieu of the stock 460cc secondary injectors.

*edit* would you stand to gain performance from swapping to larger injectors? Not unless you have a midsize or larger street port and at least a header, in my opinion. Stock 460cc injectors are more than enough for 150hp.

 

--Gary

 

Absolutely not. You do not gain power from simply tipping in more fuel. In fact richer mixtures will cause a drop in power. You gain power by improving the engine's breathing and then making sure you've got enough fuel to suit.

You do not need to upgrade the NA injectors with just a street port. They're good for around 250fwhp, which is bridgeport territory. You certainly don't need to run anything bigger than stock if you want 150hp, since that's only 4 more than stock...

 

What NZ said. I'm using 460cc injectors on my street ported 6-port engine. I've only seen duty cycles of about 63% at close to 7K rpm. I am using a stand alone fuel computer and the car is running a little rich till I get to a chassis dyno for its proper tuning.

 

thanks for the input fellas. that was the suspicion i had, but i wanted to make sure 'cause several people recommended i use my SE injectors on the FC engine and i was under the impression that they were a good idea for a turbo app, but unnecessary for a mildly tuned NA.

also, another question. atkins rotary's website advertises a MT-4 computer for $500 sans software. seems like a decent price, correct? is the software expensive proprietary stuff, or would i be able to come up with it on my own, reasonably easily?