Any downfall to 80lb injectors vs 60lb mototrons?

[ryans1000]

Any downfall to 80lb injectors vs 60lb mototrons? idle or cruise issues? 80's are usually more costly but that isn't the issue. 60lb's will flow enough for me for now but in 2-3 years I may want more. If there are absolutely no downfalls, I'll just throw the 80's in.

[jonfic]

Any downfall to 80lb injectors vs 60lb mototrons? idle or cruise issues? 80's are usually more costly but that isn't the issue. 60lb's will flow enough for me for now but in 2-3 years I may want more. If there are absolutely no downfalls, I'll just throw the 80's in.
check this out.
http://www.ls1tech.com/forums/fueling-injection/1207002-2-day-60lb-siemens-sale.html

[5.7ute]

Any downfall to 80lb injectors vs 60lb mototrons? idle or cruise issues? 80's are usually more costly but that isn't the issue. 60lb's will flow enough for me for now but in 2-3 years I may want more. If there are absolutely no downfalls, I'll just throw the 80's in.

I am not too sure on the small pulse abilities of the 80lb injectors but I would think you would have a few issues. Even the 60lbers are hard enough to get a reasonable afr at idle or decel with stock internals.

[ryans1000]

I could run the fuel pressure at 43.5psi instead of 58psi. I need the extra flow from the pump anyway

[jonfic]

I could run the fuel pressure at 43.5psi instead of 58psi. I need the extra flow from the pump anywayyou could but the injector still will 83lbs as it is rated at 39.15 (ford pressure) The 60 also rated at ford pressure is 73 in your rail pressure. With the price of the 60 so low now, you could use them for the 2 years then sell them for around 250.. In a few years there will be tons of 80's out there that you could buy right also. My advise is not to over inject an engine for mods 2 to 3 yrs down the road

[rally1]

Just did a tune last week for 80lb injectors (we came down from 120lb) and getting the idle sorted is a little tricky, you also may end up with slow speed AFR that a quite rich as you wont be able to get the MS low enough, I agree with jonfic don’t go over board now learn the tricks needed to tune for bigger injectors now with 60lb and it will make the jump later to 80 easier.

[ryans1000]

Just did a tune last week for 80lb injectors (we came down from 120lb) and getting the idle sorted is a little tricky, you also may end up with slow speed AFR that a quite rich as you wont be able to get the MS low enough, I agree with jonfic don’t go over board now learn the tricks needed to tune for bigger injectors now with 60lb and it will make the jump later to 80 easier.

What is MS?

What brand injectors were you using and at what fuel pressure? Only thing holding me back is where I live e85 is readily available and I may want the option to run it. So if i run 80lb'ers would tuning at idle / cruise be easier than tuning with 93 octane because I wouldn't need to bring the pulse width down as much?

[joecar]

By "MS" he means the milliseconds pulsewidth... i.e. the PCM commanded on time.

Big injectors have a minimum on time that is typically bigger than the commanded on time at idle, as said by 5.7ute...

when trying to command less than the minimum on time, big injectors either won't open at all, or they will open for the minimum on time... so idle will be rich, as said by rally1... this is the downfall.

The solution is, as you mentioned, to run with FPR set at a lower pressure, so now your injectors will flow less (you have to edit the IFR table), and hopefully the commanded on time will be at least as big as, or close to, the minimum on time... hopefully.

Jonfic has a very good/interesting observation.

[WHYTRYZ06]

Ima be useing the 83#ers or a modded 09 zr1 injector.... i need alot of injector for my dry setup....