i dont plan to put more than 400hp to the ground, but a friend has some 720 cc injectors that he will sell me cheap. i know that they are good for sure.... but im wondering if i should get them because i know they are a little over kill for my hp range.... i have a aem ems, will that controll them enough to where i can get good gas milage.....my other option is 550cc injectors.....also if i get the 720's do i need another fuel pump...i have a bosche internal one right now.
If you are looking at 350whp range, 550cc should be fine but 720cc injectors would be better for anything near 400whp. It just gives you more room to play with. What's the brand on your friend's 720cc injectors?
okay, im thinking about getting the 720's but will the aem ems controll them enough to where i can get good gas milage....this
car is a daily driver
thanks
Not sure about ems but I know my hondata will be controlling 1000cc injectors on my race motor.
What is the flow specs of your Bosh pump, You need atleast a 255l high press pump to do the numbers you want. That will be good up to 500hp at crank and 420-450 at the wheels depending on how good your power transition is.
I will be using the Aeromotive 1000hp fuel pump, It will support a boosted engine up to 700whp. And yes that is the goal, I have spares incase the motor blows, and I will attempt the same once again, and yes my engines are and will be fully built
Originally posted by anubyss I am pretty sure clendaniel is using 720cc injectors on his turbo prelude right now.
Yeah, I've got 720's but I'm really not too sure about the gas mileage part!
The idle a/f is ~13.8-9 according to my wideband...that's at a .74% duty. Any lower and you develop a stumble as the injector can't open for a short enough period. Once off idle the a/f's are "normal" and on the lean-ish side for low throttle cruising. If you don't boost too much I'd think that you could maintain decent mileage...but then if I wanted good mileage I'd have bought an Insight.
Clendaniel, what's the pulsewidth resolution in ms on the AEM?
The gas mileage for daily driving should definitely go down some. The spray pattern just wont be as nice with much larger injectors. If 400whp is your goal, absolutely get the 720s. I would get them just in case, anyway.
__________________ DirtyLude
Mark Higgins
Toronto Prelude Club www.hondaprelude.to
i remember reading on one of the ems systems either aem or greddy that it will control 30% larger injectors. Anyways 720 is significantly more than 30% so i don't think that option on the aem ems will work for them. How precise is the fuel tuning on the aem. How much can you lean out a certain rpm point?
__________________
Memories: 257whp & 207wtq @6psi
I quit boost!
Originally posted by DirtyLude Clendaniel, what's the pulsewidth resolution in ms on the AEM?
The gas mileage for daily driving should definitely go down some. The spray pattern just wont be as nice with much larger injectors. If 400whp is your goal, absolutely get the 720s. I would get them just in case, anyway.
Exactly...I didn't necessarily go with them for the immediate need, more to "grow" into them. At idle the pulsewidth is usually between 1-2ms with a 40psi static f/p. It messed me up for a while as I was looking at the "raw" value (I still haven't totally figured out how it's derived) and it's value was approx 6...dropped it to 5 and it stumbled. When I finally changed it to ms I realized that the injector wasn't even opening.
My idle runs around 1.2->1.5ms injection time at 750rpm with 550cc injectors 40psi fuel pressure at idle. Can you check to see what the minimum ms value is that you can change each cell? I think the Haltech has an advantage at small injector pulse widths since it uses a peak and hold injector driver and with sequential injection I can get 0.016ms resolution. With batch fire I can get down to a 0.008ms resolution.
I have 550cc injectors and I regret it. I should have just gone with 720 -> 850cc injectors, but at the time I got the 550s, 720s were much more expensive. Now you can find 720s for the same price as 550s.
99Prelude_LC, you can lean any rpm/load point to 0 if you want. This is a full replacement management system. Stock isn't used as a reference point anymore. Any EMS can handle any size injector, it's partly the injectors fault for being too big that it just can't physicaly open and close fast enough to maintain the minumum fuel needs at idle.
__________________ DirtyLude
Mark Higgins
Toronto Prelude Club www.hondaprelude.to
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