I am wondering if there is much in the way of benefit to using a lrger injector, say 310, 440's with cams and 11.5:1 CR.

When I dynoed my car, I found that it was running rich in some parts of the powerband, and lean in others. I balanced the fuel out, and ended up with a nice, flat fuel line.

Could someone outline the pros/cons of going to a larger injector?

TIA

 

as a general answer, the bigger injector will require you to lower your fuel pressure (less strain on fuel pump and injectors) and a fuel controller can be used to dial in the entire fuel curve. The absolute advantage is when using a fuel controller such as the apex units, no matter if you try to richen the curve past 12-14%, it really wont richen more than that. However, if you lean the curve and reduce the amount of lean across the board you will have more control of the fuel band. This is because the controller simply modifies the voltage signal to the ecu fromt he map sensor. To rich you can only add so much of a voltage to get max load and therefore larger inejctor pulse, however to lean you can reduce the voltage as much as 0v so this gives more control.


Greg

 

So in absolute terms, all I will get in better control over the xisting stock injectors, less load on the the current injectors and fuel pump... is this correct?

 

I think so - but there is also the issue that higher fuel pressure gives you better atomization of the air/fuel mixture.

BPR - who is think he should upgrade to 310s

 

I was running out of fuel with the stock injectors above 7,000rpm with my Spec B's and Toda pistons (12.4:1 compression). With 11.5:1 compression, you're probably not going to run into the same problem. Even with a Hondata ECU I couldn't get a enough fuel to avoid leaning out on the top end, so I had to upgrade (went with Toyota 440cc, which are not plug-n-play as I had thought...you need the Toyota clip and you'll also have to modify the rubber washer than holds the injector into the manifold). If you're not leaning out, I wouldn't bother upgrading unless you're worried about blowing up your fuel pump. What kind of fuel pressure are you running?

 

I would get a ecu with a richer program. You only want to upgrade to new injectors, when you have to add alot of fuel pressure if your car is leaning. I've been running stock injectors on my old set up with 11.5:1 compression and that was fine. Get a Toda or skunk 2 ecu program. you should be fine.

 

Toda program?

Where to get this?

 

wow..i was having this exact disscussion last nite..
what would be the optimal injector size with spec b's?

 

Richnes/leaness is not a problem, I am just wondering if there is a performance/reliability gain with this upgrade.

I sometimes get a weird stutter of idle when I accelerate; it makes me think there is not enough fuel...

Fuel pressure is set at 54psi.

 

My current setup does not include a FPR...I am running an indicated 50psi of pressure at full throttle. I am using 440 cc/min unjectors from RC...the 310 cc/min injectors that I had were running at 95%+ duty cycle, I didn't like that. Without increasing my Fuel Pressure the 370 cc/min injectors would of been able to provide the necessary amount of fuel for my current setup, the 370's are the largest that you can use without a programable/reprogrammed ECU, however since I have a programable ECU, and after much discussion RC and I decided to o with the 440 cc/min, which also happen to have a better atomization pattern than the 310's and the 370's, as they only have 1 discharge port, whereas the 440's have 3...

This may not be the best photo, but you can see the 310's on the left, 440's in the middle, and some Ford injectors on the right, which were going in a 850+hp Mustang.

Austin

 

Could you please elaborate on your current motor setup?

thanx.

 

Sorry about that...it's listed in my Signature, but I ignore most people's signatures...
Here is what I have installed:

TODA B cams
TODA cam gears
TODA valve springs
Portflow Ti retainers
Comptech Icebox intake
HyTech header
Carsound 54006 cat
Comptech cat-back
A'PEXi PowerFC
J&S safeguard
RC 440cc/min injectors

 

You forgot about the Blingh-Bling Austin!

 

Just for you Dion...

 

I got a brand new set of 440cc's for sale.

If anyone's interested email me.