BURN!

 

exactly...mine put 177/136 with the cat on.

 

All right bro, it'll be a few weeks. I'll call you.

 

what's with the oversized injectors on this build? You have about 200 cc too much for this set up. Are you certain your a/f is where you say and are not dumping too much fuel. Backing off those fire hoses in tuning seems to be a lot of hassel when what you really need are some 270 or 310 cc. It's the one oddball item in your set up and if your leakdown comes out OK, I would be looking there.

 

Well, if the ecu is tuned correctly (Which it is John Vega = JDM) then those injectors wont be running Full Duty Cycle so he could have the biggest injectors he wants

 

Biggest injectors he wants? Interesting notion.

There are thresholds at which injectors like to operate and artificially trying to compensate for oversized injectors is something you do when A: you can't afford the right set of injectors or B: You are the kind of guy who wants to stretch the limits of his ecu, the patience of his tuner and enjoys part throttle and idle headaches.

Albeit safer than trying to squeeze more out of undersized injectors, trying to reduce the duty cycle down by more than 20 percent above or below a reasonable 80 percent duty cycle is not wise and not keeping with a build that otherwise seems to be well thought out.

How much are these injectors being pinched? Difficult to say, but he's only putting down 175 hp. He says his a/f is good and if so, approximately 25 lbs of fuel per hr is needed to produce that output. 525cc injectors put out double that, at around 50 lbs per hr. Its about the same size factory injector used on a twin turbo supra.

Also, regarding the tuning of the ecu: in this case being tuned "correctly," applies only in the broadest sense of the word. The ecu is being instructed to do the incorrect thing to achieve a correct (or as close to correct as you can get) result.

My original point was to remove variables that only complicate troubleshooting the problem. Fidgeting with poorly mathced parts to try and make them do the job of the right part only muddies the waters and keep you guessing longer.

If running oversized injectors is as easy as getting a tuner who = Japanese Domestic Market (whatever that means), there would be no need for long-established formulas to properly select injector size or even the need for so many sizes. Just buy big and dial them down.

Call Russ over at RC and tell him you want to make 200 N/A hp and see what comes on the UPS truck. Hint, it won't be anything close to 500cc injectors.

 

duh......cause your a real tuner.... lol

 

I was origionally gonna get 440 cc's as they are about $40 cheaper than 380 cc's. I didn't think it would make a difference when the car was tuned. John had these lying around we made a deal to use them. I figured it wouldn't make a difference once car is tuned. Are you saying it does? I thought the ECU would tell them how much fuel to put out.

 

i wouldnt consider those too big. I would always suggest to go with a little bigger injector than you really need. You really shouldnt press the injector passed 80% duty cycle. With that said, you can tune around the fact that they are bigger by adjusting the fuel multipliers that is integrated in most EFI tuning programs.

 

You are confusing me, now. In your original post you said you had 525cc injectors. 440cc also are too big for your application in my opinion, though it is more reasonable to dial that size down with a new fuel map than it would 525cc.
Still, keep in mind proper injectors for a 200 hp street engine are 310cc or 320cc. Note that the integra type Rs at 200 hp came with 240cc injectors and an H22 engine rated at 195 hp came with 270cc or 280cc (as I recall). My calculation shows 440cc support about 300 hp at 100 percent of duty cycle, making them ideal for something putting out perhaps 250+hp. Speaking of H22 injectors, using them on a b18 vetc buildup is a pretty common upgrade.
Regarding 440cc, if that is what you are running, never tried to detune them but if you have your a/f good across the rpm range, I would say your tuner worked it out. Just saying, when you are selecting injectors for the type of build you have, 440 and most certainly 525s would be over the top.
Remember, you increase fuel so you can keep up with increased air flow. Nothing short of some very radical intake porting and manifold work (ITBs maybe or some boost, of course) would ever get you so much air that you needed injectors that big.
I would worry that the fuel map would be all over the place from idle to rev limit.
I saw a case of 440cc injectors left in a GSR motor after a turbo with small boost setup was converted back to a stock setup. It would start and choke on fuel. Even keeping the revs up it was drowning in gas and dying out.
The map might have been adjusted to deal with 440s, but why fight it? The 240cc stock injectors went back in and solved the problem.
It's all about proportions and balance and while you can always try to shift things around to try and make it work, a canoe with a 550 lb passenger capacity will be happier with a couple 225 pound people than one 440 pound dude and his 110 lb girlfriend.