+1 Its all about duty cycle and you are way beyond it with a stock injector at 80PSI.


You havent mentioned your test method. What type of O2 system are you using? Werent you going to fabricate something that is inserted thru the rear? I am curious of test results, repeatability and accuracy. Tell us more about test equipment and test procedure so we are sure you arent swaying the data.

Yes i was working on a sniffer pipe set-up made out of copper tubing. I was making some progress with it when I came across a guy selling a used Port side Lightning header very cheap.

I have Lightnings on my boat but did not want to cut and weld on them. ( They have the mild steel outer pipes with a ceramic coating ). So I welded a bung into the used header and hooked up an AEM Wideband Air/Fuel UEGO gauge.

I seem to get an accurate reading with this method.

I am still learning alot about Fuel Injection and plan on researching a whole system approach that will work together that I can possibly self-tune. If it is even feasible for a novice like me to self-tune? This would be something I will install during the off-season.

Well, I stand corrected. I haven't looked for replacements in a while since we have been replacing them. Thanks for the info, That's good to know.
Eddie

Absolutely, theres a couple FAST systems on the market that you could install the ECM and wiring harness on your engine, answer some questions on the hand held tablet that comes with their EFI system, start it up and let it tune itself.

I have never used that system personally but it cant be that much different than tuning MegaSquirt EFI. You could go MegaSquirt as well, only thing there is that you would need to make your own wiring harness.

You would hook your current O2 sensor (as long as they support the AEM, which I believe most do) to the ECM so it reads the air/fuel ratio and basically go drive the boat (or have someone do it for you). After a couple hours of that the tune would be close enough to run on, and then you can use your laptop and make fine tune adjustments where necessary.

Having EFI will really shine where you can get it to idle at say 12.5:1 AFR, cruise at 3500 at 13.0:1 for fuel economy, and then whatever ratio you want while its under boost.

The FAST system sounds very interesting. I would think installing larger injectors without any machining work necessary, then hooking up the FAST system could be a good direction for me to go in.

No worries. I had a tough time doing the Keihin injector research when I did my rebuild since I wanted minimal changes to the EFI rails etc. When I found this place I was elated. No drilling or modding at all. They don't do much marine work but were more than accommodating to my situation. Again, I'm not affiliated nor endorsing them as the be all - end all EFI source but they did provide a solution to my problem.

Do you know what size injectors they offer? I am very interested in replacing my injectors and going wirh a self learning EFI controller.

I am currently running a Procharger at 7 lbs. on a stock 502 mpi with Keihin injectors. Hoping they have something that will work for my application.

They offer quite a few different size (flow rate) injectors and injector dimension. I don't remember off hand what the biggest injector was but they have a web site that shows most of their products. I know some of the injectors will not work due to body size and/or they were low impedance peak & hold style, but they had quite a few that fit the stock application.

This is their web site : http://www.rceng.com/index.aspx

I don't know what HP you are at, but for 800 hp with a BSFC of .55, 43.5 psi fuel pressure you'd need a 69 lb injector assuming an 80% duty cycle. If you are making less HP that size injector gives you a little headroom. You could also bump the fuel pressure a little (50 psi) for some additional flow but I am not a fan of bumping fuel pressure above 43 psi. RC has a 71 lb injector with Denso and Honda style tops and one other. Those might fit the bill.

I hope this helps.

Thank you !!

also keep in mind, the rails, lines, fittings everything are not good on the factory stuff..