fmu and timing questions for ka-t setup

[AustinSilvia]

i posted something similar to this under someone elses post but i wanted to get as much feedback as possible here. the only thing i am changing in my turbo fuel managment setup from stock is adding a 12:1 fmu. i am running 7 psi on a stock engine and no ignition upgrade. is this going to be safe? i have heard a lot about 240's having no problems at 7 psi and below on stock stuff, and my friend runs this same setup on his stock civic del sol (and he does 10 psi with bad compression). well what about the timing for this application? i know i will have to experiment myself, but anyone have any information about timing the 240 for 7 psi?

20 deg. advance seems a little high, but this 20 deg. advance works on low grade fuel (87 octane), so i am wondering if my setup will require me changing the timing since i never use that low grade fuel anyway. i will probably set it back about 1-2 degress initially to see how things go, but i just wanted to see if anyone else out there has or has had similar setup and could tell me their experience. of course i would like to avoid blowing my engine up. thanks for the help.

one more thing... will the stock fuel pump be enough for 7 psi with the fmu?
Modified by AustinSilvia at 12:50 AM 12/4/2004

[nissanfanatic]

12:1 seems a little rich. I'm using a 8:1 as are a lot of other people. Intercooler is a really-really good idea at 7psi. I would say it is manditory. Don't run 87 octane fuel with forced induction. Its a bad idea. It runs well on 91 or 93 before a turbocharger is added. You will probably need to back the base timing off running 91 octane. I use 16 BTDC but make sure you unplug the TPS before adjusting. Stock fuel pump is crap. Get a walbro 255.

[S14tat]

don't be cheap and try to save a few bucks a tank and run 87 crap gas. it clogs fuel filters and injectors.

your car will probrably run faster by just switching over to 93 octane becasue your probrably knocking right now and the knock sensor is pulling back timing on you. with 93 octane you will get no pings with teh correct timing and fuel.

i just find it very very hard to believe that your running 87 octane on a boosted car. shame on you.

this reminds me of a time when i drove a customer's brand new 05 Maxima and his car was knocking!!!! those bastards was too cheap to put 93 octane in the car and it was knocking constantly on 87. so if it did that to a n/a engine think of what its doin to your boosted KA with 9.5:1 comp ratio?

not worth blowing up an engine over.

[AustinSilvia]

thanks for the replies... i wasn't saying i use 87 octane, i was saying that the car won't knock with 87 in there. like the car comes stock NA with the timing adjustment reccommendation of 20 degrees btdc, and i know that the car can run stock on 87 octane. i always use 91 octane. i was trying to make a comparison between running the timing set at 20 degrees btdc with boost on 91 octane, and running the car NA with 87 octane... I was just trying to say that maybe it would be safe to leave the timing alone, but i will turn it down about 2 degrees probably. and is the walbro pump 100% necessary for my application? i was thinking of getting one but if i don't really need it for 7 psi then i'm not gonna get one right now because the boost isn't going to go above 7 psi. thanks again.
Modified by AustinSilvia at 7:04 PM 12/4/2004

[C-Kwik]

I ran stock timing off an 8:1 FMU with 6.5psi. I ran into some boost spike issues and didn't notice knocking until it hit about 8-9 psi. But it may have been fuel related at that point. You might just give it a shot and keep a close ear on it for a bit. Also check again as the temperature in your area changes.

12:1 is excessive. Once you hit the max flow, the pressure will not increase any more so it will no longer be able to flow anymore fuel. I'm fairly certain even the 7:1 and 8:1 max out at 7 psi, so the only difference will be is that the 12:1 will max out sooner. This will cause the motor to run rich until higher airflow catches up to the fuel flow and starts to lean it out. My 8:1 ran pretty rich already.

As far as upgrading to a new fuel pump, it depends. The Factory Fuel pump should be able to flow enough to manage 7 psi through an FMU. But since the newest 240 will likely have a 6 year old fuel pump at best(if still the original) there may be some question as to whether or not it will be flowing it's rated capacity. Running an FMU requires both more pressure and flow. This is inversely related and increasing one decreases the other. Asking it to do both means you will run it at max capacity quite a bit. It's cheap insurance to get a fuel pump at this point.

[AustinSilvia]

thanks a lot for the reply... i knew the fmu's maxed out fairly quickly, otherwise my fuel lines would burst. i can replace the disc and gasket on the fmu to change the ratio to whatever i want... i'll probably go to about 8:1. i'll do that and get a walbro 255lph pump... they have a very reasonable price on ebay. plus i'm going to need one for the future anyway. again, i really appreciate the replies.