29scarab

Engine is on the dyno right now. Fuel is good from idle to 2800rpm then it starts leaning out according to the exhaust temps. I guess this means the exhaust temps are going up. We did go with a bigger cam close to a 600 lift. It has stock heads on it. Engine builder had Dustin at Whipple reprogram it , but it still shows it needs some work. The engine builder is sending the ECM to a different guy in Louisiana this time that is suppose to be pretty savy when it comes to marine engines. Not sure who he is sending it too.

I'm from the old school when it comes to building engines, so this computer stuff is all new to me.

Anyone have any idea where the fuel needs to be?? We scrapped the whole fuel system for one big pump and regulator to feed everything. Were running close to 39lbs of pressure on the fuel.

Any help from you guys would be appreciated.

Thanks,
shawn

Outdrive1

Call Az Speed and Marine, they are the resident experts on remapping ECU's for blowers.

zt260

Are you running an O2 sensor? AFR readings would help.

If you have large enough injectors, and good fuel pressure, the fuel curve is off. Are you increasing fuel pressure with rpm? I increase from 38 to 45psi over the rpm range, but I use an accel dfi system with calmap gen 7 to program on the fly. You will need to have your ecm reprogrammed again. I would stay with Dustin for at least the next reprogram.

Either way you need to be on the rich side to start. You could just increase your fuel pressure as a temporary fix just to get close.

29scarab

I'm not sure of the pressure increase over the rpm range. I will get some more info from my builder. I do know they are using there O2 sensor on the dyno.

Thanks

800XCR

iTrader: (2)

What shop is it at?

Smitty

iTrader: (1)

The guy in Louisiana is Mark. He definitely is good at doing this. I just went thru exactly what you are doing. If you want it done right, you need to install an oxygen sensor in the exhaust, and take the boat to Louisiana and have mark set the fuel maps in the boat under real world conditions. After I built my motors we broke them in on a dyno, set the fuel maps perfectly and it made lots of power. Then I put the motors in the boat and it was too rich in some spots and too lean in others. Once you get it right you will never go back to a carb setup again.

P.S. I am running 50 psi of fuel at idle and 56 at full boost using a modified fuel rail and Aeromotive pump.

29scarab

Its at Owens Racing in Pearland. He's been around since I was a lil' kid and now I'm almost 40. I trust him,, but your probably right about setting it in the ideal condition. How would I install the O2 sensor in my manifolds. I have stainless marine??

Thanks again

Smitty

iTrader: (1)

Take one off the motor and have your builder weld in an Oxygen sensor bung.

amer3

here ck out jeff set on his 33 scarab http://midwestboatparty.com/phpBB2/viewtopic.php?t=3982

JT Klein

You didn't mention if you are using the stock ECU. If your on the dyno you need an engine management system you can tune on the fly. IMHO you can reprogram the stock stuff till you blue in the face but you will never " nail it " for your unique application. Been there, done that, burned it down!