can only turn 4000 RPMS on a 500 EFI, rebuilt drop in
 

Well like the title says, i have a 98 271 fastech. Motor went last year, so i bought this one and dropped it in. former motor was a 502, now ive got this rebuilt 500 EFI, supposedly 600+ HP, had 10 hours when i bought it, but it had a whipple on it prior. i can only turn about 4000 revs in it, GPS'ed 59 mph, too slow! old motor took the boat to 70 and had 500 HP. drive is a Bravo I, with a 28 pitch labbed prop. this thing should easily go 75 mph. that being said, the motor is running rich, like Warren Buffet rich....plugs are black after not much time. It idles ok, but will die sometimes if the stick is all the way back. prev owner said to just change the pressure regulator and i would be ok, it would just run a little rich. so that was done. its running a stock 500 EFI reg, with a return. out of the hole its a bit of a pig, but will plane out eventually. i can only put the throttle about 3/4" of the way forward until it wont go anymore, but i checked the throttle body and it seems this is as much as it will open anyways. i didnt know if using the black motor throttle linkage on a blue motor has anything to do with this?

i guess im asking, 1, is this thing running so rich that i just cant get any power out of it on the top, being that the tune is for a procharger? 2, is there something im missing thats causing me not to be able to get all the speed out of the boat that i should be.

thanks!

If its still tuned for the blower it's way too rich and prob gas washing it.

are the pistons still low compression pistons for the blower? if so... you created a pig.... no power..........

supposedly this thing was dynoed before the blower at 710 HP. hard to believe with the stock intake...i havent heard of a single one of these going above 650 with the merc intake. and then dyned at 900 something with the blower, so i know the power is there somewhere...

http://www.offshoreonly.com/forums/b...sport-90s.html
Might want to get in touch with this guy and see what's wrong with the motor.

That's incredible...how can u not love this forum! Going to PM him now. Endless thanks!!!

+1
If you lower the fuel pressure then you are leaning it out at the lower rpms and can cause major problems. You need to have the ECU reprogrammed. I would contact Whipple or any of the other guys on the forum to get it reprogrammed. Without knowing what parts are in the motor they will just be guessing on the program, so it may take a few attempts to get it programed. Whipple reprograms the ECU when you install the system, and you are running way to rich in the upper rpms and lowering fuel pressure will not fix your problem.

That motor is a 540ci, far from stock 500efi. so it's going to need a totally different tune atleast if the pro charger isn't on it anymore. That motor ran like a top in the Baja it was in.

According to that thread he never got it running right and totaled the boat?

Actually I just talked to the guy that built the motor, PM me and I'll give you his number and he will give you any/all info you want on it. Save you the run around.