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Originally Posted by sutphen 30
(Post 4638737)
I don't use the extra injectors(80lbs also),I run 60lbs in the rails,most boost I've ever seen is 4.5psi and I have(when I tried to lean the motor out for some type of cruise economy :D)seen a couple of degrees of retard here and there.when in boost,I run 31-32 ° and out out boost kinda aggressive w/ timing,all in by 3000rpms.I've been running it like that for 12yrs.run a full maximus 32pitch props,only thing That gets me on plane,so a pretty good load.I've never dynoed my motors.
how's your timing in comparison? |
Originally Posted by articfriends
(Post 4638925)
what size motor, what size upper pulley for 4.5 lbs boost?
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Originally Posted by articfriends
(Post 4638858)
re-pinned his mefi1 harnesses to mefi3, rooted out the knock module, turned setting to "on" for 2 bar map sensor, added boost multiplier to bpw boost table (added 45% at 150 kpa, graduated up to that). I also switched from firing the injectors once every 4 stroke revolution to once every revolution, cuts pw in half automatically but then you add a little pw for the two dead bands. That helps even up the afrs in these mpi engines. I also developed the spark reduction table above 100 kpa. Because a mefi 3 is cruder than a 4 (boost table does NOT scale to rpms), you have to tweak the 100 map tables anywhere its rich or lean after finding a happy medium in boost multiplier table. I really like mefi now that i been doing it a while.
I invested in a 8 pak o2 sensor system too for my dyno so i can go back after pulls and look at sll the cylinders and quickly make fuel corrections, Smitty |
Left motor 1 on dyno while i finish its twin. Ordered next size bigger pulley to try on supercharger, heavy boat, just shy of 9-1 w iron heads, little innercooler, might not get longevity out of w 7.5 lbs boost. Ive ran more than that on iron headed motors w prochargers BUT they made the higher boost on top, not acrossed the board. keeping the 3 1/8 pulleys that made 750 something, will be selling the 2.900 and 2.625 whipple pulleys down the road if anyone's interested, Smitty |
forgot to add,compr. ratio is 9-1.figure I'm not in boost most of the time,,light boat,so no need to make the motor a slug when not in boost.
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Finished up with motor 1 today on dyno. So we ordered the next two bigger size pulleys. Had a harmonic balancer seal leak i fixed, put dui module back in distributor since we found the coil as cause of this thing breaking up earlier in testing.
Pulled it w 3.375 pulley, was just shy of 700 hp (695), (showed 707 on depac), made 4.5 to 5.5 lbs boost thruout the pull Pulled it with 3.250 pulley, made roughly 725 hp (723 to 728 on couple different pulls as i smoothed out tune). Made just under 6 to about 6.5 psi of boost. So im ready to move on to #2, these are going to go in boat w the 3.375 pulleys at 700ish hp for durability . Customer had 385 hp previously so will still be a big jump. We can always bolt smaller pulleys on in boat if its not enough! |
Curious,what rpm was the peak hp/tq?
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Originally Posted by sutphen 30
(Post 4640552)
Curious,what rpm was the peak hp/tq?
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With the "6 lb pulley" we saw 640 ft lbs from 2900 to 5900 peaking at 684 at 4400 but again, from 3800 to 4600 was 680 or higher so no "real" peak. Max hp was at 5900
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Good to know, now I kinda know what I have.
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