[dominator scott]

NEED HELP FROM ANYONE WHO HAS SOME
INPUT.HAVE A FRIEND WHO HAS A 98 22 FT.
SCARAB WITH A 7.4 ,CARB. ENGINE NOT A MAG.
COMPLETLY STOCK,WITH BRAVO DRIVE &23P
MIRAGE PROP.
MOTOR IS NOT MISSING & DOES'NT SEEM TO BE
HITTING REV LIMITER ,BUT WILL ONLY TURN
4600 RPM'S AT W.O.T.,&TRIMMED OUT. SEEM'S A LITTLE LOW TO ME.
I TOLD HIM TO GO BUY A SUNSATION,BUT HE
DID'NT SEEM TO SHARE MY OPINION.ha,ha

DOES ANYONE HAVE ANY IDEAS WE CAN TRY!

 

[OldMagicfloat]

Im not the expert, but I think that 4600 is the limit for those motors. I have the same motors but MPI and it says 4400-4600 RPM.

 

[Speedwake]

nasdboy raises a good question. Has the engine ever turned rpms high than what he's seeing now?????

- jeff

 

[dominator scott]

HE JUST BOUGHT BOAT LATE LAST SUMMER,SO
IN ANSWER TO YOUR QUESTION,NO 4600 RPM'S IS PROBABLY IT.WHAT STARTED THIS
WHOLE THING IS BEFORE I BOUGHT MY 32
DOMINATOR,I HAD A 91 BAJA 223 BANDIT WITH
THE SAME MOTOR,AND EVEN BEFORE I MODIFIED MINE,I WAS TWISTING 4900 TO 5100 RPM'S WITH A 23MIRAGE .
WHAT WOULD YOU SUGGEST .MY OPINION IS
AN EDELBROCK RPM INTAKE AND HOLLEY 750
VACUUM SECONDARY CARB,ALONG WITH A
K&N,WHICH IS WHERE I STARTED ON MY BAJA
AND WENT FROM THERE.

OPEN TO SUGGESTIONS AND COMMENTS!

 

[obnoxus]

thats exactally where it shoud be,,, my 454 350 hp plus headers turned the same prop same rpms

 

[dominator scott]

SORRY OBNOXUS WHAT IS EXACTLY WHERE IT
SHOULD BE 4600 OR 5000 RPM'S?

 

[jimgoog]

I have the same motor 99 version MPI however. Rev limit on mine is supposed to be 4600. I believe that the tachs Baja installs are slightly off because mine shows 4900 and I do not think I am hitting the limiter yet either. I also run a 23 pitch mirage on a hammer. Not labbed.

 

[crmax]

sound to me like it right where it needs to be, its real close to the rev limiter what is the mph using a gps? should be around 65. new cam, heads (from a 7.4 mpi) good intake, carb and exhaust will get you another 100hp

 

[cuda]

I don't think I would twist that engine much higher. It doesn't have the heavy duty bottom end. Unless you don't mind rebuilding it once a year or so.

 

[MXZ800]

try throwing a smaller prop on it and see if it will wind up tighter or if it is hitting the rev limiter at 4600

 

[obnoxus]

should be 4600,,,,,,, rev limiter should have come in just before 4700,,,, my guess is your factory tach is not accurate either

 

[dominator scott]

update on the rpm problem with scarab he
thought it was a 23 mirage,but in fact it is a
25 mirage plus spinning 4600 rpm's.
boat also has hard time getting up on plane.

what is everyones technical opinion,drop to
23 pitch,or breath on the motor a little?

 

[jimgoog]

Try the 23 at a demo dealer and see what that does. May not help getting out of the hole much, but will give him a 1-3 hundred more rpms and let the engine run with a little less stress.

 

[obnoxus]

yep ,,, drop to a 23,,, Its hard to believe he is spinning a 25 to 4600 though,,, I would double check the tach

 

[crmax]

I agree , he must have a damn good running 330 to turn a 25. I have a 23 and can pull a sking right up with no problem but it tops out around 4400-4500 rpms