More HP or Torque
#1
More HP or Torque
Trying again with a new thread: Formula PC27 single 502 weighing 10000 pounds. Need more of something to get me out of the hole. WOT at 4700 RPM doing 45 MPH 1/2 tank fuel reading with a GPS, normal cruise at 3600 RPM at 32MPH. Put six folks on the boat and other stuff and it has a heck of a time getting on plane, turns 3750 RPM to do 32 MPH. Have a 2:1 bravo 3 drive turning 22 degree pitch props. Do I build/buy a 540 or do change out rectangular port heads for oval port (oval port heads suggested by another offshore member). I'd like to go through the engine this fall and have it ready for spring.
#2
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Fixx
Trying again with a new thread: Formula PC27 single 502 weighing 10000 pounds. Need more of something to get me out of the hole. WOT at 4700 RPM doing 45 MPH 1/2 tank fuel reading with a GPS, normal cruise at 3600 RPM at 32MPH. Put six folks on the boat and other stuff and it has a heck of a time getting on plane, turns 3750 RPM to do 32 MPH. Have a 2:1 bravo 3 drive turning 22 degree pitch props. Do I build/buy a 540 or do change out rectangular port heads for oval port (oval port heads suggested by another offshore member). I'd like to go through the engine this fall and have it ready for spring.
option 2 pull the 502 and and sell it, change stringer arrangement and drop a pair of 6.2 mpi's in it and reuse your gimball and drive and add another..
option 3 sell the boat and find a 28ss and save a ton of money on converting your current boat..
#3
21 and 42 footers
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That is a HEAVY boat for a single engine. You can build more motor......but set aside enough $$$ for another drive, you'll be buying one of them soon. Best bet is to drop pitch to get the RPM's up. I'm assuming you have the 502mag (fuel injected) which should have a recommended WOT of 5,000 rpms. Prop the boat to get to that and you'll likely have enough "umph" to get on plane when loaded down.
Actually, you should probably have your props sent out with instructions to tune them to acheive what I described. A good shop should be able to work them and if they have any damage what-so-ever, you shouldn't loose any performance.
BTW: HP makes you go fast, TQ will get you out of the hole.......but TQ is what breaks drives!! (I know, made 700 TQ and busted a couple XR's)
Actually, you should probably have your props sent out with instructions to tune them to acheive what I described. A good shop should be able to work them and if they have any damage what-so-ever, you shouldn't loose any performance.
BTW: HP makes you go fast, TQ will get you out of the hole.......but TQ is what breaks drives!! (I know, made 700 TQ and busted a couple XR's)
Last edited by t500hps; 09-21-2010 at 07:27 PM.
#8
Probably should have mentioned my WOT use to be 4800 RPM but forgot about some of the slime that builds up. I have four sets of props and tried verious things just to get it up quicker, different rakes and cupping. Matter of fact I mis spoke I currently have 24 pitch props on it. When I run 22's it creeps to close to 5000 and I'm turning 3700 to 3800 to stay on plane. When I'm up that high I start getting in to the major fule burn issue. The 3600 RPM range gets me about 1 MPG. With the wife and I it does OK and I know it's not a runabout but I'm looking for what is the best choice. I do have trim tabs and they are all the way down, without them I don't stand a chance of getting up unless by ourself. If I can just figure out the right way to go.
#9
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Probably should have mentioned my WOT use to be 4800 RPM but forgot about some of the slime that builds up. I have four sets of props and tried verious things just to get it up quicker, different rakes and cupping. Matter of fact I mis spoke I currently have 24 pitch props on it. When I run 22's it creeps to close to 5000 and I'm turning 3700 to 3800 to stay on plane. When I'm up that high I start getting in to the major fule burn issue. The 3600 RPM range gets me about 1 MPG. With the wife and I it does OK and I know it's not a runabout but I'm looking for what is the best choice. I do have trim tabs and they are all the way down, without them I don't stand a chance of getting up unless by ourself. If I can just figure out the right way to go.
# 30 http://www.mercruiserparts.com/Show_...nd+Drive+Gears
#10
remove the outter trim ram pin,their should be a white trim insert where the pin slides through,try noving the insert to the rear of the pin hole..this will tuck the drive closer to the transom and hopefully this may help you get on plane quicker..
# 30 http://www.mercruiserparts.com/Show_...nd+Drive+Gears
# 30 http://www.mercruiserparts.com/Show_...nd+Drive+Gears