Going up on prop pitch need some thoughts
10-29-2020 | 10:59 AM
#11
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From: Ringwood + Manahawkin, N.J.
How much does your boat weigh? I'm running 945 horsepower with IMCO scx's and getting the same speeds you are. If we are similar in weight, my tiger weighs around 10,500 lbs, then you should be easily into the mid to high 110's. Again I'm thinking there may be something off with your speedo. A truely accurate measurement from something like a v-box or dragy would answer some of our questions.
I don't mind losing some rpm to gain speed seems everyone wants the engines running at 6000 why is that?
In my 22 donzi 502 mpi bbc I went from a 23p tempest 3 blade @5200(hitting rev limiter) and 70mph gps accelerates hard and gets to top speed very fast
Switched to a 4blade hydromotive 25p hit 71mph at 4800rpm boat was too tight in the water but got to top speed moderately quick
Then switched to a 27p mirage 3 blade hit 74.3 mph at 4800 it's sluggish takes a while to get up to max speed but it's the fastest with that prop and that's what I like I don't mind if it's sluggish. And it gives me room to make improvements like remapping ecu
Right now with the nortech it has incredible pin you back in the seat torque once on plane. I feel I could lose some rpm and gain some top speed. I know there are various ways of thinking for prop selection and for me I'm a top speed guy and don't mind if I have to tweak trim and have it slowly get up to top speed instead of instantaneous top speed but I don't want it too sluggish
Last edited by beerock; 10-29-2020 at 11:09 AM.
10-29-2020 | 11:04 AM
#12
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From: Ringwood + Manahawkin, N.J.
I would try dropping down to a 32 pitch prop. This should allow you to turn the needed rpm without trimming up the drives to do so. Right now it sounds like you are just trimming the drives up too far which is causing the props not be in the water enough, inturn giving an increase in slip and rpm but no mph gain. I have a set of 32 pitch herrings on my 42 cigarette tiger which allows me to run 105 at a little over 6000 rpm. I have IMCO scx drives so I should be seeing more slip than you normally would. I think your boat is simply over propped with the 34's.
10-29-2020 | 11:45 AM
#13
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From: Michigan
My herrings are 5 blades, 15.25in diameter. They are bravo style props so I'm not sure on the rake but it is not a lot, maybe 15 degrees.
As for wanting the motors at 6000 rpm vs 5500. As long as you are making good power at 6000 rpm, close to peak, then you will help the best mechanical advantge, ie the fastest speeds. From talking to Teague it sounds like your props are just too large in diameter. They said the supervee's should have props closer to 17 or 17.5 inches. You could get your props taken down to a smaller size by Mercury, Herring, or BBlades. Your best bet would be try and get a set of 17x32x18's off of someones boat and give those a shot. You should gain a little slip and more mph.
As for wanting the motors at 6000 rpm vs 5500. As long as you are making good power at 6000 rpm, close to peak, then you will help the best mechanical advantge, ie the fastest speeds. From talking to Teague it sounds like your props are just too large in diameter. They said the supervee's should have props closer to 17 or 17.5 inches. You could get your props taken down to a smaller size by Mercury, Herring, or BBlades. Your best bet would be try and get a set of 17x32x18's off of someones boat and give those a shot. You should gain a little slip and more mph.
10-29-2020 | 12:05 PM
#14
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From: Ringwood + Manahawkin, N.J.
My herrings are 5 blades, 15.25in diameter. They are bravo style props so I'm not sure on the rake but it is not a lot, maybe 15 degrees.
As for wanting the motors at 6000 rpm vs 5500. As long as you are making good power at 6000 rpm, close to peak, then you will help the best mechanical advantge, ie the fastest speeds. From talking to Teague it sounds like your props are just too large in diameter. They said the supervee's should have props closer to 17 or 17.5 inches. You could get your props taken down to a smaller size by Mercury, Herring, or BBlades. Your best bet would be try and get a set of 17x32x18's off of someones boat and give those a shot. You should gain a little slip and more mph.
As for wanting the motors at 6000 rpm vs 5500. As long as you are making good power at 6000 rpm, close to peak, then you will help the best mechanical advantge, ie the fastest speeds. From talking to Teague it sounds like your props are just too large in diameter. They said the supervee's should have props closer to 17 or 17.5 inches. You could get your props taken down to a smaller size by Mercury, Herring, or BBlades. Your best bet would be try and get a set of 17x32x18's off of someones boat and give those a shot. You should gain a little slip and more mph.
Going to a 17 or 17.5 will increase rpm but I get it, you thought I wanted an increase in rpm which is opposite of what I want. Also I'm running m6 race drives which is apples to oranges comparing your imcos even though the drag is more then a bravo I'm pretty sure it's less then a nxt/#6/m6 drive I could be wrong though.. who told you that at teague about the nortechs, curious . Usually nortechs run around 90-95mph wot I can cruise easily at 90
Last edited by beerock; 10-29-2020 at 12:33 PM.
10-29-2020 | 12:53 PM
#15
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From: Omaha/LOTO
You should be fine propping it to run anywhere from 5500-6000rpms at WOT. I wouldn't prop it to run less than 5500rpms. It puts more load on the engine even though the rpms are lower, Kind of like when a truck is going up a steeper hill.
Have you called Nortech?? Not sure what boat you have, but there was one with 1200's at LOTO a few years back.
Have you called Nortech?? Not sure what boat you have, but there was one with 1200's at LOTO a few years back.
10-29-2020 | 01:47 PM
#16
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From: Michigan
I recognized that you were looking to drop rpms and try to gain speed but that is unlikely to work. I agree with Griff, when you are running your topspeed you should be between 5600-6000. Anything less and you will not be getting all of the horsepower that you could. Thus a smaller diameter, easier to spin prop, should help resolve your issues.
