Steve Lewandowski
Member
- Joined
- Apr 27, 2012
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- 13
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01 tournament V-18 with a 90 4stroke merc. Original prop from guy i got boat from 13.25--17P 3 blade. Top speed on dash gauge 42mph and tach reading around 5200rpm. Prop has a few dings and we dont care for how long it takes to planes off so we went ahead and ordered one from local Bass Pro store. Wanted to try the new spitfire 4 blade because its supposed to help with plane. Guy behind counter looked in some books and said we need a 12.5 - 19P for our boat/motor. Said it will push more water and keep same top speed if not more and get better holeshot.
Took 7 weeks to get and heres what we got.
Put it on today and holeshot/plane was alot faster--we really liked how it gets up and moves but heres the kicker(if any) our top speed is 38-40 mph and the tach will only get to 4000-4200rpm at full throttle. If I'm going say 5-10mph and hammer down the motor stalled twice--never happened before with 3 blade 17p. Is this prop pitch too much for our motor. Motor sticker says max RPM 6000--its a 4 stroke--will this hurt it lugging motor this much. Please chime in and give me some options/ideas as what to do if any.
re: 4 blade Spitfire prop review-i think i got too much pitch--need help?? by Bob B.,5/22/2012 07:32 ET
If you were only getting 5200 rpm with a 17", the correct prop would be a 15".....to "recommend" to go up on pitch when that motor needs to be propped to turn close to 6000 is crazy. Yes, you could hurt the motor by "lugging" it. I'd return the prop and get the correct pitch, which would be the 15". Merc props are generally sized pitch-for-pitch to achieve similar top end rpm.....
All of the above information is based on your motor being in a "good-state-of-tune"....
Certified Merc Service Manager ......cut me and I bleed BLACK.
re: 4 blade Spitfire prop review-i think i got too much pitch--need help?? by scuba147,5/23/2012 00:56 ET
By going to a 15P would our top speed go way down or would the motor be able to turn easier/faster making up the difference for the smaller pitch. We were hitting 42 on the dash gauge before we started the prop extraganza-lol. Thanks for the reply Bob!
I will give updates when we get the new prop just deciding between 15 or 17p???? I am leaning toward 15P Bass Pros says 17P. Does the diameter matter a whole bunch?
This spitfire prop did what it was supposed to do but it was not the right size for our setup as of yet. I hope this info helps others out. Steve
re: 4 blade Spitfire prop review-i think i got too much pitch--need help?? by Bob B.,5/23/2012 07:47 ET
I know speed is "nice", but honestly, irrelevant. The WOT RPM is CRUCIAL to engine longevity, and proper boat performance. See first response.
Certified Merc Service Manager ......cut me and I bleed BLACK.
re: 4 blade Spitfire prop review-i think i got too much pitch--need help?? by scuba147,5/27/2012 14:57 ET
well got a 15 pitch spitfire prop and holy cow!! Boat really gets up and scoots--planes in a second or two!!! From the first time I gassed it I tell what a difference. My dad actually could use the boat with out--why wont it plane- etc. He is new as so am I but I grasp new things better due to younger age--LOL.
Here are our results-- 5200-5300 WOT rpm and 38-40 mph on our dash gauge-I think this should be ok for max RPM I hope??-if we lost a few mph it is so worth it in how it speeds up. The prop will blow out if we make a sharp turn and its trimmed up but only happened twice in 45 minutes of boating. Our motor is in the middle hole and seems to be somewhat "dialed in". Motor actually sounded alot more peppy. Did notice that is you slowed gas down right away you could hear it like free wheeling so we ease into slowing down more now.
Thanks for you help Bob---if we want topspeed we can throw our 3 blade on but its fun getting to speed faster than waiting like a train to get going. Now gotta get our trim switch on handle replaced due to up does not always work--only in full throttle((works from bow so its should be the switch). Have a safe weekend!!!
Took 7 weeks to get and heres what we got.
Put it on today and holeshot/plane was alot faster--we really liked how it gets up and moves but heres the kicker(if any) our top speed is 38-40 mph and the tach will only get to 4000-4200rpm at full throttle. If I'm going say 5-10mph and hammer down the motor stalled twice--never happened before with 3 blade 17p. Is this prop pitch too much for our motor. Motor sticker says max RPM 6000--its a 4 stroke--will this hurt it lugging motor this much. Please chime in and give me some options/ideas as what to do if any.
re: 4 blade Spitfire prop review-i think i got too much pitch--need help?? by Bob B.,5/22/2012 07:32 ET
If you were only getting 5200 rpm with a 17", the correct prop would be a 15".....to "recommend" to go up on pitch when that motor needs to be propped to turn close to 6000 is crazy. Yes, you could hurt the motor by "lugging" it. I'd return the prop and get the correct pitch, which would be the 15". Merc props are generally sized pitch-for-pitch to achieve similar top end rpm.....
All of the above information is based on your motor being in a "good-state-of-tune"....
Certified Merc Service Manager ......cut me and I bleed BLACK.
re: 4 blade Spitfire prop review-i think i got too much pitch--need help?? by scuba147,5/23/2012 00:56 ET
By going to a 15P would our top speed go way down or would the motor be able to turn easier/faster making up the difference for the smaller pitch. We were hitting 42 on the dash gauge before we started the prop extraganza-lol. Thanks for the reply Bob!
I will give updates when we get the new prop just deciding between 15 or 17p???? I am leaning toward 15P Bass Pros says 17P. Does the diameter matter a whole bunch?
This spitfire prop did what it was supposed to do but it was not the right size for our setup as of yet. I hope this info helps others out. Steve
re: 4 blade Spitfire prop review-i think i got too much pitch--need help?? by Bob B.,5/23/2012 07:47 ET
I know speed is "nice", but honestly, irrelevant. The WOT RPM is CRUCIAL to engine longevity, and proper boat performance. See first response.
Certified Merc Service Manager ......cut me and I bleed BLACK.
re: 4 blade Spitfire prop review-i think i got too much pitch--need help?? by scuba147,5/27/2012 14:57 ET
well got a 15 pitch spitfire prop and holy cow!! Boat really gets up and scoots--planes in a second or two!!! From the first time I gassed it I tell what a difference. My dad actually could use the boat with out--why wont it plane- etc. He is new as so am I but I grasp new things better due to younger age--LOL.
Here are our results-- 5200-5300 WOT rpm and 38-40 mph on our dash gauge-I think this should be ok for max RPM I hope??-if we lost a few mph it is so worth it in how it speeds up. The prop will blow out if we make a sharp turn and its trimmed up but only happened twice in 45 minutes of boating. Our motor is in the middle hole and seems to be somewhat "dialed in". Motor actually sounded alot more peppy. Did notice that is you slowed gas down right away you could hear it like free wheeling so we ease into slowing down more now.
Thanks for you help Bob---if we want topspeed we can throw our 3 blade on but its fun getting to speed faster than waiting like a train to get going. Now gotta get our trim switch on handle replaced due to up does not always work--only in full throttle((works from bow so its should be the switch). Have a safe weekend!!!
