Another BFN Prop Question.... |
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Air206
Grand Poobah Joined: September-28-2008 Location: Roanoke, VA Status: Offline Points: 3000 |
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Posted: October-15-2012 at 12:25am |
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Ok Prop Gurus....Here's the deal: 1991 Barefoot Nautique V-Drive with Stock 454 Previous Owner shortened the prop shaft (to remove the prop clearance issues that these boats have) and replaced the 3 blade with a 4 blade ACME "SAN Prop" (as told to me by the PO).....The boat is in the lift so I can't get any markings off the prop.....So, she should be able to accommodate any 1 1/8" Bore prop. The vitals: 46.9 mph (on GPS) @ 3600 rpm WOT So the question is........ Is she propped close enough for either end of the speed/use spectrum - Foiling/Wakeboarding/Trick on the low end and Barefooting on the upper end .... (ski wake is poor and we have the 206 for GREAT ski wake)... She just about pulled me out of my bindings on wakeboard start but doesn't want to hold under 20 mph.......she gets to 34-35 mph VERY easily.......and 3000 to 3600 rpm only give a few more mph top end. My Excel would only top out at 41-42 mph with the 240 HP PCM on the stock 3 blade and would work to get there...... the Barefoot climbs to speed easily but I still wonder if she's setup right...... What should I be expecting / looking for in a prop? Is this best result I can get for our purposes?........... Thanks! |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21183 |
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You've either got a grossly mismatched prop or a very inaccurate tach. 3600 is nowhere near where you want to be... And a prop holding you back that much would be a total slug, so I'm guessing your tach is wrong.
Based in what I've been told about the v-drive bfn's, you're missing a good 3mph. Tough to say why without an accurate idea of the rpms you're turning. Knowing your tranny and v-drive ratios, as well as your prop size would be critical as well. THEN we'd have the info we need to make a decent recommendation. |
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snipe
Senior Member Joined: July-13-2009 Location: United States Status: Offline Points: 157 |
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I had a situation very similar to yours. On my 351 PCM I had a 4 blade Acme 12.5X15 that gave me 45 MPH on a GPS @ 3800 RPM. I called Acme and Jim convinced me to put a 12.5X13 Three blade on. I did and the speed came up to 49MPH @ 5000RPM. Night and day. I know 5000RPM is a little high, but we don't hold it there anyway. Call him At 1.888.661.ACME. Great guy to talk to. He will have lots of questions to match prop and boat. Good Luck.
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Air206
Grand Poobah Joined: September-28-2008 Location: Roanoke, VA Status: Offline Points: 3000 |
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That's why I'm posting..... the prop feels wrong. The tach is original and 21 years old but it behaves reasonably and idles at the right rpms.... think my prop is WAYYYY off. The build sheet from Correct Craft (Thanks Godfather!) lists 51 mph at testing prior to leaving the factory.... so I know she's got more in her if she were set up right. |
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Air206
Grand Poobah Joined: September-28-2008 Location: Roanoke, VA Status: Offline Points: 3000 |
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I'll track the rest of the info down (if I ever can get the boat back onto a trailer....lake level low and trailer issues) and contact ACME.
Thanks for the contact info Snipe! |
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hotboat
Gold Member Joined: March-28-2009 Location: Conn Lake Pa Status: Offline Points: 814 |
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1.21 drive ratio, an acme 380 13x17 or you could go 13x16 for more holeshot either should do 50
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Brian
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21183 |
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Steve, youre going to have to help me out here. What makes you think the prop is way off? This comment gives the impression that you think it has a pretty strong holeshot:
A prop that is legitimately retarding your performance by 800+ rpm would be a real dog out of the hole. |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21183 |
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FYI, Acme lost their lead applications engineer (Bill Weeks) to retirement a few months back. Since that point, some of the recommendations that Ive seen come from them have been questionable at best, including the application of the 1214 on a 351w powered 2nd gen (above). I would expect that you would get better advice right here on CCF... after all, Acme's best data comes from people like us in the first place.
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Air206
Grand Poobah Joined: September-28-2008 Location: Roanoke, VA Status: Offline Points: 3000 |
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Gotcha.... I'll check the tach, the ratios, the current prop, etc....I'll do my homework.
Good to get some starting point recommendations and props to think about for comparison... Thanks guys! |
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Air206
Grand Poobah Joined: September-28-2008 Location: Roanoke, VA Status: Offline Points: 3000 |
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But OJ took back their rec'd prop that didn't work on our Excel ....Reasons why to use a manufacturer and a dealer... it wasn't a several hundred dollar mistake.....Just looking for a starting point for the prop discussion.
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hotboat
Gold Member Joined: March-28-2009 Location: Conn Lake Pa Status: Offline Points: 814 |
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Would like to know exactly what prop is on it now
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Brian
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snipe
Senior Member Joined: July-13-2009 Location: United States Status: Offline Points: 157 |
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One more comment for what it's worth...
Acme is a CNC machined prop v.s. cast and hand finished. The blades are thinner but larger than a cast. Better hole shot for my set up. As far as performance it was night and day for vibration. CNC are in my opinion, far better when it came to vibration issues. I got "none" with mine. I'm not trying to sell anyone on Acme; just my two cents on my experience with them. They also were willing to take the prop back if it didn't perform as eected. I kept mine because they nailed it the first time. |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21183 |
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Im an Acme guy as well... their props just seem to run better on everything Ive had the chance to compare. OJ does offer a CNC line of props (XMP), though their selection for CC's (RH) is pretty limited.
Werent there driveline reduction changes sometime during the Excel's lifetime? Confirming the tranny and v-drive ratios will be key. Id put a shop tach on it as well to confirm the RPM's regardless of whether you think its a major source of error or not. Oh, and Delta will allow you to try and return props within a window as well- no need to go directly to the manufacturers (who tend to charge full retail in order to protect their dealer network). |
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shirley0123
Newbie Joined: October-09-2012 Location: USA Status: Offline Points: 2 |
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Now if you want to join an outdoor activity, such as rock climbing, I suggest you a pair of Onitsuka Tiger Mexico 66 shoes. I can guarantee you that Asics Onitsuka Tiger shoes are very likely to be your finest life partner, which is so great.
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Air206
Grand Poobah Joined: September-28-2008 Location: Roanoke, VA Status: Offline Points: 3000 |
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Ok...found PO Notes.... looks like an ACME 1160 - 13.5 x 16VR4B 0.135cup is what is on it now...
BTW Shirley, ...I don't need any shoes...Thanks! Boy, She posts as much as Pete! |
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hotboat
Gold Member Joined: March-28-2009 Location: Conn Lake Pa Status: Offline Points: 814 |
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That prop should be good, and should perform well out of the hole. The rpm and speed you're getting make me wonder if the secondaries are opening on the carb? Does it have a protec ignition?
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Brian
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21183 |
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The speed vs. RPM numbers that were posted (46.9mph @ 3600rpm) are not consistent with a "normal" sized prop. A 1.21 driveline ratio should mate well with a ~13x16 prop, and turn within a few hundred rpm of 1:1. IE, 47mph should be ~4700rpm +/-. If he had discovered a 13x20 prop on there, then the numbers may have been believable, but thats not the case. Theres just no way that the tach can be correct. There may still be a slight tuning or prop mismatch issue that we can help pinpoint (to identify the ~3mph loss in speed vs. expected), but we still cant figure out what those are without accurate RPM info. |
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hotboat
Gold Member Joined: March-28-2009 Location: Conn Lake Pa Status: Offline Points: 814 |
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I had a 17.5 pitch on, could a 16 slow it down that much? If so his Rome I would guess would be 45 - 4800. My tach rarely read anything close either but by ear you should be able to pick a 1000 rpm difference.
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Brian
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Air206
Grand Poobah Joined: September-28-2008 Location: Roanoke, VA Status: Offline Points: 3000 |
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Also sent along with the boat an OJ 14x18 prop...
ProTec still on it........... |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21183 |
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Possibly... depends on what revs he's turning. If its well beyond the power peak (4400-4600) then that may be part of the issue. Do you know how many revs you pulled that 17.5" pitch? |
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hotboat
Gold Member Joined: March-28-2009 Location: Conn Lake Pa Status: Offline Points: 814 |
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No I don't, by ear I'd call it 42 - 44
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Brian
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21183 |
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Whats the stock prop on these things? Some were 1.21, some were 1.5 ratios? Small blocks should have gotten smaller props.
14x18 sure seems big for a 1.21 ratio... even for the big block. (The 1:1 direct drive big blocks used 14" pitch, 14 * 1.21 = 16.94... so a 17" pitch would have made more sense). Did you get up to full RPM in your quick video? |
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hotboat
Gold Member Joined: March-28-2009 Location: Conn Lake Pa Status: Offline Points: 814 |
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Acme made a prop for the small blocks, as far as I know they did not for the bbs, Don could tell us the specs on the sb prop I believe
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Brian
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6157 |
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Tim, I think Bruce told me the original prop on a V drive BBC footer was a 13x14. I'll try and verify. Marks 91 is fresh with MSD and a performance Eddy intake. He claims right af 50mph GPS 4200.
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hotboat
Gold Member Joined: March-28-2009 Location: Conn Lake Pa Status: Offline Points: 814 |
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That'd be a 90 and earlier dd not vdrive, you're at a dealer correct? Pick up the acme book and it lists the specific prop made for 91 n up excel sb
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Brian
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hotboat
Gold Member Joined: March-28-2009 Location: Conn Lake Pa Status: Offline Points: 814 |
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Did a little research, acme 328 13 x 15.5 small block boats 1.21 ratio. Seems a few got the 1.5 ratios not many and got an 18 pitch. Back to original post, 16 to 17.5 pitch on bbcs with 1.21 ratio
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Brian
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6157 |
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328. There isn't much of a selection in the RH 1-1/8 stuff.
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21183 |
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Assuming all the v-drives got some sort of reduction (be it 1.21 or 1.5), 13x14 is not the correct size prop for any of them. That would be too short for even a small block. 14x14 was the common size on 81-89 (1:1) direct drives.
Lots of RH 1-1/8" props available... though if the Excels have rudder clearance issues, not all may fit? Acme ski boat list |
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hotboat
Gold Member Joined: March-28-2009 Location: Conn Lake Pa Status: Offline Points: 814 |
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Last I was at a dealer n looked in the book they broke it down to specific boat models but it's been yrs and were talkin a 20 yr old boat but that 328 is the pancake they made for the sb boats
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Brian
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6157 |
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Apparently the 13.25 is not to large in diamater so ACME says the 644 has been used multiple times on BBC 1.21 applications. I was just unclear if anything larger than 13 would be to close to the hull.
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