ACME Prop and rpm’s
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Category: General Correct Craft Discussion
Forum Name: General Discussion
Forum Discription: Anything Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=1274
Printed Date: December-04-2024 at 2:31pm
Topic: ACME Prop and rpm’s
Posted By: Darrel
Subject: ACME Prop and rpm’s
Date Posted: March-02-2005 at 5:09pm
| Last weekend i had the opportunity to try out my new Acme (#422)4 blade prop. I have a 95 ski naut. w/ 351HO pro boss. Motor has always tached out to 4800 @WOT. With the new prop out of the hole is great, top speed is also good and about the same as with other props ive tested (about 47-48mph). However, the big difference is now i can only tach out to about 4500 rpms. Should this be a concern that ive lost 300 rpm? Will it damage engine or trans? Tach appears to be operating normal and proper. Thanks in advance. Darrel |
Replies:
Posted By: Tim D
Date Posted: March-02-2005 at 6:35pm
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Did you switch from a 3 to 4 blade? Where do you live? ------------- Tim D |
Posted By: Darrel
Date Posted: March-02-2005 at 7:13pm
| Yes, i was running an OJ 3 blade 14X16. I am in So. Calif. |
Posted By: 64 Skier
Date Posted: March-03-2005 at 4:28am
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At max RPM you know your engine is fully loaded and typically a 4 blade has more drag than the 3 blade so I think what your describing is pretty common after the switch in prop's. I bet the hole shot is fun with the 4 blade.
A fully loaded engine at 4500 RPM should be no problem...but if you had lowered the pitch more and gone over 5000 RPM you may be in trouble and over the hump on a HP curve so IMO the 4500 is OK. ------------- 64 Skier 66" HO VTX and 67" HO Triumph http://www.correctcraftfan.com/diaries/details.asp?ID=1071&sort=&pagenum=3&yrstart=1971&yrend=1975 - 71CC |
Posted By: Tim D
Date Posted: March-03-2005 at 3:43pm
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Well the 4 blade improved the hole shot, but maybe on top end you're seeing that the extra blade has made more resistance but at the same time its more efficient with lower rpms. ------------- Tim D |
Posted By: new86owner
Date Posted: March-03-2005 at 6:23pm
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Why didn't you go with the ACME 540 or 542. ACME claims the 3 blades are better than the 4 blades.
I love the 542 for wakeboarding. ------------- http://trianglewatersports.com/Ebay/sn.html" rel="nofollow - My 1986 SN 2001 FOR SALE!!! 
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Posted By: David F
Date Posted: March-04-2005 at 1:14pm
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According to ACME, they do not make a 3-blade prop suitable to the mid 90's SN's. I talked to ACME as well and also purchased the 422 due to their knowledge and advice. I have yet to try the prop as I am still repairing the hull on my '93 SN.
I agree with 64Skier that 4500rpm at WOT is fine and maybe even optimal for the 351W. Remember Ford and Chevy small blocks are not high revving engines and make most of their torque and HP at low revs. I am sure their is a torque/HP curve on the internet somewher to reference. |
Posted By: Darrel
Date Posted: March-04-2005 at 3:47pm
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new86, the 540 is made for the earlier, smaller Nautiques dont kno about the 542. I contemplated the 3 blade 612 when speaking with Bill Weeks at Acme. He said that soon he will have a 3 blade that will blow away all other props. That could be my "next" prop. Then i found a deal too good to pass up on the 4 blade on Planutnautique.
I appreciate everyones input on this topic. I am e mailing w/ Bill Weeks now, maybe a little cupping or adjustment will make a difference, maybe lower rpm = engine longevity? |