ACME Prop and rpm’s

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   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

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Darrel Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: June-16-2004 Location: United States Status: Offline Points: 340	Post Options Post Reply Quote Darrel Report Post Thanks(0) Quote Reply Topic: ACME Prop and rpm’s 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

Tim D Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: August-23-2004 Location: United States Status: Offline Points: 2635	Post Options Post Reply Quote Tim D Report Post Thanks(0) Quote Reply Posted: March-02-2005 at 6:35pm
	Did you switch from a 3 to 4 blade? Where do you live?
	Tim D

Darrel Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: June-16-2004 Location: United States Status: Offline Points: 340	Post Options Post Reply Quote Darrel Report Post Thanks(0) Quote Reply Posted: March-02-2005 at 7:13pm
	Yes, i was running an OJ 3 blade 14X16. I am in So. Calif.

64 Skier Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February-08-2004 Location: United States Status: Offline Points: 415	Post Options Post Reply Quote 64 Skier Report Post Thanks(0) Quote Reply Posted: March-03-2005 at 4:28am
	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 71CC

Tim D Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: August-23-2004 Location: United States Status: Offline Points: 2635	Post Options Post Reply Quote Tim D Report Post Thanks(0) Quote Reply Posted: March-03-2005 at 3:43pm
	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

new86owner Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Groupie Joined: August-02-2004 Location: United States Status: Offline Points: 78	Post Options Post Reply Quote new86owner Report Post Thanks(0) Quote Reply Posted: March-03-2005 at 6:23pm
	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.
	My 1986 SN 2001 FOR SALE!!!

David F Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum Member Joined: June-11-2004 Location: United States Status: Offline Points: 1770	Post Options Post Reply Quote David F Report Post Thanks(0) Quote Reply Posted: March-04-2005 at 1:14pm
	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.

Darrel Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: June-16-2004 Location: United States Status: Offline Points: 340	Post Options Post Reply Quote Darrel Report Post Thanks(0) Quote Reply Posted: March-04-2005 at 3:47pm
	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?

ACME Prop and rpm’s

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