alum. vs stainless

[jebb]

I have an evinrude 150 Ficht equipped with an aluminum prop. Performance is fine with good rpms and speed, but I have been told I could expect better performance with a stainless prop. Is that true? If I did change would I use the same dia and pitch as the alum. prop?

 

[walleyehed]

Re: alum. vs stainless

That depends on what RPM you are actually turning...what is your max RPM????<br />Yes, the SS will provide the "opertunity" to allow more performance in most cases...if you'll list your max RPM and with what aluminum prop, we'll start from there.

 

[jebb]

Re: alum. vs stainless

walleyehed -<br />maximum RPM is 5000 and present prop is 15X17

 

[Dave Abrahamson]

Re: alum. vs stainless

It sounds to me like you're about 7-800 rpm's low. Walleyehed will get ya set up, he knows his stuff.

 

[walleyehed]

Re: alum. vs stainless

That DFI is rated at 5250 as a max...5750 on the 175.<br />If your 15X17 is OEM, likely it's a 391200, which is one of the best aluminum props performance-wise you can use (In aluminum).<br />If we shoot for about 5300 (Factual evidence shows BRP testing that indicates anything below 5200 requires MORE gph, so we don't want to be below 5200 at WOT for best economy and obviously, best engine life...<br />My next recommendation would be based on the type of boat, and if you have a jackplate????<br />We can do some figuring, and pin things down a bit more if you can give me a few more details...

 

[gatorred]

Re: alum. vs stainless

stainless prop cost more to buy, weight more then alum is,but ss bit's water better and don't flex like alum can, don't forget this when getting a prop

 

[ricksrster]

Re: alum. vs stainless

Kenny, This question applies to this topic. If you go from aluminum to stainless, should you go down one inch in pitch?

 

[walleyehed]

Re: alum. vs stainless

Rick, as a general rule, yes...the SS is more efficient and pulls a bit harder in most cases, BUT, this does not take into account the fact that if it's an outboard, we may be able to raise the engine and use the same pitch or greater. Depends on current prop and set up.

 

[jebb]

Re: alum. vs stainless

walleyehed - boat is a 21' HydraSport (glass) CC. It is not equipped with a jack plate but does have trim tabs.

 

[jebb]

Re: alum. vs stainless

Additionally, the present prop is a 391200

 

[Dhadley]

Re: alum. vs stainless

Roger, are your tabs mounted (the base with the screws) flush (even) with the bottom? Or are they up slightly?<br /><br />IE -- when the tabs are parallel with the hull are they flush with the hull or are they up 1/4" or so?

 

[jebb]

Re: alum. vs stainless

They are up about 1/8"

 

[Dhadley]

Re: alum. vs stainless

Yeah, I have a 22 Hydra Sport and mine are mounted too low too. Bummer, huh?

 

[jebb]

Re: alum. vs stainless

Dhadley- I didn't realize that the tabs were mounted "too low" or that it was an issue. What are the consequences?

 

[Dhadley]

Re: alum. vs stainless

They are supposed to be mounted at least 1/4" up. Otherwise you'll never get them completely out and they will always effect the attitude. The sad but typical thing is, mine look like they were done at the factory. <br /><br />And folks swear the "factory" knows best.