Impeller selection

[Speednn]

Is anyone running concord 14/18? I have a ported 760 with a protec head and a riva red pipe. I care more about top speed for racing. Was wondering if the 14/18 would be too steep for my setup.

 

[Speednn]

Forgot to mention I also have group k modded 38s and a tdr water box.

 

[kevbo]

Yes, much too steep. It can easily be bent a little flatter and work well.

 

[fastgtfairlane]

If you're looking for top end, why not swap the 38s for 44s? You'll make a noticeable improvement with the 44s from around 1/4 throttle up

 

[Speednn]

Was trying to preserve some fuel efficiency. I think I’m going to try the 14/18 and go bigger on the nozzle if I have to.

 

[kevbo]

Try it, if it’s too much load it will be very slow spooling up to the pipe. Until a few years ago nearly all available Yamaha impellers overloaded the engine. I have flattened out a lot of them and it saved the owner a lot of frustration.

 

[Speednn]

Try it, if it’s too much load it will be very slow spooling up to the pipe. Until a few years ago nearly all available Yamaha impellers overloaded the engine. I have flattened out a lot of them and it saved the owner a lot of frustration.

True…I just ordered the concord 13/17A for 200 on eBay. Guy said he only used it one time. It looks brand new. Hopefully it’s not one of the older steeper props.