06-17-2007, 10:36 AM #1
VX 110 Impeller testing - Concord YH-CD 18/24
Original Testing - June 17 2007
Testing was done with an unported GP1300R stage II ski
I have been working with the Solas Concord YH-CD-18/24 impeller designed for the VX110 for 9 months now. I have been testing this on my carbed unported 1300 GPR.
To do this I copied the VX110 pump set-up that uses 2 driveshafts. I purchased the short Yamaha VX110 driveshaft and had the 2nd longer driveshaft custom made.
As an alternative to this you can have Impros modify the Solas impeller to fit the GPR driveshaft.
Stock this is a monster impeller, the impeller I purchased last year came with a 18/24 pitch - the root angle is huge. (I believe Solas is now offering a 18/22 impeller - I don't know if Solas changed the root angle with this new lower pitched impeller.)
Compared to a Dynafly 14/20 pitched at 15/25 the YH-CD 18/24 impeller had 250 less RPMs on my ski.
The YH-CD 18/24 gave me the same RPMs on my ski as a Dynafly 14/20 pitched at 14/27.
In stock form the YH-CD 18/24 impeller was 1 mph slower than the Dynafly 15/25 and 1.5 mph slower than the 15/27.
I then had the pitch of the YH-CD 18/24 impeller reduced to 14/22 by Impros. With the new reduced pitch the impeller is the same speed and RPMs as a Dynafly 15/25.
On the YH-CD 18/24 I don't think you can reduce the pitch any more than 14/22 because of the very high root angle.
The YH-CD 18/24 impeller needs a lot of HP to get it to the optimum rpm range. For now this impeller is going back on the shelf. I am building a BB motor and if it works out that it makes enough HP I will give this impeller another try at that time.
There is a limit how much the Dynafly 14/20 can be pitched up. This limit is probably something like 15/27. If you have a motor that needs more impeller than a Dynafly 14/20 pitched at 15/27 than you might consider the YH-CD 18/24. (or what is now the YH-CD 18/22)
Folow-up Testing - October 28 17 2007
Testing was done with ported GP1530R stage II ski
This was done on my single pipe GP1530R - all testing done using FF plate, shimmed R&D tabs, modified worx 1200 grate
Solas Concord YF-CD 18/24 (stock) 7170 79.8
Solas Dynafly pitched by Impros to 14/27 7120 79.5
Last edited by philip_gpr; 10-28-2007 at 08:05 PM.
06-17-2007, 08:58 PM #2
IMVHO; take a dynafly beyond a 28 pitch and the point of diminishing returns begins.
06-17-2007, 09:12 PM #3
Very informative Phillip.Can you give us any cross reference on how they felt?
I trust your ass on a seat of the pants comparison
06-17-2007, 09:59 PM #4
06-17-2007, 10:02 PM #5
06-17-2007, 10:13 PM #6
Yea the dynafly can get pitched to around a 27 with a good kick on the trailing edge the leading edge however marking my tommy guage with digitial micro I had lines on my pitch guage as high as a 18 then the prop actually started to point upwards it still pushed my new motor faster then my pitch I had on the dynafly previous which was a 16- 26 with a kick so I am guessing dynafly max out around a 18- 27ish but root angle is still now where near the VX you will need a good size bb to pull the vx prop
06-17-2007, 10:33 PM #7
as far as the seat of the pants goes both felt fine - to be honest I have no idea which one accelerates harder
06-17-2007, 10:41 PM #8
Phil you say you were working with a 18-22 but you post results of the 18-24 stock impeller which one were you using?
06-17-2007, 10:46 PM #9
this is a little confusing, I bought my impeller last year - at that time Solas was selling a 18/24
I then had it pitched to 14/22
Solas is now selling a 18/22 (there may be a few 18/24s around with dealers if they still have old stock)
06-17-2007, 10:58 PM #10
Gotcha phil.. so what you did for that test boat your better off with the dynafly for that boat non ported no bb. Pitching the vx that low netted you almost same rpms and speed as your dynafly and you can continue to pitch both props up but the vx will just keep dropping the rpms on that boat to much because of the root angle of the prop.
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