Reply With QuoteNice numbers, good to see some real world results from someone stepping up beyond the Bravo. Be curious what a boat like yours would run with an Arneson?
Well !!! Finally got some speed numbers to post though I need a prop with mor pitch to get the really big #####.
First run was 116.5 mph at 6000 rpm ,11 lbs boost 16.25 x 29 four blade prop , drive ratio 1.21,cruised at 100 mph @ 4500 rpm ran smooth no bad habits.
Second run 124.8 mph @ 6300 rpm , 11 lbs boost same prop bow stayed down trim was nuetral.
Then turned up the boost to 14 lbs,she ran 135.2 @ 6700 rpm same prop as I did not have another prop to try but wanted to get some real numbers from this one I borrowed from Washed Ashore ( Thanks,I will take good care of it) it is a labbed Bronsom Hill four blade 16.25 x 29. The bow raised a little but the boat felt stable and no bad habits so far,quite a rooster tail at 120 + mph but thats the way a surface drive works. The Weisman makes a little gear noise but sounds great when your listening from shore sure got everyons attention. I hammerd the drive several times and its still there !!!!!! anyother drive would have distroyed itself with 14 lbs boost and a quadrotor 598 hitting it. So far I can't give Pat Weisman credit enough for the setup looks like he hit the Xdim perfect. Will be doing a lot more testing before an attempt at 150 mph. Will be in Havasu for the Hot Boat Poker Run Oct 1-2 and if I can find a prop to try may go ahead and go after Eliminators record of 144 mph. The numbers seem to show I need a 16x30 4 or 5 blade or something close as the 29 was maxed out at 6700 rpm .I still have at least 5 more lbs boost and 200+ hp so I think 150 is within my reach. The 135.2 was at Lake Shasta and I have found I have always ran 4-5 mph faster at Havasu at the same RPM for whatever reason I can't seem to figure out ,even when its way hotter than Shasta. These numbers are using a surface drive so there different than a brovo type drive. If anyone has a small dia # 6 prop for sale or rent please let me know would really like to try it at Havasu , and any thoughts about what all these numbers meen would be off help as this is all new to me. Thanks ROCKIT MAN
Nice numbers, good to see some real world results from someone stepping up beyond the Bravo. Be curious what a boat like yours would run with an Arneson?
At 6700rpm are you past your peak HP? I come up with 11% slip. If you hold this amount of slip you will need at least a 32" prop to get speed of 149 @6700 rpm unless you can get the slip down. 30" gets you 140mph.
Keep us posted & think safety!
At 6700rpm are you past your peak HP? I come up with 11% slip. If you hold this amount of slip you will need at least a 32" prop to get speed of 149 @6700 rpm unless you can get the slip down. 30" gets you 140mph.
Keep us posted & think safety!
I can make power to 7200 rpm and theres a lot more power ( 200+ hp)when I bump up the boost to 20 lbs. The slip is high I need to get it dowm to 8-10 %. I tried a Merc 16.5 x 32 and could not get on plane but that was at 6 lbs boost and at Lake Billy Chinook around 2500-3000 ft elevation. the numbers seem to sujest moving up 1-2 pitch and try it there as I ran with the 4x4 drive a Hydromotive five blade 30 at 6400 ,141.9 mph. A 5 blade 30 should settle down the bow and make more speed,I know the surface drive works different so hard to compare what I ran befor with what im doing now.
The arnison works the same as the surface drice probably would be about the same ,I checked with them and the Datona cat would't accept the arnison drive.
RIM=progress. sounds like your back to having fun!!! keep the info coming. I like reading your success stories. Congrats.
Racer
The arnison works the same as the surface drice probably would be about the same ,I checked with them and the Datona cat would't accept the arnison drive.
Is this because of a notched center pod?
I would think a 5 blade 30 and 20 lbs. 7000ish rpm would be needed to break the speed record. Should be easier to plane out than the 4 blade, slightly less slip too. Lake Billy Chinook is only 2000' elevation, but my boat was running piggy fat there, fouled plugs, major transom soot. Wonder why Havasu is faster than Shasta? Our local Columbia river is only 100' elevation and is pretty favorable for speed runs.135mph is a great number for 14lbs. boost, gotta love Whipples!
Doesn't Wiseman have any propellers for you?
Slippage seems on the high side, but ultimately it the speeds you go that counts not the slippage numbers.
Hows the acceleration and planning, steering compared to a Bravo?
Boat attitude seems a bit bow high you are saying?
Doesn't Wiseman have any propellers for you?
Slippage seems on the high side, but ultimately it the speeds you go that counts not the slippage numbers.
Hows the acceleration and planning, steering compared to a Bravo?
Boat attitude seems a bit bow high you are saying?
My 22' Stoker is known to be a fast hull and I come up at 9-10% slip. I'm guessing 11% isn't too bad for the 26' Elim. and surface drive. I really don't know how some of these boats claim under 8%, not saying it isn't possible but I would like to see and verify those numbers firsthand :idea:
Rock it man, thanks for the update. It sounds like you are getting there. I would love to see some pictures of your rooster tail at 120+. I would be really happy if I could get down to only 11% slip. :frown:
I think that boats run better at Havasu because the humidity there is normally way lower than up north. I have a weather computer and it typically reads around 3,500' to 4,000' of corrected altitude at Shasta on a normal 100 degree summer day due to the normal higher humidity. If I remember correctly it was reading in the 1500' corrected air range the last time I checked it at Havasu with about the same or maybe a little more temperature. The weather computer takes temperature, humidity and barometric pressure into effect when computing the density altitude for what our motors are seeing. A 2000' better air density reading will certainly help our motors make more power. (Providing we are jetted to take maximum advantage of it).
Another possibility for faster speeds in blown intercooled boats at Havasu that Greg Shoemaker told me about is the river portion of the lake has cooler water. The cooler water going through the inner cooler helps to cool the air fuel charge which also will help make more power. Makes sense to me. :idea:
RR
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