MrHavasuCat

[Nordic 18]

Question for you. One of my buddy's has a mach26 openbow with a 500hp whippled. We just took it to the lake for the first time since hot boat tested it. We were turning a 32" from 4 blade DCB but burning it out of the hole really bad switched to a 28" got a much better hole shot and gained 5-7 mph do you think getting the 32" reworked would be better than a stock 28"?
Thanks,
Adam S.

[MrHavasuCat]

Were you banging the rev limiter with the 28? What gear ratio are you running? My 32 was reworked 3 times before it was right. When it came from merc it had almost no cup. The boat would hardly plane until I got the cup right. To much cup though and you will hurt your top end. My drive is at Teague getting 1.35's so I can run a smaller prop. My opinion is smaller props (30" and under) are more efficient than the larger ones. If you are running 1.50's with big hp you kind of have to run a larger prop. If you guys gained that much on the top I am guessing you are running a non xr bravo with 1.36's. Sounds like the 28" worked well for you. What was the top speed? I am going to try a labbed 30" with my new ratio. I am running a little more hp than your friend, so if I am right about your ratio I would say the 28" should be close. I am by no means an expert on this, just my opinion from my and others experiences with the mach. Chris

[Nordic 18]

We were actually at 5000 - 5100 rpm 4 people approx 60 gals gas. Top speed was
87 on Lake Pleasant in AZ. Its got 1.50's, Hot boat tested it with their prop? and it radared @106, so they say.
It currently runs 7 #'s boost, Do you think Dustin would have upped it for the test? Kenny was a little disappointed to be so far from 100. It was 82.7 before whipple at the same testing place I figure. Here is the original write up on his boat http://www.***boat.org/dcb/***boat-July2000.html
Thanks for the input !!
Adam S.
[This message has been edited by Nordic 18 (edited August 04, 2001).]
[This message has been edited by Nordic 18 (edited August 04, 2001).]

[MrHavasuCat]

87 mph sounds a bit slow. That motor should be making a little over 700 hp with the whipple. On the other hand 106 sounds a bit high. I could be wrong on your hp numbers, but I was told that a whippled hp500 with their standard boost settings for the package was about 725 hp. I am running about 800 hp, and with the 1.50's I was getting 105 mph at 5800 rpm. You guys should be running right around 100 mph in my opinion with the right prop. Your rpm's sound like they might be a bit low. I would call dustin and ask about the motor and make sure the setup is working correctly, and I would change the gear ratio. The 1.50's are a top speed killer. My friends mach with the same motor as mine runs 113 mph with 1.36's. Good luck. Chris

[Nordic 18]

Thanks for the help. We will give them a call next week. Hopefully it does 100 when we get finished. He wants an AZHBA T-Shirt.
Adam S.

[B-rad502]

By the way, Adam, you do the best stereo work around!! The system in my Dodge is in it's 3rd vehicle and still running strong!! If your buddy comes out to the poker run in September, have him come out on the water with us on Friday morning to the radar run. If he gets it dialed in to run 100 mph, I've got the connections to get him the shirt! Even if it not 100 mph, he can get a good accurate radar speed to see where he is at. By the way, I know of a great 24' vee-hull that will be for sale in a few years if you're intertested! See ya' soon, take it easy on Kevin at work!
Brad http://free.***boat.net/ubb/smile.gif
Originally posted by Nordic 18:
Thanks for the help. We will give them a call next week. Hopefully it does 100 when we get finished. He wants an AZHBA T-Shirt.
Adam S.

[Donnie]

I would not be to concerned,remember it was hotter than hell that day.87 at 1300ft with a temp well past a hundred is not bad.We did have a great time racing around with you guys.I don't think you will be able to spin that 32 you need some more horses.Remember the hot boat bullshit factor of at least 10mph for good reading and boat sales http://free.***boat.net/ubb/mad.gif
Tell Kenny don't worry about the shirts I have some in my boat http://free.***boat.net/ubb/biggrin.gif
Donnie

[MrHavasuCat]

Altitude + temp will make a difference in performance. I have not boated at pleasant, so I did not know the elevation. I would still call dustin and ask him what he thnks.
Chris

[kab]

Mr.HavasuCat- When is your next trip to havasu? I will be staying at havasu springs august 18-21. I been looking for a demo ride in a mach 26 even though we already ordered one.

[Trash]

Here's a couple of thoughts...Looking back at the original ***boat test, they reported 29.7 mph @ 3000 rpm and 51.8 mph @ 4000 rpm. With the 28" prop originally tested that equates to a 44% and 27% slip, which is a butt load. The original top speed of 82.7 mph gives a slip factor of almost 10% which is more appropriate (I had to assume 5200 rpm as the article didn't state rpm @ top speed). This seems to correlate with a pretty high x-dimension, maybe too high for the lower speeds. The hot boat folks would have had to spin the motor to 5500 rpm with the labbed 32 to get a theoretical 111 mph, and again assuming 10% slip this brings you down to 100, which is still less than the 106 or so they stated. I would have to agree with Chris that something is amiss here. BTW, all calculations were using 1.5 gear ratios. I'll see if I can dig up some other Mach 26 info for comparison.
Chris, does DCB play around with the x-dimension for each customer when they make the hull?
Trash