The Hot Boat tests seem to be in line with what I've seen out of the Heat. First off, the mid cabin boats appear to be a couple of MPH slower than the closed bow versions. Secondly you guys need to test these things with GPS. The speedos are pretty optimistic(4-5 mph) in every boat I've seen. My boat read 78 on the speedo at 74 GPS. Even my tach reads 150 RPM high! I'm sure running in salt water on a good chop and cool weather the numbers for all our boats would be better. If you do the math on the speed/rpm numbers for the test in Hot Boat it appears that boat is actually running a 1.5:1 gear ratio. Their numbers are very close to what I have experienced with the same prop and 1.5 gears. If it has 1.36:1 gears then the prop slip is off the charts.
Bob

Speedo numbers are absolutely useless in this forum

All Heats, Rages and Flames I have been involved with have also had the speedos read 4-6 mph higher than actuals. I'm sure this is true of most all boats.

Someday maybe all boats will come with GPS tattle-tale speedos as standard issue and this illusion will disappear

I wonder how the Illmors would handle an M5 ProCharger with a mere 5 lbs of boost...Now that would be interesting

Dave

If I had my GPS with me I would have used it. Just reported the only numbers I had. Boat came in at 8:00 PM Friday night before our Poker Run.

Gary, do you notice any handling difference with the lighter motor?

BTW this boat has a GPS speedo so the numbers are accurate

For the guys that have done a procharger on a 502 mpi on the 28's. I am curious what is your cruise speed at say 3500 and 4000 rpm at approximately 500ft above see level.

LIOPA, not trying to make waves, just trying to understand. The speeds you report seem to always be significantly more than others see. I have to assume it has to do with the water and weather conditions where you are operating the boats. I'm personally testing at 700 ft. elevation, smooth water, no current, 100 degree temps and moderate to high humidity. Now that everyone has a GPS, It's difficult dealing with customers when they expect a certain speed and don't even come close. "Boatingbent" bought a 28 with a 496HO. He was initially expecting speeds in the mid to upper 60's, maybe 70... based on the mfg. and some postings on this forum. Since he is a friend and a customer I kept telling him I didn't think he'd see those speeds. Maybe 64-65 tops. Well as it turns out he's getting an average of about 62. I think he's hit a best of 64. Those are real world numbers. I'm not surprised by the numbers on the Viper. They seem to be representative of what most everyone is getting. What conditions are you testing in getting the speeds you are reporting? The speed Nordic Gary reports (78 speedo, probably 73-74 GPS) sounds about right for the 550 HP Viper in average conditions.

Magic, I don't have a procharger...but I've got a Whipple. Will that do? I'm running a 29 P5X prop and here are my numbers. The slip numbers are very high on these boats. I'm working with Throttle-Up to try to improve them some. I went from a 25 P5X to a 29 P5X and the cruise RPM did not drop very much. The speed is GPS and RPM is from a laptop reading the ECU. My tach is 150 RPM high. Anyway...35 MPH = 2800 RPM, 40 MPH = 3200, 50 MPH = 3700, 60 MPH is 4200, and 84 MPH = 5500 RPM. This is with 2 people. If I put 1-2 people in the bow the slip increases a lot.
Bob

Bobl,

Thanks for the numbers I would really love to cruise at 50-55 at 3500 rpm. From the sounds of things that is going to take some serious horsepower. Where I boat top speed is not achieved that often, Lake Michigan is not very forgiving on a 28' boat. I hate and even refuse to run my motor over 3500 rpm for extended peroids of time.''


What is the general concensus on Vortech superchargers?? Everyone seems to be down on the prochargers. Are there any clearance issues with installing a supercharger in a heat, mine is a 99.

Has anyone done anything to increase airflow into the engine compartment, besides putting a scope. I have been thinking about putting some vents in the open area between the upper and lower seat.

The difference in the feel of this boat is significant! In addition, my partner has a 2005 35 with twin 550 Vipers, you have to ride in this thing to believe the acceleration. This boat will run 100 according to my partner. The day a was in it we did not push it, saw 85. I personally own a 2005 35 Flame with 525's and have a GPS speedo which reads 91 MPH @WOT.