True Speed ?

[Gary Shawen]

What Is The True Gps Or Radar Top End On A 2003 22 Classic With A 496 Mag Ho/ 425hp.????

[RedDog]

75 on a good day?

[roadtrip se]

My 502 ran 68-70. The 496HO will run a little stronger, say 70-72.

My 502 ran 75 all day long behind the Ex, but it would never do it on its own!

Of course that 502 green machine always gave me fits when I ran with Peter at Cumberland. I bet she runs 71-72. Started me down the long road towards upgrade city!

Have some fun with the seller. Tell him that you want an additional $2000 off for each mile per hour it misses the claimed mph mark on GPS or radar and then go for a ride.

Good luck,

Todd

[hottub]

Last day out, mid-October. Myself and 2 buddies, half tank of gas, 90 degrees and sunny, late afternoon, dead calm water on the Sacramento River. Garmin handheld GPS 71.4 mph. 2003 496 HO, 70 hours old.

[Gary Shawen]

Last day out, mid-October. Myself and 2 buddies, half tank of gas, 90 degrees and sunny, late afternoon, dead calm water on the Sacramento River. Garmin handheld GPS 71.4 mph. 2003 496 HO, 70 hours old.


WHAT DID THE LIQUID SPEEDO READ ??

[Ranman]

Garmin handheld GPS 71.4 mph. 2003 496 HO, 70 hours old.
That;s exactly what I would have thought.

[hottub]

Great question. Speedo spent a good part of the summer down due to clogs in the outdrive pickup. That was the only time that I was out with a GPS so I can't give you GPS vs Speedo comparison. With some luck I will be out on the water in the next couple of weeks and will be able to tell you then.

[Cuda]

The Gaffrig on my Formula reads about dead on with the speedo from 40mph up.

[cigarette30]

What do you guys think the result(s) would be with an Imco "shortie", and a labbed prop. Each should be good for 2 mph each ???, total of 4-5. This for around $3,000 - $4,000 (with trades) Would seem to be reasonable for a honest 75 mph most of the time (load, fuel, temp. considered)

[roadtrip se]

Cig 30, saw your boat at the factory as they were finishing it up. Gorgeous and I liked the custom touches.

Your assumptions on the IMCO and props should be accurate. Unfortunately, I didn't get a chance to test your theory, because I tore my boat to pieces all at once instead of doing it incrementally.

One thing missing here though. Steering. Ask anyone who has taken a ride in my boat. Once you get up over "normal" Classic 22 speeds, the handling changes, the level of needed attention changes, and a big grin comes out.
The grin can disappear with the appearance of a rogue wave or whatever.
I wouldn't be doing any of this without bone solid steering.

Many more lessons learned with the shortie setup too. Happy to share them with you, if you would like. PM me your numbers.

Todd
"Instigator of upgrades, shouldn't everybody be doing it?"

[Barry Phillips]

My 496 Mag 375hp 22 will reach 70mph with 2 aboard and a full tank of gas at 5000 rpm non-confirmed. The 50 hp gained by the HO motor should gain 2 to 3 mph, so 71 to 73 mph would be about right. Donzi's own testing yielded 68 to 70 mph for the 375 and 70 to 72 mph for the 425. I think 75 for a 496 HO equipped 22 is optimistic. Power Boat published 74.9 MPH for the HP500 equipped 22 SE, which would be consistent with the 2-3mph per 50HP average. I though Donzi's published 78 mph for the 22 SE optimistic also, considering PB tested the same boat. Over 70 mph it takes a lot more HP to push a vee bottom.

[Air 22]

Gary...many variables involved in your question. Mostly Driver, prop and atmosphereic conditions during a speed run. By all accounts the speed is over 70 but just how far will vary. A standard atmospheric day is considered at sea level and 15C or approx 60F. Raise the temp and humidity....you loose some power/speed as w/ any engine. Sea conditions and prop also play an important roll. A Stock 2004 22' Classic has a Mirage 25Plus w/ 496HO at the Miami Boat show. A 1ft chop or there abouts will "Air" it out for more top end speed vs a calm surface creating more drag on the hull. Driver experience has a key roll as well. Knowing the handling characteristics at high speed can make a noticable difference. GPS vs. RADAR speed varies as seen in any Powerboat Mag test. Radar guns have a known error of up to +-5mph while GPS is more accurate. No matter how u look at it ...you'll have fun getting there for sure :) :biggrin: Enjoy.....

[HyperDonzi]

What do you guys think the result(s) would be with an Imco "shortie", and a labbed prop. Each should be good for 2 mph each ???, total of 4-5. This for around $3,000 - $4,000 (with trades) Would seem to be reasonable for a honest 75 mph most of the time (load, fuel, temp. considered)


I dont think 1mph is worth 1,000$. Houston Propellors does a good job from what I've read. Labbed and satin finished (unless it is hydromotive). Start there.

Tommy