22 classic HP/speed Question
 

I'm purchasing a 2004 40th anniversary 22 classic. The boat has a 496 (non HO) Merc. The previous owner says it runs 65-68 mph..... I'll find out for myself in a few days when I test drive it.
My question is: What amount of HP does it take to get these boats into the low to mid 70's? I figure someone here must have a pretty good idea.

Mark

My 1996 22C with stock 502, 750cfm carb, Gil exhaust will top out at 73mph GPS at about 5000rpm.

www.Donzi.net Seek and you will Find

A close friend had a 22 classic with a bone stock 502 mag, the boat ran 72-73 on GPS all day long. My 22 classic with a warmed over 454 with peanut port heads ran 68 on GPS. To get you over 70 with that setup, switch to the 496HO cam and either replace your ECM with an HO computer or have Whipple reprogram it. That will put you at 425 horsepower and will get you in the low 70's. I will probably have an HO cam for sale later this fall.

Thanks.
Converting to the HO setup seems to be the way to go.
Is there any way to replace the cam in a 22C without pulling the engine? I'm thinking not but can't hurt to ask

Mark

I've owned 4 with different power packages.. By far the nicest one was the 2006 Shelby with the 496HO 425HP the boat ran 77-78 all day long.. Great little boats..

Yes.




Have someone else do it. LOL.

If I upgrade to the 496 HO setup, would it be possible to duplicate the top speed of the Shelby model by shortening the drive, such as with an Imco shorty lower unit or the like?
If I understand correctly, the Shelby got it's extra speed by raising the X dimension by about 2"
If this is a viable mod.......If so, what do these lower units cost and whats involved?
Thanks.

Mark

Yes, you can bolt on a short lower; they're are not cheap though. I've thought about it a couple of time but haven't found one for under 3K.
I believe you're $$ are better spent on HP upgrade and adding external steering first.

Clocked my boat last night.
3 guys, 1/2 tank, 55deg, on glass.
VDO speedo past its 75mph max
Phone GPS read 72.6 and climbing
Tach read 4800 witch is in reality 5000rpm
Got to love those cool fall days for making HP...

It sounds like he is being straight up about the top speed. A 502 or 496 HO will get you an honest 73 mph. A 525 like mine runs 83-85. Bjorn in Sweden is running 112 mph with a pro-charged 540. And, yes, many of us are running XR/Imco -2 drives including myself and the boat in the video. Check this out: https://www.youtube.com/watch?v=mq6bSy4lfnU&feature=youtu.be

First I'm curious if these speed numbers are on salt or fresh water. Not for the Sweden, he is legit fast as he'll salt or fresh water. Salt is supposed to be a couple mph faster. Also if you are looking for speed and stability at that speed you need to raise your prop up. I have a motor i put together. It should be 550-600hp. It's going to the dyno this winter to tune it and verify hp. I have seen an honest 75 gps in fresh water. With the stock bravo 1 with a nose cone. The boat is pretty unsettling at that speed with the stock drove height. Yes hydraulic steering should help a ton. But raise the prop up and get less drag in the water. You get more speed and better ride at that speed. Just my .02. I'm no expert I just know what I am seeing and trying.

My boat has a bone stock B1 drive with the prop shaft quite low (about 7" below the bottom).
I do not have external steering but will say that my gimbal and other steering components are in solid, like new condition.
I run a 4 blade Merc Rev 4 25P Prop and the boat is rock solid trimmed up at WOT and 70+mph.
She does not handle as well with a 3 blade but will go about +1mph at WOT.
The numbers I posted from my ride last night are on the CT river (fresh water).
Lots of talk last night with my crew about upgrades I've thought about doing ie. short lower, cam swap for more HP, external steering... Thinking the boat runs so well, leave it as is...

I've not ever seen a difference running in salt vs. fresh. Maybe over 75mph you need a short lower but I'm not convinced. At over 500HP you should blow past 75 in a 22 Donzi. What are the other details of your setup? what prop? what engine rpm? Is the hull straight? Nose cones don't always help and can hurt...

I would do the Imco -2" shorty and full steering. Zeiger offers a complete kit as they make, or used to make, the factory Donzi steering.

The steering is on the list for the winter. It's a must if running anything over 70. Also so is an interior since mine is pretty rough. I only have 12-15 hours on the motor. It picks up a little rpm and speed. each time I run it. The imco -2 is on the list for most likely next winter. The motor is not completely dialed in, I'm sending it to a dyno shop this winter to get it tuned and verify the h.p.

The hull is straight and slightly strengthed. It's an 87 that looks like a black hawk. I bought my VIP to swap the bravo off it (that already had the nose cone) with the alpha off the Donzi. The motor is a Gen VI 454 bored and stroked to a 496. It's running a mild cam and 10.3:1. Aluminum heads and stainless marine exhaust. Edelbrock air gap intake with an 850dp. With the thunderbolt ignition. I just did a fun run with 21 other boats and I was by far the smallest. I was in the middle of the pack with top speed. I can run at 3600 and get 55-60 depending on my load and gas amount. I'm spinning a 27p mirage plus at 4800 rpm and getting 75.4 on gps. Like I said it still has a good bit put tinkering to be done.

I believe your boat would be more stable with a different prop.
I love the Rev 4 but they only go up to 25P.
If you have the $ a Hydro P5X is also a great prop for old school V bottoms with deep drives.
Lots of guys running modified (for extra bow lift) B1s ; a stock B1 is not a great choice.

I agree those would be the best upgrades for a 22C if one is looking to push well past the 70mph mark or runs hard in the rough. Personally, I'm not ready to spend the $7-8K on my boat; I don't push her hard vary often.

I agree there are better props, this is one a guy was nice enough to let me borrow. His buddy let me borrow a 28p bravo 1 and it just slipped to much. I got 72 at 5000 rpm. The drive high is just to low for that prop. I'm most likely going to try and get a used 27p mirage plus this winter so I can keep tweaking. Sadly like most everyone. I don't make a lot of money to be throwing into the boat. I basically save my side job money and use that to upgrade the donzi. The bravo 1 out drive is fine for what I do with it. I run on the river, it's pretty flat. If it gets choppie I slow down. I don't come out of the hole hard, there is no need. The boat planes right off at 2,200rpm. Also I only run at wot for a couple minutes at a time max. I know when I'm doing 35 and just gradually put the throttle down it pulls like no other. The acceleration is a thrill alone. I like just being able to cruse in the 2 barrel and be doing 55-60. It makes runs down the river pretty short. During the fun run the other week I had a full tank and 3 adults in the boat. We drive for 3 hours and I used less then 25 gallons of gas. I was doing 3600 with some wot when I was in front or far enough behind. Also at wot it's not chine walking or anything it just feels pretty loose. Once it's trimmed right it actually starts going a bit right because of the prop rotation.

I've had good luck with the Turbo 1 3blade props for deep drives. I've run them on TRS and Bravo. Turbo Props are also less $$ than Merc or at least they were. Not a big fan of the Mirage + stock out of the box. I do wish Merc made a 27P Rev 4...

I had a chance to put a couple hours on the new (to me) boat this weekend.
With close to full fuel, 2 adults, 2000' above sea level, 73 degrees, it ran a consistant 65 mph @4600 RPM. Remember it's a Non-HO 496 running a Bravo One 26P prop.
Anything to gain by going to a Turbo, Mirage, etc. prop?
Also, I found the boat to be VERY sensitive to trim. My last boat (going back a while) was a 24' Checkmate Enforcer, with the original 454 Mag and Alpha Drive. That boat was a "set it and forget it" setup. Full throttle 1/4 up on the trim, and forget about it.....Never once even had to use the trim tabs.
The 22 Classic seems to be a whole different story. I found the best way to operate was to leave the trim all the way down until about 40 MPH, the trim to just under half (on the gauge) and trim tabs down to stabilize things. Too much up trim and it chine walks, not enough down tabs and it seemed to get a bit squirrely.
Any operational recommendations from you experienced 22 Classic operators?

Mark

Mark, the 22 Classic is a driver's boat. It takes time to learn. Mine scared me the first time out when it nearly rolled onto it's side twice. You should usually only need to run a bit of port tab to correct listing. Drive should only be tucked down for planing. Then raise the drive to neutral or slightly up. For top speed raise the drive as you feel the boat get loose and speed increase. Now you should be able to fully raise both tabs. To turn, drop the drive to about neutral and drop port tab if needed to correct list. Turn sharp and accelerate through the turn. If ever the boat feels like it is rolling onto it's side, immediately straighten the wheel. These are just some tips as it really takes time to master. Once mastered it is very fun and rewarding to drive a Donzi Classic! Mine has never had a chine walk issue. All will porpoise at lower speeds. If you have a stock drive then a Mirage prop will work better for handling and top speed. I run a 30p Bravo 1 and -2" Imco shorty. Good luck, be careful and have fun.

I'm curious if there's anyone out there that exchanges props?....By that I mean allows you to try (for a fee of course) different props until you find one that does what your looking for.
If not, how do you know where to begin as far as what brand/pitch to buy? It doesn't make much sense to order a $400-500 prop just to find out it performs worse than what you have, and then be stuck having to sell it on Ebay.
Back in the 80's I know such places existed, but in doing an online search, I havn't found anyone that does that with performance oriented props.


Mark

From my experiences, I can tell you that a Bravo 1 prop on a stock Bravo drive that is deep in the water is not the best combo on a 22 Classic or other old school deep V with a deep drive. The Bravo 1 prop will provide too much stern lift.
A Merc Mirage, Mirage plus, or a Turbo 1 is a better prop with this setup but the boat may still be a handful. Of the 3 blade props I tried, I liked the Turbo 1.
I run a Merc Rev 4 4 blade and the boat runs great at all speeds. No tabs unless I have an unbalanced load or I'm running in the rough.
I've used BBlades for test props; I think Brett charges $25 plus shipping.

I agree with Pat on BBlades. They do the test program. Give Brett a call and he will ask you a few questions about the boat, wot speed and rpm. He will then give you some advice on which props to try.

Thanks for the info!

Mark

Props I've tested on my 22 in the order of my liking -
Merc Rev 4 25P- Best handling and best mid range speed, only 1mph slower than a 3 blade. Running this for 2+ years now.
Turbo 1 25P- Best 3 blade by a smidge over the Mirage that came on my boat from the factory. Big plus is the cost vs. Merc. This is my backup prop.
Merc Mirage (non-plus) 25P - Had this prop balanced/tuned at BBlades. Same top end speed as Turbo not as much midrange punch. Pitch may be a little high.
Merc B1 26P - slow and pore handling at WOT, Ok midrange. Worst prop I've tried. I do know these can be altered for more bow lift as I ran a "labbed" 28P on my 24' Superboat.
Hydro P5X 25P - great midrange speed and handling, slower at WOT, too much pitch and too much $$

Great info, thanks!
When you say "great mid range speed", do you mean a higher boat speed at a given engine speed, for example 2500 rpm ?

Mark

Yup. I don't have my results in front of me but I do recall that my Rev4 is 3-4mph faster than my Mirage at 3000-3500rpm. At WOT (4800) the Mirage is about 1mph faster.

This might be useful :)
http://rundquist.com/pb_application.htm

Totally stock 1996 donzi 22 classic with 502 Mag 415hp runs 74.3mph with stock 25" MPlus and 75.5mph with a labbed 27" MPlus. Fresh water, GPS speeds. The key to top end in these boats is trim, trim, and more trim, almost to the limit which is higher than most will go. Many of the speeds i have read here seem a little slow, probably due to this. Go to HO setup and you will get over 75.

My numbers are low, but not because of a lack of trim. My slip numbers are good at 8%, it's just a lack of rpm. If i get another 400 rpm its another 5mph at the same slip. My motor only has 10 hours on it. My number will be better next year after I get the motor dialed in. I taking the motor to the dyno in January to get the carb and timing set. I appreciate the advice and I will post some numbers once the summer comes around.

Just picked up a 96 22 Classic w/ 454 Magnum MPI EFI and Bravo One Drive. In storage for the winter. Previous owner said it runs 68mph. Has a pretty beat up 23p Mirage prop. It's such a cool boat. Never thought I'd own one, but it popped up locally and the price was right. Looking forward to hearing all your results...I'll be posting mine in the spring.

Larry

Do you know if the bottom of the Shelby model is the same as the standard Classic bottoms? Obviously the hatch, windscreen, upholstery and a few minor hardware fittings are different. Thank you!

Same bottom