358HP Donzi 22?

[Zinger]

Hello All, I finally was able to get some new prop results, Ihave a 97 454mag carb. with a three blade 23 pitch turbo the boat runs 63.2 @ 5050 rpm the engine has 160hrs. and is mercruiser 385hp stock engine ,I can believe that the 496 or 502 with 25 to 40 hp more can run up to 15 mph faster .Does 63 mph seem right , what is average speed that I should be running with this set-up.:pimp:

[boldts]

hummm. I'll take a shot at this one. Your speed seems a bit off. Is that GPS or speedo speed? I had the same 454MAG, carbed in my 1999 22 Classic. Only difference was I had a 1.36 drive ratio instead of your probable 1.50 ratio. I was running a Turbo1 22" pitch at 68 GPS at 48 to 4900 RPMs. Now with that said and if you have the 1.50 drive, you should be running at least as fast as mine. Actually, you should be faster than mine.

You've got some room for more pitch I believe as the MAG engine is rated for 4600 to 4800 I believe. (Anyone who knows for sure, chime in) It looks like you could easily run a 24" or maybe even a 25" pitch Turbo1. More pitch usually means more speed as long as you've got the engine RPMs in the recommended range.

The next question would be. At 5050 RPMs, were you running trimmed out or was the drive fully trimmed in. Were the tabs down? All of these items can effect speed. I'm assuming your not new to the boat. Anyway, I'm sure others have some thoughts on this. My Turbo1 was straight out of the box. No modifications were done to the prop.

[Zinger]

The boat is was trimmed and the tabs were all the way up. The ratio is a 1:5 had a 23P mirage plus on it, the turbo handles alot better . I had a 22zx and upgrade the engine to another with 125 more Hp and gained ten miles an hour which seems odd if other donzis with 502 and 496 are running in the mid 70's with has much has 40 hp more. The max I seen was 63.2 on gps and wasn't gonna go any faster unless its on the trailer. The engine runs awesome and sounds strong It's a 97 Mag carb engine but not sure on the exact hp if it is 385 or not.

[Pismo]

The carbs were slightly less hp even so I think you should be faster. Your slip is almost 15%, too high, should be more like 10-12%. More trim, almost to the limit, light chop, less gas, less weight, no tabs, let it run. Tach accurate? Bottom ok? Prop ok? Lower unit ok?

[boatnut]

For another data point: I have a '97 22 with a 7.4L 454 carb Bravo 1 Pkg that is rated at 300hp. Drive ratio is 1.5. I just tested with a Turbo 1 23" pitch and was able to achieve 62 (got to 62.2 once) GPS. Trimmed, tabs up. Run was in freshwater at 1320 ft altitude with about 1/2 tank fuel and 2 people. I am not sure of rpm as I suspect a bad tach but it was showing 5400. The engine is a gen VI which supposedly has a rev limiter and it is rated 4200-4600. I suspect that 62 mph is pretty close to what you should get in a 22 with 300 hp and I would guess I was turning in the 4400 to 4600 range. Ed

[zimm17]

I have a 1997 carbed 454 magnum. All stock with a 25p Turbo 1 I GPS'd 69mph at 4700rpm with a full tank and 3 people in the boat.

I changed the intake to an Edelbrock performer RPM air gap (so the flame arrestor would stop hitting the engine hatch) and added Dana Marine exhaust. Now I have a best of 71.4mph at 4900rpm.

Sounds like you are a 100HP short. Either you don't have a magnum engine and it's a 7.4L or something is wrong. Check the serial number on the back of the engine just behind the distributor. Look it up and make sure it's a magnum.

If it is, do a compression check and tune up, set the timing, change the plugs, wires, cap/rotor. Maybe even pull the top off the carb and see if there's anything in there- My engine had a rough idle and I took the carb apart and blew it all out with carb cleaner and put it back together with the same old gaskets- works great now. I also set the floats, they were way off on mine. Easy to do with a ruler and the Mercruiser manual.

Let us know what you find out.

[CHACHI]

Zinger........another refrence point. 1999 22C with a 454 Mag MPI, 4 blade Spinelli prop, (I do not have any info on it), best with me in the boat and less than an indicated 1/2 tank of fuel 73.1 MPH. If I trim the drive up any more I hit the rev limiter. Ken

[MOP]

Jeff you are running faster the a 330, makes me think it is a 385 but not set up right. Have you checked top timing? Base is not anywhere as important, I broke the Beast in at 29 gained near 2 miles going to 31. I am going to try bumping it up a bit more to see what that does, my best run was 65.7 that was last year. This year like everyone else I have gotten a tad slower! Alcohol is for drinking not burning:toiletpap :toiletpap

Phil

[boldts]

Zinger, did you say the boat is a 22ZX or a Classic. If it's the ZX, do you have the slots in the hull bottom? Also, if you have a ZX, that might explain the lower speed. I believe they are heavier than the same size Classic. Maybe not. Just a guess on my part.

Did you say you were running a Mirage Plus before? From past posts here and talking to 22ZX owners at our gathering, many really like the way the Bravo1 Mercruiser prop works on the ZX boats. It's a 4 blade that really seems to settle the boat down and get good speed. Grant it though, the owners I talked to had a slot bottom hull. Frank Civatano here on the boards ran a supercharged big block 22ZX. So, he would be one of my best recommendations of people to talk to about props on a 22ZX.