Milking the Mouse

[Scubado]

I've got 30 hours on the 350 MAG in my 2000 22ZX. Wishing I had the big block... could hardly pull a skiier out of the water yesterday. Any suggestions for getting more out of the 350 without sacrificing the warranty? Not too familiar with fuel injection and computer chips. My first thought is a change with the exhaust. Anyone have any experience with how much gain can be had with a performance exhaust system?

What else can I do with this thing short of cam, piston, heads, or blower?????

I have yet to experiment with the prop. Running the Bravo-I stainless 4 blade. Turns about 4900 rpm's @ 63 MPH. The thing always slips real bad comming up on plane, I was told that that was due to the step hull.

I'm also not sure what kind of H.P. the Alpha drives will endure. Maybe I need to start over with a different boat????

[Christian]

hi,
the 22 are dogs out of the hole even with a big block. I helped stick a 454 back into a 22zx last wkened and test drove it thurs and it was a shock at how long it takes to get up and going. short of procharging (FC) not sure, maybe prop? move weight around? Frank would know what to do on this one

Christian

[CDMA]

May be of interest:


http://www.offshoreonly.com/cgidir/ubbcgi/ultimatebb.cgi?ubb=get_topic&f=3&t=001453

[Scubado]

Thanks for your thoughts and the link. I ordered the "Small Block Chevy Marine" book earlier today. Hope I don't have to go with a blower because I don't want to sacrifice dependability or hurt resale.

The boat had the 22 pitch Bravo-I 4 blade stainless prop when the boat was first deliverd. Unknown top speed because the spedo didn't work but it was even worse comming onto plane than this 24 Pitch Bravo-I I'm using now. It would cavitate like crazy.

Anyone have any experience with other props with this boat? I'm wondering about how a three blade Mirage or something might work in comparison to what I'm running now. Is this typical with step hulled boats?

[Bryan Tuvell]

Scub, same boat, we have emailed before several times, I am at 4900 RPM, no more, stock Merc Bravo I 24, solid 65 MPH, and get skiers up ok (200/225 lbs guys). At the AOTH in KY I used a lab finished 23.9 Merc Bravo I with a little cup and lost 200 RPM but speeds were the same at WOT, 63/65MPH.
With a 3 blade 22 pitch no cup, rev limiter from hell, 5200+ RPM. 4 Blade SS 22 no cup, same thing, rev limiter...

Our prop shop (Murphy's) says I need to just lab the stock Bravo, no added cup and I should be the best I can get, 5000RPM and stay off the rev limiter!

In KY after I spun the boat out I learned you CAN trim to 1/2+ way on the G II gauges and gain 1 to 2 hundred RPM and get that 65 solid no sweat. Prior to the spin I never went above the first notch...
I posted last year I hit 69/70 on GPS, have yet to ever do that again. It must have been the perfect boat day in my life, November, 1/2 tank of gas alone.

I am by no means an expert on any area, just my experience.
But I will say, I would love to pro charge, but as I type they are bolting on my brand new outdrive under my Zcare warranty.... A bolt on will void that as you know.
Good luck, keep me posted please as to what you try and what works....
LASTLY, Big Griz sent me the numbers for what an Alpha can take vice a Bravo I, not sure an Alpha could handle a procharger.
Hey, did you ever get your ski tow eye on?
Bryan

[This message has been edited by Bryan Tuvell (edited 06-04-2001).]

[Bryan Tuvell]

CDMA, great link, thanks, my education continues...
Bryan

[Scubado]

Brian,

Never did get a ski tow eye. I'm using a harness attached to the transom eyes for now. I'm sure that makes getting up to plan more difficulr but the deck is so thin I'm not real excited about mounting one there. I've already had stress cracks back there. After continuing problems with my dealer I'm just glad I never have to do business with those bastards again. Any work I have done in the future, I'll do myself.

Sounds like you have played around with different props. Do you have problems with cavitation when you come up onto plane? Like I said earlier, I've been told that is just the nature of step hulled boats. I'm not sure I fully believe it but it kind of makes sense that the turbulace created by the step causes the prop to spin in the super aerated water. Did you get any more out of your lab finished 24 over the stock 24? I'll be buying spare prop, any suggestions???

If I trim my drive up as much as you say you are my boat looks more like a jet boat! Just a big rooster tail and she slows down a lot. I can only feather the drive up to the bottom of the first hatch on the guage without loosing speed.

Anyone have any comments on exhaust manifolds for this thing? How efficient are the stock manifolds?

[Bryan Tuvell]

Scub, sorry to hear about the tow eye deal.
The lab Bravo I 24 had cup and I actually lost 200 RPM, but one guy thinks that my drive could have been showing signs of the impending failure and that could be why I lost the 200 RPMs.
I will say she is not the ideal "get a skier up" set up, we have only done it a few times, we usually tube. This is my first boat I have no past to compare the hull to for sking.

My plan is to put my stock Bravo I back on and retest with the new outdrive. Then go see my prop guy. As far as the trim, I have to be WOT at speed to trim past the first notch. I get the chine walk if she has too much trim. I just started really playing with the trim in KY.

My recommendation would be talk to a prop guy and tell him what you want. Plus I am sure the experienced guys here will chime in today.
Bryan

[RickSE]

Scubado,
Do you have trim tabs? The 28' & bigger boats plane up a lot quicker when the K-planes are put down about half way. Once your under way you then pull the K-planes back in and trim up half way on the drives.

The ZX's do pull a lot of air in under the hull. Because of this I'd probably stick with the 4-blade since they typically work better close to the surface and in airated water.

[Scubado]

Rick,

I've got the little Benette trim tabs. They are a must when pulling a skier.

Anyone have any comments about exhaust manifolds for the 350??? Just curious if this is good place to start for HP gains or if the stock manifold is fairly efficeint.

How's that new truck of yours running? I'll be at lake Mead this weekend. Let me know if you are up for a trip.

[RickSE]

Sorry can't help you on the manifolds. I've heard many stories on exhaust manifolds, sometimes they help sometimes not. Since their typically expensive I've avoided them and look for cheaper H.P. I'm assuming you have thru hull exhaust. I've always wondered if a pair of IMCO elbows would make a big difference. Anyone ever tried them?

My next search for H.P. will involve switching to a set of 1.6 ratio rockers, roller tips from Comp Cams. Their less than $200 and should give me another 10 H.P. I'm not sure what they'd do on your EFI setup but you might want to consider them. The EFI setups can be difficult to work with since the fuel curves are set.

The truck is running great, 3000 miles so far, mostly towing. I put 900 miles on it Memorial Day weekend towing the 18 to New Mexico and back.

I can't make it to Mead this weekend but let's keep in touch. Where are you in California now? I sure hope this Tahoe deal takes off this year, sounds like fun.

[This message has been edited by RickS (edited 06-05-2001).]

[BigGrizzly]

My son has a big block 22ZX, Put on a Revolution 4 23 pitch on it, took off the 24 Bravo1 it made a a big difference, to his boat, still a little slow. His engine is a stoch 7.4

Randy