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jrichards
12-27-2009, 08:43 PM
How much hp can I put to this hull. It runs 60 mph. Iam putting a set hardin headers on it and a prop change now. My friend has a blower was wondering if it was to much. Thanks

LKSD
12-28-2009, 08:57 AM
You can put a pretty good amount of HP to these hulls. After a certain point you will need other items to consider like full hydraulic steering, larger trim tabs/Kplanes etc.. An exhaust change with a prop only wont usually gain you much speed. The usual is around 2mph, some stuff on rarer occasions may see 4-6mph but that is not the norm.. Those are usually Cat hulls. It is also possible that in some circumstances you only see more rapid acceleration but no top end increase..

We have done many upgrades to these boats, including superchargers. I may have already talked to you tho if you are in NJ.. Regardless of if we talked or not, if our services may interest you feel free to call me.. :) Jamie / Lakeside Restorations 570-639-2628

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Last Tango
12-28-2009, 09:57 AM
Jamie is correct about the hull accepting a bunch more power. Several years ago, one member supercharged his 454 22ZX and it was an amazingly fast boat. A couple others have since also gone that route.

At the Miami Boat Show a couple years ago I talked with Teague and we were joking around about putting a Viper-based marine engine in the boat. He thought it was a great idea to have a normally aspirated high HP motor. But he said he would probably limit it to the 550 HP model. Not because it wouldn't fit, or because the hull structure couldn't handle it, but because that amount of power would produce all of the speed that could be safely operated in the 22ZX.

A 525 EFI would be a nice addition that does not require a supercharger, but would require a supercharged wallet.

The Hedgehog
12-28-2009, 10:18 AM
You could build up a nice fire breathing 454 with another 130hp over your current setup and it would run pretty well. Build it right and you could always add a blower and it would be out of hand.

You could drop in a 540 short deck and it would also run pretty good.

Exhaust is a good mod but it won't net you much. You WILL need it though if you build a powerful N/A engine.

Lots of good things to do with that combo. You will want to dial it in WELL if you are seeing over 80.

rtgogo
12-28-2009, 07:28 PM
60 is it? I have a 2001 22zx step hull with a 454Mag and hit 71GPS last season. Has it been tuned? Seems like she should run faster than that...

quick ZX
12-29-2009, 07:40 AM
I have a 02 22zx with a 350 mag and i run between 60 and 64. yours should be faster than that.

FISHIN SUCKS
12-30-2009, 12:36 PM
I know Beerbaron had his '97 22ZX 454 non step (he just traded it on a 28' Powerquest) to 63. Hydraulic steering and tabs. Do the steps in the 22 make that much of a difference ? maybe.

Last Tango
12-30-2009, 12:58 PM
Well, before we get into a question of how fast a particular boat "should" go, we would be better off as a group to find out exacly WHICH 454 is in the boat, the drive type and reduction ratio, the prop size currently in use, and the location of the water the owner is trying to run it (altitude above sea level, fresh water/salt water, etc.) and if the numbers being quoted for said boat are GPS or off the original (and notoriously and wildly wrong) speedo.

Only then can we guage the potential real perfomance expectation of the boat.

rtgogo
12-30-2009, 06:53 PM
Uh.. well.. I'll do my best to quantify my stats....

2001 22zx stepped hull with 454 MAG EFI.
Not sure on pitch, but have a 4-blade bravo prop
71 GPS with half tank of premium gas in early spring runnin on lake in south Alabama.
As far as I know.. all is stock. Techs have tweaked it over the past year with installation of new Livorsi Throttle, etc, but no motor work..YET!

71 was max, but consistently running 65-68 range WOT.

Dr. David Fleming
12-30-2009, 10:52 PM
I talked to Chris Cxxxxxx who is the designer at Donzi who designed and did the development of the 22zx - it was in production last year for the US Government. Catching pirates or defending the USA I don't know.

Chris said that the 22zx would go 100mph. Now I have not heard of anyone getting it that fast. You can see one run in the movies - You can see a fast 22zx (which has my paint job) in the movie The Enforcer. There is a section on of this movie on u-tube. The movie boat is a non step 22zx hull and they really put it through some stunts. The step hull is known for handling problems - What is a step hull? Well the back half of the boat is not as deep in the water as the front half - sort of a small transom half way across the boat bottom - this allows air under the boat and it runs faster.

Specs for 22zx with "step hull" and fuel injected engines -

454 Chevy L-29 engine which makes 310hp does about 62-64 mph

454 mag Mercruiser fuel injected 380hp does about 68-71 mph

502 mag Mercruiser fuel injected 415hp does about 72-76 mph

They did offer this boat in 2002 with a Mercury Racing 500 EFI engine option but I have never seen it built this way.

Donzi did make a 22zx hull in 1999 that was called the Donzi 22zx Daytona which I have seen a couple of pictures of - this boat used different graphics on the side - Donzi Daytona and the upholstery cover on the engine hatch said Daytona. This boat was suposed be layed up with kelvar carbon fiber in the hull construction making it much stronger. The Daytona also came standard equipment with the big 502 MAG MPI engine and all the trim and stearing options.

The older 22zx hulls - in the 1994-1998 era had no step and usually a carburated engine option. This was a Webber four barrel carb made in Italy for Mercruiser - The Webber is really an old American carburator manufactured by Carter Carburator Company which went out of business back in the 1980s. This 810 cfm carburator was just as powerful as the late model fuel injection setups and a lot simpler to work with. Both the 454 MAG and the 502 MAG used this great aluminum four barrel carburator.

After 2002 - Mercruiser could no longer get the Big Block Chevy (bbc) engine they used the new 496 GM engine which made 385 hp in low power setup and 420 hp in high output configuration.

The Small Block Chevy 350 (sbc) engine - was also an option after 2002 and compared favorably with the no longer available 454 chevy L-29 engine that made 310hp.

Supercharging - A couple of folks have supercharged the 22ZX. I saw pics of this and it was the 310 hp 454 Mercruiser L-29 with a Wipplecharger - this is a cheap way to get around a low powered setup but the engine just isn't strong enough for this. Another early supercharged 22zx I have pics of had a GMC roots type blower setup common in drag racing - looked like a B&M blower kit. This was used in Nevada at altitude. The owner was selling the boat and said it ran 70mph - It should have run a lot faster.

Explanation of blowers at high altitude - Airplanes or any internal combustion engine operated at altitude cannot make full power. Why is this? Because there is no air pressure to feed the engine. For this reason when boats go up in altitude like boating in Nevada they don't run fast. Solution - get a supercharger this feeds the air into the engine under pressure - problem solved full power in the sky - great fighter aircraft of WWII all needed superchargers. Works for boats too. At sea level this can really make power and is the secret of all the big Mercruiser power sold in large off shore boats today. Merc 1075 is just the (bbc) 502 with supercharger and it makes 1075hp - thats right one thousand horsepower. Sometimes three of these engines in one boat - Instant 140mph - It costs some cubic money and anyone can buy one - go figure.

The Hedgehog
12-31-2009, 10:38 AM
I talked to Chris Cxxxxxx who is the designer at Donzi who designed and did the development of the 22zx - it was in production last year for the US Government. Catching pirates or defending the USA I don't know.

Chris said that the 22zx would go 100mph. Now I have not heard of anyone getting it that fast. You can see one run in the movies - You can see a fast 22zx (which has my paint job) in the movie The Enforcer. There is a section on of this movie on u-tube. The movie boat is a non step 22zx hull and they really put it through some stunts. The step hull is known for handling problems - What is a step hull? Well the back half of the boat is not as deep in the water as the front half - sort of a small transom half way across the boat bottom - this allows air under the boat and it runs faster.

Specs for 22zx with "step hull" and fuel injected engines -

454 Chevy L-29 engine which makes 310hp does about 62-64 mph

454 mag Mercruiser fuel injected 380hp does about 68-71 mph

502 mag Mercruiser fuel injected 415hp does about 72-76 mph

They did offer this boat in 2002 with a Mercury Racing 500 EFI engine option but I have never seen it built this way.

Donzi did make a 22zx hull in 1999 that was called the Donzi 22zx Daytona which I have seen a couple of pictures of - this boat used different graphics on the side - Donzi Daytona and the upholstery cover on the engine hatch said Daytona. This boat was suposed be layed up with kelvar carbon fiber in the hull construction making it much stronger. The Daytona also came standard equipment with the big 502 MAG MPI engine and all the trim and stearing options.

The older 22zx hulls - in the 1994-1998 era had no step and usually a carburated engine option. This was a Webber four barrel carb made in Italy for Mercruiser - The Webber is really an old American carburator manufactured by Carter Carburator Company which went out of business back in the 1980s. This 810 cfm carburator was just as powerful as the late model fuel injection setups and a lot simpler to work with. Both the 454 MAG and the 502 MAG used this great aluminum four barrel carburator.

After 2002 - Mercruiser could no longer get the Big Block Chevy (bbc) engine they used the new 496 GM engine which made 385 hp in low power setup and 420 hp in high output configuration.

The Small Block Chevy 350 (sbc) engine - was also an option after 2002 and compared favorably with the no longer available 454 chevy L-29 engine that made 310hp.

Supercharging - A couple of folks have supercharged the 22ZX. I saw pics of this and it was the 310 hp 454 Mercruiser L-29 with a Wipplecharger - this is a cheap way to get around a low powered setup but the engine just isn't strong enough for this. Another early supercharged 22zx I have pics of had a GMC roots type blower setup common in drag racing - looked like a B&M blower kit. This was used in Nevada at altitude. The owner was selling the boat and said it ran 70mph - It should have run a lot faster.

Explanation of blowers at high altitude - Airplanes or any internal combustion engine operated at altitude cannot make full power. Why is this? Because there is no air pressure to feed the engine. For this reason when boats go up in altitude like boating in Nevada they don't run fast. Solution - get a supercharger this feeds the air into the engine under pressure - problem solved full power in the sky - great fighter aircraft of WWII all needed superchargers. Works for boats too. At sea level this can really make power and is the secret of all the big Mercruiser power sold in large off shore boats today. Merc 1075 is just the (bbc) 502 with supercharger and it makes 1075hp - thats right one thousand horsepower. Sometimes three of these engines in one boat - Instant 140mph - It costs some cubic money and anyone can buy one - go figure.


Nice narrative and the numbers seem right on.

The 1075 is a 555. What I am not sure about is whether it is a 502 block (short deck) or a 540 block (tall deck). That is pretty big power for that block.

mrfixxall
12-31-2009, 12:12 PM
Nice narrative and the numbers seem right on.

The 1075 is a 555. What I am not sure about is whether it is a 502 block (short deck) or a 540 block (tall deck). That is pretty big power for that block.

I believe their a tall deck....

at leaste the old 572 were!

Uncle Fester
12-31-2009, 02:21 PM
I'm a '99 stepped hull with Volvo 7.4Gi and SX drive with Hydramotive quad 4 24 pitch 4 blade. Mostly run at 500' above sea level and am lucky if I see 60 at WOT. Would love to do 70, but don't know how to get there. She runs real good at 4000 RPM and 50 mph on about 10 gallons an hour so I shouldn't complain.

Last Tango
12-31-2009, 02:25 PM
rtgogo,
Whoops! LOL! I was actually referring back to the OP to post his specs so we could help him. I certainly wasn't questioning you. LOL!!!! But, your post is excellent as always and will go some distance for the OP to compare his boat specs/performance to yours.
Everyone here seems to be doing an awesome job of trying to help him out. Wish he would post back to us.

And, as usual, Dr. Fleming has once again showered all of us with great info on the 22ZX. I feel compelled again to copy his post to my long-running blog on my boat so other 22ZX owners will find it there as well.

jrichards
01-10-2010, 09:34 PM
Sorry guys I've been working alot. My boat is a 1996 with a 454 mag and a webber carb. I know it needs a 23 pic prop. It has a 21 on it now when I ran 60. Our air is bad here in the summer out in west texas. Not sure really if the hull is stepped.

Dr. David Fleming
01-10-2010, 10:31 PM
You would know if you had a "step hull" because there is a huge notch cut in the bottom that runs from side to side under the rear seat. If the hull is smooth from bow to stern it is called a "deep V" hull. If it has this notch cut across its bottom it is a "step hull."

AS the boat runs along the surface of the water the notch sucks in air and the back half of the boat becomes airborn so to speak. This reduces the drag the water places on the hull and the boat goes faster. There is a drawback, and that is the back end of the boat is not really all that secure and can under some circumstances swap ends with the bow. The "deep V" while it is slower is much more stable in the water.

1 - The "displacement hull" this is an ancient boat design where the boat stays deep in the water and goes fast by having a sharp point bow.

2 - THe "flat bottom hydroplane" was the first type of hydroplane (water plane) hull that was developed around 1910 and used in early racing. Ouboard racing used this up through 1927. This was the first design to get the hull out of the water and ride on top of the water.

2 - The "step hull" is also a hydroplane hull that was developed to go a little faster and was used to set world records in the late 1920's. Garwood, a famous Detroit businessman built a number of hulls called "Miss America." This design has the vent under the bottom to get air under the hull.

4 - The "three point hydroplane" was developed I believe by George Couch and became the championship hull in I am guessing the 1950's. This is still a championship hull design and these boats are often called "prop riders" because the back of the boat comes out of the water as it is lifted clear by the prop forcing it up. The front of the boat runs on two pontoon sponsons. Supposedly it has three points of contact, the two sponsons up front and the flat bottom on the back - unless the prop lifts it clear. You often see these hulls run today in unlimited hydroplane class and as outboard racing boats.

5 - The "off shore hull" also called the "deep v" was designed in the 1950-60's the first one was called the "brave mopsy" by the guy that designed it. This hydroplane hull is different in that the bow continues all the way down the bottom of the boat. This allows it to run fast in the waves as the bow continues to cut the waves even on plane. It is the first hull that is really fast in rough water and this is why it was given the name "off shore hull."

6 - The "catamaran" (sp) this is a hydroplane hull developed from sailing craft of the south pacific ocean natives and is basically two thin hulls tied together by the deck, cockpit of the boat a tunnel is created between the two hulls which traps air and this gave created another type of hull called the "tunnel hull" which I am not sure is different from the "castamaran."

7 - The "air foil" this hydroplane is not used much in anything but military and comercial design where max speed is wanted. The hull is lifted out of the water on legs which have small wings. The boat basically comes entirely out of the water. I believe in England there are ferryboats to France that ride out of the water. The Coast Guard might have some type of specialty boats like this.

All of these hulls have been developed in different ways by boat designers to get a lot of different combinations of performance. You can see "step hulls" with several steps, "three point" hydroplanes with steps on their sponsons, and "catamarans" with steps on their two hulls.

The Donzi 22ZX was made in only two ways both are hydroplanes. Both are "deep V" design and one has a "step." To save a lot of words the early 22ZX is called a "deep V" and the later 22ZX is called a "step hull."

If you can read and understand all this you have just graduated from Dr. D's boat university. By the way there will be a test on all this in the morning.

jrichards
01-11-2010, 07:28 PM
Sorry Dr. D My hull isn't a step hull. I seen where I missed that earlier. I think i will try the 177 blower set up this year. I can pick it up at a good price. :bonk:

Dr. David Fleming
01-11-2010, 08:29 PM
you should catch your donzi 22ZX in the movies. Go rent "The Enforcer" or you can find it on in the video section of this site under the title "classics race a ZX" The stunt boat in the movie is a early "deep v" 22zx. they pull some great stunts like swerving the boat at speed and blasting a wake into the competing donzi classics in the race. The zx does a chase seen which looks like it was filmed in florida swamp lands. the movie shows off the stability of the zx deep v hull.

last summer someone ran a post on how a 22ZX step hull threw him out of his boat while he was clowning around at low speed. The step hull tripped and he went through the windshield and almost drown. Be sure you use the safety lanyard on your boat - if you go overboard at least the boat will stop and you can get back on board. This guy watched his boat circle back and almost run over him.

I am sure with a blower you will get all the speed you want - watch out for the 22zx it takes some serious attention when it gets over 70mph. mine was running 76mph with the 502 chevy fuel injected engine. the 502 dynoed at 445 hp when we built it two years ago. I just put CMI stainless headers on it last year. this year I got two new Bravo 1 propellers 28p and 30p - it should get close to 80mph.

Several guys on this site have done blowers on the 310hp big block chevy. you should keep this thread going and learn something about what they did.

why don't you write a post with a detailed discription of your boat - does it have trim tabs? what kind? stock exhaust? what prop? the 22zx was designed to use a 4blade Bravo 1 here is a list of common propellers. Chris Cxxxxxxx the donzi engineer who designed the zx boats told me this. donzi does use Mirage three blade props on the twin engine 26ZX and 27ZX but the larger ZX go back to the Bravo 1 four blade.

300hp small block/ 310 hp big block - Bravo 1 - 24p

375hp big block 415hp big block - Bravo 1 - 26p

380hp and 425hp new "GM 496" big block - Bravo 1 26p

you should post a pic of your donzi everyone will want to see it.

jrichards
01-12-2010, 08:39 PM
Running 76 mph do you have stock tabs and steering? Thats what I have. With a turbo 4 blade 21p it would run 55mph at 4600rpm. I changed out mufflers and put tips on it and it ran 58mph. Then I put a mirage 3 blade 21p on it and it ran 60mph at 4900rpm. What you was saying I need a 26p 4 blade bravo1. Does my numbers make any sense to you? I will rent that movie. Sounds like a good one. Thanks for feedback.

jrichards
01-12-2010, 08:55 PM
Them numbers were with stock exhast. Iam putting a set of Hardin Headers on it now. I know I'll never be the fastest boat out there I just dont wont to be the slowest. Them speeds were with gps I would be happy with 70 to 75 mph

The Hedgehog
01-13-2010, 05:01 AM
You should be able to get some nice numbers out of that boat. I have found the non step ZX to do al little better with a a blade. Do the exhaust first and then see what some of our prop guys have to offer. Yours may even like a shorty as they ran a more conservative x dim on the non step.

jrichards
01-13-2010, 08:05 AM
Does anybody know the engine spec. on a 1996 454mag. Like what compression and cam size and if it has square port heads? It does have webber carb on it. This seems hard to find any kind or spec on motor without pulling it anc checking.

The Hedgehog
01-13-2010, 09:38 PM
Does anybody know the engine spec. on a 1996 454mag. Like what compression and cam size and if it has square port heads? It does have webber carb on it. This seems hard to find any kind or spec on motor without pulling it anc checking.

They made somewhere around 360 hp. Yes, rectangular ports. I am thinking around 8.5 to 1 on the comp. They are good engines.

Dr. David Fleming
01-13-2010, 10:31 PM
Jrichards,

I have some old Mercruiser catalogues so here are the engine power specs. You will see that a 454 engine with 4bbl carb and 8.5 compression has been build by Mercruiser most of the years they have been in business. The fuel injection thing has only been going for ten years. The old Merc sterndrive was called the "TRS" which had a transmission. When the "Alpha" drive was made but it was too weak to have the big block chevy in front of it. Mercruiser made a big block with "Alpha" drive but most have been destroyed or changed over to the "Bravo" drive which is very strong. Be glad you have the Bravo drive.

1999 - 7.4 mpi big block chevy (454) 310 horsepower - 9.3 compression
454 MAG mpi big block chevy 385 horsepower - 8.6 compression
502 MAG mpi big block chevy 415 horsepower - 8.75 compression

1989 - 7.4 Bravo big block - 330 horsepower - 4bbl carb - 8.5 comp
454 MAG big block - 365 horsepower - 4bbl carb - 8.8 comp

1988 - 7.4 Bravo - 330 horsepower - 4bbl carb - 9.3:1 compression
454 MAG - 365 horsepower - 4bbl carb - 8.8:1 compression
HP 420 race engine - 420 horsepower - 4bbl - 8.8 compression

1985 - 330 TRS/TR (454) - 330 hp - 4bbl carb - 8.5:1 compresson
370 TRS/TR race engine (454) - 370 hp - 4bbl carb - 8.6:1 comp
400 TRS/TR race engine (454) - 400 hp - 4bbl carb - 8.6:1 comp
440 TRS/TR race engine (454) - 440 hp - 4bbl carb - 8.6:1 comp

1984 - 330 TRS/TR (454) - 330 hp - 4bbl carb - 8.8:1 compression
370 TR (454) - 370 horsepower - 4bbl carb - 8.8 compression

1980 - 330 TRS/TR (454) - 330 horsepower - 4bbl - 8.7 compression

1978 - 330 TRS/TR (454) - 330 horsepower - 4bbl - 8.2 compression

1977 - 330 TRS/TR (454) - 330 horsepower - 4bbl - 8.2 compression

1976 - Inboard model 350 - 350 horsepower - 4bbl - 8.5 compression

1975 - inboard model 350 - 350 horsepower - 4bbl - 8.5 compression

1974 - inboard model 350 - 350 horsepower - 4bbl - 8.5 compression

1973 - inboard model 325 - 325 horsepower - 4bbl - 8.8 compression

1971 - inboard model 390 - 390 horsepower - 4bbl - 10.0:1 compression

jrichards
01-14-2010, 07:33 PM
Thanks Doc!! Do you know how hard it is to go from carb to fuel injection. Found a guy who has everything to go to a whipple super charger and intercooler with injection. He says he has wiring harns that plugs into merc system. He says its a merc set up. I have a call into whipple to do some checking on wiring. You have any ideals on this??

Dr. David Fleming
01-14-2010, 11:30 PM
jrichards,

I just wrote you a complete answer and the fricking Donzi Registry ate it. I will write another tomorrow.

Dr. David Fleming
01-15-2010, 12:32 AM
I just explained all the fuel injection setups in detail and when I submitted the Donzi Registry digested the post. So here is my second answer.

Most folks who just want to install a supercharger instead of building a naturally aspireated engine can purchase a modern supercharger setup that bolts on top of the engine. Check out Weiand or Whipplecharger and a couple of others. YOU DONT need the used mercury setup and an add on whipple, it is the technology of the past. Its big, its cumbersome, its difficult its expensive and its obsolite. And you shouldn't be messing with it.

I have a pic of a 22ZX with the 7.4mpi low performance engine and the boat cranks with a neat NEW modern whipplecharger sitting on the top of the motor with no merc parts. It runs fast, it runs strong. The engine is the one with cast crankshaft and cast pistons with small port heads. Unfortunately this guy can't run any boost because the engine internals are weak. It still goes fast enough on 1 to 2 lbs boost.

You can make 500 hp with your engine with a Holley carburator which is what Merc Racing did before 1998. Port and polish heads, racing valves, Crane rockers and pushrods and a good Crane marine cam with Holley four barrel on single plane ram manifold. Good set of CMI headers. The US Government is what drove Mercruiser to fuel injection with all the fuel emission regulation. The new Mercs have to have catalytic converter exhaust system next year.

You stay away from that used fuel injection and whiple. Before you are done you will spend $20,000 to get it running and it will be obsolite stuff. That wiring harness needs a MEFI 3 computor which is very expensive and needs professional programing for everything even changing propellor pitches.

You got a good 1996 merc/chevy engine with forged crankshaft, forged pistons and good big port heads. That Carter/webber carburator is a 750 cfm (cubic feet per minute) which is good for some 425 horsepower or more just as it is with a cam and headwork. This engine should get you to 70 mph if its in good shape and you do it right.

70 mph Mercury and Donzi recomend installing Latham external hydraulic steering. This is an "add on" hydraulic ram that is like the trim rams you have on your bravo drive. The Latham "add on" steering unit was what Donzi used on the 22ZX. it is a beautiful chrome cylinder, I have one on mine. You can take your hands off the wheel at 70mph the boat drives itself. Contact Latham and they will send a kit with all the instructions.

Donzi also used "trim tabs" on the back of the boat, which you may already have. Most 22ZX boats used the Bennett single piston trim tabs these are ok but will move if enough pressure is put to them. I have a used set if you want them and don't already have them. The optional trim tabs from the Donzi factory on the 22ZX are the "Mercury k-plane" tabs which are black painted cast aluminum with some real strong trim power.

One other thing, there are two kinds of propellors, stock and "labratory finished." These "lab finished" props are specially prepared for high speed running and are about 2mph to 4mph faster than a stock mercury propeller. They also cost about twice as much. $400 to 600 for stock $800 and up for "lab finished." You can also have any stock prop "lab finished" if you send it to Merc Racing or to a specialty house like "B Blades."

You complained about your boat being slow. Do you have the carburator all the way open. It can be out of adjustment, and the velocity valves and air valve are opening all the way, and the power pistons are not jamed or stuck down. Is your distributor timed correctly this will gain or loose you 20 to 40 horsepower. Is your centrifical advance mechanism in the distributor working and is the distributor shaft strait and not bent? Do you have good clean valves properly ground with "three angle seats." Do you have good piston rings and does the engine pass a "leak down test?"

No sense hot rodding your engine if its screwed up to begin with. Get the right prop for your boat you can loose 5mph to 10mph with the wrong propellor engine. You might gain 5mph to 10mph just tuning the engine correctly and installing the right propellor.

The Hedgehog
01-15-2010, 06:16 AM
Be careful and not put the apple before that cart. That sounds like what is going on. Talking about jumping into blowers and buying lab props before you know what you want is not a good idea. I can assure you that you will not pick up a magical 5 mph on a non-step ZX by cutting steel out of a prop. Do the lifting first and then get that extra mph or so by dialing in props.

The first question is: How fast do you want to go?

If all you want is 70 mph, you can get there without a blower. You are probably a few mph down due to tuning and possibly a tired engine. You need to address that first. If the engine is tired and you put boost on it you will be tearing it down quick. If it is indeed tired, build it back with with better components and you can get another 100hp out of it easy. You will notice a big difference. If you keep the comp ratio down under 9.0, you can add boost later. You will have a fast boat now and a screamer later.

If you want to really boogie, you will either want boost or more cubes.

Now let's assume you have a nice fresh engine. If you take it to someone good you can stick on whatever blower you like and will not need to spend $20k. No not even for the EFI system. I had a custom MEFI system built for mine and it did not cost anything like that. My guy is on the expensive side too. You will probably spend a grand or two more getting the EFI set up (after buying the hardware) if you have an experienced tuner. That includes opening up the fuel lines. My advice there, don't spend a penny on that without talking to the person you will use to do the setup. They can tell you EXACTLY how much it will cost and if the system is a good candidate for your goals. BTW, if you go with EFI, you WILL need an experienced tuner. It is not plug an play. You can play the game of mailing the ECU back and forth to the tuner. A number of us have done that. It works. The better option is to take your boat to them after you get it together and have them tune it in the water. Most of us that have played the mail game the first time take it to the tuner the next time.

The whole idea about MEFI having to go to the tuner every time you sneeze is a bunch of BS. It depends on how aggressive the tune is setup. They can leave a little juice in and you won't melt down the engine while dialing in props. I think I paid around $400 for a new MEFI 4 out of the box. If you start doing radical things to a MEFI engine you do need to watch the AFR's but that is no different than with a well dialed in carb setup.

Bottom line on MEFI vs Carb they can both be setup to run well and they BOTH have to be dialed in.

FYI, the weiand stuff is what the old merc guys used. It is pretty outdated but works. I actually spend a bunch of time with blown engines. I would go whipple or procharger. I own a procharged EFI system and have for years. I think that whipple has a better turned out product but would use either. I have fooled around with everything from a MEFI 1 and manipulating the tune with fuel pressure to driving my boat with a custom MEFI4 system while the tuner sits of the floor with a laptop. I have also gone through quite a few iterations of reading AFR's while both carb and EFI blown systems are dialed in.

jrichards
01-15-2010, 07:05 PM
Thanks guys I have done some checking today and have blowed off that ideal. Iam going to do the headers and mess with the prop this year. Getting to late to go deep into it. I will check out them ideals on my motor and go from there. Its like anything I mess with I look up and it gets out of hand. Should be happy with 60 and save my money. I've never calmed to be smart. :kingme:

The Hedgehog
01-16-2010, 09:12 AM
Thanks guys I have done some checking today and have blowed off that ideal. Iam going to do the headers and mess with the prop this year. Getting to late to go deep into it. I will check out them ideals on my motor and go from there. Its like anything I mess with I look up and it gets out of hand. Should be happy with 60 and save my money. I've never calmed to be smart. :kingme:

The headers are always a welcome addition.

Dr. David Fleming
01-17-2010, 07:19 PM
Jrichards,

I have been at work a couple of days so sorry I haven't written more.

The first thing you should do is to "qualify your engine." This is a check to see if it is making all the power it can now.

Two critical things are,

1. First does the throttle open completely and the air valves in the secondary barrels of the carburator open the way they should. Usually you can open the throttle and look in with a flashlight and see if this is the case, the secondary barrels have an air valve that trips open by airflow. See if it is not hanging up and opens freely. Also on the top of the carburator are two small metal covers. These are lids on the power pistons that lift two metering rods up out of the carburator main jets. Sometimes these power pistons get stuck down or worse someone has removed the springs that lift them. When the throttle is open the vacume in the intake drops and springs lift these small pistons which pull the rods out of the main jets and the fuel mixture goes richer. If the pistons don't lift the power mixture feeding the engine does not happen. If you slightly loosen the screws on the covers of these pistons the pistons will start to lift the covers. Then you know they are free and not stuck. Jiggle the covers back down and tighten the covers again. Be sure you don't loose the screws or covers down into the intake of the engine. Some mechanics stuff a towel into the throttle opening to make sure.

2. Check the static ignition timing with a strobe timing light. To do this you hook up the light to the boat battery, attach the signal wire to the NO. 1 sparkplug wire and then start the engine. The engine should be at idle speed and you point the light to the timing marks on the flywheel. Your engine should show a timing of about 10 degrees BTDC (before top dead center). To change the timing the ignition distributor clamp bolt is loosened and the distributor turned in a counterclockwise direction to advance the ignition timing to the specification. This adjustment of the "static ignition timing" is the most important adjustment for engine power. Advancing the timing BTDC increases power until a critical point is reached and then the engine will go into "detonation" which is very destructive. Usually the factory specifies a "static ignition timing" which is somewhat conservative so that the engine has a safety of not running on the ragged edge of maximum power. The quality of the gasoline octane will vary and this directly effects the detonation. However, if the ignition timing has not been adjusted properly and is at a "retarded setting," a large persentage of horsepower will be lost. So you must determine if it is at the factory setting.

Other things you will want to examine are to run a compression test on all eight cylinders of your engine. All should pump aproximately 110 psi pressure. If the cylinders don't pump this pressure you have a valve or piston ring failure. Most people who buy a boat will check this before the purchase. The old test for low compression cause was to put a teaspoon of oil in the sparkplug hole, if the compression returned then it was indicating the piston rings were bad - if it stayed low it was the valves.

You will also want to check the "gimble bearing" which is a bearing in the drive shaft into the lower unit. The engine in your Donzi 22zx has to have an alignment of its motor mounts occasionally. The engine shifts around and the drive shaft does not run directly into the lower unit anymore. This strains the "gimble bearing." If this bearing fails in the drive you are going to wish it didn't. So check it for noise and alignment this will help the power to get to the water. This is done by removing the lower unit from the boat and inserting a special steel shaft into the bearing and flywheel of the motor. Then you move the engine up or down, right or left until the shaft goes in. The engine is then aligned.

IF all this stuff checks out, then you will want to consider if your propellor selection is correct. I would start with the prop the factory put on the boat. Sometimes folks damage a prop and the boat gets whatever is available locally even if it is the wrong prop. Sometimes some "gyro" has been trying to fix things when the boat engine is not tuned properly and mistakenly changes the propellor trying to fix a problem the wrong way. I have given you a couple of propellor recomendations but if you really want to check you can call Donzi at the Customer service and give them your boat number and they will tell you what prop your boat was built with.

jrichards
01-18-2010, 07:05 PM
Thanks Doc I will do some checking on the carb and timing. You have been alot of help. One day my boat will grow up and be almost as fast as yours. LOL Ready for summer!!! :cool!: