View Full Version : 22ZX prop/speed question?

08-20-2010, 10:07 AM
I've just finished upgrading a 2000 22ZX,Whipplecharged 454 with Bravo XR 1.50 swinging a 30P B1 prop.WOT im getting about 4600 rpm and gps speed is slightly over 72 mph.Im trying to get a 28p to try out,any suggestions for more speed and rpm,also what is the max i can get out of her with this engine/drive combination?
Thanks in advance for any info.

Dr. David Fleming
08-20-2010, 11:28 AM
I have spent summer on 1999 22ZX step hull with 502 MAG MPI - CMI headers - port and polished heads with racing valves etc - and computer tuned by Tyler Crockett -

Am running lab finished 28P Bravo I and 30P Bravo I props - Bravo one performance drive 1.500 ratio - Latham external steering - Merc K planes with mechanical trim indicators

Running in Michigan 600ft above sea level in fresh water -28P prop runs 76-78 GPS - 30P prop runs 77-80 GPS depending on wind weather, load of gas, trim etc.

You might want to get over to Tyler Crockett - have seen him performance tune modified engines like yours just by hooking up his laptop in the boat and taking it for a ride in the St. Clair River - I wonder if you have the Whipple and the engine computer working together? You should be pulling some serious power with your engine - I am guessing potential is 500 - 600hp - your boat should see 80 - 90 GPS or more without a doubt - Bravo I 32P or 34P if I had it in my 22ZX

Are you sure you have the 454 MAG engine and not the peanut port 7.4MPI (454) which is from GM pickup trucks - if you have the 7.4MPI (454) you may be getting all you are going to get without some serious engine reconstruction - like steel crank and forged pistons etc.

08-20-2010, 01:37 PM
Thanks for the reply,It's not a 454 mag,it's the 454 310mpi w/ whipplecharger.Paperwork that came with the charger claims it to make motor 500 HP.

Dr. David Fleming
08-20-2010, 02:53 PM
Masterkey - this is a common way to get the 310 hp engine to perform - Whipple does what can be done to this motor. It compensates for the poor cylinder heads that won't make power - Down side is that the boost has to be kept low to prevent the crank and pistons form crapping out on you. Forged steel cranks are strong and when Mercruiser used them they went to bigger connecting rods with stronger rod bolts and topped it off with forged pistons which take a lot more detonation loading.

For this reason the Whipple has to have a lower boost - I watched Tyler Crockett fix up a similar motor this summer - steel crank, rods and pistons long duration crankshaft and bigger fuel injectors - the little 310 really came alive with the supercharger. You have the drive Bravo XR which can handle some more power that the stock Bravo I - I would be sure to use a lab finished Bravo I propeller - sounds like you are pretty close on the prop pitch 4600rpm - is where the power is with a stock cam.

The chief engineer at Donzi that designed the 22ZX told me it would be good for 100mph - at 80 mph trim is pretty critical - I would use the K-planes and hydraulic steering if you don't already have them. You ought to post a pic of your boat - some 22ZX lovers on this site

08-20-2010, 03:08 PM
Great info,bit disappointing considering the amount of work I've done to get the boat this far.I thought rpm for that motor would be 5000-5200.How do i post pics?

08-20-2010, 03:52 PM
What is the horsepower of your ZX after tuning?I know stock 502 is around 415.

Dr. David Fleming
08-20-2010, 05:51 PM
My Donzi had the 310 hp L-29 engine option with Bravo I performance drive, Bennett trim tabs - and most important Victory graphics - you can see a 22ZX with this in the movie The Eliminator - which has a great race scene in the first ten minutes of the film - ZX against a couple of Donzi Classics

I pulled the 310 hp engine sold it locally for $2000 - bought the MAG MPI fuel injection setup from Craigs List for $1000 - Tyler Crockett who is a major engine builder in the USA and is in Port Huron, MI - he built up the engine with a GM performance 502 short block - the cylinder heads are iron heads off the race boat "Crazy Chicken" when they went to aluminum. Stock cam for fuel mileage - CMI stainless steel e-top headers off of the race boat "Thunderstruck" Ron Reiter sold them just before he was killed in a race in New Jersey couple of years ago. Air Cleaner is performance K&N from Teague - Crane roller rocker arms - push rods, roller lifters, guide plates all Crane and Competition Cams springs and retainers, I think the big valves were Inconel - this is because the weak link in the Big Block Chevy is the valve gear - Tyler re tuned my MEFI III computer (Mercury Electronic Fuel Injection) (type III - is the best you have to use what your boat has) - Tyler had to adjust the fuel mix and timing - he ran the boat with his oxygen sensor in the headers and then corrected the air fuel mix and ignition timing -

On his dyno the engine ran 445 horsepower at 4400rpm to 4800 rpm pulled a nice flat torque curve. Tyler put a lab finish 26p Bravo I on it which ran 5,500rpm and 74-76mph GPS - I went to the 28P and 30P which give the best speed.

Pulled off the Bennett Trim tabs and added the Mercury K-Planes which were optional from Donzi on the 22ZX - small 12X12 system - added the partial cable external hydraulic steering from Latham which is what Donzi put on the 22ZX - again optional - added the external trim indicators for tabs and drive which are from Livorsi - again the factory setup - also added the 100mph speedometer and took out the electric trim indicator gauge and replaced it with a matching water pressure gauge (Livorsi) - added the matching clock and compass to the dash panel that is over the cabin companionway - Livorsi instruments - they made Gaffrig II if you have them.

Tyler was pretty impressed with the step hull performance as the boat was touching 80mph GPS with the stock cam in the 502 MAG MPI - this is what Chris ........ the Donzi Chief Engineer who designed the boat said it would run -

My opinion is if you pull the 310 - keep your whipple and set up a good 502 performance block you could get the 100mph on your boat - You need the hydraulic external steering and Merc K planes - because the hull is very tricky to handle at that speed

If you trim in too far the boat goes into severe chine walking which is dangerous - if you trim out too far at speed it can fall over and run on the flat of one side of the hull - Tyler and I did this while racing a 28 Velocity this summer. He looks at me and says "What did you do to get that?" I said "Just trimmed out a little too far" I generally keep the K planes in neutral at speed - this really calms the hull and it acts like a longer boat.

Donzi made a few of these boats for the US Government in the past year or so - now I ask you what the hell would they do with a boat like that? I told him grey was an ugly color for a 22ZX he said they were white! Every thing else about them was confidential - except aluminum gas tanks.

08-20-2010, 08:09 PM
Have done it something is wrong My son's would GPS at 78 with a 30 inch at 46 with his wipplecharged 315 hp7.4. and it did make 500 hp, with Stainless Marine exhaust. his best top speed was 82 on a really good day. My guess the ECU is not dialed.

08-21-2010, 12:17 PM
I have just purchased a 1999 22zx and im pretty much lost when it come to performance boats.. It has a 502 bored out to 540 with a whipplecharger.. Im running about 82 mph @ 4600 , i know i can get over a 100mph but not sure if i can hanlde the boat at these speeds , any suggestions...

Dr. David Fleming
08-21-2010, 05:35 PM
I said it earlier and so did Griz - the engine and computer are probably not matched to the motor - check and be sure what engine you really have - also check you don't have something broken in the engine.

The 454 MAG MPI, 502 MAG MPI and 7.4 MPI electronic ignition and fuel system computer is called MEFI - Merc Electronic Fuel Injection - and comes in Type I, II or III - the last is the best and has a special program or schedule built into it it for superchargers - the MEFI III

There is a MEFI IV but I don't know as much about the system the 525 is another but it is not tunable because it is encrypted.

The MEFI III is small, square and bolted on the exhaust manifold or injection manifold - it has the power of the average lap top - MEFI II and I are larger with different wiring terminals - not as desirable from what I know - MEFI I engines were the early ones with a large cast fuel bowl on the top of the engine - this was called a VST vapor separator tank which is sort of a large float bowl - MEFI II and III on 454/502 MAG MPI engines don't have this.

These computers are all set at the factory for stock engines - when someone goes and changes the engine it needs a different adjustments - these adjustments are to the fuel map, and ignition timing program - the MEFI system monitors - several critical engine functions including spark knock - manifold air pressure MAP - manifold air temperature MAT, throttle position TPI and a couple of others - when you go and hang a supercharger on the motor the operating parameters all need to be adjusted differently - so does the fuel system pressure and injector pressure as well as the idle air control IAC -

Several tuners like Arizona Speed and Marine - Tyler Crockett and a couple of others will FLASH your computer this means they reprogram it with changes that they think will work based on information you tell them.

Problem is if you don't know what you are talking about or don't know what was really done to the engine - you are shooting in the dark - sometimes you have to take your boat to one of these places and they have to hook up their laptops to your boat and go for a ride and adjust things while you drive. Tyler Crockett regularly does this for customers.

I have seen this computer tuning produce 10 -15 mph speed increases - Take Steve Narva for example from Illinois - sent his engine to Tyler who built it - 502 Holley fuel injection setup - 600 hp in a 28 Velocity - after all this a 65mph boat - Tyler and I were racing with him in my 22ZX - well Tyler hooks up the laptop takes Steve out on the St. Clair River - presto - 85mph Velocity - 20 mph difference and Tyler had FLASHED the computer by mail before tuning it in the boat.

As I mentioned some of the later MEFI computers cannot be tuned because Mercury Racing has encoded them with non available programing updates - This is supposed to keep professional racers competitive - In his race boat R Rated Racing this summer - the 525 computers were kicking into default and Tyler had to send them to Mercury Racing for adjustment - this limits what types of hot-rodding can be done on the race course.

08-21-2010, 09:24 PM
The boat you mentioned of your son's,was it a white ZX with red and black trim called screwed twice?

08-21-2010, 10:36 PM
Well,I did some research and found out that I own your son's old boat Big Grizz.I bought it last summer off a guy in Dothan,AL.He said everything was in good shape,but it wasn't.I ended up tearing the boat down and putting in the XR drive with new transom assembly and hd coupler,Complete Dual ram zeiger hydraulic steering system,rebuilt water pump and serviced everything else.I now have the boat in the Bahamas so carrying the boat to someone to tune isn't an option,although I can bring them to me....i'd like to hear more about the boat from you,the engine is the one thing i didn't get much info on about who worked on it and what all was done other than the whipple installation.There are no signs of engine trouble,she still runs very smooth..

08-22-2010, 10:03 AM
Alistair did you do a compression test or leak down test to see how tight everything is inside? I too would think you would be running a bit faster. Especially at sea level and in salt water.. :) Jamie / Lakeside

08-22-2010, 11:55 AM
Yes that is the boat. the 7.4 with safer heads then it came with. WE did not have the other mods.

08-22-2010, 12:47 PM
Jaime,i'm going to definately get on the compression check this week.I have to get this figured out,from what Big Griz says i'm running about 8 mph slower than when he had the boat,something's definately off.

08-23-2010, 08:57 AM
One thing I forgot to say was the ECU was re mapped by Mark Bose in New Orleans with the boat and my son driving it.!! Wipple messed it up 3 times so we got the best to do it.!!!!!

08-27-2010, 06:28 PM
I am home again.

08-28-2010, 02:38 PM
Ok,i'm getting ready to do my compression check,i will update you.A friend of my Dads does prop work for a living and he took a look at my numbers and said I had too much slip and he was sure if he recupped the prop i would regain the performance.

08-29-2010, 09:26 AM
The prop was my Son's idea. he used the boat every chance he got and never bothered to work with me on the prop. Personal opinion the prop is all wrong for the boat. Also remember 300->350 hours the engine should be gone over. i am sure that boat has at least that. Remember that blower has been on there since 2002.

08-31-2010, 05:24 PM
What prop would you suggest?

08-31-2010, 06:25 PM
I would think that combo would be good for 82 to mph 84 . Borrow a 28 pitch prop and see if it makes a difference.

08-31-2010, 07:31 PM
I wo thatuld go with a 28. Now remember I said its best speed was 82 with that prop. he did try a hydromotive and it was suppose to be better, but I was not there so I can't verify that.

09-04-2010, 01:34 PM
Just did my compression test here are the results:

#1:125 psi

My plugs are black and you can smell the fuel on them.I just put them in 15 hrs ago.