Its getting cooler and The ZR is going faster!

[fasttrucker]

The 27zr with 496ho/425hp went on a fun/lunch run this past sunday with 7 total go-fasts here in Md.We left the NE river around 10 am.Cool temps but not freezing.I had 3/4 tank and 3 crew members with me.The best top speed that Ive been able to go was 69.7 this summer with an empty tank and no riders.Well I got 69.8 and then hit 69.9 gps.Iam going to run the tank down and go out by myself,........Hope to get 70!:hyper:

[quick ZX]

Cool Bill. I know saturday i the 22zx up to 60.3 gps with 7/8 tank full fresh water tank and and a 250 lb friend with me. not sure how much more i can get out of her. good luck you should def. hit 70

[Shanghied Again]

The 27zr with 496ho/425hp went on a fun/lunch run this past sunday with 7 total go-fasts here in Md.We left the NE river around 10 am.Cool temps but not freezing.I had 3/4 tank and 3 crew members with me.The best top speed that Ive been able to go was 69.7 this summer with an empty tank and no riders.Well I got 69.8 and then hit 69.9 gps.Iam going to run the tank down and go out by myself,........Hope to get 70!:hyper:
You should get 72 in the cooler air:)

[Planetwarmer]

Cool Bill. I know saturday i the 22zx up to 60.3 gps with 7/8 tank full fresh water tank and and a 250 lb friend with me. not sure how much more i can get out of her. good luck you should def. hit 70
That would be cool if YOU saw 70 in the cooler air!

[fasttrucker]

You should get 72 in the cooler air:)
Frank,do you know anything about my outdrive switch.I have a replaced unit its a 1.5 ratio with a 26 pitch bravo-1.The boat had a 1.65 ratio and a 28 bravo-1 prop.All I know from talking to mercury is my boat came with the 1.65 bravo-x outdrive and I have a newer one now.Maybe this change will make the boat run slower?

[tomahdonzi]

Fasttrucker,

My wife and I had our 27ZR out two weeks ago on a lake here in Wisconsin. Great conditions. 70 degrees and bit of breeze, but not much chop. Full tank of gas with just the two of us. Reached 72 mph at 5,050 rpm. Recall I have the 1.65 ratio with 28 pitch prop. I also had the trim tabs down about 1/2 way. Found that 1/2 way is needed for WOT to eliminate the side to side thing with these boats. But doesn't seem to affect the top speed at all. For what it's worth, I also pull 3,400 rpms getting on plane with this prop/drive setup. Gets on plane pretty quickly with 2 people on board. Much slower with 4 people on board. Fuel level doesn't seem to affect plane time. Tabs don't make any difference either in terms of getting on plane on my boat. Hope this info helps.
Rick

[fasttrucker]

Fasttrucker,

My wife and I had our 27ZR out two weeks ago on a lake here in Wisconsin. Great conditions. 70 degrees and bit of breeze, but not much chop. Full tank of gas with just the two of us. Reached 72 mph at 5,050 rpm. Recall I have the 1.65 ratio with 28 pitch prop. I also had the trim tabs down about 1/2 way. Found that 1/2 way is needed for WOT to eliminate the side to side thing with these boats. But doesn't seem to affect the top speed at all. For what it's worth, I also pull 3,400 rpms getting on plane with this prop/drive setup. Gets on plane pretty quickly with 2 people on board. Much slower with 4 people on board. Fuel level doesn't seem to affect plane time. Tabs don't make any difference either in terms of getting on plane on my boat. Hope this info helps.
Rick
Thanks for your help.It looks like I have the wrong set-up on the replaced drive(maybe?).I would like to send my prop off to get it balanced and labbed.I think that would help.I also think the fuel tank,being it is up towards the front, makes it so that it is not a problem planing out with a full tank.Maybe the extra weight might slow the boat down.When you put someone in the back seat,it really slows the time it takes to plane it out.The tabs need to be down some but,I dont have any way of knowing how far as they didnt put in a gauge for the tabs.In powerboat mag.july 2009.They test a 27zr(two years newer then mine) with my outdrive ratio of 1.5 and 26P prop.They write that the top speed is 71.9 at 5100 rpm.They write about the high speed "wobble".I also noticed that they changed the cabin door to a three-piece door.I have the single roll up unit.They come off the track (Ive been told) but mine has not yet done that.They also added twin air scoops to the engine hatch.The steering wheel on the test boat was also nicer.

[quick ZX]

That would be cool if YOU saw 70 in the cooler air!
DAMN i would definitely love that!!! lol Good one

[tomahdonzi]

Fasttrucker,

I almost bought that boat (the one in the mag). It was for sale down in FL when I bought mine. Wasn't optioned out quite as nicely, though. Anyway, I don't have tab indicators, either. I just know it takes 10 seconds for them to go all the way down, and so I put them down for 5 seconds, so I figure I'm halfway down. That has eliminated the side to side action. I spoke with Merc about their labbed props. Basically, a labbed prop with the same pitch will probably get you 300 more RPM, so you'd probably go with a 27 pitch lab and get 150 rpm (so I'd have to go to a 29 pitch labbed prop and I'd get 150 more rpm, but since I'm close to the limit, I think I'll stick with my prop). They're pretty helpful there, so maybe give the factory a call. Sounds like the main thing you want to do is try to get closer to that 5,100 rpm, and a labbed prop would probably help. It can affect takeoff, though, and the Merc guy wasn't sure how it would affect that.

[fasttrucker]

Fasttrucker,

I almost bought that boat (the one in the mag). It was for sale down in FL when I bought mine. Wasn't optioned out quite as nicely, though. Anyway, I don't have tab indicators, either. I just know it takes 10 seconds for them to go all the way down, and so I put them down for 5 seconds, so I figure I'm halfway down. That has eliminated the side to side action. I spoke with Merc about their labbed props. Basically, a labbed prop with the same pitch will probably get you 300 more RPM, so you'd probably go with a 27 pitch lab and get 150 rpm (so I'd have to go to a 29 pitch labbed prop and I'd get 150 more rpm, but since I'm close to the limit, I think I'll stick with my prop). They're pretty helpful there, so maybe give the factory a call. Sounds like the main thing you want to do is try to get closer to that 5,100 rpm, and a labbed prop would probably help. It can affect takeoff, though, and the Merc guy wasn't sure how it would affect that.
The 2009 catalog shows the 27zr with tab indicators.Its a three panel card type....outdrive and trim tabs.Iam looking into doing this.It shows the weight as 5,500 lbs and the tank as 86 gals(Ive only can get 78.5 in max when it gets empty).If you lab a prop,you can do a rec. lab or a race lab.Thin down the blades.Balance the prop.Pickup the speed.Increase the rpm,s....

[fasttrucker]

Cold weather sunday...............Iam going out to tear up the bay!

[fasttrucker]

I got 70.8 gps today!:nilly::kingme:

[tomahdonzi]

Awesome.

[VetteLT193]

Thanks for your help.It looks like I have the wrong set-up on the replaced drive(maybe?).I would like to send my prop off to get it balanced and labbed.I think that would help.I also think the fuel tank,being it is up towards the front, makes it so that it is not a problem planing out with a full tank.Maybe the extra weight might slow the boat down.When you put someone in the back seat,it really slows the time it takes to plane it out.The tabs need to be down some but,I dont have any way of knowing how far as they didnt put in a gauge for the tabs.In powerboat mag.july 2009.They test a 27zr(two years newer then mine) with my outdrive ratio of 1.5 and 26P prop.They write that the top speed is 71.9 at 5100 rpm.They write about the high speed "wobble".I also noticed that they changed the cabin door to a three-piece door.I have the single roll up unit.They come off the track (Ive been told) but mine has not yet done that.They also added twin air scoops to the engine hatch.The steering wheel on the test boat was also nicer.

I haven't done calculation comparisons on the 1.65 vs. 1.5 at slower speeds when the prop slip is different but I can't figure what the difference is on top end.

On top end the 1.65 is almost identical to a 1.5 assuming the 1.5 has 2 inches less prop.

I know there is a 'good' range of props to use but the props we use on our boats are so mid range anyway it is hard to believe one would be faster than the other.

[fasttrucker]

I haven't done calculation comparisons on the 1.65 vs. 1.5 at slower speeds when the prop slip is different but I can't figure what the difference is on top end.
On top end the 1.65 is almost identical to a 1.5 assuming the 1.5 has 2 inches less prop.
I know there is a 'good' range of props to use but the props we use on our boats are so mid range anyway it is hard to believe one would be faster than the other.
The drive set up difference may not be why Iam a little slower.Maybe its the prop?Why was my drive changed out?I do not know?

[fasttrucker]

On the way back from the Cheasapeake Inn.73.5.............

[DonZi 26]

Wow thats super fast for stock power !!

Awesome dude....i always impress myself with the difference temperatures can make!!

[undertaker]

On the way back from the Cheasapeake Inn.73.5.............

Tide was coming in...:nilly::popcorn:

[fasttrucker]

Tide was coming in...:nilly::popcorn:
I think that may have helped a little!...One thing is I put in a small amount of 89 oct as Ive been running 87 oct all summer.Top speed was recorded on a 1/4 tank and just me.

[Greg K]

Using a simple prop calculator:
26", 1.50, 5100 rpm, 10% slip = 75.3
28", 1.65, 5100 rpm, 10% slip = 73.8

Another thing you may want to look at or compare is if you have any drive spacers between the upper and lower.

[fasttrucker]

Using a simple prop calculator:
26", 1.50, 5100 rpm, 10% slip = 75.3
28", 1.65, 5100 rpm, 10% slip = 73.8
Another thing you may want to look at or compare is if you have any drive spacers between the upper and lower.
26"p bravo-1-x. 1.50. and no spacers.Donzi is a little slow to plane up with its high x-demention.I dont want to lower it down, which I know donzi did with the stock 496.I have the HO. model 425 hp which does not need the spacers to help it get on plane.

[Shanghied Again]

26"p bravo-1-x. 1.50. and no spacers.Donzi is a little slow to plane up with its high x-demention.I dont want to lower it down, which I know donzi did with the stock 496.I have the HO. model 425 hp which does not need the spacers to help it get on plane.

You wouldn't see any difference with the fuel, The 496s can run on anything/ The ECM will adjust to the cooler air and now you see the change. You got a better speed then when I first sold that boat she topped 72 in the end of April.