Author Topic: GT-150 speed stats (Read 56912 times)

Terry_Curran · « **Reply #20 on:** August 31, 2013, 03:58:59 PM »

Hey Doug, I thought it was the cooler in back that slowed us down. Thought we were going to make it to Florida this year and see you and your new shop. Right now things aren't looking too good though.

Terry

V153 · « **Reply #21 on:** September 01, 2013, 12:03:22 AM »

Quote from: SSV-191 on August 31, 2013, 03:58:59 PM

Hey Doug, I thought it was the cooler in back that slowed us down.

Ya, musta been your prune juice ... Ah well. let's all hope times get a lil better? But I ain't holdin my breath ...

catchnedge · « **Reply #22 on:** September 04, 2013, 07:38:36 AM »

Just FYI Joe... On my GT150, I put the 2-blade bronze 21p balanced & cupped prop that I got from David on my Merc 85hp and did some GPS speed checks... just me in the boat with a 9 gallon tank in back (maybe 1/2 to 3/4 full?), 2nd hole out from transom (too far out for normal use, it will sometimes porpoise and raises bow way too much out of the hole), I couldn't believe I was getting 48mph! Not sure what rpms it was turning, don't have a tach. I was so happy with that out of an 85hp engine, I'm leaving that on there... in fact about to get a back up prop just like it. The 2-blade is not good for carrying loads though, or pulling skiers out of the hole or when the boat is loaded down (which is not often), but usually it's just me or maybe one other. I think the transom plate I have has raised my motor slightly which is probably helping me. My hull is very stable at 48mph. I don't have to worry about the "ragged edge" like Mark, I won't be going that fast. All I have to avoid is throwing it into one of those steep turns it likes to rock into at too fast a speed

Sounds like the Raker may be the way to go for you, excellent speed and probably gives you good power out of the hole with family/gear in the boat.

Hyperacme · « **Reply #23 on:** September 04, 2013, 08:50:56 AM »

Mark ...
Your new 2 blade has been lake tested and is good to 51.8 mph on GPS ...
I'm one of the "Prop Master's" certified test pilots.

David CVX-16 · « **Reply #24 on:** September 04, 2013, 11:21:39 AM »

Gregg is my one and only test pilot. He also tested a 22" Hi-Performance Mercury Quicksilver 2-blade bronze prop. The prop hub slipped on Gregg giving him a scare. Took it over to Propulsion Prop in Hudson Wisconsin this morning for rehubbing. Learned that rubber hubs need breaking in. Gentle power both forward and backward for awhile to set the rubber before giving it alot of power.

Talked with the owner Dave at length. He recognized the name Pankonin because he went to Murray HS with my first cousin Janet Pankonin. Dave is trying to retire from his prop repair business, but he probably loves his work too much to do so. They have a computerized balancing machine and tested the Hi-Performance prop. It was good, but Dave said that most Quicksilver SS props are out of balance.

catchnedge · « **Reply #25 on:** September 04, 2013, 01:37:35 PM »

Quote from: Hyperacme on September 04, 2013, 08:50:56 AM

Mark ...
Your new 2 blade has been lake tested and is good to 51.8 mph on GPS ...
I'm one of the "Prop Master's" certified test pilots.

Thanks Gregg, I know it'll be a good one! It will probably never be that shiny again though... haha

Hey, I want to be a Test Pilot... if only I could earn a living doing something like that.

Hyperacme · « **Reply #26 on:** September 04, 2013, 01:53:06 PM »

It not all it's cracked up to be Mark ...
Lots of hard work, Dave and Ross were both bleeding by the end of the testing from cuts from the razor sharp prop blades !
Shawn had to remove his prop and loan us his spacer ...
It's the price we pay for top speed ...

LOL !

V153 · « **Reply #27 on:** September 04, 2013, 04:18:38 PM »

Quote from: Hyperacme on September 04, 2013, 08:50:56 AM

I'm one of the "Prop Master's" certified test pilots.

Ya well don't count yer blessings just yet. I hear he's a harsh taskmaster ...

David CVX-16 · « **Reply #28 on:** September 04, 2013, 06:13:00 PM »

Gregg and I have a common rule. If you break it you bought it. LOL. That is why I did not go over 5,300 RPM's on his boat while testing it. Gregg was afraid to drive my boat about two months ago, but I think he would do it now. At WOT, RPM's with a 22" Raker is about 5,300 to 5,400 RPM's, well below the max.

GCarlover · « **Reply #29 on:** September 04, 2013, 10:58:25 PM »

Gregg, Mark or David. Back in Nebraska it's still around 96 here. I have my modified 2 blade 23 cup on the
CVX now. Running about 54 to 55 at 6000. We gps'd my speedo running about 1/2 under actual mph. Getting a lot of slip. 19-20%. Even at 5000 (44 or 46). Will check again. What is the rpm at 48 on the GT150? 2.3:1 gears on the 85 Merc. When I had my 80 back in the old days there was a guy with the Elephant ear 2 blade on a GT 150. He claimed 55 mph. That was an 80hp Merc. I haven't believed it to this day. I showed prop tests last week on "Just another prop"
How about the 22" HP Bronze? I think you posted them once Gregg.

Hyperacme · « **Reply #30 on:** September 05, 2013, 12:31:34 AM »

GCarlover ...
That was the first test of the 22 HP 2 blade ... Didn't go to well ... Will post results on next outing ...
YA ... 55 MPH seems pretty steep ... Maybe on his speedo it was 55 ..

Doug ...
Pretty glamorous being one of Dave's test pilots ...
I pull in to shore and turn the test mule ( Mule # cv16 ) sideways so Dave can switch props, then start downloading data from on board computer ( my old and sometimes foggy brain ) ...
We have a discussion on the data and decide on next best prop to test ...
Dave hands me a cool drink and go's back to changing the prop, so I have some free time to sign autographs for the kids and all the pretty girls ...
About that time Dave calls me back for more work ...
It's not easy ... But getting you guys the hard prop data you need , make's it all worth while !

catchnedge · « **Reply #31 on:** September 05, 2013, 06:34:38 AM »

Quote from: GCarlover on September 04, 2013, 10:58:25 PM

What is the rpm at 48 on the GT150? 2.3:1 gears on the 85 Merc.

Not sure, no tach, but my guess is it's probably a little higher than it needs to be. One of my "to do" items in the future for this rig. On the gear rations... how can I tell?... I think it's all original, can I tell by the serial number, or is there a designation on the side of the lower unit?

Hyperacme · « **Reply #32 on:** September 05, 2013, 07:24:40 AM »

Is your motor a 1977 Mark ?
I could look it up in the service manual ...

The 1974 Merc brochure lists ...

1500 ... 14:28
1150 ... 14:28
850 ... 13:30
650 ... 14:23

The 1971 Merc brochure lists ...

1350 ... 14:25
1150 ... 14:25
800 ... 13:30
650 ... 13:30

GCarlover · « **Reply #33 on:** September 05, 2013, 04:07:16 PM »

Right, all the 80s and 85s were 2.3:1. They interchange with 115s also which I did, but the guy I sold my motor to tore it out on a heavy IMP. Small tooth gears and more of them caused this. He thought he hit a log. I've got the same prop 13 3/4 x 23 no cup from my 1969 80hp. We put it on a gt160 with a new 71 135 Merc(1.78:1). Ran 52 Speedo @ about 5100. (Two passengers) That's 16.6% slip. It has a Johnson hub in it now. Had to grind down the flange on it. New tests:
54 speedo or 54.5 gps@5900 (19.46% or 18.7% slip) 46@5000 (19%) 36@4000 0-50 w/blowout 14 sec, appx 600 ft.

David CVX-16 · « **Reply #34 on:** September 05, 2013, 07:36:00 PM »

Mark, I had a 1971 80 HP Merc on the V-153 when I bought it new. Ran the 2-blade bronze props (not cupped) and went 44 MPH probably at 5,300 RPM's. The 80 HP Merc had 2.3 gears (30/13) in it just like yours. I suspect you are turning 5,700 RPM's in the GT150. Just make sure you have good gas and oil and do not go full throttle for long periods of time.

On the CVX-16 with a Raker 22", at 55.0 MPH the RPM's are 5,450. With a 20" Raker, the RPM's are up to 5,700, but the speed is down from the 22" Raker's.

GCarlson, I suspect that your 23" bronze prop is less than 23". A prop shop could tell you the true pitch by measuring it. I wondered about the pitch of some Mercury props years ago and called Allen Tucker at Supreme Marine. He had charts that told the true pitch (lower than indicated) if you told him the part number of the prop.

catchnedge · « **Reply #35 on:** September 06, 2013, 08:59:09 AM »

Quote from: David CVX-16 on September 05, 2013, 07:36:00 PM

I suspect you are turning 5,700 RPM's in the GT150. Just make sure you have good gas and oil and do not go full throttle for long periods of time.

Gregg, yea the 85hp is a 1977... original to this boat.

Copy that David, thanks! It's screaming pretty good at WOT (you can hear it in that recent video I posted "GT150 Sunrise Run" on CGOA, about 1/2 way through the video there are a few spots where I'm WOT)... I always run a little extra oil in the gas, probably closer to 40:1 than 50:1. I'll probably try to install a small tach this winter... just want to do an "under dash" or on throttle control support or something like that, don't want to cut into the untouched dash. Can I have that bronze prop "cupped" a little more to help with the rpms?... performance effect in doing so?

Hyperacme · « **Reply #36 on:** September 06, 2013, 09:09:06 AM »

Tiny-Tach
http://tinytach.com/gasoline.php

David CVX-16 · « **Reply #37 on:** September 06, 2013, 11:10:49 AM »

Quote from Mark "Can I have that bronze prop "cupped" a little more to help with the rpms?... performance effect in doing so?"

Propulsion Prop in Hudson, WI cupped that new at the time prop and drilled vent holes. The cupping is more than another 21" 2-blade bronze prop I bought new off e-bay with factory cupping in it.

If you want, I could ask Dave, the owner of Propulsion Prop if they can add pitch by adding more cupping, and the cost to do so.

Picture of the cupping as it stands now.

Mark, the prop will be polished before shipment.

catchnedge · « **Reply #38 on:** September 07, 2013, 12:56:53 PM »

Thanks David, yes please ask him for me.

GCarlover · « **Reply #39 on:** September 08, 2013, 02:37:20 PM »

Has the bronze prop been tried before and after the vents were drilled. Still having a lot of blow out. It didn't use to do that. Will check the hub again. It's marked. Gregg, are the small tach's adjustable for 2 stroke and number of cylinders? I have one on my 1 cylinder 4 stroke garden tractor from Northern Hydraulics. Don't see a setting. You just wrap the coil wire and hot to the ignition.
On another note, I think the tachs before about 1978 were T-bolt ignition driven; the later alternator rectifier driven. That's what I had on my 1970.