Setups and MPH

[cj222]

Hey guys! So Myself being a newbie to v-drive boats, I have no idea what to expect out of my Howard 20ft GN I just completed. It has 22% gears in the Casale, th400 trans, 11-1/2 x 15 two blade prop and a pump gas 548ci BBC approximately 650hp I'm guessing. Any opinions on what MPH I might see out of it based on your knowledge and experiences?
Thank you,
Nick

 

[Dog]

What RPM do you plan on running?

My guess at around 6500 rpm, low 90s

 

[cj222]

What RPM do you plan on running?

My guess at around 6500 rpm, low 90s

That's a good question lol. I don't know what that combination will allow my motor to spin. This motor was originally in my Roger's jet boat and turned 6k at 90mph but that is a whole different setup

 

[Dog]

That's a good question lol. I don't know what that combination will allow my motor to spin. This motor was originally in my Roger's jet boat and turned 6k at 90mph but that is a whole different setup

You can use the prop slip formula to get a theoretical mph and guess from there. I am not sure how to account for the transmission ratio however.

 

[obnoxious001]

Hey guys! So Myself being a newbie to v-drive boats, I have no idea what to expect out of my Howard 20ft GN I just completed. It has 22% gears in the Casale, th400 trans, 11-1/2 x 15 two blade prop and a pump gas 548ci BBC approximately 650hp I'm guessing. Any opinions on what MPH I might see out of it based on your knowledge and experiences?
Thank you,
Nick

I think if it is honestly 650 hp, you won't be seeing 90's. I don't know enough about your engine combination to take a stab at what power it will make.

Basing that on my 20' Schiada that I used to ski race, that started off with perhaps an 800 HP blown engine, and later switching to turbos that probably realistically made about 1000 HP on race gas. That should be the correct size prop, probably pretty good with the gear also, just have to see what it will turn with that combination.

 

[cj222]

You can use the prop slip formula to get a theoretical mph and guess from there. I am not sure how to account for the transmission ratio however.

Copy that. Thank you!

 

[BamBam]

My guess would be high 80's to low 90's. The shallow Vee of that Howard will take less power than the Schiada Vee. My Schiada has a 548 with 22% gears in the box and runs 86

 

[DalesSpeed]

My guess would be high 80's to low 90's. The shallow Vee of that Howard will take less power than the Schiada Vee. My Schiada has a 548 with 22% gears in the box and runs 86

Do you have a rough HP estimate? What prop are you running?

 

[cj222]

I think if it is honestly 650 hp, you won't be seeing 90's. I don't know enough about your engine combination to take a stab at what power it will make.

Basing that on my 20' Schiada that I used to ski race, that started off with perhaps an 800 HP blown engine, and later switching to turbos that probably realistically made about 1000 HP on race gas. That should be the correct size prop, probably pretty good with the gear also, just have to see what it will turn with that combination.

It's a mild built motor. 9.4 to 1 compression, Dart aluminum heads, hyd roller cam. I'm just curious weather to expect it to go 50mph or 75mph lol.

 

[cj222]

My guess would be high 80's to low 90's. The shallow Vee of that Howard will take less power than the Schiada Vee. My Schiada has a 548 with 22% gears in the box and runs 86

If I happen to see those numbers I would be satisfied for it is, family cruiser basically

 

[Dog]

If I happen to see those numbers I would be satisfied for it is, family cruiser basically

Set your "goal" at 85. if you meet or surpass it, cool, if you have to do some work to get there even better. lol

 

[cj222]

Haha sounds like a plan!

 

[Melloyellovector]

Can you start an over under ?
im thinking no fukin way is it going 90s with mild 650hp, unless it’s got 900+tq, lol
I’d say mid 70s maybe 80 maybe

 

[cj222]

Can you start an over under ?
im thinking no fukin way is it going 90s with mild 650hp, unless it’s got 900+tq, lol
I’d say mid 70s maybe 80 maybe

I dont believe it will hit 90 myself. I'd be ok with 75 to 80 off the trailer.

 

[cj222]

The boat is a heavy tank! Might only do 55-60

 

[Backlash]

No dog in the fight, but I'll guesstimate 81mph as she sits. No science behind it, just a random number. I'm definitely looking forward to watching her stretch her legs!

 

[AzMandella]

My 66 Mandella running a 12.1 comp 514 with solid roller cam would turn just under 7000rpm with 22% gears and a menkins 11-1/2 X 15 Best i got on GPS was just under 96mph .

 

[sintax]

The boat is a heavy tank! Might only do 55-60

Interested as well...

the boat specs and numbers look ballpark for sure. Assuming everything is setup and works well together, I'd be super surprised if youre not north of 70, but I dont think you'll get into the 90s on a NA setup.

If the plates work well, and you can get the boat loose enough, the 650hp and 22% gears should be about right. I have about 100hp less, and 18's in my box, turning a 11.5 x 15 (3 blade)

 

[cj222]

Interested as well...

the boat specs and numbers look ballpark for sure. Assuming everything is setup and works well together, I'd be super surprised if youre not north of 70, but I dont think you'll get into the 90s on a NA setup.

If the plates work well, and you can get the boat loose enough, the 650hp and 22% gears should be about right. I have about 100hp less, and 18's in my box, turning a 11.5 x 15 (3 blade)

Yeah I'm not expecting 90. Between 70 and 80 would be fine.

What mph are you seeing with your setup?

 

[sintax]

Yeah I'm not expecting 90. Between 70 and 80 would be fine.

What mph are you seeing with your setup?

right now I'm in the mid 60's low 70's

my plate setup is not right, and my boat runs super wet.

I need to do a total rebuild on the plate running gear. I want to extend them a bit, and add additional turnbuckles to stiffen things up

 

[BamBam]

If I happen to see those numbers I would be satisfied for it is, family cruiser basically

Mine is a family cruiser too.
When is the first water test?

 

[cj222]

Mine is a family cruiser too.
When is the first water test?

Probably not until March or April

 

[Eliminator21vdrive]

Is it just me ? I would have dunked it weeks ago lol

 

[cj222]

Is it just me ? I would have dunked it weeks ago lol

Not in a huge rush and definitely wasn't going to put my brand new hardware in Elsinore water on New Years, would come out of that lake looking like galvanized steel

 

[DC-88]

For your boat I'd try to grab a 3 blade from Hill to test with the same day just to compare the feel . All my 1-1/8 for my gn are RH 2 blades but I drove my buddy's cruiser style rayson 21 with a 3 blade on it last summer testing props with about 750 hp 94 mph with the 3 blade and was surprised how smooth and docile it was with that prop. Still cornered decent too.

 

[cj222]

For your boat I'd try to grab a 3 blade from Hill to test with the same day just to compare the feel . All my 1-1/8 for my gn are RH 2 blades but I drove my buddy's cruiser style rayson 21 with a 3 blade on it last summer testing props with about 750 hp 94 mph with the 3 blade and was surprised how smooth and docile it was with that prop. Still cornered decent too.

Thank you for your input I do have a 3 blade that is out getting checked for pitch and diameter and also cleaned up from rock damage. Got it used.

 

[Bajastu]

For your boat I'd try to grab a 3 blade from Hill to test with the same day just to compare the feel . All my 1-1/8 for my gn are RH 2 blades but I drove my buddy's cruiser style rayson 21 with a 3 blade on it last summer testing props with about 750 hp 94 mph with the 3 blade and was surprised how smooth and docile it was with that prop. Still cornered decent too.

Good info to know. I just picked up a Rayson Craft 21 and 750hp is what I want to build to push it. Right now it just has a 325 hp BBC.

 

[sintax]

Good info to know. I just picked up a Rayson Craft 21 and 750hp is what I want to build to push it. Right now it just has a 325 hp BBC.

For your boat I'd try to grab a 3 blade from Hill to test with the same day just to compare the feel . All my 1-1/8 for my gn are RH 2 blades but I drove my buddy's cruiser style rayson 21 with a 3 blade on it last summer testing props with about 750 hp 94 mph with the 3 blade and was surprised how smooth and docile it was with that prop. Still cornered decent too.

Need info and details on both of these boats plz

I try to keep track of all of the Rayson's i can!

Thank you for your input I do have a 3 blade that is out getting checked for pitch and diameter and also cleaned up from rock damage. Got it used.

If you're still hunting on prop setups in April, i'll let you run my newest 3 blade Menkens, I have another, but its not right for your setup for sure. Snowbirds have my place on lockdown currently.

 

[cj222]

If you're still hunting on prop setups in April, i'll let you run my newest 3 blade Menkens, I have another, but its not right for your setup for sure. Snowbirds have my place on lockdown currently.

Thanks bud I appreciate that!

 

[DC-88]

Need info and details on both of these boats plz

I try to keep track of all of the Rayson's i can!



If you're still hunting on prop setups in April, i'll let you run my newest 3 blade Menkens, I have another, but its not right for your setup for sure. Snowbirds have my place on lockdown currently.

always works in progress with different power and no trans post yours too love to see them️

 

[cj222]

Not a Rayson Craft but I like to share photos of my Howard 20ft GN

 

[sintax]

always works in progress with different power and no trans post yours too love to see them️

Of course man! Love showing mine off.

She’s a 2002 build, from DeFir up in Oregon. It has the updated bottom strakes and is much more of a lake build.

This was my pops first trip back to the lake after 6 months of chemo, he was stoked to say the least