Big Power Day Cruiser choice? TT or Blower

[Tahoe540]

My plans are to build a big power day cruiser (have not found a hull yet) and was planning on doing a twin turbo setup as I think it is such a cool combo but I came across a good deal on a 8.3L whipple with intercooler, dual dominators and intake. My plan is a 540 BBC and from what I have read I can get about 1200hp out of either combo. I have not had either a TT or blower boat only NA. What would be your choice if you've had experience?

 

[AzGeo]

Mild twin turbo, EFI, intercooled . Valve timing makes this motor very docile at low speeds/RPMs, while having the most torque across the power band (quickness). The quiet power made with a well tuned turbo motor is my first choice for a "play boat" .

Blower motors are great for "all out top end speeds", but always sacrifice "low speed drive-ability" when the valve timing (giant cam) is optimized for this kind of "free flow breathing" motor .

Some may say that "blowers can use mild cams", but that kind of combination will not make the kind of power the turbos offer, and would be "restricting" the power the blower offers across the power band .

Your next question should be; "what kind of drive line will accept this kind of power" ?

 

[Outdrive1]

Mild twin turbo, EFI, intercooled . Valve timing makes this motor very docile at low speeds/RPMs, while having the most torque across the power band (quickness). The quiet power made with a well tuned turbo motor is my first choice for a "play boat" .

Blower motors are great for "all out top end speeds", but always sacrifice "low speed drive-ability" when the valve timing (giant cam) is optimized for this kind of "free flow breathing" motor .

Some may say that "blowers can use mild cams", but that kind of combination will not make the kind of power the turbos offer, and would be "restricting" the power the blower offers across the power band .

Your next question should be; "what kind of drive line will accept this kind of power" ?

Art Carr Turbo 400 and Casale split case or a billet case from Prime Marine.


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[wsuwrhr]

I am still conflicted as to what to do for my repower....

 

[AzGeo]

"I'm your Huckleberry" .

I know you are WAITING for one of us to say; "why don't you put a Illmore Viper in your cruiser Brian"?

So now that I've said it ?

 

[wsuwrhr]

"I'm your Huckleberry" .

I know you are WAITING for one of us to say; "why don't you put a Illmore Viper in your cruiser Brian"?

So now that I've said it ?

No sir.

Just thinking out loud. I just know straight up 50MPH (or 55? I forget) is fuckin slow.

Nah, I hear of too many problems with a complex motor and none of the mounts would work. If I was going to change the mounts, I would put together an aspirated or twin Turbo 440 based BB Mopar all day. A motor platform I have waaaay more experience with.

I would do a twin turbo Chevy in a heartbeat though. Parts are common and UCH is already rigged for it.

Brian

 

[wsuwrhr]

"I'm your Huckleberry" .

I know you are WAITING for one of us to say; "why don't you put a Illmore Viper in your cruiser Brian"?

So now that I've said it ?

....and in my case of UCH, the identical hull in TN or wherever had 1100HP on kill, and went 80. Pretty much dashed hopes if I am practical about a big cruiser going fast. Likely I would also need to move the motor forward and for sure the strut and vdrive forward and add cav plates.

I am just conflicted in what to do is all.

 

[Tahoe540]

I am still conflicted as to what to do for my repower....

What hull do you have?

 

[wsuwrhr]

UCH is a Howard Custom Cruiser 24' 6".

It is a comfy but wide bitch.

Currently with a Harman Marine 405HP BBC.

 

[welldigger00]

I am running a 598 boostpower with an old school roots, intercooler, and a pair of boost referenced quick fuels. Since I was a kid, I have always dreamed about a blower motor ever since mad max came out, which I saw in theater. There is something about the sound and look of a blower motor to me. They are hot rod engines, not sports car engines in my opinion. There is a lot to be said about what is practical, what is the most efficient, what makes the most power. But it’s got to give you a boner when you look at it and ride in it too. I like the sound of radical blower surge, some dudes hate it. My best pal matt 025, has a twin turbo Barry obelor in his boat, and it’s bitchen too. It’s gonna be a personal preference deal.


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[HighVoltage329]

Whipple's have a bypass valve that bleeds off boost at idle for nice low speed manners.

 

[Runs2rch]

540 with a twin screw. Plenty of power and not a plumbing extravaganza.

 

[Wheeler]

Why sacrifice with one or the other when you can have both.

Give Boost Power a call.

 

[Tahoe540]

Whipple's have a bypass valve that bleeds off boost at idle for nice low speed manners.

I didn't know this about them. That is a nice feature.

 

[spectras only]

UCH is a Howard Custom Cruiser 24' 6".

It is a comfy but wide bitch.

Currently with a Harman Marine 405HP BBC.

Brian, what's the top speed of your UCH? My 72 Spectra ran 60GPS with the LS6 [ the original 1972 engine came with the boat ] after rebuild with a hotter cam install.

 

[wsuwrhr]

Brian, what's the top speed of your UCH? My 72 Spectra ran 60GPS with the LS6 [ the original 1972 engine came with the boat ] after rebuild with a hotter cam install.

It is either 50 or 55.

 

[spectras only]

It is either 50 or 55.

Yeah, with the forward cabin of these boats, they tend to run wet with V-drives that forces the bow down even more. Sterndrives are faster because trimability, for sure. When restored my Spectra, I opted for rear deck and full bench that pushed CG aft, letting the boat fly out of the water more.

 

[AzGeo]

Yeah, with the forward cabin of these boats, they tend to run wet with V-drives that forces the bow down even more. Sterndrives are faster because trimability, for sure. When restored my Spectra, I opted for rear deck and full bench that pushed CG aft, letting the boat fly out of the water more.

Wrong .

If the power is "driving the nose down", it was rigged to be that way, with NO cavitation plates .

IF the prop is under the boat (and not back touching the rudder) the correct rigging will allow the boat to run with the nose up, at any speeds .

If your 24' Spectra/Howard has a big old B29 prop on it, that prop is 10" from the transom, and the hull never had plates on it, it needs to be re-rigged if you ever want any speed .

Last Howard 24' that we rigged, had a 468 single 850, draw thru twin turbos, 7 lbs of boost . Ran mid to high eighty's, 1.29's with a 12 1/4" X 15 Az. Menkens 3 blade @ 5500 .

If the keel under the steering wheel is wet at WOT, you are dragging too much hull ...............

 

[rvrrun]

It is either 50 or 55.

Depending on your mood?

 

[Gelcoater]

No sir.

Just thinking out loud. I just know straight up 50MPH (or 55? I forget) is fuckin slow.

Nah, I hear of too many problems with a complex motor and none of the mounts would work. If I was going to change the mounts, I would put together an aspirated or twin Turbo 440 based BB Mopar all day. A motor platform I have waaaay more experience with.

I would do a twin turbo Chevy in a heartbeat though. Parts are common and UCH is already rigged for it.

Brian

Keep the engine simple and familiar to you.
A Chevy fits the boat easier but a 451 low deck stroker is more your flavor.

 

[sintax]

Is a big big EFI N/A motor an option?

What are these guys getting out of these big 600+ CI engines? Maybe good drivabiltiy without the need for all the extra bolt ons, plumbing and money?

 

[sintax]

Keep the engine simple and familiar to you.
A Chevy fits the boat easier but a 451 low deck stroker is more your flavor.

Chevy just seems like a no brainer due to the abundance of cheap parts and supportability

 

[Gelcoater]

Chevy just seems like a no brainer due to the abundance of cheap parts and supportability

I agree. But Brian is a Mopar guy. It's a sort of sickness.

 

[spectras only]

Wrong .

If the power is "driving the nose down", it was rigged to be that way, with NO cavitation plates .

IF the prop is under the boat (and not back touching the rudder) the correct rigging will allow the boat to run with the nose up, at any speeds .

If your 24' Spectra/Howard has a big old B29 prop on it, that prop is 10" from the transom, and the hull never had plates on it, it needs to be re-rigged if you ever want any speed .

Last Howard 24' that we rigged, had a 468 single 850, draw thru twin turbos, 7 lbs of boost . Ran mid to high eighty's, 1.29's with a 12 1/4" X 15 Az. Menkens 3 blade @ 5500 .

If the keel under the steering wheel is wet at WOT, you are dragging too much hull ...............

AZ, don't have a video at WOT, my buddy driving the boat in this video, his wife hates going fast. You could tell in the early part of the video we're cruising maybe 35-40. The boat runs really good in ocean chop, getting loose from surface tension I think the shaft angle is 10 degrees, the prop must be further forward than 10". I'll call my buddy to measure for sure. Yep, no cav plates.

 

[spectras only]

AZ, my wife called the Spectra a barge,lol. The Ace Champion drive [ still with the boat ] and driveline made too much rattle for her liking at idle Still have the original Vance trailer under the boat.

 

[wsuwrhr]

Depending on your mood?

It isn't significant enough to stick out in my mind. At those speeds they are all just slow.

 

[wsuwrhr]

Keep the engine simple and familiar to you.
A Chevy fits the boat easier but a 451 low deck stroker is more your flavor.

You misspelt 500 inch RB.

 

[wsuwrhr]

I agree. But Brian is a Mopar guy. It's a sort of sickness.

No, it is a sickness. Im kinda digging the Chevy cylinder head though.

I thought Hemis were heavy.

 

[RiverDave]

....and in my case of UCH, the identical hull in TN or wherever had 1100HP on kill, and went 80. Pretty much dashed hopes if I am practical about a big cruiser going fast. Likely I would also need to move the motor forward and for sure the strut and vdrive forward and add cav plates.

I am just conflicted in what to do is all.

You have to remove the hook from the bottom to get any real speed out of it. Parnelli Jones had a 24 he straightened and put a Turbo motor in it back in the day. I have “heard” it was low 90’s / not sure how much HP but back in that era I’d be surprised if it was anywhere near the 1100 from the other one.

 

[vdcruiser]

Some talk here of a blower motor being unruly at low speeds. I don't find it that way at all. I have a 548ci in my 21 Howard with a 10:71 , 2 dominators, and a fairly big roller cam, sure it surges a little at idle but I like it and with the turbo 400 it is no problem to handle around the dock using 1st gear. With a 48% v drive gear I can cruise at a fairly low rpm also, and when I want to it will hit 100+ mph at about 6200/6300 rpm. It has had some bottom work done and a 7.5 deg strut installed in a more forward location. None of these mods have caused any problems.

 

[oldschool]

I think your hull and drive choice/ set up are going to have a bigger impact on what your trying to do than your motor combo. I have an older TT setup in my Hallett v drive cruiser and it runs decent, the boat has run in the mid 80's. For it to run faster I would need to change ALOT of stuff and that would impact the way it's used 99% of the time.

 

[Cole Trickle]

I am still conflicted as to what to do for my repower....

500hp simple 496..... That boat is never going to be fast just build a reliable BBC that will get her to 60 and go enjoy the lake with your family without braking the bank.

 

[wsuwrhr]

500hp simple 496..... That boat is never going to be fast just build a reliable BBC that will get her to 60 and go enjoy the lake with your family without braking the bank.

Thanks. Noted.

 

[Cole Trickle]

Thanks. Noted.

I would talk to Barry (obnoxious) he will get you there at a fair price.

 

[SBMech]

Pfft. You can make a brick go warp speed if you put enough power in it....

Don't let anyone steal your dreams Brian!

Drop that indy block in and show em how it's done. 80+ ya baby!

 

[wsuwrhr]

I would talk to Barry (obnoxious) he will get you there at a fair price.

Noted.

Barry is cool peeps.

I kinda already know a motor guy.

 

[wsuwrhr]

Pfft. You can make a brick go warp speed if you put enough power in it....

Don't let anyone steal your dreams Brian!

Drop that indy block in and show em how it's done. 80+ ya baby!

Waaay too much motor for that ol girl.

No shit, I should start a gofundme for those dreams.

 

[wsuwrhr]

This thread aint about me, I just thought to piggy back on Tahoe540s thread and see what he comes up with, I don't think he has mentioned anything about a hull or drive type yet.

I have a similar hull described in the OP and I haven't moved forward yet because I am conflicted at what to do with her.

 

[SBMech]

He was thinking about a Spectra 20', he asked a few questions in the Spectra Forums.

You got a 20' Daycruiser too? Whatcha got?

 

[wsuwrhr]

He was thinking about a Spectra 20', he asked a few questions in the Spectra Forums.

You got a 20' Daycruiser too? Whatcha got?

I didn't see any other thread. Got it. We are in completely different realms then.

A 20 footer aint nothin I would think of being a "Day Cruiser", regardless of the name.

No sir, I have a 19 Anthony Jet and an 18 Hondo Sprint, that is enough boats for now.

 

[oldschool]

I believe the OP wanted to build a jet day cruiser that would run with his buddies flat bottoms, if I remember correctly.

 

[Cdog]

I’m curious. What kind of power does it take to get a Howard 21 RC I/O to do 85-90 mph?

Stock 454/B1 seems 70ish mph is there.

What kind of speeds are obtainable at 600 HP?

 

[oldschool]

I didn't see any other thread. Got it. We are in completely different realms then.

A 20 footer aint nothin I would think of being a "Day Cruiser", regardless of the name.

No sir, I have a 19 Anthony Jet and an 18 Hondo Sprint, that is enough boats for now.

Build that Howard for comfort and the Hondo Sprint for speed. What year is your Hondo?

 

[AzGeo]

AZ, don't have a video at WOT, my buddy driving the boat in this video, his wife hates going fast. You could tell in the early part of the video we're cruising maybe 35-40. The boat runs really good in ocean chop, getting loose from surface tension I think the shaft angle is 10 degrees, the prop must be further forward than 10". I'll call my buddy to measure for sure. Yep, no cav plates.

The boat in the photo does not have cavitation plates, and so it was rigged with the prop "way back", to lift the tail and drive the nose in for a smooth ride . They also used oversized props (13", 14") and low gears to power the boat thru the water, instead of "gliding over the top" .

This method of rigging a V-drive, does not easily improve top speeds with added power . Just as a "tournament boat" with direct or V-driven systems is designed to be "stuck in the water", the non-plate V-drive rigging style also becomes "stuck in the water" .

Moving the strut and the V-drive forward (aprox. 16") while leaving the motor back, the existing 10 degrees of shaft angle would definitely hold the nose up, well into the 80's . I also don't recall the Howard's having any significant "hook" that would slow them down under 100 .

I like these 24's (under 1000 hp) at; "8 to 8.5 degrees of shaft angle" (6" strut center line), prop 30" from transom (+-), motor and trans motor plate 16" (top of stringer) . Yes, this places the V-drive within a foot of the cabin bulkhead . The motor/trans combo should end up with the prop directly under the numbers #5 and #6 cylinders of the motor . Velvet's are shorter, but heavier, so it's the same to me . SK style 1 1/8" stainless or steel 12" rudder (single hull fin), TWO cables (under extension) for steering (or chain and cable), never used a steering gearbox on one .

Most of those "non-plate" rigged boats had bolt on bronze struts . I'd glass up the holes, gel for color, or at least Marine Tex the outside for water proofing . Fab up a nice stainless drop thru strut, and re-rig the boat .

By doing this, it will safely go as fast as you can afford ..............

 

[wsuwrhr]

I believe the OP wanted to build a jet day cruiser that would run with his buddies flat bottoms, if I remember correctly.

Right.

Noted.

 

[wsuwrhr]

Build that Howard for comfort and the Hondo Sprint for speed. What year is your Hondo?

Well of course. I had the flat well before I had babies.

'76

Brian

 

[wsuwrhr]

All filed in the noggin.

The boat in the photo does not have cavitation plates, and so it was rigged with the prop "way back", to lift the tail and drive the nose in for a smooth ride . They also used oversized props (13", 14") and low gears to power the boat thru the water, instead of "gliding over the top" .

This method of rigging a V-drive, does not easily improve top speeds with added power . Just as a "tournament boat" with direct or V-driven systems is designed to be "stuck in the water", the non-plate V-drive rigging style also becomes "stuck in the water" .

Moving the strut and the V-drive forward (aprox. 16") while leaving the motor back, the existing 10 degrees of shaft angle would definitely hold the nose up, well into the 80's . I also don't recall the Howard's having any significant "hook" that would slow them down under 100 .

I like these 24's (under 1000 hp) at; "8 to 8.5 degrees of shaft angle" (6" strut center line), prop 30" from transom (+-), motor and trans motor plate 16" (top of stringer) . Yes, this places the V-drive within a foot of the cabin bulkhead . The motor/trans combo should end up with the prop directly under the numbers #5 and #6 cylinders of the motor . Velvet's are shorter, but heavier, so it's the same to me . SK style 1 1/8" stainless or steel 12" rudder (single hull fin), TWO cables (under extension) for steering (or chain and cable), never used a steering gearbox on one .

Most of those "non-plate" rigged boats had bolt on bronze struts . I'd glass up the holes, gel for color, or at least Marine Tex the outside for water proofing . Fab up a nice stainless drop thru strut, and re-rig the boat .

By doing this, it will safely go as fast as you can afford ..............

 

[Cole Trickle]

I’m curious. What kind of power does it take to get a Howard 21 RC I/O to do 85-90 mph?

Stock 454/B1 seems 70ish mph is there.

What kind of speeds are obtainable at 600 HP?

650-700

 

[oldschool]

Well of course. I had the flat well before I had babies.

'76

Brian

I should have kept my 76, kids loved it.

 

[wsuwrhr]

I should have kept my 76, kids loved it.

I know my youngest will, I don't know about the oldest though. Jury is still out.