I'm hoping a few of you seasoned veterans can help a new guy out.  To say I'm green is an understatement.  I'm here to learn and any help is appreciated.

I have an '88 20.5 Carrera Elite family cruiser and I love it.  She rides nice and keeps my wife happy.  My issue is I want to make her faster.  I have a great motor builder that used to build all Teague Marine's off shore motors and currently builds all my race motors for my off road program.  He keeps telling me that I need to build the pump before the motor.  He says he can build a big old motor for it but its only going to pump so much water...makes sense.

My question for you guys, is 70mph even reachable in a boat like mine? (she currently runs 55 with just me and 47 with the family and full tanks)  I guess it depends on what I do to it but I'm trying to get a base idea of what I should do before i start tearing into it.  Thanks again and hope to see you guys out on the water.

I'm hoping a few of you seasoned veterans can help a new guy out.  To say I'm green is an understatement.  I'm here to learn and any help is appreciated.

I have an '88 20.5 Carrera Elite family cruiser and I love it.  She rides nice and keeps my wife happy.  My issue is I want to make her faster.  I have a great motor builder that used to build all Teague Marine's off shore motors and currently builds all my race motors for my off road program.  He keeps telling me that I need to build the pump before the motor.  He says he can build a big old motor for it but its only going to pump so much water...makes sense.

My question for you guys, is 70mph even reachable in a boat like mine? (she currently runs 55 with just me and 47 with the family and full tanks)  I guess it depends on what I do to it but I'm trying to get a base idea of what I should do before i start tearing into it.  Thanks again and hope to see you guys out on the water.

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OMHO, 70 is a lofty goal.

That hull is designed for the family of four to go 55 mph and do it in style and comfort.

For that rig to do an honest 70, it needs virtually everything.

I would not set the pump back,  but a show,  rideplate,  droop, Diverter,  stainless impeller,  inducer,  good loader ate all going to be needed to support the 700 or so hp to get you to 70.

I own a 92 Carrera Elite 20.5 that I have been building for years (total budget build) and my intention is to get it to go 72mph. With a small block and Alpha 1 gen 2 outdrive.

Just in the interior alone I was able to trim an estimated 400 pounds,  another 150 in the construction of the floor.

Using a small block saved me another 200. That's like going from 9 people to only one horse jockey.

Weight is the enemy. Especially on a jet.

How fast is it now and what mods have been done?
Any estimation on horsepower?

How thick is your wallet?

That last one stops most. Lol

One thing to remember,  to go fast means more fuel,  more noise,  more breakage,  fewer drivers and most importantly, less reliability.

If the wife is ok with all that,  your 90% there. Lol

Me personally,  I would build a hot rod.  On the end, it would probably be cheaper. Those divorce lawyers to do much pro Bono.

GT

Hey Glenn, why 72 mph? Not 70? Not 75? But 72?

Assuming the tach is correct right around 5 grand. Its a 454 BBC.  I was told it has an A/B impeller

15 mph in your hull will take a lot more thrust. That means more rpm or a bigger impeller. A bigger impeller, means more HP to spin it.

Its possible but all of the things GT said apply.

Though one, i am curious, why does he NEED a stainless impeller? Why not an aluminum AA that he can spin to 5k or 5500 with more power?

according to the impeller chart, if you have an AB now, youre making about 400 hp. Probably a stock 454

Don't take this the wrong way,  not insulting your intelligence,  but $5k will get you just a tick past 60mph.

JMHO

GT

No offense taken.  I'm new to this and have no idea of what things cost. 

The problem is I have to many damn hobbies and I'm currently building another race car so most of the coin is tied up in that.

Hey Glenn, why 72 mph? Not 70? Not 75? But 72?

I knew that would raise an eyebrow.

My dad, way back when I had my boat shop, found a Crusader 23 on the side of the road for sale.

He called me and said "can you make it go 70mph?".

I said "it's only money".lol

He bought the boat and the trailer (tri axle Trail Rite brand new) for $1,500.

I wanted to go with a 5.7L magnum efi Mercruiser repower package at 350 hp(had one in the shop brand new).

He wanted "big block power and thru hull exhaust".

The boat has a best GPS speed of 71mph with a raised X dimension on a Bravo I and a 454. He is totally happy.  We have about $13k in the boat doing most of the work ourselves (you should see the motor mounts I built for it).

Anyway,  I built an iron headed 5.7 Vortec that makes 398 hp at 5,300 Rpm on a hydro dynamometer  (uses water for the medium).

That Carrera has to do 72. For the record,  I'm in my Carrera  $820 with a tube Extreme trailer, but I'm in it for four years.

Make sense?

GT

I knew that would raise an eyebrow.

My dad, way back when I had my boat shop, found a Crusader 23 on the side of the road for sale.

He called me and said "can you make it go 70mph?".

I said "it's only money".lol

He bought the boat and the trailer (tri axle Trail Rite brand new) for $1,500.

I wanted to go with a 5.7L magnum efi Mercruiser repower package at 350 hp(had one in the shop brand new).

He wanted "big block power and thru hull exhaust".

The boat has a best GPS speed of 71mph with a raised X dimension on a Bravo I and a 454. He is totally happy.  We have about $13k in the boat doing most of the work ourselves (you should see the motor mounts I built for it).

Anyway,  I built an iron headed 5.7 Vortec that makes 398 hp at 5,300 Rpm on a hydro dynamometer  (uses water for the medium).

That Carrera has to do 72. For the record,  I'm in my Carrera  $820 with a tube Extreme trailer, but I'm in it for four years.

Make sense?

GT

Its been a while, but the bahner has done 72 with a vortec headed small block...

One of the best ways to go with a small block imo. We just need to throw a smaller cam in it

Bravo?
Alpha?

These speeds meaningless in relation to a BERKELEY jet drive.

At ~500hp on a big 21', I was at 57, gps'd, upriver, full of fuel, coolers, gear, 4 people, etc.

As Glenn said, weight is a huge factor on a jet.

I've researched into my hull, and it good to about 70, then it gets unstable. How much HP? I don't know, lot$, and then $ome, I'd guess.

Reliability goes down as HP goes up, too

Dan'l

They actually aren't meaningless,  I have the same hull and was able to trim a ridiculous amount of fat from it,  that was the intent of my post. I was asked a specific question about my boat,  I answered it.

Back off on the Rock Stars there Bro. Lol

Well I'll chime in but all its going to do is back up everything everyone already stated...
First off remember the black boat parked next to you at the Avi? Thats mine. 21ft open bow with heavy ass hull, heavy ass interior, stereo blah blah blah... Needless to say shes a big girl as far as jet boats go! That being said Im deep in the 70's full of fuel and loaded with 4 people and coolers. But its costed me cubic dollars. I went 509" of chevy with a huffer on top pushing through a chiller, roller, aluminum heads etc etc... Put this same motor in these little 18 footers and I could play on the top ten list. But for me; entertaining friends and going farther distances mean more to me than an occasional blip past 90mph. Theres not a trip I go out where I dont think about the good ol days of a stock 454 and a reliable 50mph and 50 gallons of fuel lasted all day!!!
I think my point is this, yours and my boats were designed to haul a few people around the lake or river all day but not really a race hull. If you want to throw a few bucks at the pump I say go for it. But Id reconsider chasing 70+mph in a cruiser. JMHO
Free advice is worth what you pay for it...nuthin!! Have fun
Beautiful boat btw


One fast station wagon!!!

Well I'll chime in but all its going to do is back up everything everyone already stated...
First off remember the black boat parked next to you at the Avi? Thats mine. 21ft open bow with heavy ass hull, heavy ass interior, stereo blah blah blah... Needless to say shes a big girl as far as jet boats go! That being said Im deep in the 70's full of fuel and loaded with 4 people and coolers. But its costed me cubic dollars. I went 509" of chevy with a huffer on top pushing through a chiller, roller, aluminum heads etc etc... Put this same motor in these little 18 footers and I could play on the top ten list. But for me; entertaining friends and going farther distances mean more to me than an occasional blip past 90mph. Theres not a trip I go out where I dont think about the good ol days of a stock 454 and a reliable 50mph and 50 gallons of fuel lasted all day!!!
I think my point is this, yours and my boats were designed to haul a few people around the lake or river all day but not really a race hull. If you want to throw a few bucks at the pump I say go for it. But Id reconsider chasing 70+mph in a cruiser. JMHO
Free advice is worth what you pay for it...nuthin!! Have fun
Beautiful boat btw


One fast station wagon!!!

I agree well put sir"  55 mph blasting stereo  and cold ass beers.. I'll take that all day. . 😎👍🍻 


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Anyway you look at it at least you have a nice looking boat. Being bit by the speed bug can hurt. How do you think I feel, i just did a blower install for my Dad and he is turning close to 100 while I'm the 70's with the same exact hull....SMH


IMO, I would put a small blower on it, something that you won't have to do a ton of other work and you will likely gain a min. of 5 MPH and maybe 8-10, maybe. Someone made a good point about the increased maintenance that goes hand in hand with more HP, sometimes its just nice to fill it up with fuel and go.

My 79 eliminator sprint