? HP to hit 80 mph
 

Lot of thoughts traveling through my head lately....
Winter is coming and dreams of more horsepower are weighing heavily right now.
Would like some "real world" thoughts as to how much horsepower will be needed to push my boat to 80 mph (GPS). Right now I`m hitting 66 @ 4600 rpm with 310 hp spinning a 23" Mirage Plus. Here`s the details of my little boat:
Baja Hammer. 21' 4" length. 4000 lbs "running weight".
1.50 ratio, Bravo One.
20 degree deadrise
I would like to keep max rpm`s to about 5100.

Thanks for your input!

80mph
 

A friend of mine did slightly over 80 mph, in his 21 Checkmate with a 540ci. 580hp motor.

Your speed number gives only 2% slip, not likely. I jimmied the numbers a bit and get the following results for a 454 Mag and a 575SC.

There is no free lunch!! It is highly doubtfull that a base 454-310 could economically be made to make 600hp. No forged goodies inside....... just get a 502/502 and add a 3-5# Procharger....no muss no fuss..... if the boat can handle it youwould see over 75/80 on GPS.... My old 454-450 + Procharger at 5500# dead weight & 25 ft went over 75 on GPS so yours should break 80....
If you could walk afterwards!! (pucker factor no in the above equation!!):p :D

1988 Fourwinns Liberator 21' running weight about 4200lbs. OMC King Cobra 1.43 gears 5200 rpm 25" Ballistic Prop. 540 cid Ford dynoed 625ph 710 ftlb torque. This combo would bury 80mph speedo:rolleyes:. Didn't have GPS when I owned this boat. My guess is you'll need bare minimum of 500hp , probably closer to 600 would be a better bet.:cool:

This will make your 4000lbs+ baja go 80 MPH:D :D :D

80+ Baja

Looks like TC has hit it on the head, At one time I had something close to 500hp at the crank and saw a 10mph increase on the same boat. Mid 5s to 6 should do it, and the drive might have a chance of living if you take it easy.

I had a 23 Baja Bandit with a reworked 502 Mag that made every bit of 600hp that ran 80.

Looks like I should shoot for 600hp and maybe I`ll have a little to spare. No, I wouldn`t try to make this 310hp engine put out 600hp. I`m thinking 496ci or possibly 540ci. Lots of $$$ for a 540ci though.

think about external steering as your first upgrade....always work from prop (bottom) back to the engine....the very last thing i would do is the engine...in any boat for that matter...

I completely agree with Audacity! Get the safety factor, then the mods......the only way to go!!

Ditto
 

I waited too long.

If I had to go 80mph in your boat I would probably find a good used 502 Mag EFI and rebuild it and add a Whipplecharger. At the same time I would add an offshore water pickup and sea strainer and also hydraulic steering and a good drive shower. My guess is that you will need about a Bravo 1 30" also.

That will give you 80mph, probably more. The real question is: Do you want to go 80mph is a 21 foot boat? I would supect it will get very exciting after you pass 70mph and may approach terrifying at 80mph. There won't be much hull in the water.

:D As I said before: PUCKER FACTOR!! :D

Talk about pucker! I saw a boat like mine offered on ebay. It had a 604ci bad ass engine with lots of other mods on the boat. GPS at 110 mph! You couldn`t pay me to ride in that thing!

There was an article some years back about a 502EFI hammer. The boat was used for some prop testing and I believe they had it going 77mph with a Bravo labbed prop. Your boat weighs about 3400lbs with a 21* deadrise. I have to think that a 550hp motor should have plenty of juice for 80mph. You will need to run a Hydromotive Quad4 for that Hammer to handle correctly. There is major bow lift on the Hammer along with heavy chine walk. The Hydro. will solve the handling problems along with external steering like the others have said.

Here is a proven combo that a friend of mine has for his Hammer.
7.4 carb-300hp
performer rpm intake
stock carb tweeked
stainless marine manifolds
24p hydro. turbo prop (3 blade)
72.3 @ 4650 on radar in cooler weather and 71+ always.

Hope this helps a bit. Good luck!

as i recall tehhammer is a 21 degree hull. It will be fast but running at 80+ god forbid you hit any snotty water. You'll be flying for damn sure. you coudl biuld up your 310 a little bit maybe exhaust and a more agressive cam and run alegit 70mph. Save the big $$$ for bigger boat and hotter engine if you really want to go that fast.

I`ve already installed Stainless Marine Hi-Torque III manifolds, 5" outlet through 5" dia. tips (Yes...LOUD!!!) and planning to swap to RPM intake, 750 Edelbrock carb and a bigger cam. Hoping to see low 70`s. I will see how it handles and decide if I want to go any faster.

I have a 1999 Donzi 22zx. It has a whipplecharged 7.4mpi(310hp) which I estimate makes around 500 hp. It pushes it to 79-81 gps with a 30p Bravo 1 prop, Drive is a 1.50. This engine is reliable as long as you keep the mods to a minimum. Put a blower on it and leave the rest stock and you should be fine. That is if you get it tuned properly. Many members of this board have supercharged this engine with surprisingly positive long term results. For some reason this engine has gotten a bad reputation that I feel is unwarranted. I have about 50 hours on this setup and it has performed flawlessly. Compression is right where it should be and I have no blowby or oil consumption. Maybe I am lucky but I know several people who must have the same luck I do since they have no problems either. Supercharging this engine is in my opinion the best bang for the buck. The money it would take to swap some other engine could go towards a bigger boat, plus an engine swap most likely wont give you an extra 15-20 mph unless you spend lots of money.

The only issue is this engines L-29 heads. They have a fast burn chamber that is prone to detonation. Either swap to an earlier 7.4 head or have the L-29 chamber smoothed out. I swapped to a gen V peanut port head and have no issues.

donman,
i have sold baja's for many year's and would suggest for many reason's if your gonna sink that much money into the boat sell it and get one already done and a little larger. you would literlaly be throwing your money away on the baja.

Treadwell

:rolleyes: :rolleyes: :rolleyes: :(

Here`s the facts guys:
This is probably the LAST boat I will own. I am not that well off financially or else I would already own a larger, faster boat.
When I do build a bigger engine, I can do so a little at a time, buy the block one month, buy the crank the next month, buy the heads....etc...This is the ONLY way that I can afford to play. So let`s say I build a $8000 big block. If I spread that $8000 out over, let`s say, 2 years, the sting isn`t so sharp. Now let`s say I get 5 years use out of my original engine, that`s gotta be worth something. Now, install the $8000 engine into my $24000 boat for a total investment of $32000 and hell, let`s throw in a $5000 outdrive for grins. Now I have a $37000 boat that would bring lots of enjoyment. It may not be worth $15000, but who`s saying that it`s for sale anyway?
I simply cannot afford to go out and buy a bigger boat. If I had a bigger boat, it would take even that much more horsepower to push it!
I hope you see my point.
My momma always told me "Just play with watch ya got"
It sure beats the hell out of sitting on the dock watching!

Bro...I TOTALLY do not see your point...i have told many of my friends that have had a VERY small budget as you do...don't do it!...so your telling me over 2 years of down time saving and building to take it out and gernade it....then what???...ask j here on the board about "mod'ing" a boat on a shoe sting budget...i love all boats and would be out on the water no matter what boat i'm in....

24 months of boat payments (it's insured as well!) is 333=8000....

this is not the first case where Tread and i have tried to warn people of the pitfalls in do'n exactly what your about to do...

I think a few of you have missed the whole point of this thread that I started.
The question: "HOW MUCH HORSEPOWER DOES IT TAKE TO REACH 80 MPH?"
My boat runs great right now. I would continue to drive it while I build a new engine. NO DOWNTIME. I am wondering about the horsepower, so that I may begin gathering parts for this new engine. My plan would be to buy parts as my budget allows and as I find good deals. If it takes a while, THAT`S OK. When I do get the engine finished, it will replace my current engine, which I will keep as a spare. If new engine blows, swap old engine back in and "regroup". I don`t know if I will need $8000 to build a 550hp engine. But again, if spent over a period of time, will not be a financial shock. I can`t use a bigger boat, no where to store it. I like to ski, bigger boat not as well suited for that. I am truly happy with this smaller boat. Would just like to see it go a little faster. I may be happy with 75 mph, who knows. But, as asked initially, I was curious as to how much engine I would need to run 80. If my research finds that I will be spending an unreasonable amount of money to reach this speed, I will re-think my goals.

i have no idea what the bottom of your boat looks like....you may need bottom work to EVEN make it SAFE....no where do you say what componets do i need aside from the engine to support this kind of speed. the boat was NEVER designed to go that speed! fact is the parts and rigging you need cost more than the engine upgrades!


"If my research finds that I will be spending an unreasonable amount of money to reach this speed, I will re-think my goals"?????? It's an unreasonable amount of speed to ask from that hull.

Audacity, Just wanted to let you know that there are a few Baja members with the same hull that are running into the upper 90's along with myself in the upper 80's. The Hammer has the ability to run at 80 with no ill effects as long as it's propped correctly with external steering. My post here was promoted by experience, not by chance. Don't get me wrong, the Hammer will always be a lake boat that should be respected during rough water conditions. It's always an issue of driving skills, even if the boat can handle it. I posted this to give you another idea about this hull and mean it with all due respect. Scott:)

Safety is ALWAYS my #1 concern, way beyond speed. This is a "Lake boat" and is used that way. I always respect water conditions and never apply full throttle unless water is very smooth.
I have been speaking with a board member who`s modified his Hammer significantly. He is currently at 100 mph. I have seen plenty of these hulls achieve 80+ mph with no ill effects.
Audacity, I respect your comments and concerns. I know you are a veteran of rough water. I realize my boat will never see anything like what you encounter frequently. Your thoughts and opinions are appreciated here.

"The Hammer has the ability to run at 80 with no ill effects as long as it's propped correctly with external steering." MUSIC TO MY EARS!

my only ponit here is respect the water! seems like people loose sight of it...we all love to go fast! but remember NOTHING is free. it all comes at some expense...be safe:D

Well said. ;)

DITTO!!!!!:D

You're gonna have to compomise
 

Sounds like you have a dilemna on your hands. I know you want to go 80 mph. But as you stated in an earlier post, it is a lake boat, and you also like to go skiing.

1st, if you build the boat for speed your probably gonna have to sacrafice skiing. Majority of the time, a boat build for speed is not logical for Skiing. Your gonna blow drives and couplers with all those quick starts to pull a skiier. Let alone the fact you will need to have thru hull exhaust, and you won't even be able to hear the skier say anything. you'll have to use sign language.

2nd. How large is the lake you keep it on? Are you going to race across the 3 mile lake at 80mph.

If I were you I would make a compromise, and ask yourself what do you primarily want to use the boat for? I always have ill advised people ask me to take them water skiing on my boat. I would never waste the gas it takes to constantly have to get on and off plane. I would also not want to be rebuilding my drives, and transmissions all the time.

Also, if your skiing you will only tow a person at like 30mph or less. With the big motor this is gonna be hard to do. Your not even gonna get the lump out of the cam at those cruising speeds. A bigger cam should be run over 3000rpm depending on the lift, duration, etc.

Panther, I always welcome opinions from all members, that`s what this is all about. In your last post, I feel you were off on several points. Allow me to reply to your comments as to provide my side.
I really don`t feel like I will be sacrificing the boats ability to pull skiiers. First off, a simple prop change will cure most of the things you were concerned about. My boat is pretty light (by most standards) and does not require a balls-out, kamakazi start to get a skiier up. Propping down will help this even more so. Thru-hull exhaust? My boat has ALWAYS had thru-hull exhaust. In fact it is a 5" diameter system from Stainless Marine that I added last winter. It is EXTREMELY LOUD. We always use hand signals. It is the safest way to communicate. Ever ski behind an outboard? Can`t hear over those either. I boat on two different lakes, like everything else here in Texas, they are pretty large. Ever heard of Lake Texoma? Labor Day Poker Run, one of the premier events on the circuit. As far as primary use, I typically just cruise, float or blast across the lake. We ski / wakeboard only when the water is like glass. All my ski buddies go about 34 mph, right at 3000 rpm with a 23" prop and trimmed all the way down. With a 19" or 21" it`s way over 3000, but can`t remember, we use 23" all the time. With all this being said, if bigger horsepower changes the towing characteristics of my boat, I can always ski behind my buddies boat, it is designed for that purpose. THen we can use mine for a quick adrenaline rush!

Points well taken
 

Don, I hear ya! Its just very rare to see a boat with a high horse big block to be used for skiing. Depending on the horsepower you'll be making (600hp to 80mph) you may have driveability issues while towing skiiers, and idleing for long periods of time. You may have a lot of fouled out spark plugs. Chances are with that amount of power you'll be running a pretty big wheel to get top end speed. Probably 28" to 30" pitch prop. If you run the small props for skiing you'll always have to have a spare prop on board if you plan on going fast. I just wanted to see what your boating priorities were. If you can sacrafice all this stuff than go for the speed. Good luck, just making sure you thought about everything.

If you are planning on keeping the boat, waste no more time and get some full hydraulic steering. The sooner you get it the less wear your gimble ring will have for when you do get the cash to go fast, and it will be much safer. Single ram is fine, but get it all the way to the helm. A small boat needs to be driven and you cannot drive a boat with sloppy steering. That will run you around $2500.00. With that said I would trust Brad Perrys HP estimate for what it takes to do 80 MPH in that boat since he has been there. I would take some of the comments and warnings about messing with your motor to heart. It WILL be frustrating at times and don't kid yourself, it will be expensive. On the other hand, going fast in small boats on small lakes is a blast. My 1990 Baja 210 Sport goes mid 90's and gets there quick enough to be there and back to zero in less than a mile. Thats fun!!! I did all of the work on my boat and thats rewarding. A lot of guys buy their performance, which would be nice, but it is also pretty fun to pass those guys up from time to time when the conditions are right. Remember SAFETY FIRST especially on a small lake where families are boating. :cool:

well said WV!!!:D

Hydraulic steering is in my plans. I will upgrade to that before I even pull out my current engine.
I am very cautious when it comes to driving fast around other boaters, especially PWC`s. I just don`t go fast if there is any traffic around. I work in a large manufacturing facility and they preach safety to us constantly. I guess it has rubbed off. I try to be as safe as possible in everything I do, even mowing the lawn!

My 1990 Baja 210 Sport goes mid 90's and gets there quick enough to be there and back to zero in less than a mile.

WETTEVETTE, That sounds like a good time to me! How often do you have to tighten up the screws in your bolsters from that kind of acceleration? One hell of a ride man!:D

I'm an example!!
 

"I would take some of the comments and warnings about messing with your motor to heart. It WILL be frustrating at times and don't kid yourself, it will be expensive. "




Especially when mechanics sabotage your ****!!:rolleyes:

For this winter, I think I`m just going to get rid of the fuel injection and swap to a bigger cam. Dennis Moore gave me some good info on what to go with. I hope to reach low 70`s in the springtime.