V6 to V8 swap

[dan02gt]

Re: V6 to V8 swap

What Is a good speed hull? Want to stay with ski boat open bow type.

I'm not aware of any smaller I/O bowrider with a hull design that is capable of doing 60+ and remaining stable.

Like Walt said it really needs a pad to be manageable at those speeds. Without one it's going to be a chine walking nightmare.

If you're not apposed to a outboard the Checkmate Pulsare BRX line will can get you into the upper 80s low 90s with the right power. You still have to learn how to drive a high performance V hull but they have a pad and can do those speeds.

 

[tazrig]

Re: V6 to V8 swap

Way too much power and torque for an Alpha. You'll need a bravo1 as a 3 is only rated up to 55mph and I would guestimate you'll be doing at least 80mph. That being said that much horse power on a boat not designed for it is either going to tear your transom off or you'll end up doing this and killing yourself. I have a 23' formula that weighs 6,500 lbs with twin 300 hp i/o's on it and I easily go 60 and basically only the engines are left in the water. You're talking about putting 50% more hp in a boat that probably weighs half as much. You are looking for serious trouble, no kidding.


Outboard Drag Boat Flips over Backwards in Gadsden, Alabama - YouTube

 

[thumpar]

Re: V6 to V8 swap

I would bet it weights much less than half of the 6500lbs. My 20'2' is 3100lbs with the standard trim and this is a boat with a 8'6" beam I would thing that boat weighs in at around 2300.

 

[jbcurt00]

Re: V6 to V8 swap

1993 Celebrity Boats 180 Status Bowrider
2500lbs

 

[thumpar]

Re: V6 to V8 swap

From the link above:

Engine Information:
This boat may have come with the following or other engines :
(In the interest of safety, never exceed the manufacturer's maximum horsepower rating for your boat.)
175 hp

 

[MikDee]

Re: V6 to V8 swap

IMO, That is too much motor for that hull. A worked 350 small block would be the most I'd venture to try in that boat. What speed in reality would you be trying to achieve in that hull? I can visualize some serious chine walking in that hull. Side turn fins may help keep it planted, but they'd also probably scrap a few mph off top end. In fact, have you thought about going with a surface drive system?

 

[tazrig]

Re: V6 to V8 swap

I just have a bad feeling if you go anything close to what you're thinking in terms of hp you are going to end up like this:



If your even that lucky.

 

[DubT]

Re: V6 to V8 swap

When I first purchased the boat I took the 4.3 V6 and had it build and it was dynoed at 300hp and 315ft/lbs torque I put a lil over 4000 in that engine. I had to go up in prop to 23 pitch and gps the boat at 54 mph it handled that fine and still had a good bit of hull in the water. With that being said I sold the V6 and went to the 383 stroker mostly for the sound I wanted the thru hull exhaust. The 383 peak hp is 400 hp at around 5200 rpm on dyno and 438 ft/lbs of torque at 4200 rpm I'm not looking at the dyno sheet but that's what it showed to the best of my memory. I was told with the v6 if I had a better prop I could achieve almost 60mph.

 

[DubT]

Re: V6 to V8 swap

I honestly don't think I will see that much gain in a top end speed even if it handles that power the best it will do is maybe 65mph I may be wrong but I will see and keep everyone posted I'm already to far in this project to back out and I ain't no quitter!

 

[Walt T]

Re: V6 to V8 swap

Mr. DubT asked a good question, "What Is a good speed hull? Want to stay with ski boat open bow type"

Scream and fly is a good place for answers. My opinion would be Stingray 195 or something similar. Those hulls have a flatter pad in the back. Keep in mind family bowrider type boats are compromises. A flatter hull gives a harsh ride in choppy water whereas a deeper V hull tends to smooth out the ride. Most family boats are designed for a good ride. After all it's more fun for the wife and kids if they don't have to wear kidney belts.

Someone mentioned tabs earlier, those spring loaded ones can help with the chine walking but I can't speak from experience. When it starts doing that it is frightening. The feeling of complete loss of control is like sliding on ice in a car. At any rate please keep us informed. I hope to be proven wrong.

 

[MikDee]

Re: V6 to V8 swap

So, now you're saying it's a worked V6 that has taken you to 54mph. Theoretically a worked 350/260 then should take you to maybe 65mph, and the worked 383 should theoretically take you to 70mph. I know a Celebrity is a pretty sturdy boat, I had a 22' Cuddy, but 60-70mph in an 18' boat would scare me. I just hope you have all your ducks in a row. Thru-hull exhaust is cool, those V8's sound sweet. I had it on a few of my boats, but you're not sneaking up on anybody,,,lol. Nor are you doing much residential nightime cruising, or you're a menace,,,lol. What are you boating on? a lake, a bay, a river, or offshore? Either way, your boats gonna get seriously slammed on open water, just another thing to consider. Good Luck, Mike

 

[Walt T]

Re: V6 to V8 swap

Google Image Result for http://www.aeromarineresearch.com/download/TBPNews/veepad-03-web.jpg

 

[JASinIL2006]

Re: V6 to V8 swap

Someone mentioned tabs earlier, those spring loaded ones can help with the chine walking but I can't speak from experience. When it starts doing that it is frightening. The feeling of complete loss of control is like sliding on ice in a car. At any rate please keep us informed. I hope to be proven wrong.

I put SmartTabs on my boat to help with chinewalking at higher speeds (55-60 MPH) and they completely eliminated it. I'm don't think SmartTabs use conventional springs, though; it's a gas spring, sort of like a small shock absorber. In any case, they were an easy fix for chinewalking.

Jim

 

[DubT]

Ok guys I have an update on this project I Have the 383 installed and it went in with fairly easy. I havent changed anything in the alpha 1 outdrive still has same ss prop and 1:84 gears. I broke the engine in and did some testing. It is a little sluggish out of the hole but still palins off fairly quickly with 4 large adults i just give it a little more throttle and it comes alive. Once on plane this thing accelerates like crazy will get up to 63mph on the top end and still handles the same as before and drives level in The water no torqueing to one side. The only bad thing is on the top end im turning around 6000 or 6500 rpm. I havent played with props but i did switch a prop with a friend for a few test runs and his was a 29 pitch that was a much larger diameter than my prop and i ran the same top speed at 5200 rpm and the boat had faster less labored crusing speed and got on plane better. His prop was a 4 blade and mine was a 3 blade. Any thoughts on what prop to change to or maybe if i should change the upper gear ratio. I would love to find an alpha ss drive but hear those are like unicorns.

 

[DubT]

No Title

Pics of install

 

[DubT]

No Title

 

[HT32BSX115]

The only bad thing is on the top end im turning around 6000 or 6500 rpm. I havent played with props but i did switch a prop with a friend for a few test runs and his was a 29 pitch that was a much larger diameter than my prop and i ran the same top speed at 5200 rpm and the boat had faster less labored crusing speed and got on plane better. His prop was a 4 blade and mine was a 3 blade. Any thoughts on what prop to change to or maybe if i should change the upper gear ratio. I would love to find an alpha ss drive but hear those are like unicorns.

You're REALLY out of the efficient prop RPM for any prop.....and way above the safe RPM limits for any Alpha (unless you have a seriously "built" drive)

Your best bet would be to go to a 1.5 or even 1.36:1 ratio since you have so much excess power.

Problem is that if you "use" that power for holeshots, it won't be long before you grenade the drive. (not "if", but when.)


Regardless of the ratio you use, you should select a prop that gives you MAX RPM (that you want the engine to turn) at WOT.

You'll probably have to experiment.

 

[thumpar]

How much HP do you think your are running? If it is as much as it sounds like you might want to stock up on SEI drives or convert to Bravo.

 

[DubT]

The engine dyno says 405hp 450ft/lbs tq. I have seen guys running alphas with big hp on smaller boats not having any problems. I have a bravo 1 but dont want the extra weight and drag it will apply. I talked to a guy at rlc performance.com who experimented with a 22ft boat trying to get 100mph and a good handle. He did years of r/d checkout his triple diget project. I dont want to go 100mph, but would like to see low to mid 70s. He is saying i should try something like a 4 blade 23pt hydromotive prop and change my upper gears to 1:50. But i have heard that the 1:84 is faster and puts less stress on the uppers and more on the lowers which from what i understand are bigger and stronger.

 

[thumpar]

Some may get away with it for awhile but eventually an Alpha with give up under that power. The Bravo weighs less then adding an extra person to the boat. It would be almost bulletproof with your power. You would love the way it shifts also.