350 to 454 cons

[imported_wallup]

Hello all,

I have a blown 350 merc from no oil and I am thinking of replacing a 454 big block in my 19 ft 1990 Chaparrel Villian II Eliminator. Are there any hurdles that I will have with going to the bigger engine. There seems to be plenty of room in the engine compartment. Any input will be much appreciated.

My bigest concern prior to setting up this thread was the increased gas consumption.

Thanks

 

[Haut Medoc]

Re: 350 to 454 cons

There is way more to it than gas consumption.....
A BBC is too much horsepower for an Alpha drive, you will destroy your drive in short order, not to mention most of what is on your 350 will not be interchangable......
It could be done, but replacing your blown engine with a crate or rebuilt engine will be far cheaper....​

 

[mhunt]

Re: 350 to 454 cons

a properly built SBC should give you all the power you'd need at an affordable price.

 

[imported_wallup]

Re: 350 to 454 cons

The individual has a rebuilt 454 with stainless steel mainfolds for 2k (not sure what went wrong before) I 'm going to check it out this evening and will have a better idea of what all will be included. It's out of a Donzi not sure of the year yet.

As far as too much power for the outdrive, is it the Horsepower that will shread the gears on the outdrive or just the added weight and stress that will harm the outdrive?

 

[Don S]

Re: 350 to 454 cons

It's the extra torque and HP. You will have to change props to a lot steeper pitch which would put a lot of extra strain on the gears. That is the reason the newer engines, even the 350 with 300+ hp are sold with the Bravo drives.

 

[wvit1001]

Re: 350 to 454 cons

Up until the late 80's I know that Wellcraft put out 454's with Alpha drives. As long as you don't throw the power to it real fast the drives can take it. But most of those boat's drives didn't last long because you just can't help yourself. The Alpha drives aren't rated for more than 300 hp and the stock 454 puts out somewhere between 310 and 380 hp depending how it was set-up.

 

[QC]

Re: 350 to 454 cons

Higher peak torque and horsepower. 300 is really the max for an Alpha . . . The drive doesn't know how much weight is in front of it

 

[Haut Medoc]

Re: 350 to 454 cons

A little of both.....
An Alpha drive is only rated to 300 HP, 454 delivers at least 330....
The added weight of a big block will make the stern sit lower....
So add the potential problem of water intrusion wwith the change in the static water level.....
I guess you will have to see exactly what he is offering for 2K, but I'd wager you will be far more into it cost wi$e than two grand when all is said & done....​

 

[Bondo]

Re: 350 to 454 cons

Up until the late 80's I know that Wellcraft put out 454's with Alpha drives.

Ayuh,......... But Only for a couple of years...........

Before the Bravo.... The Big HorsePower was turning TRs,+ TRSs..............

 

[Coors]

Re: 350 to 454 cons

SS , etc, for 2 grand? buy it and part it out?

 

[FreeBeeTony]

Re: 350 to 454 cons

How about a 383 Stroker? If you go easy on the throttle would the alpha last?

 

[imported_wallup]

Re: 350 to 454 cons

Thanks for all the input guys. I'm going with a 350. Mechanic said I'll be on the water this weekend!!

I can't wait to hear it again!

Thanks!