cat motors.... to bore or not to bore, that's my question

[kevinb]

Are mercruiser motors more heavy duty than a motor you'd build from a GM Crate engine?
What are the differences besides cam selection?
With that being said.. I'd like more power out of my boat. I currently have a stock 454 in this 26ft cat. It has a cam in it and I think it might be hurting me.
I get high 60's and I want 90 with reliability.
would I be better off boring and stroking my motor or buying a good used motor elsewhere?
I'm interested in good fuel economy (I dock my boat 19 miles from where I meet up with friends and go boating, so the hours rack up)... is fuel injection worth it in saved gas?
Besides a mercruiser hp500 for $20,000.... what are my options if I want more power? How is a mercruiser better than a motor I build myself?
To bore or not to bore? Or do I just buy a new motor and save mine in case it goes boom?
Thanks

[Craig]

kevinb:
Are mercruiser motors more heavy duty than a motor you'd build from a GM Crate engine?
The Mercruiser still use standard GM heavy duty parts for the most part.
What are the differences besides cam selection?
Most marine engines have a little less duration I believe in the cam to reduce the chance of reversion through the exhaust.
With that being said.. I'd like more power out of my boat. I currently have a stock 454 in this 26ft cat. It has a cam in it and I think it might be hurting me.
I get high 60's and I want 90 with reliability.
would I be better off boring and stroking my motor or buying a good used motor elsewhere?
Boring and stroking will only get you to about 496 cubes, that alone won't get you to 90. I assume your motor isn't fuel injected since you ask about adding it, you could look at a supercharger. My 22' cat originally had a 454 Mag, went low 70''s stock. Put a 250 blower on it with a cam, fuel delivery and ignition upgrade and went 94.6 mph first time out.
I'm interested in good fuel economy (I dock my boat 19 miles from where I meet up with friends and go boating, so the hours rack up)... is fuel injection worth it in saved gas?
Fuel milage really isn't that bad if you plane her out and go easy on the gas. IMHO, fuel injection isn't worth the money you'll spend for the return. Yeah you'll get better cold start and idleing and some better mileage, but it won't out perform a properly tuned set of carbs when you consider the 3-4 grand you'll drop on the system.
Besides a mercruiser hp500 for $20,000.... what are my options if I want more power?
There are a lot of good builders out there that can put you something together with a warranty for the same price or less then the Merc.
How is a mercruiser better than a motor I build myself? It's not if you build it right and don't cut corners.
To bore or not to bore? Or do I just buy a new motor and save mine in case it goes boom?
Craig
ThanksDrop me a line if youo want more details then above. The 454 lasted a year of hard running, but I was spinning too many rpm's for the stock oiling system Now I run a 509 with a 420 B&M.
[ November 20, 2002, 03:52 AM: Message edited by: Craig ]

[Charley]

Craig has some very good insight on motors Kevin.... I would take him up on that offer! by the way Craig I wanna get you a copy of the build sheet from Larry to see what you thing! can I fax ya?

[boatnam2]

lets see here you want 800hp power but you want it to last forever and get 20 miles to the gallon,hmmmmmmmmmmmm sounds like a dream i once had.j/k you can build a reliable 800hp and will last long but hp and fuel milage just dont mix.you will have to give in a little on that one.i had a 26 ft cat built three motors for it,the first place i took it was blosdales in havasu as a stock 454.including a littlefeild blower it was about 7000.00 dollars and that was pulling the motor doing all the machine work putting motor back in and rigging it for the new stuff.carbs etc; it was running just above a 100.ofcourse prices have went up i had mine before it was so cool to own a 100mph cat.

[Charley]

kevinb:
Are mercruiser motors more heavy duty than a motor you'd build from a GM Crate engine?
What are the differences besides cam selection?
With that being said.. I'd like more power out of my boat. I currently have a stock 454 in this 26ft cat. It has a cam in it and I think it might be hurting me.
I get high 60's and I want 90 with reliability.
would I be better off boring and stroking my motor or buying a good used motor elsewhere?
I'm interested in good fuel economy (I dock my boat 19 miles from where I meet up with friends and go boating, so the hours rack up)... is fuel injection worth it in saved gas?
Besides a mercruiser hp500 for $20,000.... what are my options if I want more power? How is a mercruiser better than a motor I build myself?
To bore or not to bore? Or do I just buy a new motor and save mine in case it goes boom?
Thanksfor 20k I would say skip the HP500 besides and HP500 wont make a 26' cat go in the 90's anyways......650-700 HP ought to get you there and maybe even the century mark depending on the hull and setup. There are plenty of good engine builders out there but I will put a little plug in for Larry's engine in Tucson(520)623-5373...thats who I am going with and for many reasons.....good luck
PS..... Gas Mileage and Speed is a contradiction in Terms pick 1

[mbrown2]

I have stock 502/EFI with Whipple moderate boost in a 26ft cat...It does between 91-93 lightly loaded..have not tested a lot of props, but that is where it is at today..
I like you want to hit the century mark (someday)..In talking to GT performance..they could change the heads, exhaust, etc...on the 502, keeping the whipple and get it to about 750 approximately...for right around 9-10K. This would probably get me to the century mark dialed in.
For 30K, I could purchase GT Performance's 540/Whippled (with all the polished bells and whistles and fits under the hatch) and get 802HP. This number decreases if I could sell my engine for approximately 10K, but I am stll spending an additional 11K for 50HP versus upgrading the 502...
I will probably wait another year...I only have 35hrs on the boat...And before I drop another 10-20-30K into an engine, I would really contemplate building a new boat with the engine I want...You seem to get a better deal when you are buying the boat new with the HI-PO engines...
[ November 20, 2002, 03:32 PM: Message edited by: mbrown2 ]

[pleasantcat]

25' daytona with 600plus hp naturaly aspirated runs low 90's. 550inches and 9to1 comp. it's nice to turn the key and know it'l run

[Craig]

pleasantcat:
25' daytona with 600plus hp naturaly aspirated runs low 90's. 550inches and 9to1 comp. it's nice to turn the key and know it'l run Oh my ass, you ain't happy boy, or you wouldn't be lookin' for that blower all the time

[Havasu Cig]

I will say one thing for Mercury. We just discovered a problem with one of our 500 EFI's not reaching peak rpm. After a leak down confirmed a problem the heads were pulled and some scuffing was noticed in one of the cylinders as well as some leaking valves. This motor had 74 hours on it.
Mercury sent out a whole new motor within a week to replace the one with the problems. They stood beind their product and I was very impressed. I have said before that the 575 SC is overpriced for the hp, but now after the way I was taken care of I can kind of justify the price. Just something to think about, but that motor should get you into the 90's.

[kab]

mbrown2- Litely loaded better be you in a thong with no gas and no passengers to hit 93. Seriously have you hit 93 with that Mach 26 ??