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Buy new or rebuild motors

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Old 08-08-2003, 09:08 AM
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Need some opinions here. Am looking to power up from my 98' 454/365's to around 550-600 horsepower. Shoud I buy new or rebuild existing? Innovation Marine is here in Sarasota. Would prefer to stay with natural aspiration, not blowers. Need help here.
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Old 08-08-2003, 09:16 AM
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Your gonna be hard pressed to get that HP out of them without blowers or a considerable increase in cubic inches and compression which is costly. Sounds like a nicely built pair of 540's would do what you want. Can't beat cubic inches anyway.
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Old 08-08-2003, 09:24 AM
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When I was faced with that decision I chose to rip everything out and replaced old 502's with new 500efi. Best move I ever made. They look sweet and run awesome. No blowers, no problems and rediculous reliability. Turn the key and go. You can go with the new 525's.
 
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Old 08-08-2003, 09:39 AM
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Check out the Teague ad in Powerboat. He's got 575hp 509ci Merlin crate motors for $9,999. I believe they come with a warranty. I don't see how you could go wrong with these. I'm looking at some potential project boats, and these are tops on my list.
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Old 08-08-2003, 09:40 AM
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What kind of $$$ are you looking to spend? I was going to re cam /increase some compression in my 1994 454 MAG Efi and look what I did (My Avatar).

I love my engines super reliable with Captain's call lots of goodies inside. Problem now is when you go to sell your boat everyone thinks it's been beat.

New OEM style engines are EXPENSIVE.

I really went through a lot of options before settling on blowers. Your needs my be different.

PM me if you have some specific question on estimated costs/HP/options
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Old 08-08-2003, 12:07 PM
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We can help you out- we are in Tampa- give me a call to discuss your options- Al 813-247-3049
 
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Old 08-08-2003, 02:24 PM
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Innovation could make those motors 468ci and easily make 600 hp with some ported steel Merlin heads. I had 510 ci solid roller,raceported Merlin heads, 1050 Dominater, 700 hp pump gas My Partner has had them now with 4 seasons on them. My past experience, blowers are not the way to go unless big power is needed.
 
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Old 08-09-2003, 11:09 AM
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Formula Outlaw,

My opinion is that you can get pretty close to 550 reliable HP out of a naturally aspirated 468 big block Chevy at about 5500rpm, but you'll have to do a lot of mods to do it while remaining at 468 cubes including a good set of free breathing exhausts---GIL or Stainless Marine manifolds would work well enough, but Lightening or CMI would probably be a touch better.

I had a friend who had a pair of these built in the mid 1980's with bowl ported GM rectangle port heads, solid flat tappet cam, GIL exhausts, single 850 Holley carb, ---20 years ago!!! Back then they didn't even have the Merlin heads available yet or hydraulic roller cams. It pushed his boat (over 8,000lbs 30' Carrera) w/TRS drive and trannies to guessing about mid 70's or a hair better. This was back in the 80's before they had the more accurate GPS speedos---none the less the boat was a runner and not many other boats were able to get around this guy back then. It was a very well respected running boat in it's time.

I know of another friend who recently had a pair 461's built with Merlin non-ported oval port heads, hi-perf hydraulic FLAT TAPPET cam, 800cfm Holley carb, and it made 505hp @5500rpm and 514lbs of TQ on Tom Earhart's dyno! It pushes his 28' Challenger to about 77mph (GPS).

These days, Merlin heads are much better than the stock GM heads and you can still have the Merlin's bowl ported to give you even more power and then go with a hydraulic roller cam and a good intake like a Dart. You can go with a solid roller cam and make even more power, but you won't get the reliability out of a solid roller cam compared to the hydraulic rollers. Another time consuming operation is that solids require periodic valve lash adjustment, and are very hard on valve springs and other valve train parts. Having the cylinders "bore notched" is a good thing to have done on a 454-468 cubic inch engine. This simple die grinder process will add roughly 30hp/tq (dyno tested) to your engine, but it must be done CORRECTLY! You could also send your GM heads to JimV and he could install wedges in your otherwise stock GM heads and it would really give the power curve a REAL kick in the pants!

All of this could be done to your 468's while keeping them naturally aspirated. Much beyond 550-575hp you will most likely need a super charger or go to larger cubes.

Hope this has helped. Have fun!
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Old 08-09-2003, 12:09 PM
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thanks, guys you are helping me out.
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Old 08-10-2003, 10:34 PM
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I forgot to mention---the guy with the 30' Carrera, his engines were dyno'd at about 550hp at 5600rpm.
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