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View Full Version : alum. heads or steel heads?



racingrascal
07-01-2001, 01:21 PM
I am thinking of putting together a 540 merlin for a new shadow and want to know if anybody has any input on this matter, for me its like $2,000-$3,000 more for alum. heads.

boatnam2
07-01-2001, 01:53 PM
hey rr,whats the point,alumminum heads are nice but you can get a set of merlin 345's that will flow all you will ever need,and at a lot cheaper price.its a boat so the cooling quicker deal really dosen't come into play it;s just a weight and money issue,save a lot of money and use it score a couple of chicks that are a 100#'s lighter and your way ahead.

racingrascal
07-01-2001, 02:50 PM
Thanks, I was wondering how much of a weight diff. is there? It is going a 19' tunnel.

racingrascal
07-01-2001, 02:51 PM
boatnam2, I just started using the message board. I thought all of you guys went to the river everyweekend.

froggystyle
07-01-2001, 05:01 PM
I just actually went through this debate. It is not actually so much of the cooling per se that you save, but the ability of the head to transfer heat from the combustion chamber to the water that matters. Aluminum heads mean you can run a higher compression ratio with the same fuel as cast iron heads. This equates to more power on pump gas. Now, what you should really do is buy a blower for a 509 Merlin, make 850 horses on pump gas, and save the aluminum heads for Racing Ray's doorslammer.
Or buy my Eliminator http://free.***boat.net/ubb/tongue.gif

boatnam2
07-01-2001, 07:13 PM
hey rr,i wish i work every other weekend it sucks but i only work 14 days a month so thats cool.froggstyle is right about the heat transfer.but i know using a chiller on a blown deal you can run about 1 1/2 more pounds of boost on pump gas.right now im running 8 1/2.i was running 14 pounds on av gas but im thinking about buying a new boat(no time to blow it up now) the rule of thumb is about 7 max with steel heads.racing ray could probaly tell how much more boost to safely run with alumminum heads.but i really dont think its much more then with steel.

froggystyle
07-01-2001, 08:44 PM
Ya know, not to throw too big of a whammy on the line of logic here, but I am running 10# at 6600 with pump gas. No dramas. 781 rect. port heads with a hydraulic cam. The chiller cools the charge, making it denser and more powerful, but I didn't know of the correlation with psi and the chiller vs. pump gas.
Or buy my Eliminator http://free.***boat.net/ubb/tongue.gif

boatnam2
07-02-2001, 05:30 AM
froggstyle,if the charge is denser i may be wrong but dosen't that have a big affect on detionation.if 7 pounds is close to detionation with out a chiller,by droping the intake temp and making the charge denser wouldn't that allow you to run alittle more boost.i dont really know im no mechanic but when i visited the shop pfm where they make the super chiller the info i got was what i was trying to tell rr.i might of thought the guy i was talking to was trying to blow smoke up my ass since i was not sold on the super chiller but gregg at gs marine and paul pauff told me the same information.froggstyle dont get rid of that eliminator yet maybe i will get a chance to pull up along side of it.maybe just maybe we can see how my little 471 will hold up against all them big chevy cubes.offcourse it would have to be from a rolling start.just kidding i really know for sure how it all works just as long as it works.

boatnam2
07-02-2001, 05:32 AM
my last sentence should of said i really DONT know for sure how it all works but as long as it works.

racingrascal
07-02-2001, 08:45 AM
froggy, i wanted to put together a blower motor but john said it would be like another 9 grand just for the blower. I wanted the blower for looks and power. but at the sametime the shadow runs about 45mph at 4000 rpm i think, so that means that as long as i was cruising the lake i would be on boost.Right? I was told 540" single carb all the good shit 650hp. on pump gas.

boatnam2
07-02-2001, 09:29 AM
hey rr,on my boat while crusing 40mph or so im making a pound or less of boost.only when you mash out is when you see the boost come on.if you want to make 650 ponies i would go big cubes no blower its a lots less money and stress on your motor and mind.im sure the shadow will run in the high 80's low 90's with 650 ponies.i know if i do it all over again(and i hope i get to)i will definetly go unblown and under the hatch.i let my ego build my motor the first three times and i amit it was very cool to go pretty fast but after awhile you want to go faster and sooner are later your kinda budget yourself out hoping that it dont break cause you cant afford to put it back together.so thats why im seriously thinking about getting a 25 or 26 deep vee going 75 or 80 and being happy.i really dont know why im telling you all of this but i thought maybe if you hear someones story that's been there maybe it can help you decide on your choice.another thing about a blown cat everyone wants to race.everone that rides in the boat is always screaming haul ass haul ass if your not then there not happy.so when and if i do get my new boat that goes 75 or so when people start screaming haul ass i will say ,this is it shut up sit down or i will be hauling one less ass.

racingrascal
07-02-2001, 10:50 AM
boatnam, thanks for the story that's me! I was thinking blower because it will look bad ass, but at the same time I want to enjoy my boat and do as little repairs over time as possible. I don't want to wrench on it all weekend and do 100 mph once. So your thinking between 80 & 90 mph with 650 ponies. That is what i am looking for mid to upper 80's. Thanks for all of the great advise. I have been on and owned other boats but nothing like this before.

boatnam2
07-02-2001, 03:45 PM
hey rr,i know tough decision,when i look at my boat and see the huffer sticking out of the hatch all shiny it gives me goose bumps.or the nosie it makes when you first start it before water get's in the exhaust the motor lumping over i love it.i haven't had no problems with it since i had it built right two years ago but i think its just time to move on to something thats more practical,but make sure you get enough power for your kitty.because a cat with no claws cant scratch.just try to find what makes you happy and will give you the most trouble free times.im going down to ultra tommorow to look around and talk to john.i really like the laveycraft 26ft my girlfreind like's the 27 ft warlock so maybe we can meet in the middle at ULTRA.im not sure where you live but if your in the riverside county area you could meet me at elsinore and take a ride and drive my boat and see how you like the blower set up before you do your rig.i go there during the week in the afternoons.

racingrascal
07-02-2001, 03:53 PM
boatnam, what kind of boat do you have now?

boatnam2
07-02-2001, 07:18 PM
hey rr,a 26ft american offshore cat.

racingrascal
07-02-2001, 07:35 PM
Nice boat. I would like to take you up on the offer sometime soon!