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So how do you think this 496 will run?
I posted this for opinions before, which was mostly negative. But, now I'm looking for ideas on how it will run before it's first voyage tonight. He listened to his engine builder and not the marine pros.
Single engine 26 foot sleekcraft The motor started out as a 365 mag motor, upgraded to eagle 496 ratator. compression 10.5-1 ported rectangle steel heads (really opened up!) single plane intake 850 holley carb full MSD ignition CMI tube top headers stock 454 (330) oil cooler The cam they recommended was as follows Hydrolic roller 610/610 lift 230/242 duration 112 center Looking for running characteristics, not just that it won't work. |
It doesent look too bad on paper but who "really opened the heads"?
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Originally Posted by formula242-502
(Post 3430640)
compression 10.5-1 ported rectangle steel heads (really opened up!) Looking for running characteristics, not just that it won't work. On steel heads? Detonation, lots of detonation. "ported rectangle steel heads (really opened up!)" Hogging them out does not always help, opening them up and decreasing velocity without significantly increasing airflow might hurt. It will probably run like a Raped Ape........For an hour at least My $0.02 |
to much compression....93 all the time, water injection, etc..or keep timing way back..
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It should make good power, but not sure how well it will hold up from a durability perspective. Looks like it was built to make its power on the top end of the RPM range, probably from 5000 - 6200 RPM, especially if the heads were hogged out. Those rectangle port heads are huge x wide to begin with. I think it will be a little soggy on the bottom end and mid range, and start to come to life around 4500 RPM.
That 10.5:1 CR with iron heads is what really worries me. Hopefully he went with quality forged pistons, good rods and a good steel forged crank. Best to run 93 octane with a boatload of octane booster, or add some 103 octane racing gas. Otherwise, I would worry that detonation is going to pound the bearings right out of that motor, and he will be doing this over again shortly. Also, if he plans to run that motor hard all the time with that small cooler, he better invest in an oil temperature gauge to let him know when a Chernobyl like meltdown is imminent. :eek: |
The heads were a "we have these, let's try them"
Not right for a boat aplication in my opinion, but not my boat. He gets away with the oil cooler since we have a lot of no wake areas to slow down and let the oil cool. |
Originally Posted by formula242-502
(Post 3430640)
I posted this for opinions before, which was mostly negative. But, now I'm looking for ideas on how it will run before it's first voyage tonight. He listened to his engine builder and not the marine pros.
That set up may work in a street or pro street car, but imagine that car towing a trailer up hill, in first gear, at 4000-5500 rpms all day. Then ad a 80 gallon fuel tank in a moisture rich environment where fuel degrades quickly. |
4bus,
I like the friendly way you put things. Just got off the boat actually. It plaines out ok, sounds like a pro stock at idle. Seemed lazy in the midrange to me and was breaking up some at 4700 so far. |
the issue I see with running is you are never going to get to where the engine needs RPM wise with those heads/cam/intake....sometimes less is better...
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Make sure it is jetted a little rich and timed around 34-35 degrees. Do not run a thermostat and use premium fuel only.
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Originally Posted by formula242-502
(Post 3431299)
4bus,
I like the friendly way you put things. Just got off the boat actually. It plaines out ok, sounds like a pro stock at idle. Seemed lazy in the midrange to me and was breaking up some at 4700 so far. |
Originally Posted by Boat1
(Post 3382030)
Let me start by saying I shouldn't say what I'm about to say, are we clear!! Since your friend has no interest in listening to an expert he clearly is smarter than everyone. If he was spinning a mag motor 5800 WOT he was making noise not power, that cam can't support it. A hydraulic roller combo should not turn above 5400 or you risk valve float. The cam he suggests is not large enough for 5800 rpm and needs to be mechanical roller anyway for that rpm. I think what he really wants is a boat he can talk about. He should put a large duration camshaft with a 108 LSA so he has the most knarly idle in the marina, spend his money on a really cool sticker to put on the engine that says 600 HP or heck even more if he wants. The boat will likely barely come on plane and run terrible but it will sound really cool and show great when it is broke down. I'm sure he doesn't need a 3X18 oil cooler, or a quality oil pump, or upgraded fuel system either but it's a suggestion. Let me know when the maiden voyage is, I'd like to bring a cooler and a chair to watch it get on plane. Good Luck.
http://www.offshoreonly.com/forums/g...d-496-cam.html Sorry to hear that your friend put a lot of time and effort into this and might not be happy with his results. You were not getting negative comments in your first thread, you were just getting honest opinions from members that have been there and done that. I hope some how he can get this to run without much more hassle, but the history of the components that are in there tell us different. This is going to be a broad torque engine with HP in high RPM range. Did he even Dyno it? |
I guess I shouldn't have said negative, was just looking to get ideas of what it would do not that it just wouldn't work. I had a good idea it wasn't a good setup, just hoping it stays together for him. Too much $$$$$ to keep rebuilding, and summer is too short.
Built off a desktop dyno. No real life dyno |
Well it made it through this weekend ok. He didn't use it :)
You guys were right so far, so we'll see. It sounds really good at idle, that's for sure. |
Originally Posted by formula242-502
(Post 3435666)
Well it made it through this weekend ok. He didn't use it :)
You guys were right so far, so we'll see. It sounds really good at idle, that's for sure. |
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