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Old 08-29-2017, 11:02 PM
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Im about 4 weeks away from the boating season up here from being over and i think its time to do a little maintenance and maybe go a little faster. i have a 03 575sci, 15Xhours on the clock. been on here doing a lot of reading so i know enough to know i know nothing, or just enough to spend a lot of money and go no faster haha. so far my plan is floating around the bottom end not needing anything, all leak down numbers where pretty good at the start of the season and its ran all good for the year.
  • heads. im leaning on the Brodix BB-R heads - 2061013 -, the flow numbers look pretty darn good for a "smaller" head, and flow pretty close to a lot of the bigger heads into the .600 range, the 115cc chamber should help with bringing up compression a wee-bit . they also dont raise the exhaust port so that keeps added work down to a minimum.
  • cam. seems like a very popular pick is the "741" or 525 cam and i was honestly going to go with that. if its not broken kinda deal. especially for a not super extreme build
  • Intake. going to retire the 256 and go 8-71 and aim for 6psi
My question is, am i even close? haha i had seen a few threads about the 741 not responding well to lower compression and with the 575 being a 7.5:1 motor. am i to low to try and get away with it? will it respond well to boost?
The heads, even with good numbers and what looks like maybe some good velocity, are they going to choke the motor out? i dont see my self wanting it to spin higher then 5800 (for now) will the 115 chamber vs the 118 chambers on the stock heads make any difference at all?
what head gaskets? i dont want to pull the motor and do a full tear down if i can avoid it and from what i recall MLS gaskets prefer a fresh surface.
any and all feed back is welcome please!

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Old 08-30-2017, 07:43 AM
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My suggestion is to call Eddie Young (Nashville). He did a real nice job on the 575's in our previous boat (rebuilt stock heads, custom grind roller cam, on water tuning, etc - bottom ends were in good shape, as I expect yours are).

He also has a custom fuel injection setup to get rid of the obsolete injectors in the throttle bodies - and it is very reasonably priced.
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Old 08-30-2017, 06:25 PM
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ive seen his fuel injection system and will be doing that set up when mine start to fail or i go past the stocks limits, for now im just going for some extra umph and getting rid of the one issue at a time, or two in this case i was hoping some of them would chime in haha. im still to far out i think to seriously bother someone and take up time form their day
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Old 09-07-2017, 09:59 PM
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The right ported heads and 871 will get you 750 plus easily.
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Old 09-10-2017, 03:52 PM
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i am now leaning to a 305 afr with a 114cc chamber, they dont seem to be much more and have way way more flow
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Old 09-10-2017, 09:54 PM
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NA I'd say perfect choice but sc I'd personally go a little larger int runner. 320-325 cc.
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Old 09-11-2017, 09:48 AM
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I wouldn't sweat the compression ratio. You will have plenty of blower, so use it. With the static being low, and the 871, I wouldn't sweat running 8lbs of boost.

There's lots of good head options out there. I wouldn't get caught up in port runner volume. I been running 330cc intake runners on a 8:1 iron headed 468 that makes over 800hp and are extremely responsive , that's the beauty of a positive displacement blower . The cam you want is one that coincides with how the heads you choose flow, how much boost you plan to run, etc.

Bang for the buck heads

Dart 3​​​​​​08 iron eagles

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Old 09-11-2017, 10:37 AM
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i was thinking of going bigger, i figured any newer head is going to smoke the stock heads in flow any witch way i go. 8psi un cooled? eventually id like to get a whipple cooler and really crank it up. i dont recall off the top of my head but would a stock 575sci bottom end take 8psi?

i was looking threw a bunch of the threads you had along with the build on your motors Mild Thunder. id be happy if i even came close to that kinda power in my little V
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Old 09-11-2017, 11:19 AM
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8psi non intercooled from an 871, is probably a cooler temperature than the stock little 256 blower at 6psi.

If you changed nothing except the blower, you'll see some nice gains. 575 owners who did the dyers 871 conversion kits were very pleased.

The stock forged rotating assembly in the 575 is pretty stout. With head upgrade, cam upgrade, and the 871, it will be a different animal even at 6psi of boost.

Sounds like a fun build
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Old 09-11-2017, 11:52 AM
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thats what i was thinking but couldnt find any info to back it up about the IATs on un cooled readings. another reason im wanting to go alumi heads. i think i saw one on here about a guy going from the 256's to 8'71 and picking up 5mph(?) with nothing els changed
im hoping so, its currently running to 83mph on gps, hoping with a little less weight and some more motor it should show some nice gains
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