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11-18-2009, 09:44 PM
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#1
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Platinum Member
 Platinum Member
Join Date: Apr 2007
Posts: 142
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598 CI supercharge what is the best compression?
any help would be appreciated building fresh 598SuperCharged intercoolded i would like to know if I could get a low compression piston like 6.5:1 7.0:1 or maybe 7.5:1 so i could safely run 10-14 pounds of boost on pump gas with steel heads. would this set up work I have 14-71 blower
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11-18-2009, 11:12 PM
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#2
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Registered
Join Date: Apr 2007
Location: Amherstburg, Ontario
Posts: 146
1999 Top Gun... Soon To Be 39' Unlimited.
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why so much boost???.....i have the same displacement and blower not intercooled yet(on the way) im running 9.0:1 with 6.2psi boot and making 900+hp on 93 pump....that much boost will kill your engine.....once my motors have coolers im going to raise the boos 1psi
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11-19-2009, 08:56 AM
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#3
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Platinum Member
 Platinum Member
Join Date: Dec 2000
Location: Hawthorn Woods, IL
Posts: 972
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Bigfamer,
Which blower and size head are you using?
Thanks,
Rick
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11-19-2009, 11:02 AM
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#4
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Offshoreonly Advertiser
 Offshoreonly Advertiser
Join Date: Jan 2004
Location: Tennessee
Posts: 2,835
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Sosatime,
With that blower and cast iron heads, I would get the comp. ratio to 8.0-8.5:1 and run about 5-6 psi boost. The best thing that you could do would be to get a set of aluminum heads. Then you could run 10-12 psi of boost and make over 1000 hp.
Your biggest problem with the cast iron heads will be heat. The faster you spin the blower, the more heat it will generate. To make 12 or more psi of boost in a 598, you will need to really spin the blower. This is going to make the a ton of heat and make it susceptable to detonation with cast iron heads. I would start with a higher static compression and spin the blower slower to keep the heat in check.
Eddie
__________________
True, Custom EFI and Carb. engines from 500 to 1500 HP. Also specializing in outdrive upgrades and repair, custom rigging and fabrication, we can handle all of your performance boating needs. See our entire engine line at www.YoungPerformanceMarine.com Contact us at 615-216-7449 or youngperformance@comcast.net
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11-19-2009, 01:52 PM
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#5
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Platinum Member
 Platinum Member
Join Date: Apr 2007
Posts: 142
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Young Performance,
what is a good head for my application what do you recommend AFR,DART,BRODIX, and what size head 345,355,357,375 for 598 SC intercooled application if you have any pricing available PM.
Thanks.
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11-19-2009, 02:22 PM
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#6
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Offshoreonly Advertiser
 Offshoreonly Advertiser
Join Date: Jan 2004
Location: Tennessee
Posts: 2,835
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Any of the heads you mentioned would work fine. I have used Dart's for as long as I can remember. I recently started using Brodix heads and they are making more power than the Dart's on some combo's that I build often. One engine in particular responded well to the Brodix heads. It was a 598 with a 3.3 L Whipple. I had built quite a few with Dart Pro 1 355 cnc's and they all made 940-972 hp. I used a set of Brodix BB3extras (355 cnc), with everything else being the same, and the engine made 1028 hp and 1085 ft lbs of torque.
I also recently used a set of 335 cnc AFR heads on a common package that I normally do with Dart heads (345 cc). The AFR heads made about 30 hp more than the Darts. This was a NA 540ci making just over 700 hp.
Personally, I don't thing you could go wrong with any of the above in a 355 cnc. I will pm some pricing to you. Thanks.
Eddie
__________________
True, Custom EFI and Carb. engines from 500 to 1500 HP. Also specializing in outdrive upgrades and repair, custom rigging and fabrication, we can handle all of your performance boating needs. See our entire engine line at www.YoungPerformanceMarine.com Contact us at 615-216-7449 or youngperformance@comcast.net
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11-19-2009, 09:21 PM
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#7
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Offshoreonly Advertiser
 Offshoreonly Advertiser
Join Date: Oct 2000
Location: Fresno, CA, 93722, USA
Posts: 1,169
Engine, speed, powerboats
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Quote:
Originally Posted by sosatime
any help would be appreciated building fresh 598SuperCharged intercoolded i would like to know if I could get a low compression piston like 6.5:1 7.0:1 or maybe 7.5:1 so i could safely run 10-14 pounds of boost on pump gas with steel heads. would this set up work I have 14-71 blower 
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No way, gotta run more compression and lower boost. I would say 8.5:1 and run 8psi. Going more than 10 with a 1471 is really not ideal. You run to low compression, you better have the best SC possible to fill the holes because something like a roots is going to take a lot of power to fill the cylinder.
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