598 Engine Advise
10-31-2016, 11:08 PM
#31
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I am running Jessel shaft rockers ( stock ratio)
I am running AFR 357 CNC'd heads.
8.6 to 1 ratio JE pistons ( plan on adding a M4 Procharger eventually.
Crower crank, Lunati rods, Big M block, Edelbrock sequential port EFI intake with the Holley 2000 CFM - Hp system.
Idles smooth and has so much torque it is unreal. Accelerates like it's tail got stepped on.
I am running AFR 357 CNC'd heads.
8.6 to 1 ratio JE pistons ( plan on adding a M4 Procharger eventually.
Crower crank, Lunati rods, Big M block, Edelbrock sequential port EFI intake with the Holley 2000 CFM - Hp system.
Idles smooth and has so much torque it is unreal. Accelerates like it's tail got stepped on.
11-01-2016, 07:10 PM
#33
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If you want a nice package deal. I have a brand new set of AFR CNC'd heads with custom valve job assembled ready to bolt on. Make you a killer deal with a SV 632 Intake. With the right cam it would go over 900hp on a 10:1 598. PM me if interested. Heads are Hard Annodized with Inconel Valves.
11-01-2016, 07:22 PM
#34
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If you want a nice package deal. I have a brand new set of AFR CNC'd heads with custom valve job assembled ready to bolt on. Make you a killer deal with a SV 632 Intake. With the right cam it would go over 900hp on a 10:1 598. PM me if interested. Heads are Hard Annodized with Inconel Valves.
11-01-2016, 07:38 PM
#35
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Going by runner volume isn't the way to do it. Really need to know the cross sectional area of the port different heads have different CSA's the volume or CC's is just the volume and means nothing to the motor. A motor like this 598 over 6,000 rpm is going to want a cross sectional area around 3.5sq in. Based off of the CSA of the port Cubic Inch you can figure out the rpm Choke point of the motor. It's ok to go a little bigger on CSA but not too big. It's all about air speed in the motor.
11-01-2016, 07:51 PM
#36
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GM saw fit to put 325cc rectangle port heads on 427s and 454s (for some reason). You've got 30% more displacement.
Last edited by hogie roll; 11-01-2016 at 08:33 PM.
11-02-2016, 12:35 AM
#38
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My head guy (valako) is adamant with 320's for my 565 builds. Or has even suggested starting with 310's but would ultimately end near 320 after porting. Engine builders and head guys all have the same goal just some go different routes but ultimately can end up with near same results in the end. Regardless trust your builder and don't go seeking advice from others or you'll be all messed up. Lol... Btw I know I used 572's as example but still believe 345's the way to go. The velocity should be ideal with that runner size and cubic inch.
Last edited by getrdunn; 11-02-2016 at 12:44 AM.
11-02-2016, 09:31 AM
#39
The cnc Bb2 xtra will make right around 800 hp at 9:1 compression and good cam. There used to be a problem with the machine work on the Pro 1s, they ate valve guides they may have fixed it by now.
11-02-2016, 02:32 PM
#40
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Very true but GM didn't design them for marine applications that most often run under 6,000 rpm. Just an example but look at many of the 540 marine builds that are making great power with 305-315 cnc heads. Velocity is huge and by getting it with the proper size runner vs CI is the name of the game. Some choose to go larger runner just for good flow numbers but pay for it in the long run. I'd rather start with a smaller runner and maximize velocity while achieving right runner size when done. That's where my head guy comes into play. We dyno'd several 572's marine engines downstate years ago and rarely went over 335 runners with dart heads and were typically for the lighter boats and cats. The single engine heavier boat applications would get the 325's/330's. Exception for race boats turning 7,000-7,500 different story. There are other factors involved absolutely. Supercharged engines will easily sustain a little more runner size also. Best thing to do is trust your builder and make sure he is marine savvy. Back in the late 80's early 90's some of the best engine builders in Michigan anyway made some huge mistakes from cams to heads. They learned in a hurry though drag racing and offshore were two entirely different breeds.
My head guy (valako) is adamant with 320's for my 565 builds. Or has even suggested starting with 310's but would ultimately end near 320 after porting. Engine builders and head guys all have the same goal just some go different routes but ultimately can end up with near same results in the end. Regardless trust your builder and don't go seeking advice from others or you'll be all messed up. Lol... Btw I know I used 572's as example but still believe 345's the way to go. The velocity should be ideal with that runner size and cubic inch.
My head guy (valako) is adamant with 320's for my 565 builds. Or has even suggested starting with 310's but would ultimately end near 320 after porting. Engine builders and head guys all have the same goal just some go different routes but ultimately can end up with near same results in the end. Regardless trust your builder and don't go seeking advice from others or you'll be all messed up. Lol... Btw I know I used 572's as example but still believe 345's the way to go. The velocity should be ideal with that runner size and cubic inch.
Most builders go too conservative IMO. The engine won't be as sensitive to the intake, carb and cam combo when you've got huge velocity from putting average size heads on a huge engine. I'm sure they will run great but you probably left power on the table and they'll be dead after 5500.
