496 Stroker/Dart Pro1 Heads
08-30-2002, 09:00 AM
#12
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Location: Cumming GA
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35L,
We have used that piston a lot and there is plenty of room to machine the dome. They are a good quality part but not as lightweight as the JE race pistons. They use the same forging for several pistons so there is more material under the dome. You can run slightly more compression with the Alum. heads without the detonation problems. I am not sure that I would run the thick gaskets unless there is no other choice. Also something else that we noticed was the combustion chamber size on the dart heads has been larger than stated, they have been consistant at about 120-121cc. I guess this allows for machining the heads prior to assembly which needs to be done to true up the sealing surface. My suggestion would be to use the .039-.041 gasket and machine the pistons.
Todd
We have used that piston a lot and there is plenty of room to machine the dome. They are a good quality part but not as lightweight as the JE race pistons. They use the same forging for several pistons so there is more material under the dome. You can run slightly more compression with the Alum. heads without the detonation problems. I am not sure that I would run the thick gaskets unless there is no other choice. Also something else that we noticed was the combustion chamber size on the dart heads has been larger than stated, they have been consistant at about 120-121cc. I guess this allows for machining the heads prior to assembly which needs to be done to true up the sealing surface. My suggestion would be to use the .039-.041 gasket and machine the pistons.
Todd
08-30-2002, 09:25 AM
#13
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pachangalpina,
What compression ratio can I run with the Dart Pro1 heads
and still run on 93 octaine?
The gas I run is the pollution formulated for Chicagoland.
It seems to make engines run more lean.
I would also preferr to use the .039-.041 head gasket.
Dennis
What compression ratio can I run with the Dart Pro1 heads
and still run on 93 octaine?
The gas I run is the pollution formulated for Chicagoland.
It seems to make engines run more lean.
I would also preferr to use the .039-.041 head gasket.
Dennis
08-30-2002, 10:50 AM
#14
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Just got done building the same motor for a 454 ss truck.
Parts: Stock 454 4 bolt block
Eagle crank & Rods Srp pistons 10.1 to 1
Crane Hyd Roller Cam
Performer Rpm Aire gap Intake
Large Oval Port heads Iron 2.19 , 1.88 vales
Hp 520 with 850cfm carb
Torque 570ft
Motor maxed out at 5400 rpm
Parts: Stock 454 4 bolt block
Eagle crank & Rods Srp pistons 10.1 to 1
Crane Hyd Roller Cam
Performer Rpm Aire gap Intake
Large Oval Port heads Iron 2.19 , 1.88 vales
Hp 520 with 850cfm carb
Torque 570ft
Motor maxed out at 5400 rpm
08-30-2002, 11:34 AM
#15
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35lightning,
It seems that 10.5:1 with alum heads is the max without detonation. I would not recommend going that high but around 10:1 should be safe with the Dart heads. I can not say how the oxogenated fuels perform compared to the 92 here in the South but we have noticed differences on the dyno from brand to brand and from station to station, very minor differences. Do you have a knock sensor on your engine? This is a good way to help protect against det. and also check your total timing. One of the keys to prevent det. is to keep the system cool, boats do this easily because they have an endless supply of cool water, the alum heads help also because they are easier to keep cool. I believe the Merc thundervolt V system has the built in knock system, if not MSD has one for their system that retards the timing when detonation is detected.
It is my opinion that with the mentioned combination that 10.0-10.2:1 will be safe. Hope this helps.
Todd
It seems that 10.5:1 with alum heads is the max without detonation. I would not recommend going that high but around 10:1 should be safe with the Dart heads. I can not say how the oxogenated fuels perform compared to the 92 here in the South but we have noticed differences on the dyno from brand to brand and from station to station, very minor differences. Do you have a knock sensor on your engine? This is a good way to help protect against det. and also check your total timing. One of the keys to prevent det. is to keep the system cool, boats do this easily because they have an endless supply of cool water, the alum heads help also because they are easier to keep cool. I believe the Merc thundervolt V system has the built in knock system, if not MSD has one for their system that retards the timing when detonation is detected.
It is my opinion that with the mentioned combination that 10.0-10.2:1 will be safe. Hope this helps.
Todd
08-30-2002, 04:25 PM
#16
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If the combustion chambers are polished it will also allow a little more compression before detonation. I have seen a few guys run 92 octane with 10.5 compression in boats with no probs, but they are running larger than recommended cams to bleed down some cyl. pressure. Their motors/boats still run very fast regardless of the larger cam. To small of cam will work the other way and raise cyl. pressures which will lead to earlier detonation. I just run 110 octane and forget about it. $3.00/gal.
The power is worth it I guess.
The power is worth it I guess.
08-30-2002, 06:06 PM
#17
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Wette Vette,
I'm no engine expert---I just talk like one!
Anyway, you might be okay with 325cc heads while utilizing a mechanical solid roller cam in a 496. But, if it were me I would have chosen the Dart 310cc head or even (from what I have heard) a Brodix 300cc head. From what what I read/learned and experienced that a marine engine runs better with high velocity air/fuel charges. Anything too large will not be as responsive as it could be with the right head/intake runner size BESIDES idle quality will suffer and have poor drivability at the docks. It's not how fast you go---it's how fast you get there.
On another thread "36spectre" said it well when he stated that when you're in a match with another boat, the outcome is usually decided within roughly 10 seconds. How true it is, as I have seen that formula unfold many times over several years with guys and their boats.
Docker Dave, sure---be glad to help a boater in need of horsepower.
BTW guys, I've seen Doctor Dave build some nice stuff for some guys and their boats that I know of and they're happy with the work he has done. He lives within 15 miles of Wolff's shop.
I'm no engine expert---I just talk like one!
Anyway, you might be okay with 325cc heads while utilizing a mechanical solid roller cam in a 496. But, if it were me I would have chosen the Dart 310cc head or even (from what I have heard) a Brodix 300cc head. From what what I read/learned and experienced that a marine engine runs better with high velocity air/fuel charges. Anything too large will not be as responsive as it could be with the right head/intake runner size BESIDES idle quality will suffer and have poor drivability at the docks. It's not how fast you go---it's how fast you get there. On another thread "36spectre" said it well when he stated that when you're in a match with another boat, the outcome is usually decided within roughly 10 seconds. How true it is, as I have seen that formula unfold many times over several years with guys and their boats.
Docker Dave, sure---be glad to help a boater in need of horsepower.
BTW guys, I've seen Doctor Dave build some nice stuff for some guys and their boats that I know of and they're happy with the work he has done. He lives within 15 miles of Wolff's shop.
08-30-2002, 09:33 PM
#19
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Cool, hopefully we can get some of these guys over to Hardy next weekend and we can let them rip. Will you be ready by then KAAMA? If not bring your boat over just so we can check it out. I know you have been working all summer long and it would be cool to see it run for the first time next week. I will be helping JDNCA1 install his fresh 632 this weekend so the WETTE VETTE will be parked and we will be ready to run next week. JDNCA1 put a box on and just had his motor dynoed at 850 plus hp so we are hoping for some big radar numbers when we are done. I actually agree with you KAAMA on the port volumes not needing to be very large to support good HP, as long as they are ported properly.
Will you be ready by then KAAMA? If not bring your boat over just so we can check it out. I know you have been working all summer long and it would be cool to see it run for the first time next week. I will be helping JDNCA1 install his fresh 632 this weekend so the WETTE VETTE will be parked and we will be ready to run next week. JDNCA1 put a box on and just had his motor dynoed at 850 plus hp so we are hoping for some big radar numbers when we are done. I actually agree with you KAAMA on the port volumes not needing to be very large to support good HP, as long as they are ported properly.
08-31-2002, 12:47 PM
#20
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Hopefully my boat will be ready for running by next weekend for the Hot Boat weekend at Hardy Dam. If not I may still bring it up (by popular demand---Wette Vette) and hang out for a while and meet some of you guys.
How about you Doctor Dave? You need to bring that 35' Cig and show them what big cubed blower motors sound like with 5" DRY tailpipes!!! They end up having ALL KINDS of wild hardware up there. Plus I know you'd like it.
How about you Doctor Dave? You need to bring that 35' Cig and show them what big cubed blower motors sound like with 5" DRY tailpipes!!!
They end up having ALL KINDS of wild hardware up there. Plus I know you'd like it.
