How many hours on bigger power stuff?
10-17-2015, 08:55 AM
#31
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iTrader: (1)
Piston top designs vary greatly between high compression and 'boosted' lower compression motors, especially an engine that has a large combustion chamber. Think BBC and even worse Hemi.
You are lighting the fire before a piston comes up to tdc, and the closer the piston top comes to the top, these big domes can create some bad issues including, creating partial and then multiple combustion areas, places for fuel to hide, and etc, etc. Dome designs today are far better for making power by addressing these concerns, but will still have flame propagation and combustion issues compared to a flat top or dish.
Oh, one last other issue with N/A especially domes/large domes is during tdc in overlap, it can block the exhaust valve from the intake, cutting down on the time and quality of 'pull' your exhaust can help the intake.
So again, less dome/lack of dome/etc helps alleviate many issues for many different motor designs. However, you need compression for power.
You are lighting the fire before a piston comes up to tdc, and the closer the piston top comes to the top, these big domes can create some bad issues including, creating partial and then multiple combustion areas, places for fuel to hide, and etc, etc. Dome designs today are far better for making power by addressing these concerns, but will still have flame propagation and combustion issues compared to a flat top or dish.
Oh, one last other issue with N/A especially domes/large domes is during tdc in overlap, it can block the exhaust valve from the intake, cutting down on the time and quality of 'pull' your exhaust can help the intake.
So again, less dome/lack of dome/etc helps alleviate many issues for many different motor designs. However, you need compression for power.
10-17-2015, 09:02 AM
#32
Registered
nice pics,,I like how theres nothing coming out of the breathers,,good to see someone can plumb a dry sump oiling system.
10-17-2015, 09:33 AM
#34
Registered
10-17-2015, 11:27 AM
#35
Looking at all the bigger marine builders it seems the trend is more cubes. I would imagine a 572ci@6# would possibly live longer than a 540@8psi and they both be close in power?
It`s time for my rebuilds, I`m trying to decide which route would be best bang for the buck. New pistons and rods are in my future probably anyway so what do you do on a 540 bow tie block?
I`d like to go bigger cubes and less boost. 565ci. keep the 4.250 crank or 572ci. New crank?
Sell my stuff buy Dart M block ( i don`t think the budget is there for that unless my math is wrong)
Never been down this road any advice is appreciated
It`s time for my rebuilds, I`m trying to decide which route would be best bang for the buck. New pistons and rods are in my future probably anyway so what do you do on a 540 bow tie block?
I`d like to go bigger cubes and less boost. 565ci. keep the 4.250 crank or 572ci. New crank?
Sell my stuff buy Dart M block ( i don`t think the budget is there for that unless my math is wrong)
Never been down this road any advice is appreciated
10-17-2015, 07:45 PM
#36
Looking at all the bigger marine builders it seems the trend is more cubes. I would imagine a 572ci@6# would possibly live longer than a 540@8psi and they both be close in power?
It`s time for my rebuilds, I`m trying to decide which route would be best bang for the buck. New pistons and rods are in my future probably anyway so what do you do on a 540 bow tie block?
I`d like to go bigger cubes and less boost. 565ci. keep the 4.250 crank or 572ci. New crank?
Sell my stuff buy Dart M block ( i don`t think the budget is there for that unless my math is wrong)
Never been down this road any advice is appreciated
It`s time for my rebuilds, I`m trying to decide which route would be best bang for the buck. New pistons and rods are in my future probably anyway so what do you do on a 540 bow tie block?
I`d like to go bigger cubes and less boost. 565ci. keep the 4.250 crank or 572ci. New crank?
Sell my stuff buy Dart M block ( i don`t think the budget is there for that unless my math is wrong)
Never been down this road any advice is appreciated
10-17-2015, 07:57 PM
#37
Compression test done on port engine today.
#1=150psi #2=155psi
#3=147psi #4=152psi
#5=145psi #6=150psi
#7=155psi #8=152psi
Did leakdown test. Particular leakdown tester showed 15-20% leakage on all cylinders. Not sure on the accuracy of this particular Napa tester. First gauge on leakdown tester, was set/regulated to 100psi. When hooked to cylinder, leakage would show 20%. But gauge would drop from 100, to 90psi. My old leakdown tester had two psi gauges. If you set it to 100psi on first gauge, and second gauge read 90psi, you had 10% leakdown, if second gauge read 80psi, you had 20% leakdown. I may get a new tester, and retest.
However, no leakage at all at the valves. Any leakage was past rings. Looking into cylinders with borescope, crosshatch pattern on cylinder walls, looks like the day they were honed.
PS, Matt, Dan/icdedppl's Intake air temps, are like 150ish WOT full boost if I recall.
#1=150psi #2=155psi
#3=147psi #4=152psi
#5=145psi #6=150psi
#7=155psi #8=152psi
Did leakdown test. Particular leakdown tester showed 15-20% leakage on all cylinders. Not sure on the accuracy of this particular Napa tester. First gauge on leakdown tester, was set/regulated to 100psi. When hooked to cylinder, leakage would show 20%. But gauge would drop from 100, to 90psi. My old leakdown tester had two psi gauges. If you set it to 100psi on first gauge, and second gauge read 90psi, you had 10% leakdown, if second gauge read 80psi, you had 20% leakdown. I may get a new tester, and retest.
However, no leakage at all at the valves. Any leakage was past rings. Looking into cylinders with borescope, crosshatch pattern on cylinder walls, looks like the day they were honed.
PS, Matt, Dan/icdedppl's Intake air temps, are like 150ish WOT full boost if I recall.
