Re: 0 deck, any power to be had?
[Re: mopar dave]
#878659
12/12/10 11:48 PM
12/12/10 11:48 PM
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Joined: Nov 2004
Posts: 4,330 Lynchburg, VA
Leon441
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master
Joined: Nov 2004
Posts: 4,330
Lynchburg, VA
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Sure if you have unburnt fuel due to bad combustion you stand to have predetonation on the next firing cycle. This is a negative force trying to push piston down when momentum is moving the piston up.
This is one of the areas of attack I am doing on a stock build. Not looking for power but wanting fuel economy. Power will just be a bonus.
Leon
Career best 8.02 @ 169 at 3050# and 10" tires small block power.
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Re: 0 deck, any power to be had?
[Re: ahy]
#878663
12/13/10 02:07 AM
12/13/10 02:07 AM
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Joined: Feb 2007
Posts: 5,080 organ
maximum entropy
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master
Joined: Feb 2007
Posts: 5,080
organ
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it is definitely worth it. at the very least, the engine will be less prone to detonation. at best, the engine will be less prone to detonation AND you'll go faster. this assuming that your compression ratio and cam are compatible.
for what is the good life if not doing things thoughtfully?
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Re: 0 deck, any power to be had?
[Re: Baxter61]
#878670
12/15/10 04:54 AM
12/15/10 04:54 AM
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Joined: Oct 2010
Posts: 9 California, USA
Tiger Core
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member
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Posts: 9
California, USA
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Quote:
does anyone know of any tests done to test this theory? just curious because the shape of .020 of bore could affect the flame front differently from seeing that .020 in a head gasket correct? not saying would, just saying could. be an interesting test to see none the less
I've tested this but in a laboratory and not on a Mopar engine or in terms of drag times, unfortunately. It was during engine development for an Jaguar engine. Burn duration is measured in 10-90% burn time. What was found was that when the squish was maintained at 0.9 to 1mm (35 thou to 39 thou) there was a measurable improvement in burn duration of a couple of degrees. This manifested itself as less ignition advance required when optimised for best torque. Once squish clearance increased to 1.2 to 1.3 mm (47 to 51 thou) you ended up with a flame front quench zone which was detrimental to combustion (forming a rich pocket) and in some cases was a source of detonation. Effective squish not only depends on the clearance but also the stroke length/mean piston speed. This means that squish is more effective on longer stroke engines, such as the older Jaguar AJ16 and less effective on the shorter stroke motors such as the Jaguar AJ26 V8. I would venture to say that it becomes more effective once a stroke length of greater than about 90mm is used. In our case our RBs have a healthy stroke of about 95mm as standard
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Re: 0 deck, any power to be had?
[Re: Tiger Core]
#878671
12/15/10 05:18 AM
12/15/10 05:18 AM
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Joined: Nov 2004
Posts: 2,495 Oregon City, OR
Baxter61
top fuel
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top fuel
Joined: Nov 2004
Posts: 2,495
Oregon City, OR
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Quote:
Quote:
does anyone know of any tests done to test this theory? just curious because the shape of .020 of bore could affect the flame front differently from seeing that .020 in a head gasket correct? not saying would, just saying could. be an interesting test to see none the less
I've tested this but in a laboratory and not on a Mopar engine or in terms of drag times, unfortunately. It was during engine development for an Jaguar engine. Burn duration is measured in 10-90% burn time. What was found was that when the squish was maintained at 0.9 to 1mm (35 thou to 39 thou) there was a measurable improvement in burn duration of a couple of degrees. This manifested itself as less ignition advance required when optimised for best torque. Once squish clearance increased to 1.2 to 1.3 mm (47 to 51 thou) you ended up with a flame front quench zone which was detrimental to combustion (forming a rich pocket) and in some cases was a source of detonation. Effective squish not only depends on the clearance but also the stroke length/mean piston speed. This means that squish is more effective on longer stroke engines, such as the older Jaguar AJ16 and less effective on the shorter stroke motors such as the Jaguar AJ26 V8. I would venture to say that it becomes more effective once a stroke length of greater than about 90mm is used. In our case our RBs have a healthy stroke of about 95mm as standard
I wasnt referring to the squish itself but as to were its found. Such as a piston being .020 down in the bore and using a .019 head gasket vs. 0 deck piston and .039 head gasket, all else being equal.
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Re: 0 deck, any power to be had?
[Re: Baxter61]
#878672
12/15/10 05:21 AM
12/15/10 05:21 AM
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Joined: Feb 2003
Posts: 21,318 Manitoba, Canada
DaytonaTurbo
Too Many Posts
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Too Many Posts
Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
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Quote:
I wasnt referring to the squish itself but as to were its found. Such as a piston being .020 down in the bore and using a .019 head gasket vs. 0 deck piston and .039 head gasket, all else being equal.
I've heard of guys doing it both ways and I really don't think you're going to see any measurable difference.
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Re: 0 deck, any power to be had?
[Re: DaytonaTurbo]
#878673
12/15/10 05:36 AM
12/15/10 05:36 AM
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Joined: Nov 2004
Posts: 2,495 Oregon City, OR
Baxter61
top fuel
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top fuel
Joined: Nov 2004
Posts: 2,495
Oregon City, OR
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Quote:
Quote:
I wasnt referring to the squish itself but as to were its found. Such as a piston being .020 down in the bore and using a .019 head gasket vs. 0 deck piston and .039 head gasket, all else being equal.
I've heard of guys doing it both ways and I really don't think you're going to see any measurable difference.
my thoughts also are that theres not much different, just curious if anyone has tested it to find out.
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Re: 0 deck, any power to be had?
[Re: DaytonaTurbo]
#878674
12/15/10 05:38 AM
12/15/10 05:38 AM
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Joined: Jan 2003
Posts: 6,163 Melbourne , Australia
LA360
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master
Joined: Jan 2003
Posts: 6,163
Melbourne , Australia
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On the flip side I recall Jon Kaase running a thick head gasket with the piston crown out of the bore. Some of the engine master contestants have running some pretty tight quench in the past (around 0.030")
Alan Jones
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Re: 0 deck, any power to be had?
[Re: mopar dave]
#878676
12/15/10 12:44 PM
12/15/10 12:44 PM
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Joined: Jan 2006
Posts: 587 IL . usa
cjs69mope
mopar
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mopar
Joined: Jan 2006
Posts: 587
IL . usa
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I Would venture that if the piston comes out of the bore the easier it would be to burn the top ring and also would be hard to run 36 to 38 deg total timing . The thicker the top ring land with cooling groves helps prevent detonation.
1969 Dodge Charger
1969 Dodge Superbee
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