|
Re: 0 deck, any power to be had?
[Re: mopar dave]
#878659
12/12/10 11:48 PM
12/12/10 11:48 PM
|
Joined: Nov 2004
Posts: 4,330
Lynchburg, VA
Leon441
master
|
master
Joined: Nov 2004
Posts: 4,330
Lynchburg, VA
|
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.
|
|
|
Re: 0 deck, any power to be had?
[Re: ahy]
#878663
12/13/10 02:07 AM
12/13/10 02:07 AM
|
Joined: Feb 2007
Posts: 5,080
organ
maximum entropy
master
|
master
Joined: Feb 2007
Posts: 5,080
organ
|
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?
|
|
|
Re: 0 deck, any power to be had?
[Re: Baxter61]
#878670
12/15/10 04:54 AM
12/15/10 04:54 AM
|
Joined: Oct 2010
Posts: 9
California, USA
Tiger Core
member
|
member
Joined: Oct 2010
Posts: 9
California, USA
|
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
|
|
|
Re: 0 deck, any power to be had?
[Re: Tiger Core]
#878671
12/15/10 05:18 AM
12/15/10 05:18 AM
|
Joined: Nov 2004
Posts: 2,495
Oregon City, OR
Baxter61
top fuel
|
top fuel
Joined: Nov 2004
Posts: 2,495
Oregon City, OR
|
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.
|
|
|
Re: 0 deck, any power to be had?
[Re: Baxter61]
#878672
12/15/10 05:21 AM
12/15/10 05:21 AM
|
Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
DaytonaTurbo
Too Many Posts
|
Too Many Posts
Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
|
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.
|
|
|
Re: 0 deck, any power to be had?
[Re: DaytonaTurbo]
#878673
12/15/10 05:36 AM
12/15/10 05:36 AM
|
Joined: Nov 2004
Posts: 2,495
Oregon City, OR
Baxter61
top fuel
|
top fuel
Joined: Nov 2004
Posts: 2,495
Oregon City, OR
|
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.
|
|
|
Re: 0 deck, any power to be had?
[Re: DaytonaTurbo]
#878674
12/15/10 05:38 AM
12/15/10 05:38 AM
|
Joined: Jan 2003
Posts: 6,137
Melbourne , Australia
LA360
master
|
master
Joined: Jan 2003
Posts: 6,137
Melbourne , Australia
|
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
|
|
|
Re: 0 deck, any power to be had?
[Re: mopar dave]
#878676
12/15/10 12:44 PM
12/15/10 12:44 PM
|
Joined: Jan 2006
Posts: 587
IL . usa
cjs69mope
mopar
|
mopar
Joined: Jan 2006
Posts: 587
IL . usa
|
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
|
|
|
Re: 0 deck, any power to be had?
[Re: Tiger Core]
#878678
12/15/10 10:18 PM
12/15/10 10:18 PM
|
Joined: Dec 2008
Posts: 1,200
UK
602heavy
pro stock
|
pro stock
Joined: Dec 2008
Posts: 1,200
UK
|
Thanks for posting Tiger , some interesting reading there. Can you explain some more regards piston 5mm above deck & effect on head gasket? , are you saying the piston acts as a shroud of some sort? Thanks again. 
Last edited by 602heavy; 12/15/10 10:27 PM.
|
|
|
Re: 0 deck, any power to be had?
[Re: 602heavy]
#878679
12/17/10 01:51 AM
12/17/10 01:51 AM
|
Joined: Oct 2010
Posts: 9
California, USA
Tiger Core
member
|
member
Joined: Oct 2010
Posts: 9
California, USA
|
Quote:
Thanks for posting Tiger , some interesting reading there.
Can you explain some more regards piston 5mm above deck & effect on head gasket? , are you saying the piston acts as a shroud of some sort?
Thanks again.
Hello fellow Brit!
To reduce the strain on the cylinder head gasket the pistons intrude by about 5mm into the head, so as to cover the gasket area at top dead centre where pressure and temperature are highest. The gasket is made of a spring steel recessed in a groove in the upper flange of the cylinder. The head is machined accordingly
|
|
|
Re: 0 deck, any power to be had?
[Re: dvw]
#878681
12/17/10 10:26 PM
12/17/10 10:26 PM
|
Joined: Jan 2003
Posts: 6,591
Canton, Ohio
Sport440
master
|
master
Joined: Jan 2003
Posts: 6,591
Canton, Ohio
|
Quote:
OK lets add this question. Aluminum rods need more piston to head. This has been discussed before. It varies with the type of rod,weight ,RPM,etc. Lets say the combo requires .060" piston to head. How much quench distance is there while the engine is running? If the piston touches the head at .057" do I have effective quench?
Doug
Absolutely, Why wouldnt it? 
|
|
|
Re: 0 deck, any power to be had?
[Re: Sport440]
#878682
12/17/10 11:11 PM
12/17/10 11:11 PM
|
Joined: Feb 2003
Posts: 12,675
Columbia, CT
moper
I Live Here
|
I Live Here
Joined: Feb 2003
Posts: 12,675
Columbia, CT
|
Another source of miniscule power "loss" would be the dead space above the top ring. With a piaton below deck, the ring is down further in the bore (assuming identical ring placement on the two comparable engines' pistons) and that will allow air/fuel to be trapped there and not burn. I routinely run pistons at .005" above deck, mainly because I want .030-.035" quench distance with the Felpro .039 gaskets. You also want to minimize the chamfer on the top of the bore as this too can work as "dead volume".
On the aluminum option, you have to maintain some distance between the piston and head, but some of the fastest engines I know of just touch at very high rpms. Just enough to leave a mark. The less "dead space" you have in the chamber the more mixture gets burnt completely and more power is realized.
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
|
|
|
Re: 0 deck, any power to be had?
[Re: Sport440]
#878683
12/18/10 12:07 AM
12/18/10 12:07 AM
|
Joined: Jan 2007
Posts: 3,695
nc
emarine01
master
|
master
Joined: Jan 2007
Posts: 3,695
nc
|
Quote:
Quote:
OK lets add this question. Aluminum rods need more piston to head. This has been discussed before. It varies with the type of rod,weight ,RPM,etc. Lets say the combo requires .060" piston to head. How much quench distance is there while the engine is running? If the piston touches the head at .057" do I have effective quench?
Doug
Absolutely, Why wouldnt it?
Heat soak with alu rods before you make a pass and the quench should be close to a steel rod engine, most alu rods need hot oil before you load them up anyway
|
|
|
Re: 0 deck, any power to be had?
[Re: emarine01]
#878684
12/18/10 02:00 PM
12/18/10 02:00 PM
|
Joined: Feb 2003
Posts: 12,675
Columbia, CT
moper
I Live Here
|
I Live Here
Joined: Feb 2003
Posts: 12,675
Columbia, CT
|
I'm not way into aluminum rods but from what I know they are very elastic and they will stretch as the piston changes direction at TDC.. They do grow in length (and in term compress) while running hard even after reaching operating temp. The temp thing is more about stabilizing the oil temp and it's ability to do it's job.
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
|
|
|
Re: 0 deck, any power to be had?
[Re: Tiger Core]
#878685
12/18/10 09:26 PM
12/18/10 09:26 PM
|
Joined: Dec 2008
Posts: 1,200
UK
602heavy
pro stock
|
pro stock
Joined: Dec 2008
Posts: 1,200
UK
|
|
|
|
Re: 0 deck, any power to be had?
[Re: 602heavy]
#878686
12/18/10 10:11 PM
12/18/10 10:11 PM
|
Joined: Oct 2010
Posts: 9
California, USA
Tiger Core
member
|
member
Joined: Oct 2010
Posts: 9
California, USA
|
Quote:
Quote:
Quote:
Thanks for posting Tiger , some interesting reading there.
Can you explain some more regards piston 5mm above deck & effect on head gasket? , are you saying the piston acts as a shroud of some sort?
Thanks again.
Hello fellow Brit!
To reduce the strain on the cylinder head gasket the pistons intrude by about 5mm into the head, so as to cover the gasket area at top dead centre where pressure and temperature are highest. The gasket is made of a spring steel recessed in a groove in the upper flange of the cylinder. The head is machined accordingly
Thanks.
Some guys on here would'nt have bothered answering seeing as i come from little ole UK.  , or they got us on 'ignore this user' 
I wouldn't worry too much. Most Americans treat Brits extra special- specially the ladies. Those blokes that don't  are usually bitter that we're nicking all their women and I'm ok with that  
|
|
|
|
|
