Moparts
0 deck, any power to be had?
Posted By: mopar dave
0 deck, any power to be had? - 12/13/10 03:32 AM
i understand 0 deck gives good quench and more compression,but would their be any power loss just by having piston in the hole vs 0 deck with same compression and quench?
Posted By: Leon441
Re: 0 deck, any power to be had? - 12/13/10 03:48 AM
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
Posted By: dOc !
Re: 0 deck, any power to be had? - 12/13/10 03:51 AM
ZERO deck with what type of head ? .... closed or OPEN chamber ??
Posted By: mopar dave
Re: 0 deck, any power to be had? - 12/13/10 04:00 AM
closed. just curious of any power loss with piston in the hole. thanks
Posted By: ahy
Re: 0 deck, any power to be had? - 12/13/10 04:05 AM
I believe the main benefit of "zero deck" is to help achieve effective quench meaning about .040" clearnace between a good sized area of the piston and head - this with a closed chamber head. A similar result could be achieved with a FT piston below deck and a thin head gasket or with a piston below deck with quench dome.
Its just easiest - $ and hours of labor - to do well with a zero deck piston, closed chamber head and .040 head gasket.
Posted By: maximum entropy
Re: 0 deck, any power to be had? - 12/13/10 06:07 AM
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.
Posted By: Sport440
Re: 0 deck, any power to be had? - 12/13/10 07:07 AM
Quote:
I believe the main benefit of "zero deck" is to help achieve effective quench meaning about .040" clearnace between a good sized area of the piston and head - this with a closed chamber head. A similar result could be achieved with a FT piston below deck and a thin head gasket or with a piston below deck with quench dome.
Its just easiest - $ and hours of labor - to do well with a zero deck piston, closed chamber head and .040 head gasket.
It does make quench the easiest to obtain with most standard gaskets that fall around the .040 range. A Piston .020 in the hole with a .020 gasket will net the same result.
Also with Zero deck you may not need any Dome to acheive your "desired" compression. Flat tops have a slight advantage over domed pistons because of the easier/faster flame travel. IMO mike
Posted By: Mike Swann
Re: 0 deck, any power to be had? - 12/13/10 01:59 PM
Quote:
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
Backing Leon up, eliminate the valve pockets too if you don't need them.
Posted By: mopar dave
Re: 0 deck, any power to be had? - 12/14/10 04:17 AM
thanks for the opinions guys. now i know.
Posted By: Baxter61
Re: 0 deck, any power to be had? - 12/14/10 04:39 AM
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
Posted By: ahy
Re: 0 deck, any power to be had? - 12/15/10 04:03 AM
I haven't seen any test results but I'd confidently predict that on a typical street/strip engine at around 1 HP/cu in the difference would be too small to measure.
On a more extreme combo like a "super stock" Hemi at 2 HP/cu in, or NACSAR, or F1 it could make a noticible or critical difference.
Posted By: goldmember
Re: 0 deck, any power to be had? - 12/15/10 05:22 AM
If your set on running on the ragged edge of the fuel you'll buy go for tight quench. I'll buy better fuel and quit the BS. Power adder combo's,I'd skip quench and not look back.
Posted By: Tiger Core
Re: 0 deck, any power to be had? - 12/15/10 08:54 AM
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
Posted By: Baxter61
Re: 0 deck, any power to be had? - 12/15/10 09:18 AM
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.
Posted By: DaytonaTurbo
Re: 0 deck, any power to be had? - 12/15/10 09:21 AM
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.
Posted By: Baxter61
Re: 0 deck, any power to be had? - 12/15/10 09:36 AM
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.
Posted By: LA360
Re: 0 deck, any power to be had? - 12/15/10 09:38 AM
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")
Posted By: mopar dave
Re: 0 deck, any power to be had? - 12/15/10 03:27 PM
yeah, is there any harm or power loss with the piston above the deck?
Posted By: cjs69mope
Re: 0 deck, any power to be had? - 12/15/10 04:44 PM
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.
Posted By: Tiger Core
Re: 0 deck, any power to be had? - 12/16/10 01:38 AM
The 1996 to 1998 Porsche 911 (993) Turbo piston protrudes 5mm above the deck BY DESIGN at TDC.
This engine makes about 450 Bhp and 420 lb ft of torque from a 3.6 litre capacity. The Chamber design isn't disimilar to a Gen 2 Hemi (with some refinements).
This is done in order to reduce peak cylinder pressure load on the cylinder head gasket just after TDC.
Posted By: 602heavy
Re: 0 deck, any power to be had? - 12/16/10 02:18 AM
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.
Posted By: Tiger Core
Re: 0 deck, any power to be had? - 12/17/10 05:51 AM
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
Posted By: dvw
Re: 0 deck, any power to be had? - 12/18/10 02:05 AM
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
Posted By: Sport440
Re: 0 deck, any power to be had? - 12/18/10 02:26 AM
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? 
Posted By: moper
Re: 0 deck, any power to be had? - 12/18/10 03:11 AM
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.
Posted By: emarine01
Re: 0 deck, any power to be had? - 12/18/10 04:07 AM
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
Posted By: moper
Re: 0 deck, any power to be had? - 12/18/10 06:00 PM
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.
Posted By: 602heavy
Re: 0 deck, any power to be had? - 12/19/10 01:26 AM
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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' 
Posted By: Tiger Core
Re: 0 deck, any power to be had? - 12/19/10 02:11 AM
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 
