The quest for quench

[octanejunkie]

In conversation with Dave (dgc333) the subject of quench came up and a discussion ensued, of course more research was required on my part, and I found this article. Anyone not familiar with what quench is please read the article I linked to. But reading the article and getting a general idea of what qunech is does not end my quest...

It seems apparent that quench, or squish, is yet another variable to consider or manipulate when designing an engine build, but it is NOT related to any one specific compression ratio as much as it does to ONE specific dimension, the space above the flat surface of the piston and the roof of the cylinder head, if I understand it correctly.

Though higher compression ratios are more prone to detonation than lower under corresponding circumstances, the ability to reach an optimal quench will bring us to higher compression ratios. Obviously though, to achieve the optimal quench range of .040 - .050 the compression ratio will be quite close to 10:1, as my calculations have proven, but sometimes higher or lower depending on the piston profile, volume, etc.

A few thoughts and questions:
The obviously easy way to set your quench is to zero deck your block/pistons and use a .040" head gasket. But it seems to me you can have the optimal quench setup as well with your pistons in the hole a bit too; for example: with a deck height of .035" (pistons in the hole .030) you can use a .015" compressed thickness head gasket and get a .045" quench - yes?

In the real world, even a zero decked block may not guarantee ALL pistons at zero deck height, rod and piston variations may push a piston above the deck or allow it to sit below, not accounting for rod stretch during operation at higher RPM. So the next question is, when choosing a head gasket thickness to tune your quench, do you go by the deepest deck clearance value, the shallowest or the average deck height?

Here is a real-world example, my SBC 357ci. Deck heights when assembled were as follows:

Cyl 1 - .028
Cyl 2 - .032
Cyl 3 - .025
Cyl 4 - .027
Cyl 5 - .030
Cyl 6 - .030
Cyl 7 - .024
Cyl 8 - .025
​

Average deck height .027625"

Using my average DH of .027625 the deck volume of all 8 cylinders is only .354ci, but is an average value accurate enough?

Using a standard .040" (compressed thickness) head gasket, my quench distance, using my average deck height, would be .067625, not within the quench sweet spot, and my compression ratio is 9.354 SCR and 8.531 DCR. But switching to a .015" head gasket would net me a .042625" quench distance, well within the desired range, and my compression would jump to 9.904 SCR and 9.026 DCR.

Using the example of my chevy engine, which is not entirely ping resistant, am I better off with a lower DCR or an optimal quench - if I were looking to optimize combustion and power production and eliminate the possibility of detonation?

I have two more engine build projects in the works, one for my Scamp and one for my buddy's Mustang, so mastering this concept is of valuable significance to me. Looking forward to input and discussion on the subject.

 

[rumblefish360]

WOW! You ARE getting this real good. Congrads! I don't have alot of time to this post/here now today, but I'll run over somethings.

In the real world, even a zero decked block may not guarantee ALL pistons at zero deck height, rod and piston variations may push a piston above the deck or allow it to sit below, not accounting for rod stretch during operation at higher RPM.

Since everything in the engine has a measurement as put forth by the factory, the diamentions computed for a zero deck height between the crank rod and piston height vs. the deck height should be considered and worked out by the machinest and met as a final assembly.

Variations in rod length should be corrected by the machinest or through new rods and double checked. Crank throws should be double checked by the machinest. It's called crank indexing. Making sure each throw is exactly what it should be. A 340 crank is a 3.31 throw and each and every part of that crank must meet that spec or be machined to correct it. Each piston should also be looked at in this fashion.

Once the crank, rods and pistons diamentions are exactly known and corrected if need be, it's off to the block, which will be measure against the factorys diamentions to see where it is exactly. Factory deck height is generaly stated here as 9.6. That is a general statement that is not allways found in real life.

MoPer has found various deck heights and that a KB 107 in a 360 may very well be below deck while I have had the good luck of the piston being at zero deck.

These block variations will need to be corrected and once done, with the thought of setting the piston at a zero deck height should be met. This problem of figureing everything out is the machinest's chore.


On rod strech, each metal has a known amount of strech. Within reason of course. Some will strech more than others depending on material (Metal) used to make the rod and also under load/rpm, the amounts will vari to a slight degree and are known by the manufacture and compotent shops.

Since rod strech is a item most look past or don't worry about due to a mild build/ low compresion build/ample head cc and flat tops etc.... There should not be a big issue in head gasket selection.

Once you go into a domed piston or a closed chamber and a zero deck flat top slug, you may really want to know what you have and how it reacts under load/stress/rpm/life expectancy.

As a general set up with a zero deck piston and a closed chambered head, you may have seen me recomend a .039 Fel-Pro gasket. Mostly since they are very easy to get. Though maybe not the greatest once to use depending on how my sci. and exactness your looking for. But the head gasket will pass for 90% of street builds with flying colors.

Once you get into dome pistons with open chamberd heads, you have alot of work infront of you in figureing things out. I don't go this route in street builds. The extra work is not allways worth it on the street but will pay dividens on the track.


A quick word on the pinging issue, at 10-1 and a sizeable cam, medium size, nothing to big, 93 should be fine. A smaller cam will not be, like a 216* may very well ping bad. Increase the compresion to say, 11.5-1 and that Med. size cam will ping like the smaller one and then that 93 will be no good and race gas must be sought. OR, get a bigger cam. It's a catch 22 and such. Sometimes, you can dial the timing down for it to run. IF you do that, you just lost more power than if you ran a lower compresion ratio.'

This is also a good topic racers cover. For a street car, a tad less is better than a bit to much if the timing has to be dialed back to run.

I'll be back later. Gotta run.

 

[Brian Hafliger]

In conversation with Dave (dgc333) the subject of quench came up and a discussion ensued, of course more research was required on my part, and I found this article. Anyone not familiar with what quench is please read the article I linked to. But reading the article and getting a general idea of what qunech is does not end my quest...

It seems apparent that quench, or squish, is yet another variable to consider or manipulate when designing an engine build, but it is NOT related to any one specific compression ratio as much as it does to ONE specific dimension, the space above the flat surface of the piston and the roof of the cylinder head, if I understand it correctly.

Though higher compression ratios are more prone to detonation than lower under corresponding circumstances, the ability to reach an optimal quench will bring us to higher compression ratios. Obviously though, to achieve the optimal quench range of .040 - .050 the compression ratio will be quite close to 10:1, as my calculations have proven, but sometimes higher or lower depending on the piston profile, volume, etc.

A few thoughts and questions:
The obviously easy way to set your quench is to zero deck your block/pistons and use a .040" head gasket. But it seems to me you can have the optimal quench setup as well with your pistons in the hole a bit too; for example: with a deck height of .035" (pistons in the hole .030) you can use a .015" compressed thickness head gasket and get a .045" quench - yes?

In the real world, even a zero decked block may not guarantee ALL pistons at zero deck height, rod and piston variations may push a piston above the deck or allow it to sit below, not accounting for rod stretch during operation at higher RPM. So the next question is, when choosing a head gasket thickness to tune your quench, do you go by the deepest deck clearance value, the shallowest or the average deck height?

Here is a real-world example, my SBC 357ci. Deck heights when assembled were as follows:

Cyl 1 - .028
Cyl 2 - .032
Cyl 3 - .025
Cyl 4 - .027
Cyl 5 - .030
Cyl 6 - .030
Cyl 7 - .024
Cyl 8 - .025
​

Average deck height .027625"

Using my average DH of .027625 the deck volume of all 8 cylinders is only .354ci, but is an average value accurate enough?

Using a standard .040" (compressed thickness) head gasket, my quench distance, using my average deck height, would be .067625, not within the quench sweet spot, and my compression ratio is 9.354 DCR and 8.531 SCR. But switching to a .015" head gasket would net me a .042625" quench distance, well within the desired range, and my compression would jump to 9.904 DCR and 9.026 SCR.

Using the example of my chevy engine, which is not entirely ping resistant, am I better off with a lower SCR or an optimal quench - if I were looking to optimize combustion and power production and eliminate the possibility of detonation?

I have two more engine build projects in the works, one for my Scamp and one for my buddy's Mustang, so mastering this concept is of valuable significance to me. Looking forward to input and discussion on the subject.

No matter how you do it, getting the piston to head clearance between .035 and .050 will give you effective quench.
If I were you I would use a shim gasket on that chevy and take advantage of the quench and compression increase. Your still safe for pump gas, you'll increace engine efficiency, fuel mileage, and power by doing this. How much just depends on the engine's power level but we've noticed differences with as little as 350HP engines.
You want to make sure you don't get the piston to head clearance below .035 unless it's specifically built that way (meaning good rods, crank, block, pistons, and rpm limited).
Brian

 

[rumblefish360]

Good mention Brian. I was a bit short on time and tried to make the post quick but complete in the short time.

Con Rod material will strech at different rates/distances. Like it's said above, the engine must be built with very certain parts to get a quench area very low.

You really do not want to go more than a .050 amount or the quench effect goes away.

 

[octanejunkie]

In the example of my SBC 357ci, my tallest piston deck height is #7, which is only .024" in the hole, this is obviously the tightest of all the piston measurements and the critical dimension to be concerned with in regards to piston/cyl head collision.

So to that effect, if I put a .015" compressed thickness gasket on the chevy here is how the "quench dimension" would net out on all 8 cylinders

Cyl 1 - .028 + .015 = .043
Cyl 2 - .032 + .015 = .047
Cyl 3 - .025 + .015 = .040
Cyl 4 - .027 + .015 = .042
Cyl 5 - .030 + .015 = .045
Cyl 6 - .030 + .015 = .045
Cyl 7 - .024 + .015 = .039
Cyl 8 - .025 + .015 = .040​

A little random I'll agree, but all still within the target range. Considering when I built this engine I was advised by most folks "just throw a standard gasket on it and call it good," which is not bad advice for most daily drivers, but I want to optimize as much as I can control - truthfully I did not know then what I know now, and deck height was just a mundane variable to me then; but my next engine will be better... Non withstanding that statement, I am not racing or building engines as a career so when is good enough just that, good enough? I guess when I the builder, the machinist and the bean counter say so.

Now I have posted the same thread on other forums and have gotten some interesting comments, one fella said

Quench is independent of CR- ANY CR can be achieved w/any quench measurement-within the parameters of the engine's internal parts- be it good or bad.
What I'm saying is, you can have an 'ideal' quench of 0.040" and have a CR of 6:1. Or 15:1. Just as you can have a quench of 0.125" w/a CR of 10:1.

I'm honestly having trouble getting my pea-brain around this statement, but I guess if you have a super short stroke engine or a ton of overlap and don't start building compression till the piston is well on it's way back up the bore you can have 6:1 CR with .040" quench, which begs me to ponder this thought: If you can set the ideal quench on ANY engine and optimize the mixture/flame front you can maximize the power output regardless of CR, but ultimately the CR is the deciding factor on how much power per stroke the engine will produce if the right fuel and fuel/air mixture is introduced into the cylinder (assuming all other variables like spark, timing, etc are correct.)

And if that thought is correct then it stands to reason that there is ONE perfect combination per engine type and purpose. Understand that I am not naive enough to think there is only one engine we should all be building, there are dozens, if not hundreds, of specialty-built engines out there, I know that; but for most guys driving 100% on the streets this should really be more cut and dried. Am I oversimplifying this? Or are manufacturing tolerances and the myriad of quality level parts out there just wildcarding this process to the shameful reality of most folks having to build safe, mediocre performing engines in the interests of budget and "good enough?"

I might actually be "getting it" after all

 

[Brian Hafliger]

As long as the chamber in the head is of the closed type, and the piston has a flat part where the piston and head will meet, you can attain quench. It's just the close collision between the flat part of the piston and flat part of the chamber.
And yes quench can be had with any compression, they are 2 seperate things.
Go to www.kb-silvolite.com and search on there. They talk about it I believe...

 

[Stormy69]

i think you are over complicating it. you have a grasp of the basics but are trying to make them co-dependent. separate them from each other and you will get it, cr can be changed by combustion chamber size as well as piston dish or dome. best practices these days with pistons are to mirror combustion chambers into the piston dish (if so equipped) thus maximizing quench and dialing your compression in at the same time. as you are seeing, it can get expensive as many custom parts or machine work can be needed....

 

[rumblefish360]

I agree with stormy. You can have a piston (picture this if you can) where one half is a flat top, the other half is a dish .090 deep.

The flat part can meet the bottom of... lets say, an Edlebrock head since it's a closed chamber.

That deep dish isn't doing anything for compresion.

Now raise up the dish part to equal the flat on the otherside. Now, the ratio just jumped to 10-1 plus. The quench didn't change but due to the piston being flat across, the ratio jumped since theres less room in the head now while the piston is @ TDC.

The same idea can be used on the head.
The same idea can be used with the piston and head as described first.

 

[Guitar Jones]

You want to make sure you don't get the piston to head clearance below .035 unless it's specifically built that way (meaning good rods, crank, block, pistons, and rpm limited).
Brian

You can get tighter, my engine has .028 piston to head. It's nothing special, stock rods, stock crank and hyper pistons. I twist it to 7200 regularly but it has been as high as 7800. I didn't do this on purpose, it's how the short block came and the only readily available gaskets were the .0385 FelPros. It works but maybe a little more clearance would work better, I don't know. I used .038 on the 340. I've been told by an accomplished race engine builder that you can go as little as .025 with a steel connecting rod, I think I'm close enough though. I was already cringing when I first fired it up and still was prepared for the worst on it's first burn out and full pass but it's made many, many runs since then without a problem. lol

 

[Brian Hafliger]

You can get tighter, my engine has .028 piston to head. It's nothing special, stock rods, stock crank and hyper pistons. I twist it to 7200 regularly but it has been as high as 7800. I didn't do this on purpose, it's how the short block came and the only readily available gaskets were the .0385 FelPros. It works but maybe a little more clearance would work better, I don't know. I used .038 on the 340. I've been told by an accomplished race engine builder that you can go as little as .025 with a steel connecting rod, I think I'm close enough though. I was already cringing when I first fired it up and still was prepared for the worst on it's first burn out and full pass but it's made many, many runs since then without a problem. lol

When you take that engine apart, look for ghost tracks either on the head or piston or both...you may be surprised!

 

[375inStroke]

I think you're confused because what affects quench does affect compression ratio, but one doesn't lock in the other. With a given quench, combustion chamber size or piston dome or dish can be altered or selected to give you your desired compression ratio. I think any increased tendency for detonation due to an increase in compression ratio from a thinner head gasket is more than offset by having the proper quench dimension.

 

[octanejunkie]

[FONT=Verdana, Helvetica, Arial]

As long as the chamber in the head is of the closed type, and the piston has a flat part where the piston and head will meet, you can attain quench. It's just the close collision between the flat part of the piston and flat part of the chamber.
And yes quench can be had with any compression, they are 2 seperate things.
Go to www.kb-silvolite.com <http://www.kb-silvolite.com> and search on there. They talk about it I believe...

Understood, really I do. I also believe that there IS a relationship and that it can be mathematically expressed. I have found the kb-silvolite site very informative and I use their calculators regularly

Really like their KB-373 piston too...

i think you are over complicating it. you have a grasp of the basics but are trying to make them co-dependent. separate them from each other and you will get it, cr can be changed by combustion chamber size as well as piston dish or dome. best practices these days with pistons are to mirror combustion chambers into the piston dish (if so equipped) thus maximizing quench and dialing your compression in at the same time. as you are seeing, it can get expensive as many custom parts or machine work can be needed....

Well I guess I am overcomplicating it, because I think it is a complicated relationship, and numerically (sometimes different than actually) one or more combinations will be superior over others &#8211; the trick it to find the formula

I agree with stormy. You can have a piston (picture this if you can) where one half is a flat top, the other half is a dish .090 deep.

The flat part can meet the bottom of... lets say, an Edlebrock head since it's a closed chamber.

That deep dish isn't doing anything for compresion.

Now raise up the dish part to equal the flat on the otherside. Now, the ratio just jumped to 10-1 plus. The quench didn't change but due to the piston being flat across, the ratio jumped since theres less room in the head now while the piston is @ TDC.

The same idea can be used on the head.
The same idea can be used with the piston and head as described first.

Good visual. Not to come off as argumentative, but in the second example the effectiveness of the quench effect should increase as a larger percentage of the piston profile mirrors the chamber profile &#8211; which makes me want to ask, is more quench area better than less, is there an optimal quench percentage, can you over quench?

You can get tighter, my engine has .028 piston to head. It's nothing special, stock rods, stock crank and hyper pistons. I twist it to 7200 regularly but it has been as high as 7800. I didn't do this on purpose, it's how the short block came and the only readily available gaskets were the .0385 FelPros. It works but maybe a little more clearance would work better, I don't know. I used .038 on the 340. I've been told by an accomplished race engine builder that you can go as little as .025 with a steel connecting rod, I think I'm close enough though. I was already cringing when I first fired it up and still was prepared for the worst on it's first burn out and full pass but it's made many, many runs since then without a problem. lol

Happy accident it seems, I would have been right there with you cringing as it runs it&#8217;s first few choked cycles waiting for the din of components furiously colliding

When you take that engine apart, look for ghost tracks either on the head or piston or both...you may be surprised!

Explain ghost tracks please, I think I have an idea though

I think you're confused because what affects quench does affect compression ratio, but one doesn't lock in the other. With a given quench, combustion chamber size or piston dome or dish can be altered or selected to give you your desired compression ratio. I think any increased tendency for detonation due to an increase in compression ratio from a thinner head gasket is more than offset by having the proper quench dimension.

Now I feel vindicated in my quest, got it.[/FONT]

ps. Guitar Jones, what is the secret scamp owners society? My 71 scamp is curious

 

[dgc333]

When I built my 360 I wanted a strong street motor, I resisted the temptation to use a big cam, big carb and very high compression. I had read about the benifits of a quench combustion chamber and wanted to take advantage of it.

It's much harder with open chamber heads (you need to make custom pistons to follow the chamber profile) so I chose closed chamber magnum heads (they are stock). The quest for a proper quention combustion chamber is the reason vertually all modern engine designs have a closed chamber design.

I hemmed and hawed about whether to use a flat to piston or a step dish piston, either would allow a good quench, the step dish would keep the compression below 10:1. Since I had the idea that I would like a set of alumnium heads sometime I went for the flat tops and had my fingers crossed that the mid 10's compression ratio would run on pump gas.

I built the short block with KB107 pistons. I had to machine about 0.020" off the deck to get the surface square with the crank. This put the piston at zero deck and I used a common 0.040" thick head gasket.

What I wound up with was a 10.6:1 360 with a Comp XE268H Cam (224/230 @ .050" and .509/.512 lift), the magnum heads use 1.6 ratio rockers which accounts for the addtional lift over the advertised numbers. The cranking pressure measures between 185 and 195 psi which is close to the limit for pump gas but in actuallity the quench and high swirl design of the magnum heads allows me to run 89 octane and in a pinch I have used 87.

I have had carbs between 600 and 750 cfm on the engine and finally settled on a Holley Street Avenger 670. This carb produces all the power (by the butt dyno) of the 750 and still has the throttle response and low rpm driveability of the 600. Plus the car gets 5 mpg more with the 670 over the 750.

My Barracuda has an A833OD tranny with 3.55 gears and a 27" tall tire. The only 1/4 mile times I have were with a 25" tall tire and the 600 cfm carb. It ran a best of 13.7 @ 102 mph with a very traction limited 2.2 sec. 60' time. If I get the traction issues straightened out it shoudl be a low 13 maybe a high 12 sec car. Both Engine dyno and the 102 mph trap speed support that this engine is making approx. 370 HP.

The car will idle in traffic in high 90 temps all day, will accelerate from 1000 rpm in 4th gear and pulls hard from 1500 rpm to 6000+ rpm. It gets between 16.5 and 18 mpg around town and 21-22 mpg on the hiway.

I couldn't be happier with the preformance of this engine and I have been putting approximately 7500-8000 miles a year on it since 05 when I installed it.

 

[toolmanmike]

Without getting too in-depth, it seems that the closed chamber head/flat top piston combination works the best. Maybe it's because after the spark ignites the air/fuel mixture and the piston is on its way down on the power stroke, the force of the explosion is more even on the piston surface. It would push on the whole piston surface evenly instead of pushing harder on the domed area of a pop-up piston. Just a thought.

 

[octanejunkie]

I couldn't be happier with the preformance of this engine

Thank you Dave for sharing all this info, in thread and PM, with me and us. All the parts I have for my 360 build mirror Dave's 360 almost identically, execpt that I have Sealed Power 5cc (Z8KH116CP30) pistons instead of KBs, and I am leaning heavily towards the XE268H (20-223-3) cam and was interested in knowing how it would perform in my engine. Hearing of Dave's success and praise of his build only reinforces my enthusiasm for my build, this is why the subject of quench became so important to me all of a sudden

Thanks for the wake up call on quench Dave. When I get some space cleared out in the shop I will mock up my 360 and see whether I need to shave the deck to get to the magic quench dimension.

BTW Dave, if you CC'd the chambers on your magnum heads I'd like to know what you came up with, I have been using 63cc in my calculations but don't know for sure till I CC mine

 

[moper]

I think,as with anything else, there will be a bunch of opinions on what's "the right" distance. It's also important (I feel) to make sure you understand that the distance the builder sets and the type of parts being used is critical to get the quenching effect. That, btw, is caused by the squish. Narrow distance and flat surfaces cause a lot of squish, and that in tern causes a good quench effect. Note I'm not stating any distances or models. just stating the cause and effect relationship there. The distance must be carefully controlled toget the best result. That means verifying the stroke, rod length, and crank centerline on the build in addition to square decking. Not decking. Square decking as they are not the same thing.

As for my own guidelines... Much more important to me than rod material are chamber design, piston compression height, and bore size. It is not cost effective to worry about quench when using an open chamber head. At best, you get a build with marginal results. At worst you think you're all set and the end result is more prone to detonation. It is not safe to worry about quench when the pistons are so short that there is little support to keep the rocking at TDC under control. Which leads into the larger the bore. The larger the bore the more distance you have to build in because of the rocking. This can be significant as a 4.340 400 piston with a 4.15 crank is so short that it will rock .008-.010 at TDC. if you build a .035 quench into it the piston will hit the head at some point in it's life. Not good... I know of race engines running as tight as .025" with steel rods and bores under 4.07. I also know of several who have the ghost marks on the piston tops...lol. For me, I always aim for .035. I've only seen one aftermarket budget crank that was .002" tall in the stroke and I have the rods length matched as part of the rod re-sizing when I use stock rods. Aftermarket rods are ususally within that same .002" length. Good rods are exactly the same. So all this means is I have at closest .031" and at furthest .039". I know quench loses affect as the parts get further apart. The best is less than .030. The wider it gets, the less the affect. So if you're looking to hit .040 or .045, and the errors are not corrected in lengths, then you could have nothing at all. Because once you hit .050, it's not doing anything for you.

 

[dgc333]

My magnum heads cc'd at 64. A second set I sold also cc'd 64

 

[rumblefish360]

[FONT=Verdana, Helvetica, Arial]
Good visual. Not to come off as argumentative, but in the second example the effectiveness of the quench effect should increase as a larger percentage of the piston profile mirrors the chamber profile &#8211; which makes me want to ask, is more quench area better than less, is there an optimal quench percentage, can you over quench?


Explain ghost tracks please, I think I have an idea though.[/FONT]

Indeed, ghost tracks, what is that?

On my second example, I think I miss typed. It was to be the mirror of the first example, just the other part, head chamber, doing what the piston did (Dish).

I think you have it all real good.

Since you were talking with Dave on this in depth a bit more and through PM's, I'd bet you preety much have this well covered and your build is sounding nice. I beileve that cam is as low as I would go in terms of duration with this set up.

You also come up with a good question. Is there such a thing as going to far with a quenched area?

I don't think so, but, at the same time, there may be a problem with compresion if the slug doesn't have enuff relieif in it to drop the ratio down. This cll to mind the Chevy 348/409 head. It is just absoultely flat, no chamber. The only area that isn't flat as a board is where the valves are.

Compresion is there by regulated by the piston shape, which would be a dish where ever it needs relief from the valves.

Anybody have a picture of the 348/409 Chevy Head?

 

[Guitar Jones]

I know what ghost tracks are and yes this engine has them. I pulled it apart after the first build to cut the valve reliefs deeper to get my big cam in it. You can see where the valves are on the piston top and where the chamber is too. This engine has small chamber W5's on it that were milled .050 to get the chamber down to 47cc's.

 

[rumblefish360]

OK, again, "What are ghost tracks?"

 

[Guitar Jones]

[FONT=Verdana, Helvetica, Arial]ps. Guitar Jones, what is the secret scamp owners society? My 71 scamp is curious

Evil Scamp was the fornicator, er, perpetrator, of this dastardly secret society. I hear he's in to Dusters now so I don't know if he's willing to initiate a new member. I'll vouch for you though.

 

[rumblefish360]

Evil Scamp was the fornicator, er, perpetrator, of this dastardly secret society. I hear he's in to Dusters now so I don't know if he's willing to initiate a new member. I'll vouch for you though.

Bwa ha ha ha ha ha, ROFLMAO! That was great! :snakeman:

 

[moper]

Indeed, ghost tracks, what is that? Ghost tracks are the mirror image of the top of the piston... You will see them in the flat pad next to the chamber of the head when the piston just barely contacts the head. The trick is to close off that area and limit the area to contain the air mix to around the exh valve/spark plug. The most effective way to close off the quench area is have them touch. Not safest...lol. But most effective.

You also come up with a good question. Is there such a thing as going to far with a quenched area? In regard to available parts, yes. Otherwise, no. The best in terms of inline valves is a very small central chamber with a dished piston anda quench ring completely surrounding it. Packaging prevents that in most designs.

 

[rumblefish360]

Ahhhhhhhhh, Thaaaaaaaaaaaank you.

 

[Guitar Jones]

Packaging prevents that in most designs.[/COLOR]

Not in my engine.