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Village Idiot
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There was a lot of talk about theory and speculation as to why it works in some applications. It was fun to read what some of the individuals though was going on and why it worked in some applications better than others. I am afraid that it is all based on how tight the squish is in the first place, what fuel you are trying to run vs. the compression ratio and about a thousand other factors. I would love to do a back to back test and try it, but that would take time and money I don't have.

Paul
 

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There was a lot of talk about theory and speculation as to why it works in some applications. It was fun to read what some of the individuals though was going on and why it worked in some applications better than others. I am afraid that it is all based on my tight the squish is in the first place, what fuel you are trying to run vs. the compression ratio and about a thousand other factors. I would love to do a back to back test and try it, but that would take time and money I don't have.

Paul
I can't say I am totally certain as to what exactly they are trying to accomplish. The whole idea of a squish/quench area isto create turbulence, and push /squeeze the charge into a reduced chamber. This looks as though they are trying to light that area off. That's an up hill battle if there ever was one. That was the reason behind the open chambers of the Mopars and Ford Clevelands. To reduce the unburnt hydrocarbons snuffed out in the quench area. Don't think a couple of grooves are going to solve the problem. Don't see this as ever being a "performance enhancement".



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Village Idiot
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I see it this way, it this could create a more efficient use of the A/F in the chamber or better flame travel then it is either going to decrease fuel consumption or make more power. Now the key is weather or not we can quantify weather or not it will indeed do either of these things. Most importantly is being able to show that any improvements are based off of the slots and not some other variables.

Paul
 

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www.highflowdynamics.com
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I remember reading about this mod on the Speed Talk forums a few years back. Does any one have any first hand experience, seems like if it was worth the smallest gain it would be worth it, considering it shouldn't cost anything (done right).

http://somender-singh.com/content/view/7/31/
Quench grooves, quench trenches, squish jets, fire slots, etc. Singh is one of perhaps dozens of people to have received a U.S. patent (most of them before he) documenting and "proving" the effects of this modification through several different approaches to get the same result. As I recall, Singh is in India and is a motorcycle mechanic that had been constantly dealing with the dilemma of the "cat piss pump gas" that they are stuck with in that country and turned to the fire slots in order to control detonation.

And controlling detonation is probably what the fire slots are best for. I have never done dyno testing but know others that have and also used the fire slots in their EMC engines specifically for detonation control. There was no measured hp gain; low rpm torque was improved in that the heavy loads imposed on the engines did not result in detonation where they typically did without the slots.

The idea is that as the piston approaches the quench pad and squeezes the air-fuel mixture away from the quench pad, some of the air-fuel mixture collects in the groove and thereby "jets" at a higher velocity into the chamber in a more focused manner toward the plug. In other words, it does what the quench pad already does but "takes it up a notch." The jet increases mixture motion, particularly around the spark plug, and improves flame propogation which helps complete the burn.

It just so happens that I am currently doing a set of D3's right now for a low power personal build that will be in a 5000-pound vehicle and which I want to run on whatever I can get....87 octane gas, paint thinner, acetone, whatever.





The above pics show these D3VE heads with the fire slots machined in but still in an unfinished state, no other detailing. I've since made further progress but have not yet taken pics. My chosen depth, width and (to some extent) length of the slots varies depending on the overall combo, application, rpm, etc. In the case above, I've used a 1/16-inch ball end mill (0.0625") and went 0.075" deep in anticipation of removing 0.010" off the heads at resurfacing (will be approximately 0.0625" wide x 0.0625" deep after the heads are shaved). On other combos I may use a 3/32-inch ball end mill (0.093"). The fire slot--when there is just one per chamber--usually points toward the spark plug so as to send the jetted turbulence toward the plug. Detonation is minimized and torque is improved where it might have otherwise been hindered (from the pinging) at low rpm/high load conditions.

LO
 

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Village Idiot
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LakesOnly, how much compression are you planning on putting to this thing? I would love to hear about how this turns out.

Paul
 

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harley davidson heads

this is(has been done for a #of years) being done by some head porters in the performance aspect of HD heads.

it always turns into a major debate,it has shown no signs of adding hp to them according to dyno runs.but the head porters that do this groove in the heads basically say the same as with the auto guys that do it,they swear by it to help reduce cylinder temps and help in the detonation dept.

i myself from what i have read, seen in dyno sheets ect. call it SNAKE OIL.

maybe it does help maybe it doesnt.Travis:)hand
 

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Spiral out
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The carbon patterns on the pistons and chambers seems that the pattern is uniform in all the pics I've seen. Seems to help complete the burning of all fuel in the combustion space......which is where you want to burn it right?!:)bulb

It does not look like it hurts anything at all (perhaps just compression by a small amount).......and is a relatively simple mod......I'd say do it if you want to.
 

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With proper chamber/piston blending and design it is not needed. I believe the slots are just covering up a poor chamber/piston design or detail.
If you are noticing a burn problem across the piston or chamber, fixing the problem through proper blend and design is better than slotting.

Kinda like the old "Storm Fronting" of chambers and port surfaces! :)bulb
 

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Spiral out
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Kinda like the old "Storm Fronting" of chambers and port surfaces! :)bulb
Jay, Can you elaborate?;)

W/ the older BBC stuff, it might be a crutch.....but we probably need it cause of the science back then was not what it is now.:)bulb

Just trying to make the most of what we got.:)hand
 

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www.highflowdynamics.com
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LakesOnly, how much compression are you planning on putting to this thing? I would love to hear about how this turns out.

Paul
This is a low compression engine that is going into a heavy car, and I want the 5000+ pound car to be able to pull grades with my jet boat in tow, and on 87 octane. And I will use an RV cam but one with a 110* LSA and shut the valve early and get some squeeze, which is why I added the grooves.

But to better answer your question: Suppose I build a 460, a specific combo that generates 550 hp on 92 octane pump gas. This combo works perfectly but detonates at 10.25:1, not 10:1 as it is set up. Then, if I mill the heads to get 11:1 and add the squish jets, this engine combo will not detonate at 11:1. Does the engine now make more horsepower? Yes, BUT it makes more horsepower due to the increase in compression ratio, not from the squish jets. Case in Point: If I added the squish jets to the 10:1 version of this combo which already did not detonate, horsepower would remain exactly the same.

So this is not a magic power adder of some kind, it simply addresses detonation and, within that, may allow an engine to offer up more power through this detonation control.

LO
 

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www.highflowdynamics.com
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LO's explanation makes more sense than trying to ignite what ever charge is trapped in the quench area. Which is what the link seems to infer.
There are claims that it works both ways, 1) as turbulence jets like I explained, and, 2) that it also provides a path to help burn the leftovers beneath the quench pad. I, too, disagree with the latter. After all, if you allow the flame to propagate into the quench pad, then you have eliminated the entire purpose of the quench pad.

LO
 

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With proper chamber/piston blending and design it is not needed. I believe the slots are just covering up a poor chamber/piston design or detail.
Please show me a closed chamber design in our modified V8 engines that would not benefit from this modification. I am not aware of any. Saying, "the slots are just covering up a poor chamber/piston design or detail," is no different than saying, "the performance improvements from the custom port work shows that the as-cast ports incorporate a poor design or detail," or, "the 1/4-gram balance job shows that the factory 40-ounce balance job is a poor design or detail". In other words, just like the port work or balancing, this is an enhancement. It may or may not be beneficial depending on the combo....just like the port work, balancing, etc.

LO
 

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Discussion Starter #17 (Edited)
So all by it self it might not do much, but if it allow more compression to be run before detonation on a giving build that's huge.

Also, If it helps improves the efficiency of a poorly designed combustion chamber i would think it requires less timing to make max power.
 

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There are claims that it works both ways, 1) as turbulence jets like I explained, and, 2) that it also provides a path to help burn the leftovers beneath the quench pad. I, too, disagree with the latter. After all, if you allow the flame to propagate into the quench pad, then you have eliminated the entire purpose of the quench pad.

LO
I think in terms of "events" here.

There is alot more surface area in the quench evacuating before actual ignition of the fuel, than the "jet" could provide.

?
 

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There are claims that it works both ways, 1) as turbulence jets like I explained, and, 2) that it also provides a path to help burn the leftovers beneath the quench pad. I, too, disagree with the latter. After all, if you allow the flame to propagate into the quench pad, then you have eliminated the entire purpose of the quench pad.

LO
That's my point exactly. The idea behind the quench pad is to cool the charge in that area so that it won't self ignite (deisel) and to squeeze the charge into a smaller combustion area and thereby create some turbulence. I do see how the slots could add some what to the turbulence, and how it could allow for a given C.R. to run on lower octane fuel, or allow a higher compression ratio without detonation. But it doesn'tseem as though it could help with unburnt hydrocarbons trapped in the quench area. Best thing to do there is to just minimize the space.
These guys were all over this stuff before any of us were even born. That includes me, and I am only slightly younger than dirt.
http://www.ricardo.com/en-gb/About-Ricardo/



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Please show me a closed chamber design in our modified V8 engines that would not benefit from this modification. I am not aware of any.
LO
Show me data that proves the benefits! :D

Seriously, a properly blended chamber will reduce the chance for detonation thus allowing higher compression ratio's. It will also improve power with no other changes. Just as a profiled/blended dome will show both a power gain and resistance to detonation through more even and consistent flame travel. Back in the day's of large chambers and big domes (before the flat valve angles/small chambers used today) such as the BBC or a high compression SBC flame travel and complete burn were always a problem. To combat this the domes and chambers were blended thus improving flame travel and promoting a more complete burn. This I have seen scientifically tested, the slot deal has been a myth for allot of years, but I have yet to see actual test data that was conclusive, so for now it is "snake oil" IMO. There is quite a thread about it on Speed Talk. It may help, but like i said before, it's just showing you need to do a little "hugging and kissing" in the chamber area.

I am still very surprised at the amount of engines built by "engine builders" today that we see pictures of and they have these big domes and they are installed as they came out of the box! You see pictures after they have ran and you can plainly see a very small burn area. It is Amazing what a little detail would do for both performance and reliability (again, resistance to detonation/more efficient burn).

This slot deal seems to come up about every 10 years or so. Again, kinda like the dimple surface deal. It does something, but like I said before, this is just showing there is a problem somewhere else.

Again, just my thoughts!!! :)sphss
 
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