Topic: Squish/Quench?

[Pinhead]

When did Honda start incorporating squish and quench in their comustion chambers? Or did they? I've worked on 2 engines, a CB360 and a CB650. Neither have any squish or quench area on the head. I ask because I want to encorporate singh grooves into the chamber, but it requires squish to modify.

www.somender-singh.com
www.mpgresearch.com

This is a pic of the groove in a common cyllinder head. Note the grove goes through the "squish" area.



The groove cut in a lawnmower engine head:

[Pinhead]

bump

[Pinhead]

btt... i thought these forums were for improving our bikes... These grooves work wonders on engines that they can be incorporated into.

Also, has anyone experimented with combustion chamber dimples or intake runner turbulence?

[Terry in Australia]

Aren't those examples both from "Side-Valve" engines? Might be why no-one else has replied I think mate.

[brad weingartner]

Aren't those examples both from "Side-Valve" engines? Might be why no-one else has replied I think mate.

Agreed, this is an apples to oranges comparison. You simply can not compare an overhead valve overhead cam engine like the SOHC honda motor to a side valve or flathead. Even though the technology behind the SOHC motors is decades old, its still amazingly modern compared to the old flatheads.

You are right, the grooves do help in that style of engine, but its just not applicable to a SOHC engine. The classic SOHC honda motors had hemisperical combustion chambers, no squish or quench area to speak of. In the later 4 valve motors there will be more of a quench area as they became more proficient at building an efficient combustion chamber design. But in these motors, you will not be able to incorporate your grooves. There is not enough room for them to be effective, and the combustion chamber design is already highly optimized. The reason flatheads benefit so much from the grooves is because they are an inherently inefficient ancient design.

[crazypj]

If you '591' a 550 you have a quench area all around the combustion chamber which allows you to run high compression on lower octane fuel. Wouldnt be able to modify it without removing it though.
Is the piston top shaped as well on the side valve motor?
PJ

[Pinhead]

 

Only the second engine is "side valve" engine.

Here's another example of a common cyllinder head with the groove cut. Notice the outline of where the piston would come up in the bore.


My 79 CB650 has no squish/quench. That's why I was wondering when, if ever, did Honda start incorporating squish and quench in their engines.

[MRieck]

Fruit to vegetables in comparision. You can measure squish off the piston knowing deck height. Side valve stuff???

[Pinhead]

Why is everyone referencing to side-valve engines?   99% of the engines modified in this way are OHV or OHC engines. I've only posted 1 picture of a side-valve engine because it's easy to see the concept. I do agree that the classic Honda SOHC engine has no squish or quench area, so this mod isn't usable. HOWEVER, this mod does work on OHC and OHV engines. It's generally tougher to do, however, because the groove's purpose is to deter detonation. So most people that do the groove also increase the compression. If you plane the head for higher compression on a OHC engine, it changes the cam timing. That's why OHV engines and the side-valve engines are easier to groove.

Generally, you add the grooves, plane and shave the head for higher compression, and slightly lean-out the mixture. The groove speeds the combustion of the air/fuel mixture, and therefore increases the amount of fuel in the chamber that is actually burned. That's why you can lean out the mixture and get the same power (with the same compression). If you've raised the compression, you'll use less gas to get more power. Because the air/fuel burns more quickly (while the piston is closer to TDC) the engine also runs cooler. While the mixture is burning, since it takes less time there is less surface area of the combustion chamber in contact with the flame front.

Also, since it makes the air/fuel mixture burn more efficiently, it takes less spark to ignite it completely. In other words, if you've got a weak ignition system, this'll help you even more than someone with, say, a MSD ignition system.

I ask the question again, has Honda EVER incorporated squish/quench into any of their motorcycle engines?

[Terry in Australia]

Only the second engine is "side valve" engine. 

If the other one's not a side valve engine, then where are the valves Pinhead? It doesn't look like any 2 stroke I ever saw?

[HondaMan]

Whoa, boys: here's the skinny on the Honda chambers:

You might notice there are pockets around the valves in the stock head. These are there to guide the incoming charge into a swirl, which accelerates as the piston rises. This causes centrifugal force to spin the fuel mixture toward the cylinder walls and accelerate gas movement SIDEWAYS across the head at TDC time. This makes a richer mix appear along the metal surfaces of the head and cylinder walls, which both preheats the mixture and cools the metal parts. When the spark fires, it is "spread" along a longer bit of the mixture because it is moving very quickly across the face of the spark plug at that moment. This is the patented Honda Combustion Process (HCP), popularly known as the CVCC (Controlled Velocity Combustion Chamber) engine in the U.S. Be very careful how you modify these chambers, because introducing cross-currents can quickly introduce knock that cannot be stopped with octane or timing changes.

For a clue toward the right way to change things, look up my post about Top End Tricks (Tips). You will see my modified 750 head's chambers there. This method removes significant portions of the peak edges of the pockets, turning it inot more of a hemi-style head, to increase torque at lower RPM. It also lowers compression, so measure carefully when doing it. You MUST remove the center ridge from the combustion chamber before doing the following quench change, just like in my picture. Otherwise, the piston will hit the chamber, right on the ridges.

To modify the system and add quench, do it in the center of the piston. With a heliarc welder, draw a bead acorss the center of the piston, on axis with the crankshaft. This ridge can be as much as .125" high, but must be carefully relieved for edge-of-head clearance and tested for valve clearance. You can remove piston skirt weight to rebalance the piston to the original weight afterward, so measure carefully before and after. Be sure to smooth this ridge out, so there are no hot spots left that can hold carbon and create a heating problem. This brings your compression ratio back, too.

It's tricky, but worth every minute!

[Pinhead]

Hmm.... Well, I'm contacting the owner of the pic to figure exactly what cyllinder head that first pic is. But the last picture I've posted clearly shows an OHV head with the groove.

HondaMan: I'm going to have to read up on your cyllinder head modification. Thanks!

[HondaMan]

Het, all: I think I posted the head picture under "Inside Hondaman's Head", not "Top End Tricks". Sorry. 

[MRieck]

Any modern motorcycle engine adds quench, (as you describe) to in between(material) the valve pockets....perod. No beads, lines or troughs or any such stuff to the pistons or chambers. I've personally seen just about every chamber you can think of in regard to bikes and speak this as gospel. No real race bike etc had anything on the head or pistons....and I've seen CB's with everything from + .250 deck height and CB450 valves(in Ti) to Branch exclusive roadracing heads (SOHC and DOHC)  and that's just Honda #$%*....

[Pinhead]

So what can I do to give this bike a bit more low-end grunt? The things I can think of right now are different spark plugs to fire off the slightly lean mixture (I'm trying to go for fuel economy/efficiency).  Higher compression always aids effiency, as long as the a/f mixture doesn't detonate. How high can you go on these engines? I'd like 10:1 or higher... Is there enough clearance to simply plane the head to do that? And if so, that'd retard the cam timing, so I'd also have to get a different cam sprocket in order to re-time the thing. This gets into another issue. Can I advance the cam timing a little bit to shift the power band a little down? I never break 7k rpm on this thing, I mostly kind of putt around and shift out around 4-5k rpm. There's not much power down there, but I don't really like the sound of a bike in the 7-8k rpm range unless I'm giving it hell...

Any modern motorcycle engine adds quench, (as you describe) to in between(material) the valve pockets....perod. No beads, lines or troughs or any such stuff to the pistons or chambers. I've personally seen just about every chamber you can think of in regard to bikes and speak this as gospel. No real race bike etc had anything on the head or pistons....and I've seen CB's with everything from + .250 deck height and CB450 valves(in Ti) to Branch exclusive roadracing heads (SOHC and DOHC)  and that's just Honda #$%*....

Could you possibly find some pictures? I've worked with all sorts of engines, except for motorcycle/high-rpm engines.

[MRieck]

-

Any modern motorcycle engine adds quench, (as you describe) to in between(material) the valve pockets....perod. No beads, lines or troughs or any such stuff to the pistons or chambers. I've personally seen just about every chamber you can think of in regard to bikes and speak this as gospel. No real race bike etc had anything on the head or pistons....and I've seen CB's with everything from + .250 deck height and CB450 valves(in Ti) to Branch exclusive roadracing heads (SOHC and DOHC)  and that's just Honda #$%*....

Could you possibly find some pictures? I've worked with all sorts of engines, except for motorcycle/high-rpm engines.

Obviously compression will give you "grunt". It can be achieved best by decking the cylinder and getting .040 piston to head with the gasket. Then stuff starts running well.

[Terry in Australia]

Any modern motorcycle engine adds quench, (as you describe) to in between(material) the valve pockets....perod. No beads, lines or troughs or any such stuff to the pistons or chambers. I've personally seen just about every chamber you can think of in regard to bikes and speak this as gospel. No real race bike etc had anything on the head or pistons....and I've seen CB's with everything from + .250 deck height and CB450 valves(in Ti) to Branch exclusive roadracing heads (SOHC and DOHC)  and that's just Honda #$%*....

I think it's started.............................. The clash of the titan(ic brain)s! Fight! Fight!

[Pinhead]

Anyone want to comment on advancing the cam timnig for more torque?

[dusterdude]

should work ok,it works on cars.

[Pinhead]

I know it works on cars, but I don't think cars have nearly as much duration as our bikes do, and also most cars don't have hemispherical heads. I don't know if that effects it, but that's the problem: I don't know.

[MRieck]

Ignition lead will almost always result in improved torque in early bike engines or engines with compromised chambers (like the 5 valve Yamaha). Unfortunately it generates excessive, non productive heat and beats the crap out of parts too as the piston starts to push down too early on the compression stroke. Efficient chambers with good quench always require less ignition lead. You really don't want to light it until to you have to as atomization improves.

[Pinhead]

Ignition lead will almost always result in improved torque in early bike engines or engines with compromised chambers (like the 5 valve Yamaha). Unfortunately it generates excessive, non productive heat and beats the crap out of parts too as the piston starts to push down too early on the compression stroke. Efficient chambers with good quench always require less ignition lead. You really don't want to light it until to you have to as atomization improves.

Are you talking about advancing the ignition or the cam timing? I know that advancing the ignition timing too far will result in "excess pressure" and ping, but what about cam timing?

My bike has a 9000rpm redline. I rarely rev it past 7000 rpm. At stock settings, the 650 doesn't really start kicking in until about 6500 rpm or so and peaks a little over 8 grand, an rpm my bike seldom sees. So would advancing the cam timing be enough to shift the torque curve down from 8000 to about 6000?

[MRieck]

Ignition lead will almost always result in improved torque in early bike engines or engines with compromised chambers (like the 5 valve Yamaha). Unfortunately it generates excessive, non productive heat and beats the crap out of parts too as the piston starts to push down too early on the compression stroke. Efficient chambers with good quench always require less ignition lead. You really don't want to light it until to you have to as atomization improves.

Are you talking about advancing the ignition or the cam timing? I know that advancing the ignition timing too far will result in "excess pressure" and ping, but what about cam timing?

My bike has a 9000rpm redline. I rarely rev it past 7000 rpm. At stock settings, the 650 doesn't really start kicking in until about 6500 rpm or so and peaks a little over 8 grand, an rpm my bike seldom sees. So would advancing the cam timing be enough to shift the torque curve down from 8000 to about 6000?

I'm talking about advancing ignition timing....that's what i thought you were talking about. Cam timimg is another subject all together.

[MRieck]

Ignition lead will almost always result in improved torque in early bike engines or engines with compromised chambers (like the 5 valve Yamaha). Unfortunately it generates excessive, non productive heat and beats the crap out of parts too as the piston starts to push down too early on the compression stroke. Efficient chambers with good quench always require less ignition lead. You really don't want to light it until to you have to as atomization improves.

Are you talking about advancing the ignition or the cam timing? I know that advancing the ignition timing too far will result in "excess pressure" and ping, but what about cam timing?

My bike has a 9000rpm redline. I rarely rev it past 7000 rpm. At stock settings, the 650 doesn't really start kicking in until about 6500 rpm or so and peaks a little over 8 grand, an rpm my bike seldom sees. So would advancing the cam timing be enough to shift the torque curve down from 8000 to about 6000?

I'm talking about advancing ignition timing....that's what i thought you were talking about. Cam timimg is another subject all together.

.....and in a short answer to your question...yes, advancing the cam will do that.

[Pinhead]

I'm talking about advancing ignition timing....that's what i thought you were talking about. Cam timimg is another subject all together.

Cam timing is what I was wondering. I know in old 460 Ford engines, the cams were retarded from the factory and advancing them 1 tooth really brought the engine to life. Now, looking at the 650, horsepower peaks at about 8100rpm and 50hp. Like I said before, I never see those revs. I'm trying to maximize the fuel efficiency of this bike, while not trying to sacrafice highway riding. I want to mod it for more torque and slightly gear up the final sprockets. That way I'm not using the revs nearly as much down the highway.

I also know that in the years my bike was made (1979) emission standards had already ruined a lot of engines (hence the cam in the Ford 460). They forced things like lower compression into previously efficient engines. I don't know if the EPA had their hands in the motorcycle industry or not, but if they did the same as they did to cars, I would think it could really bring out the pep. Especially with a bump in compression.

So what are the downfalls??