Quench "flame channels" in piston vs. head quench

[Stef]

Yes, that's a Kent engine. Was the first cylinder head I ported when I was 17

I have not tried the squish jets/grooves. Most of the engines I work on now have heads that have either pent roof or big D-shaped chambers with not much squish area to speak of. I am aware of the research into it and I will have a go at one when I get a suitable head/piston crown to work with.

[Fatman]

Often it comes down to "monkey see, monkey do!"

Is this done in nascar cup engines or nhra prostock? NOPE

But think about the development that goes into those heads compared to the typical heads most people are bolting onto street/race motors.

Maybe the groves will work when the heads are lacking in some area of fuel management. Might not work on the nascar/prostock type stuff cause the heads are so well developed and designed.

[Telvm]

http://www.popularhotrodding.com/tech/0604phr_508cube_big_block_chevy_build/index.html

[Engguy]

This is stuff I thought of in the mid 70's. No $ at the time to even try it.
Just keep wondering who will beat me to this next great idea I have.
Wish I had some backing.

[andrew]

Earlier Stef mentioned SAE paper 1999-01-3664 on the in piston squish jet combustion chamber used with a flat cylinder head, here’s the results of that testing:

Compared to the engine with the bathtub combustion chamber, the experimental investigation shows that engine with the squish jet turbulence combustion chamber gives better comprehensive performance. The combustion process shortens, the lean burn limit extends. At WOT speed characteristics, the maximum power output increases by 25.7%, the average specific fuel consumption decreases by 12.9% and the average emissions of HC, CO and NOx decrease by 31.4%, 91% and 5.6% respectively

[Cobra]

I agree with Curtis' post!

If the pistons do not work out you can use them for Christmas tree ornaments!

[andrew]

I love this place, two examples of success are presented and the idea continues to be questioned. This done with no information to support the insignificance other than opinion.

[beth]

I found this interesting, I wonder how much longer it would have taken to self destruct?

[Cobra]

Please name just one top professional racer successfully using Singh heads.

[andrew]

Sorry, I was referring to the squish jet design of Evans and the BES Racing Engines entry shown.

Professional racers, heck I don’t know what they run. I’m interested in grooving pistons for the BBC in my Chevelle.

[KennyM]

No experience here yet but am considering this alteration.
On certain head configs, I would think there could be an advantage.
Example: The Ford N351 factory race head we run, is so fast in burn rate even on alcohol that ignition timing becomes critical and has to be kept under 30° in the motor combination we run them on.
I am given to believe the grove alteration may tame this down a bit without losing the benifits of the bowtie chamber and the very good power the heads make.
We here have a little problem of tracks penelizing the Fords with extra weight because the Gm heads, within the unaltered head rules, don't make as much power on 358 engines as the Fords do. Sucks when they have to "legislate" the rules to favor.

[mpgmike]

As far as street vehicles, I've grooved the mundane up to the radical, all with beneficial success. The grooves are part of a package I do, not just the star attraction. Some examples of grooved heads I've done:
- '89 LeBaron, 2.5 turbo; went from 152 HP to 400+ HP and 23/27 mpg to 35/42 mpg. Car had bigger turbo, larger injectors, large IC, and other mods as well. Able to run 23 psi boost on "pump gas" (Florida).
- '96 Saturn SOHC; went from 100 HP to 130 and 38 mpg average to 56 with 10.5:1 compression on 87 octane fuel (in Indiana).
- '89 LeBaron 2.5 turbo; went from fast at 28 psi boost to faster at 20 psi boost.
- 2000 Ford Ranger 2.5; from 21 mpg to 27 mpg and had the power of the 3.0 V-6

There are more, but since I ship the heads I can only go on what the people tell me, hence the sketchy "data". In many cases I increased the compression. Like AB, I have discussed and argued the theory of the Grooves with some very educated people and it boils down to: There are 2 camps, those who have tried it and those who are against it.

Mike
www.PowreHaus.com

[dwilliams]

Ah, I finally found my notes: there was an article in the March 1998 issue of "Sport Compact Car" describing the Toyota 1ZZ-FE engine's combustion chamber, which had a squish channel. I thought it was interesting enough to write it down; it just took a while to dig it up again.

So Toyota found some benefit to it. And squish channels are common enough on Diesel engines, going back before WWII.

[mike_belben]

There are 2 camps, those who have tried it and those who are against it.

it does seem that way.

[img]
http://i65.photobucket.com/albums/h205/ ... 220112.jpg [/img] <-- tag editor is giving me lip.



i didnt want to do them in the head because the deck surface had been milled into a flat quench configuration from a formerly open chamber. plus, the piston grooves i feel gave me more control in directing the gas. i was trying to make the two squirts collide half way between the dome and spark plug, hence the ramps ground into the dome. compression was low 12:1 range, 81.5mm bore, about .038" piston to head. mild cams and stock intake/exh at the time.

i have no scientific evidence. here is what stood out to me.

-the motor had to come back apart immediately to correct an issue after startup and obvious flame marks were centered on the piston. probably means nothing, as it was only idle time and i have nothing to compare it with.

-first engine ive built that started and idled on what seemed like the very first spark on initial startup. it was 35 degrees outside and it ran like the car was daily driven and shut off just a moment before. normally takes me a few starter cycles to get them running during warm weather, harder in the cold.

-during a very basic a/f ratio street tune, the throttle position log would show about 8% tps angle while cruising. it would go to 11% and the car would accelerate as if it was given a quarter throttle. the driver/owner was saying he thought something was wrong with the cruise control, the car was taking off on him and he hadnt stepped on it yet.

i am convinced that grooves are the cat's ass with respect to cold starts, part throttle, low load, economy, emmisions and so forth. im anxious to build a test mule for myself and see how it does on 87 octane with a good dose of compression, before and after grooves. [/img]

[automotive breath]

...i am convinced that grooves are the cat's ass with respect to cold starts, part throttle, low load, economy, emmisions and so forth. im anxious to build a test mule for myself and see how it does on 87 octane with a good dose of compression, before and after grooves.

With wedge heads I'm finding burn rates 10 to 15 crankshaft degrees faster at idle, it works wonders with cold starts. In addition the modified engine will accept a .5 increase in compression ratio with out reaching knock limitations. Very useful when the application calls for low RPM resulting in low in-cylinder turbulence.

When you get your test mule up and running you will find additional benefits at RPM if a condition exists where the piston speed outruns the flame velocity. I have experienced examples where the useful RPM range of a combination was extended by 500 RPM or more.

Very clever the way you used the piston dome to direct the squish flow into the spark plug.

Here's an example of something I did for a low RPM application.