Chamber Grooves - what do you guys think?

[automotive breath]

A small number of people here have shown interest in the work I have been doing grooving SBC heads. I got a couple of sets in the shop for porting and grooves. This is a set of pro topline 220s from a 383 bracket engine. The best to hope for this one is more testimonials, no dyno test scheduled. The engine has been together for several hundred runs and the only modifications being done are the grooves and mild porting.

The cylinder head squish area displays relatively uneven burn around the squish circumference near the intake valve and the gasket area. I hope to get these heads back next year to see if the burn pattern has changed.

[MadBill]

Just stumbled on this. Looks like the discussion has died out at least for the moment. Maybe everybody is off testing for themselves?
One test that would reveal at least the potential of the groove to impact combustion would be to run back to back dyno tests with A. .070" squish/quench, B. thinner gaskets for .030" squish , C. 0.070" with grooves and D., 0.030" with grooves.
Running a fairly high CR engine equipped with knock detectors on a variety of fuels and looking at power, F.E. and knock resistance should certainly answer a lot of questions. Now, where did I leave that winning lottery ticket I was going to use to pay for the dyno time?

PS: The thread digressed at one point to Smokey's hot vapor engine and to the use of acetone to reduce surface tension and improve vaporization. My question is: If complete vaporization is such a panacea, why do natural gas and propane engines (even those using liquid propane injection) get at best virtually identical fuel economy to gasoline ones? (and before anyone claims they don't, I worked for 10 years on GM's Alternative Fuel programs. The bi-fuel natural gas trucks and car we sold were usually certified within 1% city and highway mileage (energy basis) on the two fuels.

[Calypso]

Let me take a stab at this. For staters, I think it would work.

1. Compression stroke burn improvement: Hi speed jet in the middle of the chamber would cause 2 contra rotating swirls (intake and exhaust side) that improve the burn rate and make it more complete by throwing gas into the flames. Actually this mod would likely allow more compression by swirling the unburned detonation sensitive mixture from the area cylinder wall side of the intake valve. (based on the thinking that better ionized exhaust side mixture tends to burn first and compress the end gas to the intake side)

2. exhaust stroke idle improvement. This is based on how I think reversion behaves. Most of the flow in the ports at low lifts is along short turns. Hi speed jet near intake short turn causes local pressure minimum pulling mixture to the chamber at overlap. Pressure recovery from the jet at plug side causes a local hi pressure region at exhaust port short side inhibiting exhaust flow into the chamber.

#2 also would explain why bigger quench distance would improve burn: Low pressure area at groove would be able to more easily evacuate the the unburned mixture from quench pad area.

To me it makes sense. I think I'm going to try it... with couple of obvious improvements.

[jacksoni]

As MadBill says, have to do a real a-b-a testing with only the single design change. Automotive breath says will just put these grooves in and port them up a bit and see what happens. Indeed the chamber burn pattern may look different after but how do you tell what changed what?

The acetone thing is similar. Hey, my mileage increased a bunch. Far as I am concerned, the biggest determining factor in mileage in any given car is how heavy is your foot. To say I get say 25mpg normal and then put bit of acetone in and hey it goes to 28 is just bogus. My foot got a lot lighter doing the test. My new car has mileage function. If I wasn't afraid to put the acetone in it and wreck something, put it on cruise control, both ways over a stretch of road, several times and get some numbers. Then put the acetone in and do the same. Or real on the dyno, don't change anything else. It ought to be easy to prove (or not). I work in a job where the controlled clinical trial is king and anecdotes aren't worth anything. Should be easy to do. Someone step up.

[SupStk]

My question is: If complete vaporization is such a panacea, why do natural gas and propane engines (even those using liquid propane injection) get at best virtually identical fuel economy to gasoline ones? (and before anyone claims they don't, I worked for 10 years on GM's Alternative Fuel programs. The bi-fuel natural gas trucks and car we sold were usually certified within 1% city and highway mileage (energy basis) on the two fuels.

I agree with you testing chamber grooves would be interesting and auctually not that difficult.

I wasn't aware that propane certified that well. At one time I worked on the line at a Chevrolet dealership. As a truck tech I dealt with service issues on motorhomes as well. Quite often there were mileage complaints on dual fuel RV's when running propane.

It has been my experience the same vehicle on propane will have less power and about 10% less fuel economy (MPG) than on gasoline.

[MadBill]

...I wasn't aware that propane certified that well. At one time I worked on the line at a Chevrolet dealership. As a truck tech I dealt with service issues on motorhomes as well. Quite often there were mileage complaints on dual fuel RV's when running propane.

It has been my experience the same vehicle on propane will have less power and about 10% less fuel economy (MPG) than on gasoline.

Absolutely correct! Propane has significantly less energy per gallon, which is how it is sold, than gasoline, thus reducing mileage. Also, it is normally introduced as a gas, causing significant "charge displacement" (reduced volume of air drwn in), which reduces the power.

[putztastics]

Automotivebreath and I have been PMing - I'm planning to do a grooves test on my Dodge 360 dyno test mule, I just have to get a few other things done first.

It will be a back to back test on the same day. And since the grooves apparently affect more than power, ie the idle, I plan to use an LM-1 wide band meter to log any changes in the A/F ratio, idle speed and intake manifold vacuum.

This must sound scary, two guys named "automotivebreath" and "putztastics" planning a "scientific" test, or a test of any sort for that matter.

A second opinion test, or specific advice, wouldn't hurt, if any are so inclined.

[MadBill]

Well, besides the basic TBDs of comparing power curves and minimum idle speeds, the next most obvious ones would be comparison of MBT SA, LBT AFR, B.S.F.C., EGTs and cylinder to cylinder variation, engine vacuum at minimum 'non-groove' stable idle vs. same RPM with grooves and V.E.
If the dyno cell has 4 gas analyser capability, idle emissions would also be a barometer of combustion quality. [Could compare with idle mixture screws (4 corner idle preferred) at leanest good idle for non-groove, then same settings grooved, and finally leanest for grooved at same RPM.]

If the engine can be muffled or fitted with knock sensors or a stethoscope, one could track the knock limit through the RPM range, using low octane fuel...
(man, I get on a such a roll when I'm spending OPM!*)
*Other People's Money

[automotive breath]

1. Compression stroke burn improvement: Hi speed jet in the middle of the chamber would cause 2 contra rotating swirls (intake and exhaust side) that improve the burn rate and make it more complete by throwing gas into the flames. Actually this mod would likely allow more compression by swirling the unburned detonation sensitive mixture from the area cylinder wall side of the intake valve. (based on the thinking that better ionized exhaust side mixture tends to burn first and compress the end gas to the intake side)

I don’t claim to be an expert on the topic of combustion but I have given this a lot of thought. The altered fluid flow ATDC of compression likely feeds the advancing flame front and creates additional mixture movement and improved squish flow placement. The fuel air mix contains 70% nitrogen. The additional movement and placement better exposes the air fuel to generate a hotter faster flame that burns more completely. If this is indeed the case it would explain the clean running oil and plugs.

I have found that the grooved engine is more detonation resistant; I’m running 10:1 compression in my modified tow truck. I agree with Calypso, swirling the unburned detonation sensitive mixture from the area cylinder wall side of the intake valve is the key.

2. exhaust stroke idle improvement. This is based on how I think reversion behaves. Most of the flow in the ports at low lifts is along short turns. Hi speed jet near intake short turn causes local pressure minimum pulling mixture to the chamber at overlap. Pressure recovery from the jet at plug side causes a local hi pressure region at exhaust port short side inhibiting exhaust flow into the chamber.

This I haven’t given much thought but I think you are on to something. When I ask about a second groove, Somender recommends one pointing directly at the exhaust valve on the opposite side of the chamber from the first groove.

#2 also would explain why bigger quench distance would improve burn: Low pressure area at groove would be able to more easily evacuate the unburned mixture from quench pad area.

Here we agree again. I have found with the grooves there is an advantage to open up the quench distance. I’m very interested to see how the burn pattern looks on the modified engine. When you look at the last picture I posted the burn pattern was very incomplete.

To me it makes sense. I think I'm going to try it... with couple of obvious improvements.

Please communicate obvious improvements. I’m grooving two to three sets of heads a month and I’m willing to try improvements and communicate results.

[automotive breath]

As MadBill says, have to do a real a-b-a testing with only the single design change. Automotive breath says will just put these grooves in and port them up a bit and see what happens. Indeed the chamber burn pattern may look different after but how do you tell what changed what? .

I agree controlled tests will be needed. Combining grooves with porting and any other performance modification muddies the water. All of my testing has been done in cars, at the track or on the street. Many times other modifications are included, I realize this does little to convince others of the benefits.

[automotive breath]

I agree with you testing chamber grooves would be interesting and auctually not that difficult.

Automotivebreath and I have been PMing - I'm planning to do a grooves test on my Dodge 360 dyno test mule, I just have to get a few other things done first.

It will be a back to back test on the same day. And since the grooves apparently affect more than power, ie the idle, I plan to use an LM-1 wide band meter to log any changes in the A/F ratio, idle speed and intake manifold vacuum.

This must sound scary, two guys named "automotivebreath" and "putztastics" planning a "scientific" test, or a test of any sort for that matter.

A second opinion test, or specific advice, wouldn't hurt, if any are so inclined.

Well, besides the basic TBDs of comparing power curves and minimum idle speeds, the next most obvious ones would be comparison of MBT SA, LBT AFR, B.S.F.C., EGTs and cylinder to cylinder variation, engine vacuum at minimum 'non-groove' stable idle vs. same RPM with grooves and V.E.
If the dyno cell has 4 gas analyser capability, idle emissions would also be a barometer of combustion quality. [Could compare with idle mixture screws (4 corner idle preferred) at leanest good idle for non-groove, then same settings grooved, and finally leanest for grooved at same RPM.]

If the engine can be muffled or fitted with knock sensors or a stethoscope, one could track the knock limit through the RPM range, using low octane fuel...
(man, I get on a such a roll when I'm spending OPM!*)
*Other People's Money

In addition it would be good to test oil contamination. On of the most desirable benefits of the grooved engine is how the oil runs clean. Before and after oil analysis would document improvements.

This must sound scary, two guys named "automotivebreath" and "putztastics" planning a "scientific" test, or a test of any sort for that matter.

With expertise from the likes of MadBill and SupStk; could we possibly convince the world?

[putztastics]

Well, besides the basic TBDs of comparing power curves and minimum idle speeds, the next most obvious ones would be comparison of MBT SA, LBT AFR, B.S.F.C., EGTs and cylinder to cylinder variation, engine vacuum at minimum 'non-groove' stable idle vs. same RPM with grooves and V.E.
If the dyno cell has 4 gas analyser capability, idle emissions would also be a barometer of combustion quality. [Could compare with idle mixture screws (4 corner idle preferred) at leanest good idle for non-groove, then same settings grooved, and finally leanest for grooved at same RPM.]

If the engine can be muffled or fitted with knock sensors or a stethoscope, one could track the knock limit through the RPM range, using low octane fuel...
(man, I get on a such a roll when I'm spending OPM!*)
*Other People's Money

Yo Bill!

That does sound like OPM as my dyno is not that well equipped.

What do you expect from a putz anyway?

[automotive breath]

Hi all,
I have been grooving heads for one year now and I'm starting to get heads back after run time. Here's the latest from a 13:1 355. Comments?





One of my projects is my tow truck (95 Suburban). I shaved the heads 0.050" to raise the compression to 10:1 and cut the grooves. The truck runs better than ever. At 10:1 compression on 87 octane it pulls my loaded down enclosed trailed effortlessly. I was hoping to have some solid fuel consumption numbers by now. Fuel consumption has been reduced, problems with the TBI have caused inconsistent numbers.

Here's a link to some of the work that was done this year

http://somender-singh.com/content/view/68/49/

Cheers,
AB

[Stevespeed]

What happened to your dyno session?

[automotive breath]

What happened to your dyno session?

Hi Steve, putztastics is planning on testing a 360 Dodge when he catches up in his shop.

Automotivebreath and I have been PMing - I'm planning to do a grooves test on my Dodge 360 dyno test mule, I just have to get a few other things done first.

It will be a back to back test on the same day. And since the grooves apparently affect more than power, ie the idle, I plan to use an LM-1 wide band meter to log any changes in the A/F ratio, idle speed and intake manifold vacuum.

This must sound scary, two guys named "automotivebreath" and "putztastics" planning a "scientific" test, or a test of any sort for that matter.

A second opinion test, or specific advice, wouldn't hurt, if any are so inclined.