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Topic Review (Newest First)
03-18-2007 12:39 PM
automotive breath
Originally Posted by Lil Big Mec
What do you use to machine these grooves? Can you do
it by hand with a die grinder or something? Or can I assume you use a milling
Hi Lil Big Mec,
Somender Singh uses a hand held hacksaw blade and a file. I tried that once
and it was too slow for me. I know other people that use a high speed cutoff
wheel. I tried that too but was too nervous that I might mess up.

So I developed my own method, I don't have a mill so I fabricated a jig that
allows me to cut a straight line with my high speed grinder. I use a 1/16" ball
end mill to cut the initial groove, I then widen and deepen the groove into the
chamber with a file.

The most important part is to layout the bore size on the head to assure the
gasket seal area is not damaged. I mark the bore diameter and lay out the
grooves with a felt tip marker as shown.

03-18-2007 12:32 PM
Lil Big Mec What do you use to machine these grooves? Can you do it by hand with a die grinder or something? Or can I assume you use a milling machine?
03-17-2007 08:57 PM
automotive breath
Originally Posted by baddbob
What determines where to place the grooves?
For the most part the valves limit where grooves can be laid out. Most
multi groove heads that you see from me are either my thinking or ideas
I get from others.
03-17-2007 08:52 PM
automotive breath
Originally Posted by F-BIRD'88
...Something, is defiantly going on inside there...
I conclude flame speed is much faster. Conditions in the cylinder and
in the exhaust port near the valve at the end of the exaust stroke
are much different, this has a positive impact on the intact tract
during overlap.
03-17-2007 08:44 PM
baddbob What determines where to place the grooves?
03-17-2007 06:40 PM
automotive breath
Originally Posted by F-BIRD'88
One of these days I'm going to try this......
When you’re ready shoot me a line at [email protected]: I'll help
you get started.

Last night I was getting ready for first round of the Friday night races and I
got a call from Mark, a long time racer/hot rodder. He had installed his 355
with these Edelbrock RPMs in his project 63 Nova. He is very familiar with the
engine it came out of his previous street rod. He fired it up for the first time
after installing the modified heads. He couldn't believe the difference. With
a 280 degree Isky hydraulic cam the engine now idles cold at 500 RPM with
no choke. Throttle response is crisp and instant.

03-05-2007 10:40 AM
Telvm Cutaway of the Honda CVCC engine.


It managed to comply with contemporary emissions regulation without EFI or catalityc converter. That's some combustion efficiency.
03-04-2007 08:40 PM
automotive breath
Originally Posted by xntrik
...Burn efficiency and coolant/exhaust temperature, mmmmmm????? There is something else we should be measuring.
Ignition advance, air/fuel for maximum power, lean burn misfire limits and
HC emissions to mention a few.
03-04-2007 08:28 PM
xntrik This is all about combustion efficiency, right?
I never thought about this again until UR50SLO and Telvm mentioned it.

Fall of 81 I bought an 80 Honda CVCC 1600 with 16,000 mi on it. The 3 valve statified charge engine, with a precombusion chamber like a tootsie pop. The burn begins in the little spherical chamber and squirts into the main chamber through the "stem" abruptly making burning turbulence for efficiency.

That car was cold natured. I drove it all winter and froze my buns off. I replaced the 195 thermostat 3 times and unless you exceeded 50 mph at 40-* ambient, it would NEVER make enough heat to keep my feet warm. At 30* F you could literally hold your hand on the exhaust and even the heater hose would be cool. It was too efficient in town. I bought a new 83 Accord 1800 non-cvcc and it was better, but not great. (Later I got a new 87 Horizon 2.3 that got much-much better gas mileage than either.)

Burn efficiency and coolant/exhaust temperature, mmmmmm????? There is something else we should be measuring.
03-04-2007 08:27 PM
automotive breath A couple of years ago I did some testing on a mild 355 in my 67 Camaro.
Before grooves I would stage the car at the drags at 150 degrees, at the
finish line the engine temperature would be up to ~ 180.

I grooved the heads with no other changes made, at the track I would
leave the starting line at 150 degrees just like before, at the finish line
the engine temperature was 160 degrees. I knew something has very

03-04-2007 07:46 PM

Roller-Wave....What Is It?

In the mid-to-late '70's, I found that biasing the mixture to the exhaust-side of the piston netted lower fuel consumption, as well as considerably less tendency for detonation in 2-valve NASCAR and drag race engines. Those experiments ultimately lead to swirl combustion technology that dominates 2-valve race head design today.......

....I've incorporated less piston dome volume on the exhaust-side with both more piston to head (quench) clearance, as well as the trough that incorporates both exhaust valve relief's.....

.....When one has the ability to shape the combustion event using mechanical design, it's possible to also design the tuning parameters the engine will "want", rather than living with compromised tuning and performance created by the use of more generic combustion space designs.
03-04-2007 07:44 PM
Telvm The radiator fan in my grooved engine is in the unemployment now, never cuts-in even after long idling. As a matter of fact I had to keep it five minutes at 3000 rpm while static in the garage to force it to connect at 100 ºC (212 ºF), just to be sure it was still in working order.

I can now climb into a nearby 5500 ft. mountain pass two consecutive times, chastising it in third gear (just for the fun of it), and at the top the engine temp remains below 90 ºC (194 ºF).

Combustion is faster and more complete with the grooves + higher CR combo, hence less heat is dumped into the cooling system and EGTs are lowered.
03-04-2007 02:58 PM
UR50SLO I forgot to mention that this is the only car I can think of that I can hold my hand on the down pipe (just after the turbo) at Idle. It does not matter how long you let it idle it won't burn your hand. It's warm but not hot.
I've tried this on other cars with my exact engine and it'll scald your hand almost immediatly. Explain that to me if the grooves don't work
03-02-2007 12:28 PM
My Grooves...

Great pictures and storys guys...

Here's what I did to the heads on my 89 Nissan Maxima that is turbo charged.

The stock engine has 226,000miles now. It's been turbo charged for the last 60,000 with the grooves in heads. I did drive it for about 4000mi with no grooves but that's about all. When I pulled the heads I decided to do the grooves from the article in Popular Science.

It's very hard to detonate this engine. It's run a best of [email protected] with pump gas on street tires. That's 181CID (3.0) with 12-13psi boost)
V6 for those who are not familiar with the engine.

I'll be doing this to the engine going in my Camaro (87 GN engine) with allum. heads. We'll see how well that does!

Thanks, Scott~
03-02-2007 11:40 AM
xntrik I think that many have missed the point that the grooves are not there to directly create higher hp at rpm, but to reduce detonation.

The grooves are claimed to reduce detonation to a degree that might allow lower octane fuel OR higher compression which in itself gives a power increase.

Detonation is most prevalent at high load lower rpm situations. High BMEP. Such as towing, etc. Which in some viewpoints is not all that different than an accelerating drag or circle track race engine.
I think we all understand that the higher the rpm is, the less octane is actually needed since the actual "clock time" available to burn the fuel is so short (milli seconds) that detonation doesn't have time to occur. So the effects of grooves is greatly reduced as rpms increase.

"Side" effects of speeding the burn and its resultant reduction of necessary ignition timing advance reduces the power loss of expanding gases before TDC, so the overall power output is increased. Exactly the effect heart shaped combustion chambers have created.

Many of us have discovered by trial and error that under a high-rpm high-load pull in high-gear that LESS ignition timing often produces more pull. And computerized engines are programmed this way. Also this is the situation that vacuum advance cans enhance. Less timing under heavy throttle.
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