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Chasing dreams with a ball bat
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Discussion Starter · #1 ·
I am rebuilding the 406 due to some apparent detonation issues with the previous combination. That's a whole 'nother story.

The new combo: New flat top Wiseco forged pistons for 11.6:1 SCR, and with my cam of 236/244 112LSA specs, a DCR of 8.1, which should still work for pump gas if I'm more careful.

Heads: PRo 1 230cc,
Rods: 6" H beam 4340
Crank 3.75 stroke Scat 4340

The first debate:
I think that Singh's grooves might be useful in this combo due to the high compression. Pic 0005 below has a marker line where the groove would likely be cut. AB - is that about what you would do? I have somewhat limited resources as far as making the cut. Was thinking of going slow and steady with a die grinder if that's possible to do. I'm hoping for AB to chime in on this with some firsthand experience.

I'm not saying that the grooves will be a magic bullet, but merely an aid to get me where I want to go. From what I can tell, the addition of the grooves really can't hurt anything, and will likely promote a more uniform, efficient and complete combustion - all assumptions that are subject to debate by many folks.

The second debate:

Pics 0001, 2, 4 show a kind of radiused edge around the valve seats. Should I be smoothing this out? It seems like flow at low valve lifts would suffer with this feature right around the valve seats. Does anyone know if this should be totally smoothed out? Didn't want to remove it if it's actually there on purpose. You can obivously see a pretty heavy deposit in this radiused ring area from all the oil burned due to a misdesigned PCV system. This next motor absolutely won't have a PCV.

Thanks for any help / suggestions.
 

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hotrodf1 said:
The new combo: New flat top Wiseco forged pistons for 11.6:1 SCR, and with my cam of 236/244 112LSA specs, a DCR of 8.1, which should still work for pump gas if I'm more careful.
Hmmmm, I don't think so. The KB calculator says 9.45:1, way over the limit for pump gas. That's using an intake close of 47 degrees ABDC. I usually shoot for 8.0 to 8.3 on KB.

Use more cam or less scr or both and set the squish to between 0.035" and 0.045". Experiment with Singh grooves if you wish, but if you get the dcr down to around 8.0-8.3 with tight squish, I don't think you'll need them.
 

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More for Less Racer
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PM automotivebreath on this board, he is familair with the Singh's grooves. I get virtually the same DCR as techinspector, you are way too high, your .050" duration needs to be near 260° to get away with pump premium. What calculator are you using??
 

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I would NOT cut those grooves. Get a better cam and you'll be fine. your DCR calc's are WAY off, and no groove will fix that. Contact a good botique cam grinder with what you have and your goals nad they should be able to get you closer.
 

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Chasing dreams with a ball bat
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Discussion Starter · #6 ·
I am using Performance Trends' Engine Simulator program that popped out that DCR number.

I guess I'll have to calculate it another way and double-check it. That seems odd that the program would be off that far. Hmmm indeed.

I did PM AutomotiveBreath before I started this thread to see if he would be willing to give some input "on record". He probably hasn't had time to log on yet.

The squish distance will in fact be .045 as suggested. It was that way before as well. .005 in the hole with a .040 gasket gets it done.

Anyone have any input on grinding away in the chambers on those rings around the valves?
 

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Chasing dreams with a ball bat
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Discussion Starter · #7 ·
Chevrolet4x4s said:
That's about where i put them in my 406,still on the stand, I also added another small grove on the sparkplug boss (rhs vortecs)
Shane

How did you go about cutting your grooves? By hand or milled or ???

Just out of curiosity, what prompted you to try the grooves?
 

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I never calculate dynamic compression ratios so I don't know if what you
are attempting is too high for pump gas. Regardless the grooves will help
reduce auto-ignition tendencies along with other benefits.

With controlling auto-ignition; the ultimate goal is to keep the end gas
temperature below the auto-ignition temperature of the fuel. That groove
will help to speed the burn allowing a lower ignition advance setting for
maximum power. Less carbon contamination in the oil suggests lower
localized pressure in the end zone furthest from the plug.

These grooves are very common at the local drag strip, primarily used
because they result in a much cleaner running engine. Your proposed
location is good. I find additional benefit cutting the groove all the way
to the bore. Point the end of the groove right between the valves.
 

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hotrodf1 said:
...Anyone have any input on grinding away in the chambers on those rings around the valves?
The most important area in the chamber is just after the valves because of its
effect on flow cone formation. It's also the most time consuming and tedious
place to work. Grind material from the chamber wall. The final valve job
should blend right into your chamber work eliminating all ridges and as many
valleys as possible creating a smooth transition.
 

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Chasing dreams with a ball bat
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Discussion Starter · #10 ·
automotive breath said:
I never calculate dynamic compression ratios so I don't know if what you
are attempting is too high for pump gas. Regardless the grooves will help
reduce auto-ignition tendencies along with other benefits.

With controlling auto-ignition; the ultimate goal is to keep the end gas
temperature below the auto-ignition temperature of the fuel. That groove
will help to speed the burn allowing a lower ignition advance setting for
maximum power. Less carbon contamination in the oil suggests lower
localized pressure in the end zone furthest from the plug.

These grooves are very common at the local drag strip, primarily used
because they result in a much cleaner running engine. Your proposed
location is good. I find additional benefit cutting the groove all the way
to the bore. Point the end of the groove right between the valves.
There you are! Thanks for the info.

How do you cut the grooves physically speaking? Can this be done carefully with a die grinder and cut off wheel or is that a hack job that shouldn't be attempted?
 

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Chasing dreams with a ball bat
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Discussion Starter · #11 ·
automotive breath said:
The most important area in the chamber is just after the valves because of its
effect on flow cone formation. It's also the most time consuming and tedious
place to work. Grind material from the chamber wall. The final valve job
should blend right into your chamber work eliminating all ridges and as many
valleys as possible creating a smooth transition.

Okay, so the answer is that I want to smooth that ridge out and make it as smooth as possible. That makes sense to me, just wanted to get some feedback since I've not done this type of work before.

Thanks again for the info.
 

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I have seen several people cut the grooves with a cut off wheel, no problem if
you have a steady hand. One slip and you cut into the gasket area.

I cut the grooves 0.080" deep with a 1/16" ball end mill parallel with the deck
surface, I widen and deepen the groove at the outlet into the chamber roof by
hand with a file.

Gotta go change a crankshaft sensor for my daughter, be back later...
 

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hotrodf1 said:
How did you go about cutting your grooves? By hand or milled or ???

Just out of curiosity, what prompted you to try the grooves?
I first laid out the head gasket on the head,and traced around the fire rings with a sharpie,then laid out the grooves with a sharpie and a square.

I began the cut for the groves using a dremel type rotary tool(black and decker that I have half for about half my life) using a small cut off wheel,next I used a small diamond bit, and finished up the grooves with a couple needle files(round and flat,you can get these for a dollar or two at harbor freight)

Cleaner burning,which in my mind would lead to longer engine life due to less oil contamination. The detionation resistance,altho I shouldnt have to worry about this with only about 9.3:1. They also intrigued me,and since I was already building the engine I would give them a try. The mpg improvements were also a big deciding factor,as this is one of my goals for this engine.

Shane
 

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Chasing dreams with a ball bat
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Discussion Starter · #17 ·
I have the first set of grooves cut. Just used a die grinder with a disc and then used the needle files to finish them off, per AB's suggestions. I think they look pretty good. In aluminum, it really didn't take long to do either.

I used the old gasket clamped to the head with spring clamps to make sure the files didn't slip and gouge the sealing surface. Seems to have worked well. :thumbup:
 

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Chasing dreams with a ball bat
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Discussion Starter · #18 ·
Pics of Singh Grooves

Heres the heads all cleaned up, with grooves cut, CCs polished. Those standard abrasives CrossBuffs work great.

Should have the pistons this week, motor together in a couple weeks. :evil:

Contrary to suggestions that the DCR is too high (still not sure how my number is so different, I get the same thing every time) I'm gonna try flat tops with the current cam. We'll see what happens.
 

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