[automotive breath]

I'd like to thank everyone that helped me decide on the compression ratio for my current project on this thread: Ported and Milled Vortec heads on stock 350

As mentioned this is not my engine and as a result of the comments; I will take a conservative approach with compression. The chambers measured 65cc before milling, target after milling 62cc. Estimated compression ratio as follows, 0.5 less than my original target:

Cylinder Head Volume (cc) 62
Piston Head Volume (cc) 10
Gasket Thickness (in.) 0.026
Gasket Bore (in.) 4.166
Cylinder Bore Diameter (in.) 4.0
Deck Clearance (in.) 0.030
Stroke (in.) 3.48
STATIC COMPRESSION RATIO 9.53:1

Two Singh grooves were cut in the chambers as shown, I will post better pictures after the mill and valve job.

 

[DaSouthWon]

I understand the theory of the singh grooves, but it seems that this is just the opposite of the effect of polishing a combustion chamber. As I understand it, these grooves are made to create turbulance from the squish area. Let me know if you notice any difference. Why not just design a head with a convoluted squish area. I'm sure I don't have a thorough understanding of the process so I may be totally wrong. Enlighten us!!!

 

[curtis73]

If you're ever at the beach, dig a trench with your heel in the sand near where the waves reach their highest. When the water retreats, it falls into that groove and rushes back. Where the returning water hits the water line it creates a lot of turbulence.

A flat quench area is like a book that you set down on the table. The air is forced out in a flat space. Cutting the grooves makes two points of intensified flow out of the quench area just like that channel in the sand. Its just a way to add more turbulence to the quench process.

 

[automotive breath]

If you're ever at the beach, dig a trench with your heel in the sand near where the waves reach their highest. When the water retreats, it falls into that groove and rushes back. Where the returning water hits the water line it creates a lot of turbulence.

A flat quench area is like a book that you set down on the table. The air is forced out in a flat space. Cutting the grooves makes two points of intensified flow out of the quench area just like that channel in the sand. Its just a way to add more turbulence to the quench process.

Curtis is absolutely right, I did a test, lets call it privative wet flow. I put a gasket on a grooved head and placed a piece of plexi glass with a hole in it over the squish area. With a low pressure parts washer, I blew solvent into the hole; some of the solvent blew out of the squish window, the rest exited out of the groove in a stream. I concluded, with this groove as a guide, you can decide where you want the concentrated squish to flow. Now I cut them in many directions trying to decide what works best.

I've been doing this for over two years, at first with the direction of Somender Singh. Some folk’s say this won't work, I have never heard that from someone that has tried it!

 

[curtis73]

Automotive breath, I won't hijack the thread, but if you have any links or tech on Singh's grooves, I'd love to hear it via PM or email. I have a set of Vortecs going to the machine shop this week and this has been a consideration of mine. I like the benefits but I wouldn't have the first clue as to where to start cutting.

 

[automotive breath]

Automotive breath, I won't hijack the thread, but if you have any links or tech on Singh's grooves, I'd love to hear it via PM or email. I have a set of Vortecs going to the machine shop this week and this has been a consideration of mine. I like the benefits but I wouldn't have the first clue as to where to start cutting.

Curtis, contact me at [email protected]

The best information got wiped out when this site crashed: turbobricks

My good friends at mpgresearch love what it does for fuel economy.

I have a TBI iron head 350 running on 87 octane at 10:1 compression towing my race car.

I have done over 30 engines, mostly race cars, details will follow, I have a torque convertyer to change for the turkey drags !

 

[DaSouthWon]

how deep and wide? triangle or rounded cut?

 

[automotive breath]

how deep and wide? triangle or rounded cut?

how deep and wide? This is difficult to answer because it widens and contours into the chamber.

triangle or rounded cut? I have done both, round is less likely to develop cracks, by the way,I have never seen one crack.

 

[NAIRB]

If this is a stock Vortec head, you can just count on the heads cracking. They are so thin that I can't imagine them not forming a crack out the exhaust seat right into your groove you've put in that already miserably thin deck.

I hope you defy the odds, but they are against you. I hope you didn't run that right up against the fire ring of the gasket.


Nairb

 

[automotive breath]

If this is a stock Vortec head, you can just count on the heads cracking. They are so thin that I can't imagine them not forming a crack out the exhaust seat right into your groove you've put in that already miserably thin deck.

I hope you defy the odds, but they are against you. I hope you didn't run that right up against the fire ring of the gasket.

Nairb

Hi Naiab, I sure hope you're wrong about the cracks, I never cracked a head before.

I don't consider these heads thin, the 083 heads on my TBI truck shown are thinner with a 0.050" mill and a 0.030" deep groove, the thickness at the groove bottom is less than .200". These vortecs are thicker to begine with and I'm being very conservative with a 0.030" mill, should be plenty thick enough for a mild street engine.

These grooves end 0.080" short of the fire ring to relieve pressure at the bore, it works wonders to help control detonation and to prevent carbon contamination of the oil, I do this to all of my race engines.

 

[DoubleVision]

If there stock vortecs, I have to side with Nairb. I`ve seen Vortecs come into my former machinists shop, they were run hot once, and not very hot at that, one had 5 cracks, there was a crack from the water jacket out, where it`s a really thin area that`s obvious to the naked eye, the other area a crack developed was on the quench pad of the number 2 chamber.
We ordered some vortec heads from RHS, they were very heavy castings with real thick decks.

 

[automotive breath]

Here's a picture after the mill and valve job, these are production vortec heads 062 castings. The chambers ended up at 60cc, final compression ratio will be calculated when the deck hight is measured.

 

[jimfulco]

I seem to recall something in one of those articles from last year that Singh said the piston-to-head clearance had to be kept to around .070" to get any benefit with the grooves.

Anybody remember this, or has my feeble brain gone flatulent again?

 

[automotive breath]

Hi jimfulco,
I have had several discussions via email with Somender Singh on that subject.

With grooves and a large squish to bore ratio > 25% squish area with minimal detonation as the primary objective; his recommendation was between 0.050" to 0.70" piston to head clearance at engine assembly. Of course there are many variables to consider like intended RPM range and such.

Most people running with out grooves tend to go with a very tight piston to head clearance to eliminate detonation. This difference has been and will continue to be the subject of countless discussions.

In this example using a dish piston, the squish to bore ratio is very low, it is advantageous to tighten the clearance to generate more squish action.

Some of this may be my own general opinions, I hope I haven't mis quoted him.

 

[xntrik]

Thanks for the update. After lots of studying, I am totally convinced they work. :thumbup: And will be using them on my new SBF heads.
x

 

[xntrik]

Curtis is absolutely right, I did a test, lets call it privative wet flow. I put a gasket on a grooved head and placed a piece of plexi glass with a hole in it over the squish area. With a low pressure parts washer, I blew solvent into the hole; some of the solvent blew out of the squish window, the rest exited out of the groove in a stream. I concluded, with this groove as a guide, you can decide where you want the concentrated squish to flow. Now I cut them in many directions trying to decide what works best.

I've been doing this for over two years, at first with the direction of Somender Singh. Some folk’s say this won't work, I have never heard that from someone that has tried it!

As I said in a previous thread, :welcome: I knew a man who was doing this in '61-'63, some with 3 tapered grooves on each cylinder. His race engines performed well. I recall seeing a 2 cycle engine head he did that had 6 grooves because of the massive concentric quench area, tiny chamber, true flattop piston, and 14/1 compression.

 

[automotive breath]

Thanks for the update. After lots of studying, I am totally convinced they work. :thumbup: And will be using them on my new SBF heads.
x

Hi xntrik, the idea is really catching on locally. I have grooved several SBF engines. One in particular has been the biggest success to date.

A local Super Pro bracket racer heard about what I was doing and came to me for help. He is running very high DCR with a dome piston and a relatively small flat tappet camshaft. Detonation at the starting line went unnoticed and was causing engine damage.

We cut one groove in each chamber and opened his squish clearance to 0.070”. The car responded like I have never seen. The first night out it ended up on the trailer unable to control wheel standing. After a rear end gear change and chassis adjustment he is back on track running quicker and with more MPH than ever before.

Here are some pictures:

 

[rale]

the grooves??

do the grooves have to be strate or can they be at angels or curved? dose it mater how Minny grooves there are?? would it make a difference if the spark plug is lined up with the grooves wild that make a difference??

 

[automotive breath]

do the grooves have to be straight or can they be at angels or curved?

Does it mater how many grooves there are??

Would it make a difference if the spark plug is lined up with the grooves wild that make a difference??

Hi Rale, it has been determined that straight grooves provide greater benefit than curved. This is something that I have not tried; I’m reporting what I have heard from other people that have.

One groove work’s well, additional grooves add to the benefits, the most that I have tried is three in each chamber. I’ll attach a picture to show you what I did. With the SBC chamber it is difficult to fit multiple grooves because the intake valve can be close to the deck surface.

The grooves need to point towards the advancing flame front, not necessarily the spark plug. The objective is to create turbulence in the flame itself to speed up development. Here’s a post from another board that explains the benefits of turbulence in the combustion chamber.

… Spark ignition (SI) engines all work on the principle of a turbulent flame front (TFF) consuming the air-fuel charge. A normal combustion event would be considered one where the spark ignites the air fuel mixture (a complex process in itself) and the flame propagates throughout the air-fuel mixture with this turbulent flame front.

First, think of a chamber (say a cube or a disc for simplicity) full of nice calm, still air-fuel mixture. A spark in the middle ignites, and begins to consume the mixture. Ideally, the flame front (in this case a laminar flame front, since the mixture is still) would form a spherical shell, as it progresses. Now, this flame front is propelled by a couple of forces. First, the mixture in the wake of the flame front is obviously heated by the combustion. This heat translates to an increase in pressure. This higher pressure burned gas compresses the mixture ahead of the flame front. Since the volume of the burned gases expands it helps accelerate the flame front. Think of blowing up a balloon. The compression of the end gas also raises its temperature. Flame speeds are higher in higher temperature mixtures.

For a turbulent flame front, consider instead of a calm chamber, a chamber full of turbulent eddies, of all size scales. As the flame front approaches one of these swirling eddies, the flame edge is 'torn' and spun around by the eddy, into fresh mixture. This helps to shred up the flame front, and helps to progress the burn of the mixture. In short, this is really why SI engines work at all…

 

[bullheimer]

dead for 9 months

yo. can't believe this thread ended after less than two pages. anyway.
auto breath, why are the groove in your pic above coming from the exhaust valve? how did this work in comparison to coming from the spark plug and how did the multiple lines work compared to the single?

this is a great idea to me and my 400 pontiac because i am at .032 down in the hole and with a .039 gasket would be right at 71 down so perfect for this groove-thang!!! i have been planning on zero decking.