DavidNJ

"The advantages of this patented, three-valve, retrofit cylinder head are:
"• Increased curtain area not only provides better performance and drivability from mildlytuned
engines, but also on engines with high performance and racing components the new “three-valve”
outperforms conventional heads

"• Provides exceptionally good cylinder filling with smaller valve openings
"• Smaller valves require smaller and lighter valve springs; therefore lighter valve-seat pressures,
less inertia, higher revs, and more power
"• On mildly tuned applications, higher valve lifts are unnecessary as low valve-lift flow is
dramatically improved
"• Impressive power and drivability with less wear-and-tear on rockers and springs and valve gear"

BrentB@TEA

chambers look similar to rotated 3 valve mustang heads. Would have been nice if they did not put the exhaust valves together like a regular small blaock chevy .

Wnts2Go10O

iTrader: (12)

super expensive and not really worth it

Another_User

I think these have proven to be a failed GM gimmick.

Grant B

The spark plug is in the side of the head... Horrible for effeciency and det. resistance.

prostock_bigblock

iTrader: (11)

Are these new ls1 / ls6 heads production or what exactly ???? If it is , r there any kind of test results on them or dynos? ,, how reliable r theses heads ..... etc .

info plzzzz

Why ?

DavidNJ

These are a new Barry Grant aftermarket head for SBCs. An an indication that it can be done for LS1s.

The port locations were probably diictated by a requirement to use existing manifolds. I believe the target audience is the hot rod community (rather than the racing community).

Another_User

Just because it CAN be done, does not mean it should be done, or even that it will be worth a crap.

Speedfreaks101

At the same time it is possible that that it could offer advantages.

Also there are are the dominion cylinder heads that are a four valve design for SBC (non LS1).

prostock_bigblock

iTrader: (11)

Thats what I thought ...

rons 00z

iTrader: (10)

do you really know that or are you talking out your ***? last time i knew barry grant didnt even release a price yet nor did he let out any flow charts. if he did it was a very recent release that i didnt know about.

actually the dominion heads no longer exist they are now being redone with a company called arao enginerring. dominion had problems with castings and cutting corners with product. also for a FYI arao also has BBC, and SBF heads theres even a rumor about some cad drwaings fo the four valve ls1 head but like i said it's all rumor

DavidNJ

Wow!!!

http://www.araoengineering.com/
Stock cam and pushrods. Head, valves, springs, shaft rockers, valve covers, gaskets for under $7000. VE stays there right to the redline providing way more peak power with a much flatter torque curve with seamingly mild cams.

How about 660hp with a 750 carb and 226/.52" lift cam? How about 300cfm at .4" lift on the mildest 4" bore version, or 330cfm on the stronger 4.125" more (In the 350-375 cfm peak range). And don't forget the racing only custom intake straight high rise port version (clear straight view of the intake valve from the port).

E-mailing them about an LS1 version.

Why did Barry Grant even bother?

Their info on my 4-valves are better:

Intake valve flow and horsepower
This huge valve area can be used with no loss of low end torque. This is because the ports can be made with the same cross sectional area as a 2 valve head. (the CC’s of the runners that is commonly used). This means that the port will have the same velocity as a 2 valve head, hence the same low end torque. Similar to a long hallway that is the same size, but with 2 big doors at the end instead of 1. The hallway will get up to high flow earlier because the area of the doors opening can reach the full flow of the hallway much faster. So with each opening and closing of the doors, since they get up to the large area earlier are flowing the full capacity of the hallway for a longer period of time. (Meaning more crankshaft degrees of high intake port flow). This gives us a higher overall average velocity, and this fills the cylinder with more air fuel mixture on the intake stroke and makes more horsepower, since more air fuel mixture in, means more to explode, a higher cylinder pressure to push the piston down and more horsepower.

Curtain flow area defined, is the (perimeter of the valve) X (the height of the lift). This is the actual flow area (the actual flow window) that the air sees. The band of area around the lifted valve to seat.

INTAKE:
1) A 2.02” intake valve X .600” lift has a curtain flow area of: (2.02”) X (3.14) X (.600)= 3.81 sq. in.

2) 2: intake valves at 1.65” each X .600” lift has a curtain flow area of: (1.65”x 2 valves) X (3.14) X (.600)= 6.22 sq. in.


What this huge curtain area increase does is open the flow window of the air much faster and earlier in the valve lift cycle. Even if we take two heads, a regular 2 valve head and a 4 valve head. They are both ported for 300 CFM of intake flow. (by the way none of our heads flow this little) The 4 valve will still make substantially more horsepower and torque. Why? Because with the intakes reaching high flow much earlier, (for example most of the 4 valve heads flow 50% more air at only .050” lift than an aluminum 2 valve head) there are many more crankshaft degrees of really high intake flow to more fully fill the cylinder. The same peak port velocity, but a higher average port velocity because it starts earlier and ends later.

This can be shown graphically when the two intake flow graphs are overlaid on the same page. The area under the curve difference shows how this phenomenon works. This difference in the way the two different types of heads work must be understood to fully comprehend the performance gain.

This is the main reason for the difference in performance over the standard head.

Exhaust valve flow and horsepower
EXHAUST:
1) A 1.6” exhaust valve has a curtain flow area of: 1.6” X 3.14 X .600” lift = 3.01 sq in.

2) 2 exhaust valves at 1.40” each has a curtain flow area of: (1.40” X 2 valves) X (3.14) X (.600” lift) = 5.28 sq in.

What this increase in exhaust curtain flow area does is enables the cylinder to be evacuated with less energy from the piston needing to push out the spent gases. This less back pressure allows the cylinder to be more fully evacuated, leaving less hot dead no oxygen gases to take up precious space that the new incoming fresh charge can occupy. This works well in normally aspirated motors, but is further exemplified in blown or nitrous motors.
This is why the 4 valve heads have nearly twice the exhaust sound than 2 valve heads. The sudden hot gases opening to atmosphere, makes the largest sudden pressure differentiation and the most noise. This is why the Small Block 32 valve sounds like a KB Hemi.

On the exhaust stroke this faster area opening of the doors means that the superheated exhaust gases are taking less pressure to push out the ports, which means the piston doesn’t need to push as hard against the gases. And taking less crankshaft horsepower to evacuate the cylinder. Meaning more crankshaft horsepower available. There is also a more complete evacuation of the exhaust gases, meaning a cleaner chamber with no contamination of non oxygen carrying gases to just take up useless space on the next intake cycle.

Combustion Chamber Design
The 4 valve per cylinder head incorporates the most modern of combustion chamber designs. The centrally located spark plug offers the shortest flame front to any spot in the cylinder bore. The 360 degree squish band accelerates all of the air on the compression stroke to the center, making the fastest most completely burning chamber of all. Making the motor less prone to detonation. This is why the 4 valve head can run half a ratio higher on pump street gas than any 2 valve head. Another advantage is the 2 exhaust valves, even though combined have much more area than one valve, do it with 2 smaller valves. They run cooler because of more cooling up the same size valve stems. This has less tendency to glow red and pre-ignite the mixture.

WS-Sick

I remember seeing something on these heads a long time ago and from what I have heard there were problems with them after installation. Maybe they are new and improved.

Wnts2Go10O

iTrader: (12)

its simple reasoning... there is a company that has 4valve heads for the sbc... those cost 7k now simple reasoning would put these heads at 4-6k... thats a lot to pay for in some cases no more hp than a 1400dollar afr sbc head.

DavidNJ

Actually, maybe 20-30% more hp, a lot flatter torque curve, and better low speed performance, for a given cam profile

Big-DEN

If efficiency of multivalve head is so much better than 2V, then RWTQ figure
of say a modular 5.0L ( 4.6L with 3.7" sleeves ) should be noticably higher
than that of a built 5.0L ford.

It isn't.

Curtain area formula's are suspect, because it doesn't account for
valve stem impedement to flow, also frictional losses of the air against the cyllinder wall.

We are talking about stuff here, how a single 3.5" or 4" pipe flows more than 2-2.5" pipes, this already is established.

Biggest benefits of multiple intake valves is to me:

Reduced valve weight,allowing higher valve train speeds before float.
Ability to close one port at lower speeds promoting better cyllinder fill/tq
at lower speeds.

Exhaust valve sizing is a tough one. Some really high HP N/A motors with only a 1.6" exhaust valve, the high pressure and temp on the exhaust side of the system along with the efficiency of tuned length headers really gives exhaust side alot of help.

DavidNJ

Peak TQ should no or only a modest increase. It typically occurs at a low engine speed and should reflect optimal VE. However, the 4-valve maintains that at higher engine speeds. And with less radical cams.

Most of the discussions here have focused on weight and packaging. And in those, the compact LS1 allows more low end power and equal HP from more displacement instead of the the complex, large, DOHC 4-valve systems.

This, however is a relatively compact pushrod 4-valve head. And it gets combustion chamber advantages in addition to larger curtain area with similarly sized ports to 2-valve heads.

There site claims very extreme power levels.

slyws6

Personally I'd rather see something like this produced....



-Sly

Another_User

Aaah yes. I was looking for that link. Thanks!

slyws6

What's sad is they have made them for SBF's (at least according to articles I have read) and made something like 445rwhp on a stock 302. Once again just rumors from articles. I would like to see an LS1 based head like this. Put in a good set of rod bolts and you can rev that thing to the moon!

-Sly