3100/3400 Cylinder Head/Port Specs

[TGP37]

Thought I share my results. Stock heads, no extra mods. Measured with water and a syringe. Sealed with glass plate with 1 little hole to prevent surface tension distortion of reading.

Volume (inc valves, plugs)
- Intake port volume: 98.2 mL

- Exhaust port volume: 65.5 mL

- Cylinder Head: 27 mL
(no gasket, no piston..just the head)

Other Stuff
- Exhaust port cross section: 1.35" square
equivalent to 1.3" ID

- Exhaust port circumference: 4.2"
equivalent to 1.3" ID

- Distance from exh valve seal to port end: 3.4"
(includes the curve in path)

- Exhaust port exits 75 degrees from parallel of head (left/right axis), perpendicular (up/down axis)

- Valve and port "D" shape are rotated 10 degrees from center.

[robertisaar]

knowing GM.....

27ml = 27cc. the compression ratio calculator shows the 3100/3400 heads to be 28.6cc, probably within their tolerance.

[SappySE107]

Intake port cc = 111.6
Exhaust port cc = 70

http://60degreev6.com/forum/showthread.php/24980-3100-3400-Head-Flow

The 28.6 cc chamber is also one of my measurements.

[TGP37]

111.6 against 98.2, that's a substantial difference ratio of 1.13. I sure hope that is not the average error ratio across all 3 ports.

Hmm, now I'm curious to see what the ratio of difference is across the 3 ports. And if that difference is persistent across many heads of the same type.

It would take a long time but this seems like a great method to balance the port volume....and thus balance the velocity and displacement among cylinders.



Would it be feasible to skew an injector to reflect the port volume difference from average base line?

It wouldn't compensate for injector difference, but flow difference still effects AFR.

[robertisaar]

i could be wrong, but i doubt you can consistently relate port volume alone to airflow without actually putting it through a flowbench to see how well each runner/port actually does.

[TGP37]

i could be wrong, but i doubt you can consistently relate port volume alone to airflow without actually putting it through a flowbench to see how well each runner/port actually does.

Yeah, the sum of all parts. I believe it.

Probably best just to balance them. But then we would have to find where in the port the difference is at.

[SappySE107]

Nah, they aren't that different port to port. No way in hell. Something else is different between our testing, because 27cc is much smaller on the chamber than I have ever seen, and I have done more than a few heads worth of CC measurements. Intake ports, the older casting 3100 were less consistent, but 10+ cc is hard to account for. Id just chalk this up to differences in how they were measured and not comparable.

[TGP37]

Nah, they aren't that different port to port. No way in hell. Something else is different between our testing, because 27cc is much smaller on the chamber than I have ever seen, and I have done more than a few heads worth of CC measurements. Intake ports, the older casting 3100 were less consistent, but 10+ cc is hard to account for. Id just chalk this up to differences in how they were measured and not comparable.

I believe you, and what's even more funny or disturbing is I used a childs dosage syringe. Figured that would be accurate enough. Surely they can't be off by that much?

Oh right, they are used and have a small layer of carbon. But only 300 miles worth. Did you measure with the valve present? Open or closed?

From what I measured, the exhaust valve (the portion that moves into the chamber from behind the seat seal) displaces 3 cc's. So the chamber and port oscillate 3 cc's during operation. Not including the valve stem as that is a constant in the port, but isn't a constant in the chamber.

That change, I wonder if that is partially responsible for pressure waves fired up the runners. As slamming an additional 3 cc's into the port should create some form of wave. Like wise opening the valve should create a negative wave from the valve head displacement shift.

Not that is matters too much, but for extreme accuracy, maybe.

[SappySE107]

Valves installed, closed. Hard to CC a port or chamber with no valves but someone might try that. 3400 vs 3500 valves would make a difference, but you can't have 3cc in the port open vs closed because the material in the chamber never goes inside the port. It doesn't matter for compression when the valve is open and it doesn't matter any formulas I know (which doesn't mean much, I hate math) that involve runner lengths, diameters, and volume.

Have I mentioned that I really want a dyno? Some day.

[ericjon262]

Have I mentioned that I really want a dyno? Some day.

why would you want one of those! :P

[TGP37]

To own a dyno......I would love to own a shop with all the tools one could want.

[pocket-rocket]

Don't forget the strip out back.

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