Splayed Valve Heads Porting

[FieroWanaBe1]

https://www.speed-talk.com/forum/viewtopic.php?t=50362
L83 heads.
https://katechengines.com/i-30497945-ka ... -pair.html
Katech wont port the runners on L83 heads becuase they claim they see no gains. Comparing Katechs porting results to other companies with LS stuff, I wouldnt call them the and all be all, but they have all the good tools at thier disposal and ask a fair price. The DI ports are relatively huge compared to a EFI or Carb head because they dont flow wetted air. But for shape comparison this could be useful.

[FieroWanaBe1]

even down the valve center line, the bowl on the far side of the valve (when moving along the direction of air velocity), the port constricts to the valve seat area, as opposed to other designs, where the bowl radius follows the short side radius and share or have close arc centerpoints.

[SappySE107]

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[SappySE107]

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[FieroWanaBe1]

Does Dynomation estimate in cylinder cycle pressure? Engine Analyzer Pro has the data, if I had a sample engine I could try, but would be guessing a lot about the engine.

My mind wants to know what the difference is between the port pressure and the cylinder pressure during the cycle.
Of course optimizing this is important. But at what point is it most critical for total performance, This I have no Clue.
What's interesting, is at peak torque 5000rpms, around .100 lift IVC is where the wave tuning is at peak pressure on the intake.
At peak Power the wave tuning pulse peaks at IVC seat timing. At 3000RPM the wave tuning pulse is closest to the valve open point.
Thats more an experimentation on induction design.

But using the pressure data, and assuming 1 bar absolute is the scale, at peak torque and .1 lift, there could be a .25 bar differential at the valve, that's 100" h20. But it's clear at higher lifts the pulse tuning has less than 1 bar of pressure, I assume here the cylinder is at vacuum at this point in the cycle, it would have to in order to maintain flow in the correct direction.

Obviously the low-mid lift flow can have a big influence on the final parts of the intake stroke, because that is where the wave tuning is making its biggest effect.
And that is why the valve job is critical and the first 1" of the port from the valve back.

[SappySE107]

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[FieroWanaBe1]

We have less length of intake port in our heads than most engines, and more exhaust port. You can't compare flow/cc between those heads. You could for any aluminum head pushrod GM 60V6 though.

LX9 109.29 CFM/CSA 210.5/1.926
LS3 109.94 CFM/CSA 312/(260/16.387/5.591)
LS6 106.71 CFM/CSA 248/(209/16.387/5.488)

TAYLORS FORMULA FOR MCSA:
MIN CSA = (bore x bore x stroke x RPM x .00353) / 613.8 (.55 MACH x 1116 fps) = 1.82IN^2 = 3.7"X3.7"X3.31"X6000X.00353 / 613.8
PORT VOLUME MIN = 1.56 * 3.51 * 16.387 = 110CC
BELLS FORMULAS:
Intake Cross Section Area = Cylinder Volume X Peak Torque RPM/88200
1.82 =214/6*7000/88200
Intake Cross Section Area = Cylinder Volume X Peak Torque RPM/88200
Cylinder Volume=60/RPM*(Dur/360)*(FPS*12)*CSA
88000=60*220/360*200*12
Flow_@28" = ( CID * RPM * .000978474 ) / Number_of_Cylinders
FLOW=244CFM

[FieroWanaBe1]

.23 Bar peak differential at near .08 intake lift and .1 exhaust... 92 in H20

.06 Bar differential at peak lift... 24in H20

.26 Bar peak differential at near .08 intake lift IDC 104 in H20

[SappySE107]

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[FieroWanaBe1]

I bet throat dia minus stem diameter is close to that....

[FieroWanaBe1]

I fixed some arithmetic errors, after digging through this some more updating specs for the LX9 data.

[SappySE107]

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[FieroWanaBe1]

The formula is just a baseline tool developed ages ago by engine designers based on the testing at the time,
.55 mach is used because ports at the time would choke at higher speeds because of the general shape. Modern designers using more vertical ports see up to .68 Mach before choke, is the LX9 one of those, maybe, but its not a race OHC port either.

a 1.545 throat and 8mm stem has a 1.19 CSA, which formulas out to 4550 RPM.
at 6000 rpm min CSA is 1.56.
Thats minimum, based on the formula anything smaller will experience choke on smaller CSA's, the head will limit the motors ability to breath more air at that speed, theoretically.

Total airflow should always be considered. when running engine analyzer, at least the version I have used, head flow is entered, and intake flow is a multiplier input of that. The head gets a lot of attention as it's the last stop for the air fuel mix before entering the cylinder. if the intake runner isnt matched for the job, what the point?

[SappySE107]

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[FieroWanaBe1]

Is that head flow with manifold attached?

[SappySE107]

Yes, upper, lower, and 65mm throttle body.

[ericjon262]

even down the valve center line, the bowl on the far side of the valve (when moving along the direction of air velocity), the port constricts to the valve seat area, as opposed to other designs, where the bowl radius follows the short side radius and share or have close arc centerpoints.

True, I just felt like this was significantly more pronounced on the other cuts.

[ericjon262]

I fixed some arithmetic errors, after digging through this some more updating specs for the LX9 data.

so this is basically calculating average velocity for a given CFM and CSA?

[ericjon262]

I said I was going to compare these to a NASCAR R07 head, and I wasn't lying, so lets get to it.

First, a picture I found funny, the R07's Exhaust valve is almost as big as a stock LX9 intake.



The lifter spacing on the R07 is radically different than the 60V6, the following three pictures show why, for the most part, the ports on this head aren't really helpful from a inspiration standpoint. The tip end of the screwdriver points towards the pushrod of the valve the handle in rests on. Note the MASSIVE gap between the pushrods....







Now, lets examine the LX9 head and it's pushrod locations...









you can see that the positioning of the pushrods means that the port has to go around the pushrod, and the port has to have an odd shape, the R07 port is just a straight dump onto the intake valve. The exhaust side, is also a much smoother, straighter port, whereas the LX9 ports are parallel to the deck. that's not to say they're bad, they're just different.

more to come...

[FieroWanaBe1]

I fixed some arithmetic errors, after digging through this some more updating specs for the LX9 data.

so this is basically calculating average velocity for a given CFM and CSA?

Yes. The csa is input for the gasket, "pinch" pushrod area, and throat and curtian area os calculated.
In just wanted to see what area of the port has the most influence at what valve lifts.