CFD/CAD/Thread

[SpeierRacingHeads]

We will use this as the CFD thread. The CAD file Jon is simulating will be my Edelbrock Super Stock program. NHRA allows several aftermarket heads. Dart, RHS, World iron and Edelbrock aluminum. Most all combos offer an aftermarket head and NHRA adds weight to the class to run them. Traditional SS, you must run a combo that came in that car. GT, you can run any combo. GT was designed for front wheel drive conversion cars.

The combo I have the most data on is what I will be running. 1970 LT1 350, 360hp. The rule is 8.50lbs per NHRA 330 factor and 170 for driver. 2975lbs. This combo is 11/32 2.02/1.600 valve, 172cc head, NO chamber welding, 11-1 compression, up to 3.499 stroke, up to 4.080 bore, 5.70 rod, any manifold, 780 Holley Vac Secondary (QF 780 is legal), any oil pan. The piston rule is 1.41cc with a .090 max height dome, unlimited camshaft. NO Vacuum pump.

This combo is 358cid with 50mm Bullet cam 1.7/1.6 rocker, 17/8-2.00 header, 30" long, C-12 fuel, and the heads I have flow data and pics of below. This engine runs 9.40's on the 10.25 index at 2975lbs. I'm building a new combo with everything different.

The port program comes out of the machine with the epoxy already in place. I then hand tweak and hand finish. This head had a 50º seat and 92% throat.

I will add more as the thread goes.

[SchmidtMotorWorks]

Thanks Chad
This is the scanned data that we will use as a starting point.
Starting Sunday evening PST I will start showing how I work with it.

Import_IntakeCylinder5_CFD IGES.png

Import 1803Chamber5trueSize STL.png

[Erland Cox]

Thank you both for this very interesting thread!

Erland

[fordified]

We will use this as the CFD thread. The CAD file Jon is simulating will be my Edelbrock Super Stock program. NHRA allows several aftermarket heads. Dart, RHS, World iron and Edelbrock aluminum. Most all combos offer an aftermarket head and NHRA adds weight to the class to run them. Traditional SS, you must run a combo that came in that car. GT, you can run any combo. GT was designed for front wheel drive conversion cars.

The combo I have the most data on is what I will be running. 1970 LT1 350, 360hp. The rule is 8.50lbs per NHRA 330 factor and 170 for driver. 2975lbs. This combo is 11/32 2.02/1.600 valve, 172cc head, NO chamber welding, 11-1 compression, up to 3.499 stroke, up to 4.080 bore, 5.70 rod, any manifold, 780 Holley Vac Secondary (QF 780 is legal), any oil pan. The piston rule is 1.41cc with a .090 max height dome, unlimited camshaft. NO Vacuum pump.

This combo is 358cid with 50mm Bullet cam 1.7/1.6 rocker, 17/8-2.00 header, 30" long, C-12 fuel, and the heads I have flow data and pics of below. This engine runs 9.40's on the 10.25 index at 2975lbs. I'm building a new combo with everything different.

The port program comes out of the machine with the epoxy already in place. I then hand tweak and hand finish. This head had a 50º seat and 92% throat.

I will add more as the thread goes.

That's a nice flow curve. Makes very good power. Impressive torque.

Have you used up all the intake port volume, or are you running them smaller? I ask because I'm carb limited too.

[FC-Pilot]

This is the most transparency we will ever see in this class. Thank you guys!

Paul

[SpeierRacingHeads]

We will use this as the CFD thread. The CAD file Jon is simulating will be my Edelbrock Super Stock program. NHRA allows several aftermarket heads. Dart, RHS, World iron and Edelbrock aluminum. Most all combos offer an aftermarket head and NHRA adds weight to the class to run them. Traditional SS, you must run a combo that came in that car. GT, you can run any combo. GT was designed for front wheel drive conversion cars.

The combo I have the most data on is what I will be running. 1970 LT1 350, 360hp. The rule is 8.50lbs per NHRA 330 factor and 170 for driver. 2975lbs. This combo is 11/32 2.02/1.600 valve, 172cc head, NO chamber welding, 11-1 compression, up to 3.499 stroke, up to 4.080 bore, 5.70 rod, any manifold, 780 Holley Vac Secondary (QF 780 is legal), any oil pan. The piston rule is 1.41cc with a .090 max height dome, unlimited camshaft. NO Vacuum pump.

This combo is 358cid with 50mm Bullet cam 1.7/1.6 rocker, 17/8-2.00 header, 30" long, C-12 fuel, and the heads I have flow data and pics of below. This engine runs 9.40's on the 10.25 index at 2975lbs. I'm building a new combo with everything different.

The port program comes out of the machine with the epoxy already in place. I then hand tweak and hand finish. This head had a 50º seat and 92% throat.

I will add more as the thread goes.

That's a nice flow curve. Makes very good power. Impressive torque.

Have you used up all the intake port volume, or are you running them smaller? I ask because I'm carb limited too.

Yea, it's all used up. They all came out of the machine the same but I usually end up tweaking when I'm hand finishing.

[Chris_Hamilton]

Dumb question but I'll ask it. What is the expected or hoped for outcome here? A better designed port? How much improvement is possible?

[fordified]

Dumb question but I'll ask it. What is the expected or hoped for outcome here? A better designed port? How much improvement is possible?

Mapping the entire port can be used to identify what's right and what's wrong with the port design and chamber. You can't get anywhere near that kind of depth of information with a pitot tube alone.

CFD will show you where airspeed is too high, too low, gradients, vortices, turbulence, the direction of the flow path and a bunch of other incredibly useful information.

[Tom68]

Dumb question but I'll ask it. What is the expected or hoped for outcome here? A better designed port? How much improvement is possible?

Race wins I should think.

You do what ever it takes to get them.

Smart engineering can save time and sometimes money to get you there.

[SpeierRacingHeads]

Dumb question but I'll ask it. What is the expected or hoped for outcome here? A better designed port? How much improvement is possible?

Like I said in the original thread, I just want my guys faster. I would consider selling a kidney, so this is much easier if we do indeed accomplish it!

[1980RS]

Chad are you CNC'ing any BBC cast iron heads? I have a friend who is interested in some of your work.

[SpeierRacingHeads]

Chad are you CNC'ing any BBC cast iron heads? I have a friend who is interested in some of your work.

No, all my iron days other than SS are over.

[1980RS]

Chad are you CNC'ing any BBC cast iron heads? I have a friend who is interested in some of your work.

No, all my iron days other than SS are over.

Thanks Chad, I will let him know.

[SchmidtMotorWorks]

I am working to line up the CAD with the scanned models now.

I could use a few dimensions but can make progress without it.

1. The head casting (I thought it was mentioned but can't find it now)
2. The valve axis to deck face intersection points?
I don't have my Chevrolet Power Books here, but I think some editions have the stock dimensions.
If it is an Edelbrock head, I think those dimensions were once in some catalogs.


3. The inside and outside diameter of the valve seats and the angles (I think the intake angle is 50)
4. Valve guide angle, I am using 22.5 but it isn't lining up exactly with the scan.
5. Valve job depth, measure from deck down the OD edge of the sealing cut (50)

[SpeierRacingHeads]

I am working to line up the CAD with the scanned models now.

I could use a few dimensions but can make progress without it.

1. The head casting (I thought it was mentioned but can't find it now)
2. The valve axis to deck face intersection points?
I don't have my Chevrolet Power Books here, but I think some editions have the stock dimensions.
If it is an Edelbrock head, I think those dimensions were once in some catalogs.


3. The inside and outside diameter of the valve seats and the angles (I think the intake angle is 50)
4. Valve guide angle, I am using 22.5 but it isn't lining up exactly with the scan.
5. Valve job depth, measure from deck down the OD edge of the sealing cut (50)

Edelbrock (basically Performer RPM)
I don't know #2
2.200/1.650.
1.860/1.470 throats 40/50/65/75/82
Try 22.3 on valve angle
The free drop is .020 intake and .100 exhaust with .060 intake margin and .080 exhaust