CFD/CAD/Thread

[SpeierRacingHeads]

The only downfall to all the new simulations is the entire roof to the back of the bowl will be epoxy, which is not a problem.

How important could a legal pro port type head be!

[F120]

I'm gonna bring on something I've seen a couple of times on here that's very much related.

Can you do exhaust flow?

This cfd image of presumably a nascar engine with what appears to be a nearly perfect curve in the exhaust is revealing at worst and revolutionary at best.

exhaustflow.jpg


It's just... If this is representative of reality I can't think of a port and exhaust layout what I've seen that would have full utilisation of the port or even the first few inches of primary. (Except maybe an extremely steep port on an inline engine)

I'm not sure a flow bench would show this at all?

Intake and exhaust manifolds affect the port shape dramatically. The length of the port itself and interface angle is arbitrary. The ports I've worked on were really much longer and then cut by the intake/exhaust interfaces. You often see ports that are modified to be perpendicular to the interface for no good reason.

[hoffman900]

I'm gonna bring on something I've seen a couple of times on here that's very much related.

Can you do exhaust flow?

This cfd image of presumably a nascar engine with what appears to be a nearly perfect curve in the exhaust is revealing at worst and revolutionary at best.

exhaustflow.jpg


It's just... If this is representative of reality I can't think of a port and exhaust layout what I've seen that would have full utilisation of the port or even the first few inches of primary. (Except maybe an extremely steep port on an inline engine)

I'm not sure a flow bench would show this at all?

Intake and exhaust manifolds affect the port shape dramatically. The length of the port itself and interface angle is arbitrary. The ports I've worked on were really much longer and then cut by the intake/exhaust interfaces. You often see ports that are modified to be perpendicular to the interface for no good reason.

They do because they’re only developing 2.5-3.5” of a duct that might be 10-14” total on the intake side and 18-32” or so on the exhaust side. That’s what the engine sees, not the 2.5-3.5” that resides only in the head casting.

[BLSTIC]

No I don't have an example port, but I'm kind of expecting this to follow a few trends and most exhaust ports to have a similar problem. Perhaps someone here does? Or if a "generic" port is easy enough to create could you do a low tight radius one like an MGA/Holden 6 and a more upright long radius one like an LS3? See how large the radius needs to get before the port is good and then we can all cry about how that will never fit in our chassis or rulebooks? :p

Oh, this is the same port/video as close as I could capture to tdc on my mobile. It's a little better in the pipe but not significantly better in the port, still supports the view that tiny off the head is good. Would be good to get at TDC though.

Screenshot_20230526-074029_YouTube.jpg

[SchmidtMotorWorks]

I had an interesting discussion with a CFD engineer.
His career was mostly involved with simulation of fuel motion and burning as it relates to fuel efficiency, emissions and durability mostly.
Detroit passenger cars and trucks, some high performance OEM stuff but not purpose built racing engines.

I told him about the controversy over whether intake ducts should have two relatively straight sections with a sharp blend
or
A gradually curved duct with tangent continuity.

He looked at me like this:

Dog-Tilting-Head-While-Listening.jpg

He said that of course the curved duct will flow more.
and
If the fuel is dropping out in either design, the solution would be to have smaller fuel drops.

[In-Tech]

I saved that picture, thank you
My dog understands all the electronics, cfd, etc. We just can't seem to have a decent conversation unless it's about dinner or snack time, carry on

[HQM383]

.....He said that of course the curved duct will flow more.
and
If the fuel is dropping out in either design, the solution would be to have smaller fuel drops.

Choose your carb venturi boosters and emulsion wisely and take note of fuel RVP.

[F120]

How important could a legal pro port type head be!

What does this mean.Does it have to be an approved casting?

Show me the list, I might have one, I need to look at it

[SpeierRacingHeads]

How important could a legal pro port type head be!

What does this mean.Does it have to be an approved casting?

Show me the list, I might have one, I need to look at it

Yes NHRA has several aftermarket approved castings. I sent them a ProFiler porters casting and they rejected it.

If you don't use the aftermarket, you must use the casting that came on the combo your claiming.

List of aftermarket

[williamsmotowerx]

I had an interesting discussion with a CFD engineer.
His career was mostly involved with simulation of fuel motion and burning as it relates to fuel efficiency, emissions and durability mostly.
Detroit passenger cars and trucks, some high performance OEM stuff but not purpose built racing engines.

I told him about the controversy over whether intake ducts should have two relatively straight sections with a sharp blend
or
A gradually curved duct with tangent continuity.

He looked at me like this:

Dog-Tilting-Head-While-Listening.jpg

He said that of course the curved duct will flow more.
and
If the fuel is dropping out in either design, the solution would be to have smaller fuel drops.

So which is it? Straight ports with quick short turns are the norm in the high revving 4 valve world currently. The curved duct is old school. That STL I sent you Jon is the last of the high performance curved ducts... Port was designed in 2022

[hoffman900]

I had an interesting discussion with a CFD engineer.
His career was mostly involved with simulation of fuel motion and burning as it relates to fuel efficiency, emissions and durability mostly.
Detroit passenger cars and trucks, some high performance OEM stuff but not purpose built racing engines.

I told him about the controversy over whether intake ducts should have two relatively straight sections with a sharp blend
or
A gradually curved duct with tangent continuity.

He looked at me like this:

Dog-Tilting-Head-While-Listening.jpg

He said that of course the curved duct will flow more.
and
If the fuel is dropping out in either design, the solution would be to have smaller fuel drops.

So which is it? Straight ports with quick short turns are the norm in the high revving 4 valve world currently. The curved duct is old school. That STL I sent you Jon is the last of the high performance curved ducts... Port was designed in 2022

How much does that have to do with packaging vs outright best practice?

I think the problem with these V8s is the single Holley manifolds. FI or tunnel ram straightens them right out. FI is even better since you don't have to worry about placing the runner under a booster.

[williamsmotowerx]

I had an interesting discussion with a CFD engineer.
His career was mostly involved with simulation of fuel motion and burning as it relates to fuel efficiency, emissions and durability mostly.
Detroit passenger cars and trucks, some high performance OEM stuff but not purpose built racing engines.

I told him about the controversy over whether intake ducts should have two relatively straight sections with a sharp blend
or
A gradually curved duct with tangent continuity.

He looked at me like this:

Dog-Tilting-Head-While-Listening.jpg

He said that of course the curved duct will flow more.
and
If the fuel is dropping out in either design, the solution would be to have smaller fuel drops.

So which is it? Straight ports with quick short turns are the norm in the high revving 4 valve world currently. The curved duct is old school. That STL I sent you Jon is the last of the high performance curved ducts... Port was designed in 2022

How much does that have to do with packaging vs outright best practice?

I think the problem with these V8s is the single Holley manifolds. FI or tunnel ram straightens them right out. FI is even better since you don't have to worry about placing the runner under a booster.

There's always a what if...

And there may be a difference between a 2v and 4v... but I'm really surprised that engineer said curved flows best, or am I reading this wrong?

[hoffman900]

So which is it? Straight ports with quick short turns are the norm in the high revving 4 valve world currently. The curved duct is old school. That STL I sent you Jon is the last of the high performance curved ducts... Port was designed in 2022

How much does that have to do with packaging vs outright best practice?

I think the problem with these V8s is the single Holley manifolds. FI or tunnel ram straightens them right out. FI is even better since you don't have to worry about placing the runner under a booster.

There's always a what if...

And there may be a difference between a 2v and 4v... but I'm really surprised that engineer said curved flows best, or am I reading this wrong?

I think the former. They're talking a sharper turn into the plenum and a straighter shot into the port vs a general sweeping bend... think the outer 4 cylinders on a V8 with a single, centrally mounted carburetor / throttle body manifold.

[SchmidtMotorWorks]

Let's design some shapes to compare.
Define a location and angle at the start and end.
One can be 2 straight sections with whatever blend radius you choose.
The other can be the least tension curved shape.

Post some dimensions and we can test it.

[SchmidtMotorWorks]

There's always a what if...

And there may be a difference between a 2v and 4v... but I'm really surprised that engineer said curved flows best, or am I reading this wrong?

In the test I did in the other thread, the curved duct did flow better than the mitered and blended duct.

Have you seen those cheap Chinese fabricated manifolds with the straight ducts?

s-l500.jpg