Low Angle Port

[PackardV8]

Fortunately, the vintage flathead classes don't allow EFI and certainly not DI, as I've always felt flowing dry air should help NA flatheads increase their VE and that would be a very expensive experiment with a steep learning curve.

But then, DI nitro and there you have it, VE no problem ;>)

[LotusElise]

Fortunately, the vintage flathead classes don't allow EFI and certainly not DI, as I've always felt flowing dry air should help NA flatheads increase their VE and that would be a very expensive experiment with a steep learning curve.

The carburettor technology went far away from the huge Venturi's, today they use local spread under pressure source which allows less Venturi and less loss concerning the VE. I made a patent years ago for gaseous fuel carburettors, the pressure drop at WOT on a 2600 hp engine went from 45 mbar to less than 12 mbar at a much better mixture quality, which went from 85 % before compressor wheel to 96 % on that specific engine. I know not only few EFI systems which makes less sense as a good designed carburettor system. Seems like the EFI technology introduced a lower interest on the mixture preparation side.

When I see e.g. the injectors having a 10° spray cone, located at around 100 mm before the intake valve with an 45° spray axis I just get reminded knowhow comes in waves and is not added, it is sort of lost and found again. I like historical technology books of ICE's and I am so impressed what was already known. In 1939 NSU already reached a VE of 130 % with carburettor systems, in the same year Mercedes had the first direct injection gasoline engine on the track (legendary 300 SL engine) and the 200 hp/Liter threshold was already exceeded by the 2-stroke ICE's in some race applications. Crankshaft to oscillation mass balancing, who does it today? All talk about parts which are within some g, but who talk about balancing of rotational to oscillating masses and it's ratio? The legendary NSU Rennmax, a 0.25 Liter 4-stroke engine made 42 hp for the Bonneville application, which is 168 hp/Liter in 50'ies of last century. If these guys had the fabrication and materials available, we have today, we would all look just like to be very old fashioned. Does anyone of you know "Offy", from the US engine engineer Fred Offenhauser, which ruled 30 years long the 500 miles of Indianapolis. Key concept was the casting, which included block and head in one piece, a I4 with 109x111 mm. It was already old when it won the first time, but it was outdated when it won still 30 years later.

Our history is full of examples, showing the most of us are just repeating stuff which was already old fashioned 60 years ago. Even if technology went further, the system was still not that improved as it could be as knowledge got lost with the guys who took it with them into the green yard. A very good example that carburettors are still capable of very high VE are the NASCAR, which runs higher BMEP's and VE's as the NA Formula 1 area engines.

I lately got my first NA engine finished and tuned, 155 hp/Liter at 8200 rpm on a 2-Liter-NA engine with a very nice torque curve: 96 ftlb/Liter from 4500-8200 rpm. It is just a bit better than the BTCC engines 30 years ago. My next 2-Liter-NA-engine aims for 180 hp/Liter, the same torque level just shift to the right and a 900 rpm idle capacity. We have the year 2022, I am ashamed for being that late with that.

Finally, nothing wrong with the carburettors, worked already on 200 hp/liter engines in the 60'ies.

[Desmoguzzi]

I understood that this kind of low Port Is not so new as design. Looking more carefully at its design ut seems to me that the Blow area and other featured are missing. Generally It Is always recommended tò have diameters of the Blow not larger than 90% of the valve diameter and the Port should be among 80/90%. In this case Blow Is missing. What are the geometric ratios among the different sections of this kind of Port?

[Ks Fats]

It is easy to fall into the mindset in which one thinks that ratio's are absolute; in application they are relative to too many
variables. Bowl to valve ratio's can be anywhere from .86 to .90 + depending upon intended use. Using jacks' example above, a n.a flathead at Bonneville would have a different ratio than one that would have been used in short track racing. In my n.a. flatheads the bowl is not symmetrical, so the "ratio" is not constant. When the bottom angles are blended to get the desired flow pattern the "ratio" is changing relative to the valve head. Then one has to evaluate what is happening at the valve, seat and port relative to the cylinder head/combustion chamber. When working with existing ports it is sometimes necessary to make concessions in one or more areas to achieve the desired end result in the cylinder. If you are designing a new port, then it is a clean slate, but I don't think you would like one shaped like the drawing.

[digger]

It is easy to fall into the mindset in which one thinks that ratio's are absolute; in application they are relative to too many
variables. Bowl to valve ratio's can be anywhere from .86 to .90 + depending upon intended use. Using jacks' example above, a n.a flathead at Bonneville would have a different ratio than one that would have been used in short track racing. In my n.a. flatheads the bowl is not symmetrical, so the "ratio" is not constant. When the bottom angles are blended to get the desired flow pattern the "ratio" is changing relative to the valve head. Then one has to evaluate what is happening at the valve, seat and port relative to the cylinder head/combustion chamber. When working with existing ports it is sometimes necessary to make concessions in one or more areas to achieve the desired end result in the cylinder. If you are designing a new port, then it is a clean slate, but I don't think you would like one shaped like the drawing.

ratios are linear, areas are squared and valve seat widths are often almost absolute so you cant compare small valves to big valves using the same metric.

[Desmoguzzi]

The point Is that in this kind of Port the Blow seems to be missing so i don t see how It Is possible to define the ratio.

Indeed this Port has additional features Like the Hill in the Red circle and the roof on the Blue circle. What are the relations among the Port, valve and these features in order to get a Port that work properly?

IMG_20221007_082520.jpg

[Tom68]

The point Is that in this kind of Port the Blow seems to be missing so i don t see how It Is possible to define the ratio.

Indeed this Port has additional features Like the Hill in the Red circle and the roof on the Blue circle. What are the relations among the Port, valve and these features in order to get a Port that work properly?IMG_20221007_082520.jpg

No combustion chamber, is that a Diesel ?

In that case it's all about swirl with some cost to flow.

[Desmoguzzi]

No It s gasoline