4-2-1

[miro-1980]

Guy,

As you know I was on a market for some time for a 4-2-1 for my new engine.

I recently managed to gt one. It was apparently taken off a Racing engine from the US. The extractor is on good condition and first of all it is not one of the new constructions that look like antlers of a ram. It also is not made of short stretches of bent pipe but hot formed original.

For some reason I do not like or trust the shiny steel ones made of dozen of elbow connectors.

Anyway , I have just measured my new acquisition : primaries are internal diameter of 36mm and 48 cm length while secondaries are 42 internal diameter and 60 cm length.

my 4-2-1 small .jpg (40.19 KiB) Viewed 4434 times

It seem these are neither old theory "proportions" (short primaries/long secondaries) not new theory ( short primaries,long secondaries).

I have ma de a calculation of capacity of both primaries and secondaries, Primaries have capacity of 488 cc and secondaries have capacity of 831 cc. The secondaries capacity is 70% larger than the capacity of the primaries.

Now, I have no knowledge of the gas flow theory , but remember Einstein saying that every good theory should also look elegant. The theory is not look elegant is inadvertently wrong. 70% increase of volume increase from primaries to secondaries does have a touch of elegance.

Not pretending that have the knowledge to make the judgment , it would be presumptuous to make such claim. Will it provide max performance of a highly tuned engine - no clue , but I would expect ( and hope) it to work nicely ...

What do you think of such proportions, Guy?

Miro

PS and how do you like the elegance test of a theory...?

[Guy Croft]

Mit Eleganz?

You should have been a fighter pilot Miro!

G

[miro-1980]

Well Guy

Based on partial results of the dyno test of the engine you just built for me I am seriously considering adding wings and a parachute as well as apply for a 131 Abarth flying license.

Thanks, Guy

PS: Elegantz is something very becoming of a gentleman, especially in his driving machine ...

Miro

[Guy Croft]

I'd copy the dyno header if I were you!

viewtopic.php?f=9&t=2154

GC

[miro-1980]

But it is a 4-1 ?

Miro

[Guy Croft]

Yes Miro it is a 4-1 but by some quirk of fate it's quite perfect. Don't imagine for a minute that 4-2-1 will always be better and the relative lengths are more important than the configuration.

Frankly I never expected results like that so the combined inlet and ex lengths must be working VERY well. Light a cigarette before watching, you'll need one..

http://www.youtube.com/watch?v=vjzsUZLlgkI

GC