289/302 Ford V-8 engine

[Admiral_dk]

I agree with Kim - the Right side looks like the Elegant 'Logical Route' and the Left leaves you scratching your head  -> why ...?

I know that these things sometimes are self-explanetory if you see them 'together with the rest' / in situ.

Per             

[gbritnell]

My models closely follow the actual headers for the 302 Ford engine. The brand is BBK. I don't understand the engineering or flow theory behind them but they certainly are different.

[Vixen]

The cylinder firing order for the 289–302 era - Old School Mustang was 1, 5, 4, 2, 6, 3, 7, 8

Cylinders are numbered 1–4 down (front to back, left side) 5–9 (front to back, right side)

Therefore the left side fires in the order 1 - 4,2 - 3 - -   and the right side fires - 5 - - 6 - 7,8

You can see the sequence is totally different on each side, therefore the 'tuned' length, high performance, header pipes need to match the firing order and cannot be mirror images.

It's this uneven firing order the gives the V8 it's distinctive sound.

Cheers   

Mike

The alternative, cast iron 'low performance' exhaust headers are shown in Georges post #9 above

[Kim]

Fascinating! ... Who knew?     

Thanks for sharing that, Mike!

Kim

[Admiral_dk]

very interesting explanaition Mike - is it a 'Cross-Plane Crank' since it has this sequence ?

Per

[Vixen]

Hello Per,

The cross-plane (or cruciform) crank is by far the most common configuration. It's easy to balance with big counter weights. One characteristic, which produces that distinctive 'muscle car' rumble, is due to two cylinders in each bank firing one after the other. High performance, race tuned exhaust headers (such as the BBK headers in Georges model) use unequal length tuned, primary pipes to overcome this issue. The position of the adjacent firing cylinders is different on each bank, therefore the headers are different on each side. Which, I hope, helps to answer the original question.

After market exhaust headers (often mirror imaged) are available, which are intended to enhance the 'muscle car' rumbling sound rather than outright performance.

The flat plane crank configuration is much less common, usually only found on exotic European sports cars (Ferrari, McLaren, Porsche etc) and full race engines. second order vibration makes balancing much more difficult. The firing order in each bank is evenly spaced which makes for simpler (mirror image) exhaust systems.

My Mercedes W165 uses a cross plane crank, but is from the era when 'tuned' exhaust systems had not yet been invented. The W165 exhaust manifold is a simple 'V' fabrication.

Cheers   

Mike

[Vixen]

The BBK headers, on Georges model, are intended for oval racing, where the engine spends most of it's time at high revs, just below the red line.

The designers play around with the lengths (hence transit time) of the primary pipes from the adjacent firing cylinders (4,2 and 7,8) into the 4 into 1 collector. The aim is to achieve a more even train of pressure pulses at the collector, which then enhances cylinder scavenging. This 'race tuned' system only works over a narrow rev band and would therefore be of little use on the road (except for the bragging rights?).

All this stuff, of course, is of great interest to race engine builders/tuners but less so, to steam engine builders.   

Mike

[Kim]

All this stuff, of course, is of great interest to race engine builders/tuners but less so, to steam engine builders.   

Mike

But fascinating, never the less!
Kim

[Vixen]

Thanks Kim,

Goes to show there is a whole exciting new world outside 'steamland'.   

Mike

[Admiral_dk]

Again thank you for the extra info / insight Mike - very educational     

Per