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engine nerds: inline 4 timed as parallel twin?

ohio

ohio

Active member
Joined
Nov 4, 2007
Location
San Francisco
Moto(s)
Anything with two wheels
Name
Marc
I couldn't turn anything up on this on the google, so here's what may be a dumb question: has anyone ever built an inline four with the following firing order: 0-180-180-0 (or 180-0-0-180)?

It seems like that would produce the traction characteristics of a parallel twin with perfect (primary) balance and the rev range of a four. Am I missing something?
 
ohio said:
I couldn't turn anything up on this on the google, so here's what may be a dumb question: has anyone ever built an inline four with the following firing order: 0-180-180-0 (or 180-0-0-180)?

It seems like that would produce the traction characteristics of a parallel twin with perfect (primary) balance and the rev range of a four. Am I missing something?
Click to expand...
The HONDA RC211V used a "big bang" timing. The Yamaha YZR-M1 uses a "big bang" timing. The latest R1 have a semi- "big bang" timing. I don't know if any are exactly 180 degree, but you could check those out.
 
Reading more about big bangs really explains why my RC51 is so compliant and quick to regain traction when that rear end starts to step out.

And yes, it has been built before. Thinking of doing it to the R6?
 
I'm really leery of the Big Bang theory of engine timing. I personally think it's a load of complete shit; a marketing gimmick. I can't understand why anyone wouldn't want the smoothest power delivery possible with a vehicle designed for paved surfaces.
 
Dr. Evil said:
I'm really leery of the Big Bang theory of engine timing. I personally think it's a load of complete shit; a marketing gimmick. I can't understand why anyone wouldn't want the smoothest power delivery possible with a vehicle designed for paved surfaces.
Click to expand...

There was an article in RoadracingWirld a while back on the R1 motor. The actual analysis showed the Long Bang motor actually delivered power more smoothly with less agressive spikes in power at each crank rotation.
 
nazgulnarsil said:
what's wrong with 0-180-0-180?
Click to expand...

That's gotta be hard on the crank/crank bearings (two forces pulling up, two strong forces pushing down).

You would also need a heavier flywheel to maintain engine inertia through the firing cycle, and bigger (overall) counterweights to mitigate first-order vibrations.
 
nazgulnarsil said:
what's wrong with 0-180-0-180?
Click to expand...

bluenoser said:
That's gotta be hard on the crank/crank bearings (two forces pulling up, two strong forces pushing down).

You would also need a heavier flywheel to maintain engine inertia through the firing cycle, and bigger (overall) counterweights to mitigate first-order vibrations.
Click to expand...

Okay, I'll bite. What's the standard firing order for inline 4's? I'm no engineer, and neither was my dad, but I thought the standard was 180 degree crank with a firing order like nazgulnarsil outlines above - essentially cylinder numbers 1 & 3 are 360 degrees apart, as are 2 and 4. Where am I mistaken? :confused
 
flying_hun said:
Okay, I'll bite. What's the standard firing order for inline 4's? I'm no engineer, and neither was my dad, but I thought the standard was 180 degree crank with a firing order like nazgulnarsil outlines above - essentially cylinder numbers 1 & 3 are 360 degrees apart, as are 2 and 4. Where am I mistaken? :confused
Click to expand...

I think the typical setup is the outer 2 cylinders moving together, while the inner 2 move together, and each set of cylinders is 180 degrees apart. I hate to use a wiki link but its a pretty good graphic : http://en.wikipedia.org/wiki/File:Cshaft.gif

The 2010 R1 is 270-180-90-180, so its more like a 'fluttering' effect, I've read that its supposed to smooth out initial torque. *shrug*

Edit: I think having them 360 degrees apart would cause too much momentum?
 
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flying_hun said:
Okay, I'll bite. What's the standard firing order for inline 4's? I'm no engineer, and neither was my dad, but I thought the standard was 180 degree crank with a firing order like nazgulnarsil outlines above - essentially cylinder numbers 1 & 3 are 360 degrees apart, as are 2 and 4. Where am I mistaken? :confused
Click to expand...
A typical I4 has crankpins at 0, 180, 180, and 0. Firing order is 1-3-4-2.
 
I4 to parallel twin
You need custom cams and then reroute injector and sparkplug leads to match.

Cams are ~ $1000
 
DataDan said:
A typical I4 has crankpins at 0, 180, 180, and 0. Firing order is 1-3-4-2.
Click to expand...

This, but a firing order of 1-2-2-1, is what I'm asking about. It's different than the Yamaha Big Bang which has a 90 degree crank. Basically it's a new set of cams plus some ignition trickery in an existing I-4. I guess I'm surprised no one has tried the combo, but I'm sure there are good reasons for it. Hoping someone can tell me what they are.

fawndog said:
I4 to parallel twin
You need custom cams and then reroute injector and sparkplug leads to match.

Cams are ~ $1000
Click to expand...

So do you know of anyone that has done it? What was the result like?

I have no intention of doing this to my R6, but after a ton of conversations with flat trackers about the improved traction of singles & twins vs triples and fours, and the racing success of big bang fours, it just seemed like a logical thing to try.
 
ohio said:
I couldn't turn anything up on this on the google, so here's what may be a dumb question: has anyone ever built an inline four with the following firing order: 0-180-180-0 (or 180-0-0-180)?

It seems like that would produce the traction characteristics of a parallel twin with perfect (primary) balance and the rev range of a four. Am I missing something?
Click to expand...

This was done in 2005 by Rob Mac's Virgin Yamaha team. It was called the Pig. The firing order was 1-2-1 at every 90 degrees. So the firing order was 1- 2,3 - 4. They found out the hard way that the power pulses at 180 was too much for the cylinder head to take. It worked so well that Haga crashed riding off the front tire first time out. WSBK promptly banned it.

You'll need 2 very pricey things to make it work on a street bike. A Motec M8 and a set of custom cams. So about $5k just to tinker. There's a guy in Australia that'll sell you the kit.
 
Yamaha likes to liken the new R1 to the big bang MotoGP bikes, however it is not a big bang engine in any sense of the word. Technically, its a crossplane crankshaft I4.

The same is true of the V8 engines, which are available in both a crossplane and a flatplane configuration.
 
ohio said:
So do you know of anyone that has done it? What was the result like?

I have no intention of doing this to my R6, but after a ton of conversations with flat trackers about the improved traction of singles & twins vs triples and fours, and the racing success of big bang fours, it just seemed like a logical thing to try.
Click to expand...

No, $1000 custom grinds was too much to experiment with, I'm sure it would sound like a SV though.
 
Burning1 said:
Yamaha likes to liken the new R1 to the big bang MotoGP bikes, however it is not a big bang engine in any sense of the word. Technically, its a crossplane crankshaft I4.

The same is true of the V8 engines, which are available in both a crossplane and a flatplane configuration.
Click to expand...


None of the MotoGP bikes are actually big-bang either but rather fire 2 cylinders in close succession.

Sort of like the R1.
 
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