4 cycle engine and number of cylinders

[29662]

Originally Posted By: ZeeOSix
Originally Posted By: 29662
Originally Posted By: ZeeOSix
Originally Posted By: 29662
A BIG BANG does not fire multiple cylinders at the same time. they are separate events.


Sometimes ... "Big Bang" Engines


Never. They never fire multiple cylinders simultaneously.


In the article it said:
"The Honda NSR500 began and ended its life as a screamer. However in 1990 Honda connected both of the pistons in one bank to the same crankpin and both of the other pistons to a crankpin offset 180°. This NSR500 was called a 'big bang'."

In that V4 engine, two of the four pistons fired at the same time. It was essentially like a big V-twin in terms of power pulses from the pistons firing (two at the same time in the same bank).


You do realize that the NSR 500 was a 2 cycle engine right. So has absolutely no bearing on this discussion.

And for the record I work in a Machine Shop. I see more disassembled engines in a month than most gearheads will see in a lifetime. not kidding.

 

[ZeeOSix]

Originally Posted By: 29662
You do realize that the NSR 500 was a 2 cycle engine right. So has absolutely no bearing on this discussion.

And for the record I work in a Machine Shop. I see more disassembled engines in a month than most gearheads will see in a lifetime. not kidding.


Yes, it's a 2-stroke ... but it's also defined as a "big bang" engine because it fires two of its four pistons at the exactly the same time.

If you read that article, they sometimes call engines that don't fire at the same time "long bang" instead of "big bang".

"A four-cylinder engine with a regular firing interval is sometimes referred to as a screamer. The regular delivery of power strokes can overwhelm the rear tire, and generally makes a slide harder to catch as well. A long bang fires both pairs of cylinders in quick succession; the power delivery is identical to a parallel twin with a 180° crank and similar to a v-twin. In 2005 Kawasaki experimented with this configuration on the ZX-RR MotoGP bike."

 

[29662]

Correction on what I said previuosly. The v4 has a 180deg crank not a 90 deg crank that when combined with the included 90 deg angle of the V configuration means that pistons are at 90 deg relative positions to each other.

 

[ZeeOSix]

Originally Posted By: 29662
Correction on what I said previuosly. The v4 has a 180deg crank not a 90 deg crank that when combined with the included 90 deg angle of the V configuration means that pistons are at 90 deg relative positions to each other.


In that configuration, the pistons still fire 180 degrees apart (if it's not a big bang or long bang odd-ball), so that means two pistons would be at TDC when the other two are at BDC - all on different stokes of the 4-stroke process of course - out of "cycle phase" by 180 degrees, or 1-stroke.

Well I DO have to work tomorrow ... so carry on.

 

[29662]

Originally Posted By: ZeeOSix
Originally Posted By: 29662
You do realize that the NSR 500 was a 2 cycle engine right. So has absolutely no bearing on this discussion.

And for the record I work in a Machine Shop. I see more disassembled engines in a month than most gearheads will see in a lifetime. not kidding.


Yes, it's a 2-stroke ... but it's also defined as a "big bang" engine because it fires two of its four pistons at the exactly the same time.

If you read that article, they sometimes call engines that don't fire at the same time "long bang" instead of "big bang".

"A four-cylinder engine with a regular firing interval is sometimes referred to as a screamer. The regular delivery of power strokes can overwhelm the rear tire, and generally makes a slide harder to catch as well. A long bang fires both pairs of cylinders in quick succession; the power delivery is identical to a parallel twin with a 180° crank and similar to a v-twin. In 2005 Kawasaki experimented with this configuration on the ZX-RR MotoGP bike."


Not sure what article you're referring to. I am a long time Honda fan, and intimately familiar with their products, and R&D.

Look up Yamaha R1 Crossplane crankshaft. That will better explain an inline 4 engine that would not have 2 pistons at TDC and 2 at BDC. similar to the KAwi motor you just referenced. And it's not something new. What they tried to do was replicate the power delivery of a V4 motor in an inline engint.

If you really want to have your mind blown look up the Honda v5 motogp engines or their nr 8 valve per piston engines, where each piston had TWO connecting rods. I know what I'm talking about.

Where's BusyLittleShop when you need him.

 

[29662]

Originally Posted By: ZeeOSix
Originally Posted By: 29662
Correction on what I said previuosly. The v4 has a 180deg crank not a 90 deg crank that when combined with the included 90 deg angle of the V configuration means that pistons are at 90 deg relative positions to each other.


In that configuration, the pistons still fire 180 degrees apart (if it's not a big bang or long bang odd-ball), so that means two pistons would be at TDC when the other two are at BDC - all on different stokes of the 4-stroke process of course - out of "cycle phase" by 180 degrees, or 1-stroke.

Well I DO have to work tomorrow ... so carry on.

You're forgetting the 90 deg angle of the V. Causing a 90 deg piston sepration . Each bank has a cylinder on an opposite throw of the crank 180 deg.. Do the math.

 

[ZeeOSix]

Originally Posted By: 29662
Not sure what article you're referring to. I am a long time Honda fan, and intimately familiar with their products, and R&D.


You gotta click on the links I put in my posts.

Originally Posted By: 29662
Look up Yamaha R1 Crossplane crankshaft. That will better explain an inline 4 engine that would not have 2 pistons at TDC and 2 at BDC. similar to the KAwi motor you just referenced. And it's not something new. What they tried to do was replicate the power delivery of a V4 motor in an inline engint.

If you really want to have your mind blown look up the Honda v5 motogp engines.


I hope nobody makes a "V8" engine out of four V-twin Harley engines siamesed together.

 

[ZeeOSix]

Originally Posted By: 29662
You're forgetting the 90 deg angle of the V. Causing a 90 deg piston sepration . Each bank has a cylinder on an opposite throw of the crank 180 deg.. Do the math.


Doesn't change the fact that 2 pistons are on TDC when the other 2 pistons are on BDC. That's all I'm saying ... if it's a typical 4 cylinder, 4-stroke engine with 180 firing, then it has to be that way.

 

[29662]

Originally Posted By: ZeeOSix
Originally Posted By: 29662
You're forgetting the 90 deg angle of the V. Causing a 90 deg piston sepration . Each bank has a cylinder on an opposite throw of the crank 180 deg.. Do the math.


Doesn't change the fact that 2 pistons are on TDC when the other 2 pistons are on BDC. That's all I'm saying ... if it's a 4 cylinder engine with 180 firing, then it has to be that way.


No it doesn't. If It's a 180 deg crank and its an inline 4 then yes. If it's a v4 with a 180 deg crank you have to account for the angle of the v, which causes a 90 deg separation in piston position. What you're visualizing is an inline 4 with a flatplane crankshaft.

 

[29662]

God I love BITOG.

Be Chill Z, we can debate some more tomorrow. It's 4:30 here I'm off to bed so I can go for a ride in the mountains tomorrow on my V4 Interceptor...lol

 

[ZeeOSix]

Originally Posted By: 29662
Originally Posted By: ZeeOSix
Originally Posted By: 29662
You're forgetting the 90 deg angle of the V. Causing a 90 deg piston sepration . Each bank has a cylinder on an opposite throw of the crank 180 deg.. Do the math.


Doesn't change the fact that 2 pistons are on TDC when the other 2 pistons are on BDC. That's all I'm saying ... if it's a 4 cylinder engine with 180 firing, then it has to be that way.


No it doesn't. If It's a 180 deg crank and its an inline 4 then yes. If it's a v4 with a 180 deg crank you have to account for the angle of the v, which causes a 90 deg separation in piston position. What you're visualizing is an inline 4 with a flatplane crankshaft.


So please explain how a V4 with 180 degrees of crank rotation between piston firings can't have 2 pistons at TDC when the other two are at BDC. If two piston rods are on one crank journal, then those two pistons will be at TDC or BDC at the same time. That's the configuration I'm talking about. There are too many engine configurations to talk in general terms anymore it seems.

 

[ZeeOSix]

Originally Posted By: 29662
God I love BITOG.

Be Chill Z, we can debate some more tomorrow. It's 4:30 here I'm off to bed so I can go for a ride in the mountains tomorrow on my V4 Interceptor...lol

... I had an Interceptor many moons ago. Collectors bike now. Be safe!

 

[Olas]

There has been some controversy regarding cross plane and flat plane crankshafts in motorsport in the EU, here's ann excerpt from wiki to explain;

There are two types of 90 degree V8s which differ by crankshaft:

The cross-plane or two-plane crankshaft is the configuration used in most V8 road cars. The first and last of the four crank pins are at 180° with respect to each other as are the second and third, with each pair at 90° to the other, so that viewed from the end the crankshaft forms a cross. The cross-plane have half as strong (and twice as frequent) secondary vibration than flat-plane, but requires heavy counterweights on the crankshaft to counter Rocking Vibration caused by plane imbalances (See Engine balance for details). With the Secondary Vibration advantage, the cross-plane V8 can be scaled up to large displacements without causing destructive vibration. However, the use of heavy counterweights makes the cross-plane V8 a slow-revving engine that cannot speed up or slow down quickly compared to flat-plane because of the greater rotating mass. While the firing of the cross-plane V8 is evenly spaced overall, the firings on the 'L'eft and 'R'ight banks are LRLLRLRR or RLRRLRLL, resulting in uneven intake and exhaust pulse spacing for each bank. In stock cars with exhaust manifolds merging four exhaust ports into one exit, this results in uneven filling/scavenging of intake/exhaust gas in the cylinders (that prevents combustion to be uniform across cylinders) causing the typical V8 burble sound that many people have come to associate with American V8s. In all-out racing cars it leads to the need to connect exhaust pipes between the two banks to design an optimal exhaust system, resulting in the long exhaust pipes that resemble a bundle of snakes as in the Ford GT40. This complex and encumbering exhaust system has been a major problem for single-seater racing car designers, so they tended to use stub exhaust pipes in the 1950s, or place exhaust ports on the inside of the V angle as on the 4.2 L (256 cu in) Ford Indy engine in Lotus 38.

The flat-plane or single-plane crankshaft has crank pins at 180°. As they always move two pistons together, the Secondary Vibration is twice as strong (and half as frequent) as cross-plane, unless balance shafts are used, with a counter rotating pair flanking the crankshaft transverse to the crankshaft centreline. As it has nearly perfect plane balance,[16] it does not normally require counterweights. The crankshaft with less mass and thus inertia allows quicker revving up and down, in addition to the firing being LRLRLRLR or RLRLRLRL with regular overall and per-bank pulse spacings for uniform combustion without requiring a complicated exhaust system. The design was popularized in modern racing by the Coventry Climax FWMV 1.5 L (92 cu in) V8 that evolved from a cross-plane to a flat-plane configuration (with longer conrods). Flat-plane V8s on road cars come from Ferrari (every V8 model they have ever made, from the 1973 308 GT4, to the new 458), Lotus (the Esprit V8), TVR (the Speed Eight), Porsche 918 Spyder and McLaren (the MP4-12C). This design is popular in racing engines, the most famous example being the Cosworth DFV.[17]

 

[A_Harman]

Originally Posted By: 29662
Originally Posted By: ZeeOSix
Originally Posted By: 29662
I think you misunderstood. I said each "cycle" encompasses 180deg of crank rotation. so on a V8 there are 2 pistons in the same cycle but in a different phase (position) at any given time for a complete power cycle(720 deg of crank rotation).


No ... each 4-stroke "cycle" comprises 720 degrees of crank rotation (ie, 2 crank revolutions). If people don't use the correct terminology all thoughts are jumbled.

There are never two pistons in the same part of the 4-stroke cycle on a typical, common V8 engine.


Originally Posted By: 29662
A v4 is not an oddball design as there are millions of them out there. Just look at all of Honda's v4 engines.


I didn't say a V4 engine was "an odd ball design". I said if a V4 fired two of the 4 pistons at the same time then it would be odd ball. Just like any muti-cylinder engine that fired multiple pistons at the same time.


A "cycle" is a 180 deg rotation of the CRankshaft. An Otto cycle is 720 deg of crankshaft rotation. I think youre the one who is not using correct terminology. That's why it's called a 4 cycle engine.

A v4's pistons don't line up like an L4's pistons do. you're forgetting the separation in piston plane alignment due to the V.

A BIG BANG does not fire multiple cylinders at the same time. they are separate events.


You're the one with terminology trouble.

A "cycle" is 720 degrees of crankshaft rotation.
A "stroke" is 180 degrees of crankshaft rotation.
Hence the term "4-stroke cycle".
And Big Bang engines do fire multiple cylinders at once. The only such examples of this that I am aware of are Honda F1 V12 and CART V8 turbos of the 1990's. I wouldn't be surprised if there are some Big Bang motorcycle engines, though.

 

[supton]

The odd-fire V6's, do those qualify as odd-ball motors? I think the GM 3.8L was originally odd-fire. And made in quantity, at least for a while, until they used split pin crankshafts to get even-fire.

 

[meep]

an easy way to answer the first 3 pages of posts here is to look at a distributor rotor on any *common* v8, v6, I6-.... the rotor points to one spark plug at a time.

 

[asand1]

Originally Posted By: ZeeOSix

So please explain how a V4 with 180 degrees of crank rotation between piston firings can't have 2 pistons at TDC when the other two are at BDC. If two piston rods are on one crank journal, then those two pistons will be at TDC or BDC at the same time. That's the configuration I'm talking about. There are too many engine configurations to talk in general terms anymore it seems.


Easy
A paired set of cylinders in a 90* configuration sharing a common Journal can only have one cylinder perpendicular to the crank at any given time. While Cyl 1 is at BDC, Cyl 2 is at 90* BTDC.



In a V4 without a split journal crank, and with a flat plane;
cly 1 TDC Compression
cyl 2 90* BTDC ex
cyl 3 BDC In
cyl 4 90* BBDC Power

depending on the cam, the specific order of the cycles can be different, but the fact remains. No two cylinders are doing the same thing at any given time.

If you don't believe it, think about this. In a typical V8 with a distributor, the rotor can only point at one terminal at a time. You can only fire one cylinder at a time.

 

[ARCOgraphite]

Change up.
My big Q of the last decade:
Why dosent Subaru use a shared centre crankpin on their boxer to make the crank less complex?

 

[Win]

But some engines use dual plane distributors with dual rotors.

An example is the Marelli dizzy in my Xj12 - one rotor for each bank of six. So it could fire two cylinders at the same time - each bank has its own independent ignition system sharing only the dizzy housing and cap - but it only fires one at a time - 1a-6b-5a-2b-3a-4b-6a-1b-2a-5b-4a-3b is the firing order, I think ....

I think some Ferrari's also used dual plane Marelli's, even on their V8's. Never owned a Ferrari, so not sure about that

Never really thought about it until this discussion.

 

[asand1]

Were not talking about exotic engines here, just production average engines.