Exotic "SOUNDING", high revving V8! Read "ENTIRE" thread before posting!!!

[Jerminator96]

I really liked the idea of that motorcycle based V8. It reminds me of the old Conventry-Climax 2.0L V8s that went into the Alfa Tipo 33s. 10,000 rpm and 300hp.I was thinking about designing one based on the Kawasaki ZX14 motor. If I could do it cheaper than the Busa motor you think there would be a market?

[Gollum]

AMV8(1day) - I think realistically the first one made will have to be by someone who works in a machine shop and can eat the labor and machine costs, and just needs some help designing it. Then once that first one is made and proven we can talk about prices.

 

But realistically, if I could get a flat plane crank for a SBF for under $2,000, it'd be on my wish list. If it were under $1,000 then I'd consider it a "must have" for any SBF build up.

 

Jerminator96 - I think there might be a small market for it, but also realize that americans are generally into big cube V8 engines, and kit car, or ground up builders are few in the USA. Locost and other track kit cars are much more common in the UK, though it's a growing market in the USA I believe. And once the economy bounces back and people are spending money I think we can expect the hobby racers to really come out of the woods.

 

 

My latest real contribution to this thread:

 

I quickly stopped by my old friend's house who ran a sucessful ferarri shop, and asked him what he knew about flat plane cranks, and if he thought it'd be cheaper to get a ferarri engine or design and build a flat plane crank.

 

When I asked about the vibration, he kinda chuckled and said:

 

"Well what's the use of the car?"

 

"Racing" and before I could even get that out he said

 

"Well who cares about vibrations then?"

 

He seemed to think even in a high displacement V8 the vibrations wouldn't be catostrohpic, and would be more annoying than damaging.

 

He also seemed quite surprised that the crank companies out there havn't been willing to give us an honest down to earth quote, and that it shouldn't be THAT hard for them to do.

 

I really pressed him for a guess on prices for ferarri engines but he insisted I contact a guy he knew rather than take his word for it, but he said an engine in the 3 liter range with around 250hp would probably cost around 10-15k, depending on condition. Makes the hyabusa V8 seem like a deal for the HP, and the fact replacement parts wouldn't be that hard to come by.

 

But I seriuosly believe that if an engineer on this board put thier mind to it they could design and build a usable flat plan crank for any american small block. And I also believe there'd be a market for it.

[Jerminator96]

But I seriuosly believe that if an engineer on this board put thier mind to it they could design and build a usable flat plan crank for any american small block. And I also believe there'd be a market for it.

 

Well if I ever have access to a serious machine shop I'll get to work on it for you.You're probably right about the market being small in the US for a custom ~3.0L V8, even if I could get 500hp out of it. Maybe I'll just try to build one for myself. But who said anything about dropping it into a kit car? It's a motorcycle engine, right? Hehe

[Gollum]

Well, main application would be a light vehicle of some sort right? Doesn't matter if it's 2 wheels or 6.

 

Kit cars are just the most logical leap.

[Jerminator96]

Well, main application would be a light vehicle of some sort right? Doesn't matter if it's 2 wheels or 6.

 

Kit cars are just the most logical leap.

 

Yeah I know, I just have this idea for a bike that would look really cool, sound really cool, and probably handle like crap.I'm sure the motor would eventually make it into a car of some sort. I envision a small open-wheel, mid-engine, roadster. Something like an ariel atom but with a little more body work and a 500 hp 3.0L V8.The other question is what gearbox do I design it for? Hewland maybe? Something less exotic, maybe an audi?

[Gollum]

I'm not sure it's fair to call the harley V-Twin the most loved engine sound. Though I agree they're good sounding.

 

Thinking about the single pin crank design of a harley though, I cheap way to simulate this would be to get a custom cam for a 4 cylinder and make the two innter pistons and the two outer pistons fire together. Seperation would be 180 degrees with pretty loud bangs, with 540 degrees of silence.

 

You could use factory everything on the longblock other than the cams. Pistons, crank, rods, valves, etc. You just need to change the timing of the valves to match, and then also modify the ignition system (unless it's wasted spark, then I think no modifications would be needed).

 

Now I'm kinda curious what that'd sound like...

[Guest BonesDT]

I'm not sure it's fair to call the harley V-Twin the most loved engine sound. Though I agree they're good sounding.

 

I anticipated that this would be the very first response to my post and that is why I dedicated a paragraph to try and explain myself. I have been intrigued with trying to find/create the best sounding engine, leaving all other qualities behind. The best place for me to start is to try to determine which current engine has the best sound. Of course, every individual person will have their own opinion as to what is the best sounding engine, but it's like music, and I think more people would agree that they like the sound of a Harley than the amount of people that would agree that they like any other kind of engine. I can think of no other engine that sounds as respectable with no exhaust. I also understand the concept that headers can greatly modify an engine's sound, but the Harley creates its sound "naturally" beginning at the heart.

 

Now I'm kinda curious what that'd sound like...

 

Exactly!

 

 

BRAAP, I meant a true single-pin crankshaft for a, say, V8. All 8 pistons would share the same single crank pin. All 4 pistons on one bank would all fire at the exact same time and then all 4 pistons in the other bank would fire next. This is different than the flat-plane shared-crank-pin crankshaft where only 2 pistons share a crank pin that is discussed in this thread. Although, this creates a beautiful sound, it is different than a Harley's because there are multiple explosions during a 2 revolution cycle rather than only 2.

[BRAAP]

 

BRAAP, I meant a true single-pin crankshaft for a, say, V8. All 8 pistons would share the same single crank pin. All 4 pistons on one bank would all fire at the exact same time and then all 4 pistons in the other bank would fire next. This is different than the flat-plane shared-crank-pin crankshaft where only 2 pistons share a crank pin that is discussed in this thread. Although, this creates a beautiful sound, it is different than a Harley's because there are multiple explosions during a 2 revolution cycle rather than only 2.

 

Hmmm…. Interesting concept… It wouldn't be a smooth harmonious exhaust note as this thread is about, but the exhaust note would be interesting.. Hmmm...

 

I think a real big issue with that design would be vibration, and OMG lots of vibration, but again, the exhaust note.. Hmmmm…

[Careless]

I hope you have some tri-cycle wheels bolted to the perpendicular to the fenders (perhaps on the doors?) and suspension coils for engine mounts because a 4 on 4 firing order from side to side is going to flip that car upside down without dampening.

[Daeron]

.....and I think more people would agree that they like the sound of a Harley than the amount of people that would agree that they like any other kind of engine.

 

 

 

BRAAP, I meant a true single-pin crankshaft for a, say, V8. All 8 pistons would share the same single crank pin. All 4 pistons on one bank would all fire at the exact same time and then all 4 pistons in the other bank would fire next. This is different than the flat-plane shared-crank-pin crankshaft where only 2 pistons share a crank pin that is discussed in this thread. Although, this creates a beautiful sound, it is different than a Harley's because there are multiple explosions during a 2 revolution cycle rather than only 2.

 

I would have said that a Ferrari V8 or V12, or possibly a Porsche would have had that exhaust note title.... To me, the Harley claim sounds pedantically American. NOT to sound insulting, though!!! Personally my thoughts about Porsches have been well aired elsewhere in the past, and I vowed to stop talking about my opinion to avoid making anyone less than happy.. and as much as I love a Ferrari blasting down the straight, or gear-braking before a hairpin...... my L-gata is HEAVEN to my ears.

 

But I am trying to understand something here.. when you say "single-pin crank" you cannot actually mean one single contiguous pin along the length of the crankshaft, right?? You mean, for ease of description, a "half single plane" crank, where instead of the minus sign that the single plane implies, or the plus sign that a dual plane crank describes, that all four crank pin throws describe the same line, correct? The pins themselves would HAVE to have journals and be separated, unless you only had two main bearings??

 

I don't know what the internals of a harley engine look like, but I somehow doubt it would help me understand what youre talking about any better. I THINK I can visualize what you mean, I am just making sure I have the right track... and it certainly WOULD be a very interesting sound.. once you got to high enough RPM it would be insane..

[Clifton]

I believe the engine that has the most universally agreed best sound is the Harley V-Twin. if you put straight pipes on your Harley, people roll down their windows next to you at stop lights to hear it even better.

This fact gives credibility to the statement that the Harley V-Twin is the most universally loved internal combustion engine sound.

 

You are joking right? There is nothing exotic about the sound Harleys make. My lawn mower without a muffler sounds about the same, it actually might sound better as it can rev higher and make more hp/L. Single plane sounds more like a I4 sport bike at 10k (nice)

[OlderThanMe]

Ok, The idea of a single crank pin would not be particularly advantageous because all the weight of the crankshaft would be putting tremendous forces on the block at one point in rotation.

By going to a single pin with all cylinders on that axis, without full counterweighing, you would munch through your main bearings in a matter of seconds or minutes if you are lucky. If you were to fully counterbalance your single-plane-single-pin crankshaft it would weigh as much or more than a standard cross plane crankshaft, thus eleminating any advantge that you previously had with a standard single plane crankshaft.

 

Think of this example: swing a rope above your head with a 5 pound barbell on the end of the rope. You would be putting extreme stress on your extended arm and you would tire quickly.

If somehow you were able to do the same test with a rope in equal and opposite directions with equal weights and spin them, there would be no forces pulling your arm in any particular direction(i.e. not moving your arm in a circle)

With a "standard" single plane V8 crankshaft, each crank pin counterbalances the opposing pin, thus reducing your required counterweight by a significant percentage.

 

Then you would have to worry about vibration as BRAAP stated. That is why you would need to fully counterweight the crankshaft, which defeats the purpose.

[Guest BonesDT]

you cannot actually mean one single contiguous pin along the length of the crankshaft, right??

 

That's the idea.

 

The pins themselves would HAVE to have journals and be separated, unless you only had two main bearings??

 

You're right. The pin would not be literally continuous, it would be broken up for strength, but they are all on the same line.

 

 

I didn't intend to get into an argument re: what engine sounds the best. I wanted to throw out the idea of this single pin crank (or half flat plane crank). In my own mind, I certainly see the intense vibration issues as well. But it works in V-Twins, so why wouldn't it work just by increasing the displacement.

 

 

swing a rope above your head with a 5 pound barbell on the end of the rope.

 

I just tried this, and the rope broke and the barbell fell on my head. I'm going to sue.

[Daeron]

Thanks for clearing that up for me

 

But it works in V-Twins, so why wouldn't it work just by increasing the displacement.

Because by increasing the displacement, you wind up with a square increase in size of metal pieces doing work (resisting work in this case) and a cubic increase in amount of work to be resisted. It goes back to why the home-brew single plane SBC would be running a displacement of around 3.5 liters.. keep size down, you keep rotational mass down, and there are less forces being thrown in every which way but centered.

 

 

 

I just tried this, and the rope broke and the barbell fell on my head. I'm going to sue.

 

 

no one is getting into an argument or a dispute, you just made a bit of a bold comment that deserved a few dissenting opinions at the very least For every person who puts the V-twin at #1 on their list is another man who rates it dead LAST, and I cannot offhand think of another engine grouping that has as many vocal opponents than the Harley, either. I suppose there are people who loathe the rotary engine, but thats an alien concept to me.. but the pointed needed to be..

 

 

..counterweighed...

[Gollum]

Maybe this will help stirr up some ON TOPIC thread discussion...

 

...just because I can:

 

[Daeron]

One question I have had in mind throughout my reading this thread is, what kind of tolerance is there in between those connecting rods and the journals? I can understand that the rod stays in its place to a degree because it is held by the piston and wrist pin, but how much clearance is there between those pieces and how possible/frequently would one see "walking" and serious engine damage in this area?

 

And, above and beyond that, a more elemental question of "nitty-gritty" engine inexperience.. how much MORE of a problem would this be with this single-plane V8 design than with a simple inline four cylinder?

[OlderThanMe]

Gollum, how did you decide on counterweight mass? Have you done any stress/distortion math on it?

 

Here is one crank I did... but with a 100% counterweight. (overkill, just to get practice in crank design)

 

Daeron, There is typically about .3mm of side play in the connecting rods. Just as a rough number and varies some...

[Daeron]

Daeron, There is typically about .3mm of side play in the connecting rods. Just as a rough number and varies some...

 

Thanks, and for the illustration too. Every rendering you post, I consistently fail to recall for at least a moment or two that the image is a solidworks rendering. For a second I actually thought that was a photo of a crankshaft you had found.

[kiwi303]

a 100% counterweight. (overkill, just to get practice in crank design)

 

that looks like a 1 up, 2 down, 1 up flat plane crank, is that sized to fit a Small block chev? or a ford? or just drawn with generic diamensions simply to get some practice in arranging things in the program you are using?

 

As to calling 100% counterweighting overkill, as I follow it, the more counterweighting, the more mass to rotate and the slower the engine will rev. How low could you go on a flat plane without excessive (rebuilding the engine after every drive) vibration?

 

From the discussions on here it sounds like one can actually go to a very low counterweighting, almost 0%. What would a 0% counterweighted flat plane ford 302 crank look like?

 

 

I've actually found a OEM crankshaft manufacturor who's willing to quote on making cranks

[Jerminator96]

Why don't we just use boxer engines, then counter-weighted cranks become unnecessary. Porsche sure did well with their 917/30. I believe that was a turbocharged 5.0L flat-twelve, making upwards of 1400hp in qualifying trim if I'm not mistaken.Maybe not the pinnacle of low maintenance, and certainty not an easy package to cram into our little Z cars....what was my point again? Oh yeah, 1400hp!