Random thoughts thread

[Dimman]

Originally Posted by serialk11r

Oh god. 3 piece collapsible coiled pipe...Servos would need some sort of belt or something to make that work.



Nope, because the unequal lengths will give it the V8 sound only at 1 engine speed. Okay no, it'll have a similar effect at all harmonics too. Tis why you need constantly adjusting.

If the minimum "working" speed requirement is raised from 1000rpm to 3000rpm, then the length of the pipe will need to be variable from 1.66m to 0.55m (if the engine hits 9000rpm), which is much more manageable. Raise that to 4500 rpm then we only need 1.11m of pipe, but then the engine will refuse to shriek below that speed which sorta sucks :/

Are you certain?

My thinking is just that the longer pipes' lengths (come to think of it, entire exhaust) need to be tuned to reach atmosphere between the firing of cylinders.

[serialk11r]

Originally Posted by Dimman

Are you certain?

My thinking is just that the longer pipes' lengths (come to think of it, entire exhaust) need to be tuned to reach atmosphere between the firing of cylinders.

Right, but the rate at which the cylinders fire is engine speed dependent. If you have just unequal length header tubes, then you need to add half the wavelength to land one pulse right in between 2 others, which is the speed of sound * 1/2 the frequency. Then at 3 times this speed, the tube will work correctly again, as it will land the pulse right between the next 2 "primary" (in-phase should be the better term) pulses. At 5 times this speed, the tube will land the pulse right between the 2nd and 3rd pulses after, etc.

The minimum tube length needed will be that which lands the pulse between the primary pulse it "originated from" (was once in phase with) and the immediate next primary pulse.

With a tube that can reflect the waves, you cut the required pipe length in half.

At any rate, even a 1.5m long pipe is quite difficult to manage.
Dream engine: 2 CBR600RR engines put together at the crank Hayabusa style. 15000rpm of V8 glory, 230 horsepower from 1.2 liters. Oh yea.

[Dimman]

Originally Posted by serialk11r

Right, but the rate at which the cylinders fire is engine speed dependent. If you have just unequal length header tubes, then you need to add half the wavelength to land one pulse right in between 2 others, which is the speed of sound * 1/2 the frequency. Then at 3 times this speed, the tube will work correctly again, as it will land the pulse right between the next 2 "primary" (in-phase should be the better term) pulses. At 5 times this speed, the tube will land the pulse right between the 2nd and 3rd pulses after, etc.

The minimum tube length needed will be that which lands the pulse between the primary pulse it "originated from" (was once in phase with) and the immediate next primary pulse.

With a tube that can reflect the waves, you cut the required pipe length in half.

I think it would do the job of creating a 'wtf is in your car?' without worrying about variable length exhaust components. Maybe match it with something similar on the intake side?

The thing is that the nature of the fabrication will create variables in the length and pressures in the runners so it may always have some out of sync waves to maje it sound smoother than a normal 4 cyl.

[serialk11r]

Originally Posted by Dimman

I think it would do the job of creating a 'wtf is in your car?' without worrying about variable length exhaust components. Maybe match it with something similar on the intake side?

The thing is that the nature of the fabrication will create variables in the length and pressures in the runners so it may always have some out of sync waves to maje it sound smoother than a normal 4 cyl.

Yea, so ideally there's digital controller with a programmable map. A preliminary map should be generated based on theoretical behavior, and then adjusted to work with the more complex dynamics that can happen. Then a "trim" calculation to account for different levels of pressure and temperature.

WTF is in your car is not the same as "how did you fit a V8 into that thing?!"

[Dimman]

Originally Posted by serialk11r

Yea, so ideally there's digital controller with a programmable map. A preliminary map should be generated based on theoretical behavior, and then adjusted to work with the more complex dynamics that can happen. Then a "trim" calculation to account for different levels of pressure and temperature.

WTF is in your car is not the same as "how did you fit a V8 into that thing?!"

Or you could put a V8 in it?

Cadillac Northstar engines (transverse mountings) have been crammed into Fieros...

[Calum]

Originally Posted by S2kphile

Get healthy man. Live longer and can post more in these forums. Not to mention your SO will think you sexy as ****. She'd have to shape up just to keep up with you.

I have no issues passing my annual physical fittness test for the military, my heart rate isn't any different then when I biked 60-70 kms a day, and my blood pressure is actually lower now, typically about 115 over 75. I'm just built like a truck. I stopped lifting weights when I was ~13 when I could max out the leg press and the ab machine and do 5 sets of 10 reps on each. I could use some cardio but honestly it's not as bad you'd think.

This might seem like an excuse, but whatever. As a stoker in the Navy, working in temperatures as high as 65 deg C, there's typically two body flavors that can hack it, marthone runner types whose bodies can handle the dyhydration and guys like me that just store enough water.

The biggest problem is that guys like me aren't in vogue anymore. Skinny metrosexual type guys are. Well, that and I would look rediculous on a sport bike.

[serialk11r]

Originally Posted by Dimman

Or you could put a V8 in it?

Cadillac Northstar engines (transverse mountings) have been crammed into Fieros...

Too heavy.

Dream V8 (added in previous edit) would be 2 CBR600RR motors put together. 230hp of 15000rpm glory. Probably lighter than a 1ZZ too lol.

Actually a CBR600RR on its own sounds really good already at 15000rpm. Pretty sure I heard a sport bike screaming at well over 12000rpm yesterday, it was more glorious than the Lambos I've heard shrieking around town, imo.

I wonder what Mazda is going to do with their Skyactiv lineup. The 6 speed gearboxes look promising, but the strokes don't look very high rpm friendly so far.

[Calum]

Originally Posted by serialk11r

Too heavy.

Dream V8 (added in previous edit) would be 2 CBR600RR motors put together. 230hp of 15000rpm glory. Probably lighter than a 1ZZ too lol.

Actually a CBR600RR on its own sounds really good already at 15000rpm. Pretty sure I heard a sport bike screaming at well over 12000rpm yesterday, it was more glorious than the Lambos I've heard shrieking around town, imo.

I wonder what Mazda is going to do with their Skyactiv lineup. The 6 speed gearboxes look promising, but the strokes don't look very high rpm friendly so far.

Why not the v8 from the Ariel Atom? Atleast it already exists, and should do everything else you need.

[serialk11r]

Originally Posted by Calum

Why not the v8 from the Ariel Atom? Atleast it already exists, and should do everything else you need.

Not dream. Only hits 10,500rpm, plus 500hp is complete overkill imo. 230hp at 13krpm is just so much more fun :P

[Dimman]

Originally Posted by serialk11r

Not dream. Only hits 10,500rpm, plus 500hp is complete overkill imo. 230hp at 13krpm is just so much more fun :P

Well get in touch with your local foundry and machine shop. There are individual-made versions of bike V8's around the world. Common theme seems to be use the bike heads, pistons and rods, custom machine a crank and cast block. The heads are put on so that the cam drives are on opposite ends of the motor (one head is 'backwards') so the intake sides are on the inside of the V.

Or what about the 60° Yamaha transverse V8 that ended up in the second gen Ford Taurus SHO? 3.4L 235(?) Hp. That would probably fit easily, and cost 5% of the bike V8 idea... Heh.

Edit: http://vancouver.en.craigslist.ca/rc...216585451.html

[serialk11r]

Nah, I'm not serious about that dream, it's just a dream :P Maybe someday, although I think I'd rather have a slightly lower bore/stroke ratio for low end efficiency (don't want crazy heat rejection, I can just buy a rotary for that :P).

Now that my concept of "high rpm" has been changed significantly (lol), I'm wondering what I can do with a Mazda Skyactiv-G 1.3L...only problem is this motor is wayy undersquare. Stroke alone isn't too horrible, 82mm is shorter than an F20C.

[serialk11r]

Whoa, I just noticed that there's a limited edition GRMN iQ supercharged (probably not for the US)!

That would actually be a perfect starting point for this build. Seeing how Honda L15s are about the same bore and poop out at around 140hp, my guess is that the 1NR can take 9000+rpm before the heads are maxed out, maybe a little head work can get it up past 10000. 80.5mm stroke should be easy to work with too. I suspect the rods are nice and long as well.

10,500rpm limit with 10,000rpm power peak at 133Nm (lets say a rather mild NA build) is 140kW or just under 188hp. If that's possible, I'm not even sure I'd want to S/C it! But for fun, 25% boost on that would be 175kW~=235hp. Altogether for about the same service weight as 1ZZ hopefully. That would be freaking awesome.

[ichitaka05]

Originally Posted by serialk11r

Whoa, I just noticed that there's a limited edition GRMN iQ supercharged (probably not for the US)!

yeah it was internet order only

[CSSM]

Just worked out at the neighborhood track, the only other person there was a old man walking laps in a long flowered dress. Disturbing... it doesn't help that he drives a PT Cruiser.