...What is the cylinder firing order and timing on the '99 V-four?
Do two cylinders fire at the same time or is it sequential?
Wondering what causes the VFR torque?
Thanks.
I guess I've finally stumped you guys?!
1-3-2-4
look up 'big bang' for more info on this site
turtlecreek, Nov 14 2007, 04:50 AM1-3-2-4
look up 'big bang' for more info on this site
The big bang search was what I was looking for, but not sure there was a consensus?
At any rate, it is the unbalanced timing that gives the sound and torque as I suspected.
Thanks for the post lead!
-Al
vfral1, Nov 11 2007, 10:28 PMWondering what causes the VFR torque?
Thanks.
Um - rapid firing of fuel/air mixure around a crankshaft?
MD
vfral1, Nov 15 2007, 12:22 AMturtlecreek, Nov 14 2007, 04:50 AM1-3-2-4
look up 'big bang' for more info on this site
The big bang search was what I was looking for, but not sure there was a consensus?
At any rate, it is the unbalanced timing that gives the sound and torque as I suspected.
Thanks for the post lead!
-Al
The sound yes. Torque no.
The VFR Torque is not really all that higher than other 4 cylinder engines with similar displacement. For instance the GSXR 750 has peak torque that is much higher than the VFR. But the GSXR peak torque comes at higher revs compared to the VFR.
The VFR engine is 'tuned' for a fairly broad power band. Just a combination of tons of factors including intake/exhaust port size, fuel injector / throttle body design, cam profile (how long are the valves open / close, overlapping etc.).
vfral1, Nov 11 2007, 10:28 PMWondering what causes the VFR torque?
Torque of an engine is directly related to displacement. Two engines of the same size, assuming no losses/identical efficiencies, will produce the same peak torque.
Torque = Force x Distance. Putting this into an engine's perspective, Torque = (the force of the piston moving down the cylinder bore) x (the throw of the crank). So while a smaller bore piston will not have the same force from combustion as a larger bore, it will have a greater throw on the crank, with both the long stroke/small bore & short stroke/large bore configurations ultimately generating the same torque.
In the real world, torque is affected by cam selection, intake & cylinder head design, compression ratio, frictional losses, momentum losses, etc., so it is possible for a smaller engine to have more torque than a bigger engine. Case in point -- VFR vs. GSXR. The GSXR has a higher compression ratio, shorter stroke, and (I am guessing) more radical camshaft design & greater valve area. Here are the two bikes' dyno graphs:
VFR800GSXR750The 750 puts out slightly more torque than the 800 (781cc) due to the small changes I noted above, but note how close the curves & overall numbers actually are. Since the 750 puts out more torque at a higher RPM, it also produces much more HP. Where the torque peak hits & the redline of the engine can be majorly effected by stroke length (and also valvetrain components, camshaft selection, rotating components, etc.), thus it is no surprise that the shorter stroke engine can rev higher, with a higher speed occurrance of peak torque, and greater horsepower.
In other words, what goldVFR said...
vfral1, Nov 15 2007, 06:22 PMAt any rate, it is the unbalanced timing that gives the sound and torque as I suspected.
The "1-3-4-2" isn't unbalanced or unusual - that's a fairly typical firing order for 4-cylinder engines.
It's the degrees at which ignition is occurring, combined with pairs of cylinder sharing a crank pin.
Is there a larger version of your avatar? Where did that come from?
toro1, Nov 15 2007, 11:16 AMVFR800
GSXR750
The 750 puts out slightly more torque than the 800 (781cc) due to the small changes I noted above, but note how close the curves & overall numbers actually are. Since the 750 puts out more torque at a higher RPM, it also produces much more HP. Where the torque peak hits & the redline of the engine can be majorly effected by stroke length (and also valvetrain components, camshaft selection, rotating components, etc.), thus it is no surprise that the shorter stroke engine can rev higher, with a higher speed occurrance of peak torque, and greater horsepower.
Nice explanation. What's interesting on the graphs (to me), is that the GSXR produces more torque than the VFR even at fairly low RPM, starting around 4k. Even at the GSXR's 5,500 rpm hole, it's about the same as the VFR. So, the argument that the VFR is tuned for mid-range torque doesn't really hold water.
If you also look at the torque curves for some of the liter twins, you'll see why some of us find these so attractive for street riding. The peak power isn't uselessly high, but the pull from 3k up to ~10k redline is much higher (normally aspirated, of course).
RSV/RC51/999
