500bhp N/A 4 cylinder...

[PhillipM]

If you're using the rpms to correct for road speed/gearing, then that is the equivalent to bhp, so at some point the 2nd gear should coincide with or cross the honda line or vice versa.
Here's a graph in your format using the figures from that Honda (the bottom end is scaled a bit from some 2.4 figures but the top end is theirs), vs a 500bhp YB dyno graph, with '2nd gear' scaled to meet the same rpms as the honda:

Note the graphs converge/cross up top and also there a large deadspot where you change gear on the YB, because the gears end up so far apart. It'd be even worse in reality because you have your gearchange/clutch disengagement time and a tenth or two of turbo lag unless you were flatshifting.
In fact you'd run a longer first gear to get out of that, which would bring that initial torque output down by about 25%. (You'd make the redline in first gear in the YB probably match the Honda for speed at 9000rpm)


Yes, the YB is faster, but it's not quite as bad as your graph makes out.

 

[PhillipM]

And of course, that's using 2 gears to the honda's single one. Really you should just be comparing the Honda to the second gear figure. As obviously a previous gear in the honda to match the ~7k rev range of the YB would then mean the Honda would be just as fast or faster.

 

[McGherkin]

No, it is a torque plot, not a power plot. The lines do not have to touch to make the same power.

The YB dyno you found is 50lbft down and revs about 1000rpm less, so you’ve had to use a bigger second gear ratio reduction. If you were using the dyno same figures as me you’d end up with the same graph, and the 2nd gear line is genuinely above that of the Honda.

Regardless as you can see, the YB gains a huge advantage in the first gear and doesn’t really lose anything in the next. You can’t just pretend the first gear doesn’t exist, if anything if you were only going to look at one gear you would look at the first one as it is the gear where the ratios are matched. In which case the YB has far more acceleration but the Honda will eventually reach a higher speed.

 

[PhillipM]

No, you made it a power plot as soon as you corrected to engine speeds, because now you've matched gearbox input speed between the two. Power is just torque x rpm after all.

And as I said, you could run a 1st gear for the honda there too which would be just as impressive as it would then be peaking around 450lbft of torque too.

I used a couple of YB graphs straight off google that were pushing very close to 500bhp, nothing cherry picked. Regardless, at 500bhp the result would be the same because all that would happen is you have more down low before it meets the honda graph (as it would have to, because the torque would have to drop off at the same rate to keep it under 500bhp)

 

[PhillipM]

E.G - You give the Honda a 1st gear that's matched to the same road speed:

It's a touch rough as I just did a quick paint edit, but close enough for examples.

If you normalised graphs of wheel torque against road speed as is industry standard it'd be a lot simpler, but you've effectively got the same graph anyway. But the bottom label is wrong. Because it's no longer rpms but rather effective speeds. And your torque outputs are now post gearing rather than at the flywheel.

Now, of course you could have a turbo making shedloads of boost lower down, and spooling up 1000rpm or so earlier, to give it more advantage while it still runs out of steam up top to keep to the 500bhp, but my point still stands, it's nowhere near as bad as you were trying to make out with this phantom 'extra gear' for the YB.

 

[davo172]

probably only about 200lb/ft torque though ?

If that ! ??

 

[McGherkin]

No, you made it a power plot as soon as you corrected to engine speeds, because now you've matched gearbox input speed between the two. Power is just torque x rpm after all.

It’s still torque, it’s just offset. A power curve for this engine would look totally different.

And as I said, you could run a 1st gear for the honda there too which would be just as impressive as it would then be peaking around 450lbft of torque too.

So the Honda starts in first and the YB starts in second? How is that a fair comparison.

Because it's no longer rpms but rather effective speeds. And your torque outputs are now post gearing rather than at the flywheel.

Nope, it’s still RPM. By selecting a higher gear it gives the same effect as having a higher revving but lower torque engine, essentially a second power band. We can tie wheelspeed to it by defining the actual gear ratio and then plot wheelspeed and wheel torque, but we are not talking wheel figures on the original graph.

Anyway, this has gone off topic enough.

 

[PhillipM]

It's a lot more fair than the Honda only having one gear when the YB has two. Given they have similar power they'll be geared for similar speeds.

It's no longer engine RPM because you're putting it through gearing, so you're no longer talking either flywheel torque or engine rpm. But rather torque and rpm after whatever gearset you're using. Which is effectively wheel speed + wheel torque for both.

 

[Al_G]

A 200bhp civic is just as quick as a 200bhp boosted car with 30% more torque (due to the gearing and peak power) so why is a 500bhp vtec any different to 500bhp boosted car? Surely the same rules apply?

 

[Waitey]

Some people in here need to watch this...

 

[Pauleds]

BHP is how fast you hit the wall
Torque is how far you take the wall with you

 

[PhillipM]

You can have all the torques you like, french tin + wall = wall wins.

 

[Goodj]

In any event, rev that ricer block to 10k half a dozen times, and it'll be off for a rebuild.

 

[bloke]

The one thing everyone has forgotten about and the most important thing about a Honda is how big is the grass cuttings box?

 

[JamesBryan]

The one thing everyone has forgotten about and the most important thing about a Honda is how big is the grass cuttings box?

Gallo 24.

 

[Kev@KAM]

never forget the gearbox as a torque multiplier and the importance of revs in combination with short ratio transmission.
Its why diesels are rarely fast like for like vs petrol unless rules skew things in their favour.

 

[bloke]

never forget the gearbox as a torque multiplier and the importance of revs in combination with short ratio transmission.

NNNNNNOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO....

don't start talking about torque multipliers and ratios, i've gone round the twist trying to explain that to people in the past.