Gear ratios.

[akuma]

hattech-v,
those 2 kemaman vtecs(d red EG n silver/white EK) r using it ler.sapa laie?hehehhehe

 

[eddie_vtec]

evoX2,

n yeap..heard of feilo's gbox nowadays oso....darn it..sum more got marking kenot open 1..hehehehehhe

got marking aaa...cannot curik formula ratio sifu feilow la like this....:confused_smile:
red eg kemaman using feilow ratio also ka...no wonder lerr....i want see feilow ler like this...hehehehe

 

[akuma]

dats wat i was told ler

 

[shiroitenshi]

Actually you can calculate what ratio he's doing by finding out his final drive, the his speed vs. rpm, and tire size.

I can calculate backward and give closely approximate ratio, depending on how much info you can give me.

Just drive it once, and then let me know what's the top speed for each gear depending on rpm. easy.. no need to open gearbox.

If all these engines are running more than 9K rpm.. probably using spoon ratio most likely.

 

[wil_alastor]

Does this means all the top vtecs (2litre above--pasaran gelap) using the same ratios from FLV (Fei Lo Vtec)?..if yes no fun already laa..just concentrate engine and tuning only..gearing all the same...

 

[shiroitenshi]

Actually gear ratios quite easy to study..

you want the car to pull the hardest and gain speed without dropping out of the powerband.

If you swap ratios, you make consession for the next gear you didn't swap.. it might be good, it might be bad.

If you have good torque, you just need the gears to fall in the same spot for each gear, so you can use full-throttle shift function. If not, you will only be able to use full throttle shift for certain gears.

 

[wil_alastor]

Shiro which one is consider closer :

example:

Same car same engine same weight same driver same tyre/rim/ofset size same road/track same air temperature same night same time same road temperature ALL SAME..

Car A : 20whp + Gear Ratio A
Car A : 20whp + Gear Ratio B

Gear Ratio A : 1st gear shift at 5000rpm & reach 80kmh (speedometer)
Gear Ratio B : 1st gear shift at 5000rpm & reach 100kmh (speedometer)

So which one considered 'closer' compared to the other?..the closer ur ratio means top speed drops too right?so in this case Gear ratio A is closer rite? (just ignore the gearings,lsds,final drive combo)

 

[shiroitenshi]

if 1st gear reach 80kmh, most likely using kaaz/os?/spoon at 2.7(or was it 2.5?) with 4.2/4.4 Final drive. If 1st gear can reach 100kmh.. "Oi! B-series gearbox ke tu?" or "Shit, how much rpm were you pushing?"

As to how close it is, hard to say.. because I don't understand the question.

Because close ratio is dependent on how much RPM you're pulling.. if you're driving a 6500rpm B-series (theoretically), then the stock Y21 will feel very like a super close ratio gearbox. For a 8K rpm limited engine.. it's an average close ratio gearbox.

"close-ratio" term as far as I know is defined by the speed you gain with each gear, so it's determined by all the gears. The more speed you gain per gear, the 'wider' the ratio.

So, if you have an 11,000RPM monster.. then the Y21 will be a wide ratio gearbox, even though it's considered close ratio for a 6500rpm and 8000rpm engine.

I think that's the best way I can describe it. Yes, speeds do decrease as you run 'lighter' gears, which is why if we can't make the speed on the gear, we have to play with rpm.

Example of close ratio for a 6500 rpm engine and 8000rpm engine.

It might seem the ratios are nearly the same, but if you rev gearbox A up to 8000 @ 5th gear, you can hit 290km/h!! Thats amazing, but only up to the point you realise "how long" the road you will need, and "how long" the time it will take for you to reach that. hahaha.

Most close ratio gearbox (since they were designed for the track) can't even hit 240km/h at all, stock Y21 can, but it takes AGES! hahaha.

So in summary, if you put in ratio for gearbox A in your 8000rpm engine, you will feel like it's a wide ratio. If you plonk in gearbox B in your 6500rpm engine (that makes the same power) you'd be shifting like a madman, because it's super short, so gearbox B becomes a super close ratio transmission in the 6500rpm engine.

There's no preset definition of a close ratio gearing.. if you take a close ratio gearing from a 6500rpm engine, then it will be a wide ratio for a 8000rpm B16A. It's just not the numbers, but rather the gear stagger.. how much speed does each gearing give you? As you can see on the chart, the more speed you can gain in one gear, the 'wider' you can consider the ratio.. so it's dependent on RPM as well, because gearbox A can be considered close ratio, if it's in the 6500rpm engine.

Usually gear one and two is a bit close (at least for honda transmission), so it's hard to say that it's a close-ratio or not with just two gears.

Confused yet? I was at first too.. lol.

The chart above is useful because you can gauge how 'heavy' the gear is by it's steepness.. the more steep it is, the more torque you will need. The more closer it is to being horizontal, the less torque you will need. But you really need to calculate the incline if you're really fickle about numbers. Notice the incline angle for the two gearboxes are nearly the same, so they're both close ratio for their specific engines.

Sad to say, this is not even the half of it.. There's also the subject of the torque curve and 'usable power' that relates to gearing... but that's another story.