Gear ratios.

[shiroitenshi]

Hmm.. I know that this is going to sound unbelievable, and I'm probably going to get statements of 'that's not possible', 'you lie' and etc. so I'm going to make it a 'theoretical' question.

I'm asked to find out the gear ratios for a 'theoretical' monster B20B engine with 290hp (not on wheel) on a load dyno, of which the main duty is 0-400 drag on the net.

Now, I'm telling the guy that like hell I'll ever be able to get an answer to that question, and asking other drag teams about the gear ratios (the complete 1-4 + FD) is like asking them to divulge team secrets.

Still.. I told him I'll post here for the sake of it.. and here it is.

You guys think there'll be takers to this question?

 

[J101]

give ppg a call.

http://www.ppgearbox.com.au/

i believe if you are serious and willing to spend this would be a great site to start with. at least they are near to us. furthermore, its a fact that for whatever reasons ppl dont divulge trade secrets from both legal and the illegal world of racing. i think the guys build too much power around this region forgottenly thought power makes things goes faster. its the RACING TRACK gearing they are busy wasting time mix-matching which are not meant for 0-400m actually. at the end of the day, we see a milo-can shell(throw as much weight in junction of pushing the car) travelling at un-safe journey at blistering quatermile. so i think if we stick to these TRACK gearing set, just say, we must hit around 350whp on an n/a engine to pass 10.9sec on the quaters PLUS the milo-can body which is un-safe. all because of the gearing.

i hope this helps shiroi.

 

[hattech-v]

how do we know what ratio/spec to use before asking ppg to make it?
or maybe they got ready template (spec) to use?

 

[J101]

lotsa things when it comes to drag
- engine power (some ppl have less power and need gearing to push them..some ppl have too much power,maybe they need automatic 3-gear box)
- tyre SIZE
- track surface (normal or VHT coated)
- distance (this one very important, 300m, 350m or 400m *ahaks*)

so when u gonna buy your 300m-only gearbox hattech? heh

 

[hattech-v]

i'm looking for 200m punya... kekekkekeke

 

[shiroitenshi]

how do we know what ratio/spec to use before asking ppg to make it?
or maybe they got ready template (spec) to use?

I think they need the dyno's torque curve to know workable ratios.

Not too sure though.. anyway.. if it's too expensive also cannot, since currently the owner current budgeted, for intake part already.. The gear ratio will probably be the last thing he will get.. unless someone know where to rojak a honda gearbox for testing purposes.

 

[akuma]

J101,
whoa!u very d active arr nowadays?so,ur not gonna let us in on ur 300m-onry gearbox ratios ar?ehhehehehe

 

[J101]

maybe the guys in thailand has drag ratios youve been looking for :) long lasting i dunno. as long it serves the purpose, it should be alrite.

I think they need the dyno's torque curve to know workable ratios.

Not too sure though.. anyway.. if it's too expensive also cannot, since currently the owner current budgeted, for intake part already.. The gear ratio will probably be the last thing he will get.. unless someone know where to rojak a honda gearbox for testing purposes.

 

[J101]

not active le, just pinpointing to the RIGHT direction. :p

J101,
whoa!u very d active arr nowadays?so,ur not gonna let us in on ur 300m-onry gearbox ratios ar?ehhehehehe

 

[V8_nutter]

I think they need the dyno's torque curve to know workable ratios.

Not too sure though.. anyway.. if it's too expensive also cannot, since currently the owner current budgeted, for intake part already.. The gear ratio will probably be the last thing he will get.. unless someone know where to rojak a honda gearbox for testing purposes.

Ask him to use stock ratio first and check his RPM when reaching 400 metres. Example if he's in the beginning of 4th gear, then change 4th gear only, Spoon and Kaaz have different 4th gear units just take the highest ratio posibble. In the end of 400 metres, 4th gear must reach below "max" RPM.

 

[V8_nutter]

Hmm.. I know that this is going to sound unbelievable, and I'm probably going to get statements of 'that's not possible', 'you lie' and etc. so I'm going to make it a 'theoretical' question.

I'm asked to find out the gear ratios for a 'theoretical' monster B20B engine with 290hp (not on wheel) on a load dyno, of which the main duty is 0-400 drag on the net.

Now, I'm telling the guy that like hell I'll ever be able to get an answer to that question, and asking other drag teams about the gear ratios (the complete 1-4 + FD) is like asking them to divulge team secrets.

Still.. I told him I'll post here for the sake of it.. and here it is.

You guys think there'll be takers to this question?

You dont need a buy 1-4th ratios, the only thing you must know is how to "study" gearing. If you using 15 drag slicks, meaning you have to "usik" 4th gear only. Study your 1st and 2nd gear, if you can have quicker time with 13,14,15 slicks than it's already OK.

Change your 1st or 2nd only if your gearing is too short, otherwise stick with the stock one. The best way to "tune" 1st and 2nd gear is to make sure that it can reach approx 120kmh with 1-2. You need long-long-medium-short (1-2-3-4) gearing.

 

[hattech-v]

2nd gear 120kmh? 1.9?

 

[V8_nutter]

Hmm.. I know that this is going to sound unbelievable, and I'm probably going to get statements of 'that's not possible', 'you lie' and etc. so I'm going to make it a 'theoretical' question.

I'm asked to find out the gear ratios for a 'theoretical' monster B20B engine with 290hp (not on wheel) on a load dyno, of which the main duty is 0-400 drag on the net.

Now, I'm telling the guy that like hell I'll ever be able to get an answer to that question, and asking other drag teams about the gear ratios (the complete 1-4 + FD) is like asking them to divulge team secrets.

Still.. I told him I'll post here for the sake of it.. and here it is.

You guys think there'll be takers to this question?

Before spending any money, ask him to test and get the timing at the track first. From that he will learn what when wrong with the ratio,. For horsepower wise, his 290hp b20 is ok already but can it perform well on the track ?

Ive seen 230hp beat 250hp with roughly the same weight, so take that car to the track and study the "power delivery" first. We want useable power, not high horsepower.

 

[shiroitenshi]

Yeah.. thanks.. I understood the 'usable power' part.

I'll get the current gearing map of the car up, in a while.

 

[shiroitenshi]

Eh.. posted the map on the wrong thread.. oops!

Anyway.. here's it again.

I think it's too close a ratio for a B20B with oodles of low end torque.. although for a B18CR revlimited to 9.5K.. these ratios might actually work well enough (not sure though.. I'm not really a dragster techie)

 

[V8_nutter]

Shiro, from that ratio what is the max speed for 2nd gear ? What is your estimated time though ? If you can, try to max rev it till 10,000rpm though, most of the low 12sec and high 11s did maxed out at 10,500rpm the least. This will help a lot to balance out the unmatched gearing.

For a guidance, terminal speed of 180+ kmh will do mid 12s with a good launching, bad launching with good horsepower will also do mid 12s with 190+ kmh. If you plan to go 11sec, 1-2nd must do at least 120-130kmh with a power maxed out at 10,000rpm "and" still going strong at 4th gear.

If you can maxed out 205+ kmh speed at the end of 400metres you sure will getting low 12 or even high 11s. Providing you have a good tires though.

We get mid 12s on a 1.8cc with a max speed of 190+ kmh, with the advantage of 1st, 2nd gear jump. 3rd gear is ok, but 4th gear is weak. Power taper off early at 4th gear starting 8000rpm and at that point it's just cruising not "attacking". If you feel your machine can go strong on top of 4th gear or even on 5th (same feel it did on 1st and 2nd gear) you'll defenitely have an 11 sec car.

 

[shiroitenshi]

If you meant ET by calculation.. it'll 11.4xxxx.. car weighting in at 990+kgs... it's not a lightweight drag machines like you see in sepang.

But the reality is different.. it's making low 13's, which suggest some issues with the gearing (or the driver/owner) :P

The top speed for each gear is as shown.. second gear hits 109kmh at 8K, and if rev to 9K, the torque curve start to taper drastically already.. nothing bigger injectors and a retune can't fix. (I hope :P)

Like yours, the power taper off just a little later than 8K, but it's a B20 short stroke, and running high rpms is rather risky, although it's highly possible, since it does have forged internals.

I'll consider what you said.. I don't really fancy doing drags since I feel my reaction time is worse than a tortoise, but I guess I'll have to try it out and think of what you said, and perhaps try some new ratios...

Thanks.. I appreciate your help. PM your contact number, and I'll treat you for makan when I head down.

 

[J101]

ive been wanting to reply this thread since yesterday but i thought now would be the best. so now, since we have the chart and have all the estimations, how do we NOW go about making/buying the gear ratios?

there are so many gear calc online and most of them sum-up to gear speed and not the reverse instead? how now? the only way to this is buy is putting some ratio estimation, look at the speed chart plus your real speed and CUSTOM the ratio that has been plotted. Custom means money. Custom is always double the price.

i dun think we wanna buy everything from ATS, SPOON, KAAZ, QUAIFE and the rest of the gearing families to just calibrate and TEST with the engine power that we have right? imagine if we were to throw 50kg-100kg weight from the car. now thats buying another gear, again. then it will be a no-end story.

just my 2 cents and free opinion.

 

[shiroitenshi]

You're right.. that's why I need to have at least a rough idea of how the gear stagger is like..

Then, hopefully by looking at the torque graph and driving the car, I can see where the RPM drop to, and check the time between shifts under full acceleration, and see how the torque curve affects the acceleration time.

From there, I can at least estimate a ratio that might work, rather than doing the common way of swapping gears and test for each run. I'm not saying that I'll manage to avoid doing that, just that it takes less tries.. probably once or twice.

Anyway.. I'm having second thought yet again about driving that car.. It scares me.. probably just have to get someone to sit in it, and just get the results off the datalog.

And do a custom gearing calc for yourself.. the formula's not a secret. Then shift the chart points for target max speed at a particular gear, reverse the formula, and you get a ratio... then get a closest ratio, if not going the custom route. Or, you can plug in ratios, and see how it affects the top speed... then see time between shifts to see if the torque can pull the gears hard enough to shorten the acceleration time.

 

[J101]

http://www.race-technology.com/WebPage2/Other/Utilities/GearCalculations/GearCalculation.html

i can imagine the headache. give ppg a call :)