#16: Re: Changing the gearing for a quicker 0-60, help? Author: lee1985, Location: North WestPosted: Wed Sep 19, 2012 1:26 pm ---- Some of this is like reading polish but I've said many-a-time I feel like an old'granny when it comes to vehicles and engineering/mechanics :D!
So in essence all this means that despite gearing down the ratios for quicker acceleration, the 0-60 time would actually be slower, as Seabook originally said?
#17: Re: Changing the gearing for a quicker 0-60, help? Author: Seabook, Posted: Wed Sep 19, 2012 1:37 pm ----
E5GDM wrote:
Seabook wrote:
E5GDM wrote:
Seabook wrote:
macca1411 wrote:
A van gearbox usually has shorter gearing so should give you quicker acceleration. How long a standard clutch would last with the harsher acceleration would be anyones guess.
torque doesn't work that way round, it's going out from the engine to the clutch then gearbox.
changing gear ratio won't affect clutch
I think he's on about the possibility of torque from a more powerful engine (138) effecting the clutch on a van gearbox that was designed for an engine with less power.
you joking? all turbo diesel van with BE4 box run better clutch (higher torque loading) than the 138/180.
i can't see why a 180/138 has more torque than a diesel van. torque kill box, not horsepower.
you joking? I know it's torque, I even say it in the post above.
I think your still missing the point, &/or trying to be to clever, as the fact is that if you increase the power going through a gearbox & clutch, you may have to upgrade the clutch (& even the gearbox maybe) to cope. If not why are there so many variants of clutches & not just one?
but the opener only got a 180.....
why would he need to upgrade the clutch? he not even ITB or cam or turbocharged the engine.....
and i have said before, diesel box are design to handle higher loading than petrol box
#18: Re: Changing the gearing for a quicker 0-60, help? Author: Edward, Location: In the garagePosted: Wed Sep 19, 2012 2:13 pm ----
lee1985 wrote:
So in essence all this means that despite gearing down the ratios for quicker acceleration, the 0-60 time would actually be slower, as Seabook originally said?
Do you only even specifically only accelerate to 60mph? Generally your car will be quicker because you'll have access to the power band of your engine more readily.
#19: Re: Changing the gearing for a quicker 0-60, help? Author: lee1985, Location: North WestPosted: Wed Sep 19, 2012 3:58 pm ---- Is anybody here equipped to tell me how much I would shave off a 0-60 by reducing the maximum speed to around 110mph. I know I could go to a gear specialist but you never know whose on these forums.
Just a thought.
I don't want to reduce the top speed too much, but I have no need for a car that does 140mph
#20: Re: Changing the gearing for a quicker 0-60, help? Author: Seabook, Posted: Wed Sep 19, 2012 4:15 pm ----
Edward wrote:
lee1985 wrote:
So in essence all this means that despite gearing down the ratios for quicker acceleration, the 0-60 time would actually be slower, as Seabook originally said?
Do you only even specifically only accelerate to 60mph? Generally your car will be quicker because you'll have access to the power band of your engine more readily.
plus you always got more torque at wheel compare to before.
#21: Re: Changing the gearing for a quicker 0-60, help? Author: E5GDM, Location: EssexPosted: Wed Sep 19, 2012 5:34 pm ----
Seabook wrote:
but the opener only got a 180.....
why would he need to upgrade the clutch? he not even ITB or cam or turbocharged the engine.....
and i have said before, diesel box are design to handle higher loading than petrol box
Initially there was no mention of a 'diesel box', just a suggestion to use a van gearbox & a warning the clutch might not handle the extra power. Not sure why you had to go all techno over that.
#22: Re: Changing the gearing for a quicker 0-60, help? Author: Johnbyron, Location: ScunthorpePosted: Thu Sep 20, 2012 6:07 am ---- Most vans are diesel tho and seabook iv just got to say this , if the clutch and box is from a diesel then you are right it is designed to withstand more torque therefore should be strong enough to cope with a gti 180 engine, some people have to realise the difference between torque and bhp
#23: Re: Changing the gearing for a quicker 0-60, help? Author: Edward, Location: In the garagePosted: Thu Sep 20, 2012 6:42 am ---- Transmissions dont even know what BHP is. Torque is the only thing transmitted through to the wheels.
#24: Re: Changing the gearing for a quicker 0-60, help? Author: Seabook, Posted: Thu Sep 20, 2012 7:41 am ---- well at least someone has back me up......
but back to the questions:
lee1985 wrote:
Is anybody here equipped to tell me how much I would shave off a 0-60 by reducing the maximum speed to around 110mph. I know I could go to a gear specialist but you never know whose on these forums.
Just a thought.
I don't want to reduce the top speed too much, but I have no need for a car that does 140mph
by calculation for 110 mph (@7000 rpm, 5 th) top speed you need 5.07 final drive; which means compare to the original final drive (3.79), you got at least 34% more torque at wheel all time. So it could mean you could shave off 34% 0-60 times but got to remember you got 1 extra gear shift.
#25: Re: Changing the gearing for a quicker 0-60, help? Author: lee1985, Location: North WestPosted: Thu Sep 20, 2012 9:11 am ---- Thank you Seabook, perfect answer mate.
What is the calculation you are using for this? In terms of like 110 @ 7,000 rpm etc. Are you just basically saying that 5.07 is 134% of 3.79 hence this is how much more power I will have? If I know how to calculate it then I can play around with it until I get what I think might be the ideal final drive/gear ratios I think is best in terms of top speed etc.
Also, would you say it takes .75 seconds for the extra gear change?
One last question: is it definitely right to assume that 34% extra power directly equals a 34% quicker 0-60 time (excluding the gear change)? I suspect that there is more to this and the extra power doesn't necessarily mean that is exactly how much time you can shave off. Perhaps it gets a bit complex here?
#26: Re: Changing the gearing for a quicker 0-60, help? Author: Seabook, Posted: Thu Sep 20, 2012 9:46 am ---- www.grimmjeeper.com/gears.html
gear ratio calculator is all you need.
stock gti gear ratio = 3.455 1.870 1.360 1.051 0.861
Final Drive:3.790
====
the last questions it what i am not sure about. ideally you need a RR graph to do the proper calculation (need the integration of the torque curve before and after, the 0-60 time will be proportional to the torque curve area);
so no. it is not that straight forward and unluckily it is next to impossible to shave off that much time (unless you torque curve is dead flat from 800rpm all the way to redline, then it will be directly related to the change in the ratio of the final drive). most likely it can shave off about 1 sec but with an extra gear shift you should see around 1/2 sec improvement max.
And easier way would be to find that out in any decent car game like GT5, LFS etc. they should have a very good formula to do the calculation for you.
#27: Re: Changing the gearing for a quicker 0-60, help? Author: E5GDM, Location: EssexPosted: Thu Sep 20, 2012 1:58 pm ----
Johnbyron wrote:
Most vans are diesel tho and seabook iv just got to say this , if the clutch and box is from a diesel then you are right it is designed to withstand more torque therefore should be strong enough to cope with a gti 180 engine, some people have to realise the difference between torque and bhp
Most vans but not all are diesel, & for the record the 1.9 D has
94 lb-ft of torque, the 1.4 HDi has 120 lb-ft of torque, & the 180 has 140.
So some people have to realise that something designed for a lower powered vehicle might not cope.
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and seabook iv just got to say this , if the clutch and box is from a diesel then you are right it is designed to withstand more torque therefore should be strong enough to cope with a gti 180 engine, some people have to realise the difference between torque and bhp
