PuppiesBalls
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 posted on 18/11/10 at 04:24 PM |
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Should I be worried about blowing the gearbox?
Should I be worries about over powering my gearbox? on the normal car which weighs 1200kgs the stock gearbox is rated to around 250hp and I will be
running 300ish ~& r888's However im hoping that as the cars going to be half the weight it wont be possible to put it under the same
load?
Do i need to look out for an OS Gilkin box of will my standard be okay?
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coozer
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| posted on 18/11/10 at 04:28 PM |
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Don't worry, be happy.....
1972 V8 Jago
1980 Z750
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alistairolsen
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| posted on 18/11/10 at 04:31 PM |
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What box is it? Whether is will break will depend on how close to failure it was in its original application and what the failure mode is.
For instance, standard cossie 4x4 box dies at about 300bhp and because 3rd gear fails. in a locost you can still lay down 300bhp in third so it may
still fail.
If the box is known for shearing the input shaft on a hard launch in a heavy car, then in a much lighter car youll probably be ok.
My Build Thread
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madteg
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| posted on 18/11/10 at 05:29 PM |
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I have been running 320BHP through a type 9 for 2 years doing track days and santapod not broke it yet, i think its because it breaks tracksion first.
I am also on R888s.
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peter_m7uk
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| posted on 18/11/10 at 07:13 PM |
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quote:
Originally posted by PuppiesBalls
Should I be worries about over powering my gearbox? on the normal car which weighs 1200kgs the stock gearbox is rated to around 250hp and I will be
running 300ish ~& r888's However im hoping that as the cars going to be half the weight it wont be possible to put it under the same
load?
Do i need to look out for an OS Gilkin box of will my standard be okay?
Hiya,
The weight of the car is irrelevant, it's all about the driver's right foot! What I mean is that whether you floor the pedal in a heavy
or light car, the engine is still at full load (torque), it's just that the light car accelerates harder. As for peak power (bhp), that is
only used at top speed or going through the gears close to redline. So, the answer is: If you drive full throttle or top speed in either car, the
box will be stressed identically. The only difference is that the light car needs less throttle to accelerate, so when accelerating either car at
the same rate, the box will have it easier in the light car.
As for the engine with increased power/torque, the box will definitely be more stressed even if it's in a lighter car, unless you back off and
don't use the power/torque. But there'd be no point in your bad-arse engine then!
Actually, I just thought of one qualfier to that statement. Does the 300bhp engine rev higher than the 250bhp one? In that case, you may be getting
much of the extra power at really high revs, which you could avoid (again not much point!). If they rev to about the same, then the extra power is
from a higher torque curve, in which case you'll definitely be hammering the box!
Pete
[Edited on 18/11/10 by peter_m7uk]
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Canada EH!
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| posted on 18/11/10 at 10:52 PM |
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It's torque that breaks things. Think of high HP bikes and their tiny gears and chains, but not much torque.
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