doobrychat
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| posted on 1/6/13 at 09:28 PM |
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speed calculation for BEC cars..
other than the fact i know the Seven reps are shaped like a brick.. Just found this on the net and its handy for those filling out the IVA form which
asks for the Vehicles top speed...
i did it and i'm well surprised as my BEC was screaming its nuts off on the IVA speed tester the other day just to get to 70mph.
 
http://www.apexgarage.com/tech/gear_ratios.shtml
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sdh2903
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| posted on 1/6/13 at 09:36 PM |
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I think there's something not right there especially with a 3.92 diff have you tried the calculator at the top of the bec forum page?
I do agree they sound like they are flogging their nuts off when on the rollers, when mine was on the rollers the other week I was just waiting for
it to go pop.
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Davey D
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| posted on 1/6/13 at 09:37 PM |
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Something not quite right there. No way will you get that top speed of 166mph in 6th gear. Especially if you have a 3.92:1 diff. I have a 3.38:1 which
will give a higher top speed and the calculator I used worked out that I have a top speed in 6th of about 140mph
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doobrychat
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| posted on 1/6/13 at 09:57 PM |
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yes i thought something was not right with it too.. I have measured my tyre which is 22inch diameter and i know it will never make 160mph as my bike
(the same) will make 186mph+ and thats got a 2.4:1 chain sprocket ratio..
seems a bit more like a pub talk calculation..
[Edited on 1/6/13 by doobrychat]
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deeceee09
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| posted on 1/6/13 at 10:27 PM |
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Download the Quaife Speed Calculator from this site and see how you get on
http://www.quaife.co.uk/
It gives much useful info too.
Treachery and old age will always triumph over youthful enthusiasm.
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doobrychat
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| posted on 1/6/13 at 10:40 PM |
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quote:
Originally posted by deeceee09
Download the Quaife Speed Calculator from this site and see how you get on
http://www.quaife.co.uk/
It gives much useful info too.
even better that one... I wont be bragging down the pub though about the results.. Probably be quicker to walk there than drive the BEC down there
with that calculator... hahaha
Gearbox:-
Tyre:-
-------------------------------------------------------------------------------------------
Top Gear gives 4.488 MPH/1000 RPM and a top speed of 44.877 MPH at 10000 RPM
Engine speeds in top gear:-
30 MPH = 6685 RPM 40 MPH = 8913 RPM 50 MPH = 11142 RPM 60 MPH = 13370 RPM
70 MPH = 15598 RPM 80 MPH = 17826 RPM 90 MPH = 20055 RPM 100 MPH = 22283 RPM
Top Speed in 1 gear = 20.175 MPH
And changes into 2 gear at 7637 RPM dropping 2363 RPM
Top Speed in 2 gear = 26.419 MPH
And changes into 3 gear at 8192 RPM dropping 1808 RPM
Top Speed in 3 gear = 32.250 MPH
And changes into 4 gear at 8626 RPM dropping 1374 RPM
Top Speed in 4 gear = 37.387 MPH
And changes into 5 gear at 8993 RPM dropping 1007 RPM
Top Speed in 5 gear = 41.573 MPH
And changes into 6 gear at 9264 RPM dropping 736 RPM
Top Speed in 6 gear = 44.877 MPH
******************************************************************************************
Gearbox:-
Tyre:-
-------------------------------------------------------------------------------------------
Gearbox:-
Tyre:-
-------------------------------------------------------------------------------------------
Gearbox:-
Tyre:-
-------------------------------------------------------------------------------------------
Top Gear gives 4.488 MPH/1000 RPM and a top speed of 44.877 MPH at 10000 RPM
Engine speeds in top gear:-
30 MPH = 6685 RPM 40 MPH = 8913 RPM 50 MPH = 11142 RPM 60 MPH = 13370 RPM
70 MPH = 15598 RPM 80 MPH = 17826 RPM 90 MPH = 20055 RPM 100 MPH = 22283 RPM
Top Speed in 1 gear = 20.175 MPH
And changes into 2 gear at 7637 RPM dropping 2363 RPM
Top Speed in 2 gear = 26.419 MPH
And changes into 3 gear at 8192 RPM dropping 1808 RPM
Top Speed in 3 gear = 32.250 MPH
And changes into 4 gear at 8626 RPM dropping 1374 RPM
Top Speed in 4 gear = 37.387 MPH
And changes into 5 gear at 8993 RPM dropping 1007 RPM
Top Speed in 5 gear = 41.573 MPH
And changes into 6 gear at 9264 RPM dropping 736 RPM
Top Speed in 6 gear = 44.877 MPH
******************************************************************************************
Gearbox:-
Tyre:-
-------------------------------------------------------------------------------------------
Top Gear gives 4.488 MPH/1000 RPM and a top speed of 44.877 MPH at 10000 RPM
Engine speeds in top gear:-
30 MPH = 6685 RPM 40 MPH = 8913 RPM 50 MPH = 11142 RPM 60 MPH = 13370 RPM
70 MPH = 15598 RPM 80 MPH = 17826 RPM 90 MPH = 20055 RPM 100 MPH = 22283 RPM
Top Speed in 1 gear = 20.175 MPH
And changes into 2 gear at 7637 RPM dropping 2363 RPM
Top Speed in 2 gear = 26.419 MPH
And changes into 3 gear at 8192 RPM dropping 1808 RPM
Top Speed in 3 gear = 32.250 MPH
And changes into 4 gear at 8626 RPM dropping 1374 RPM
Top Speed in 4 gear = 37.387 MPH
And changes into 5 gear at 8993 RPM dropping 1007 RPM
Top Speed in 5 gear = 41.573 MPH
And changes into 6 gear at 9264 RPM dropping 736 RPM
Top Speed in 6 gear = 44.877 MPH
******************************************************************************************
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dave_424
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| posted on 1/6/13 at 10:41 PM |
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Bike gearboxes also have a primary reduction ratio before the gearbox ratios, this means that each gear ratio has to be multiplied by the primary
reduction ratio for your true engine RPM to gearbox output ratio.
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tilly819
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| posted on 2/6/13 at 08:28 AM |
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You have not taken into account the primary reduction gear.
The easiest way to use it in the calculations is to just add it onto the final drive ratio.
Tilly
F20C Haynes roadster 440 BHP/Tonne www.youtube.com/handmadeextreme
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doobrychat
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| posted on 2/6/13 at 09:24 AM |
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well had a different calculation now and worked out 10000rpm to be 91.25mph which seems a bit more realistic.... on the lookout for a lower diff now
as i'd like to be able to cruise at 70mph without my left ear bleeding...
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40inches
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| posted on 2/6/13 at 09:36 AM |
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A good calculator here
It's spot on with my ZX9R.
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