madteg
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| posted on 19/8/08 at 07:51 PM |
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What ratio do i need for bec
Will be running f/blade engine, got no idea what ratio to run, can anyone point me in the right direction.
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StevieB
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| posted on 19/8/08 at 07:55 PM |
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I assume you mean for your diff?
I've got a 3.62, but no idea how it goes yet
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smart51
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| posted on 19/8/08 at 07:56 PM |
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I don't know the fireblade well my self but people on here do. They'll want to know which size or year of engine plus what tyre size
you're going to use.
I'd guess that a 3.38 would be ideal but a 3.62 would do. Are you mainly using it on the track or the road?
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madteg
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| posted on 19/8/08 at 08:04 PM |
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ratio
I am starting of with a 893 1995 engine on to a chain diff, running 16/65/195s. Trying to build as light as possible.
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LBMEFM
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| posted on 19/8/08 at 08:25 PM |
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Sierra 3.62 is perfect. Most replace the sprocket with a flange and attach a modified Sierra propshaft. How you are going to do it with a chain drive
I am not sure.
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motorcycle_mayhem
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| posted on 19/8/08 at 08:25 PM |
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With 205/60/13 you'll be happiest with a 3:36, or at least I was. Mainly used on a track, but nonetheless, it was awesomely good on the road.
Tried the 3.2 Freeloader with the engine, but way too much for the torque curve to handle.
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madteg
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| posted on 19/8/08 at 08:33 PM |
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diff ratio
Building rear bike engine car, engine front facing with chain diff similar to a atom
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mark chandler
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| posted on 19/8/08 at 08:38 PM |
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893 blade, 13" wheels and 3.62 diff for me.
It will pull 12,500 rpm in top, 13,000 going down a hill so perfect for power although a bit noisy at 70mph.
I recon its touching around 125mph flat out.
Regards Mark
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JoelP
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| posted on 19/8/08 at 09:04 PM |
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quote:
Originally posted by madteg
I am starting of with a 893 1995 engine on to a chain diff, running 16/65/195s. Trying to build as light as possible.
what you want to do, is find out the top speed of the bike, then the final drive ratio of the bike, then work out what top speed you expect your power
and body style to manage (guess 120), then compare your tyre circumference to that of the bikes standard back tyre, then merge it all together to pick
a ratio for your set up, and shimmy it about to get two teeth numbers for front and back sprocket.
As an example, if the bike is geared to 180 with a 2.5 final drive ratio, and has a 1m circumference, and your car will aim for 120 with a 0.8m circ,
then you need rato of 2.5/120*180*0.8, or 3. So maybe a 14 tooth front and 42 rear.
Simple, but bear in mind i totally made up the rolling radius.
And whilst you're buying cogs, get 3 back ones so you can change at will for different circuits. Its very annoying hitting the rev limiter on
straights!
[Edited on 19/8/08 by JoelP]
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madteg
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| posted on 19/8/08 at 09:49 PM |
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Thanks all.
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ChrisGamlin
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| posted on 21/8/08 at 05:39 PM |
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quote:
Originally posted by mark chandler
893 blade, 13" wheels and 3.62 diff for me.
It will pull 12,500 rpm in top, 13,000 going down a hill so perfect for power although a bit noisy at 70mph.
I recon its touching around 125mph flat out.
Regards Mark
Hi Mark
Unless you've got a modded (or CBR600) ECU, a stock 893/919 blade hits the limiter at 11,750rpm so if you're showing 12.5-13k then either
your clocks are over-reading or you don't have a stock ECU.
Madteg - download the spreadsheet in my sig then you can see what different ratios/tyres give you. I used to run a 919 blade in mine and with
205/60-13's, a 3.54 was about ideal for track work. You won't find one of those ratios in a Sierra so 3.38 or 3.62 would be the ones Id go
with.
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asl
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| posted on 22/8/08 at 06:48 PM |
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Chris, Thanks for the excel spreadsheet, but how should I use it?
I've got an 893 Fireblade with 195/50R15 and was at Brands and spent the whole of the straight on the rev limiter (11750) with a max speed of
107.
What diff do you think I have? I've checked the number against the sticky on the transmission forum but can't match the number (mine looks
like 83BG 4033BA)
Thanks for your help
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ChrisGamlin
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| posted on 23/8/08 at 07:29 PM |
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Id say you've got at least a 3.9 in there, if not a 4.1.
With the spreadsheet, you can if you want type in alternate diff ratios into the "Data" tab, and you can also edit the tyre sizes in that
tab and it will calculate it all properly. Once youve done that, go to the Speed Chart tab, select the engine, tyres and diff ratio and it will give
your top speeds in each gear on the chart (hover over the chart for the actual figures).
Chris
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asl
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| posted on 24/8/08 at 03:58 PM |
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Thanks, I will have a look. Do you have any data how the 0-60 changes with different diffs?
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ChrisGamlin
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| posted on 24/8/08 at 08:34 PM |
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Nope but its not a lot. A low diff will mean you'll need 3rd gear at least to hit 60 so the little you gain in acceleration you lose between
gears.
I had a 3.5 and a 3.9 in my blade BEC, and side by side against my mate's Megablade there was naff all in it with either diff. The 3.9
feels faster because the revs are rising faster and you're changing gear more often, but actually it makes little difference.
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