ffrgtm
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| posted on 12/4/11 at 02:39 PM |
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Optimum Engine Generation for Busa
Hello everyone,
I was quite keen on throwing a second gen busa engine in my MNR Vortx due to the extra 20hp however I have recently been informed that the gears are
narrower than on the first gen. This is a problem because the cars primary use will be autox where there are hillclimb type starts so first gear needs
to be stout.
Would it be wise for me to use the first gen engine? Are there any easy fixes to make up for the power deficit? I will have an extra $1000 due to the
cheaper first gen engines.
Is the busa really the correct choice in the first place? I thought it would be smart to have 100lb-ft due to the fact that I will often have a
passenger aside me in the MNR, but autox is dominated by very low sleep technical turns (under 70mph) where overall weight can be more important than
power (for example an r1).
Thanks for any and all input 
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daniel mason
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| posted on 12/4/11 at 06:13 PM |
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if its tight and twisty the extra torque of the busa should help. as for the gearing, i have no idea sorry!
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Davey D
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| posted on 12/4/11 at 06:57 PM |
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The Hayabusa has a vast array of tuning option available. I believe you can even buy different ratio gear sets. It may be an available option to buy
the Gen2, and then buy a different gear set
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Benzo
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| posted on 12/4/11 at 09:05 PM |
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My 1ts gen busa was fine, it stood up to the standing starts, but i broke a propshaft and an output shaft on the freelander diff. and that was only
using toyo road tyres in the dry. 
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Rocket_Rabbit
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| posted on 12/4/11 at 11:25 PM |
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quote:
Originally posted by ffrgtm
I thought it would be smart to have 100lb-ft due to the fact that I will often have a passenger aside me in the MNR, but autox is dominated by very
low sleep technical turns (under 70mph) where overall weight can be more important than power (for example an r1).
Thanks for any and all input
Busa torque means nothing in the real world because power is work done per time and gears are torque multipliers.
So assuming power is the same over operating rev range, a Busa engine will offer you no extra benefit over a lesser torqued thou.
However, the lighter weight of a thou certainly will help you in Auto X
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Rustybin
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| posted on 13/4/11 at 03:22 PM |
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Whilst the effect on torque of gearing is absolutely true, I would suggest that the available spread of torque from a hayabusa is of more
significance. If you do not need to change (or concentrate on changing) as often, times will be better.
As for the robustness of gears, I believe a Gen II will be fine. It seems to be the output shaft that is upgraded first and I believe these are the
same across the generations.
The other difference on the Gen I/II is the starter motor which you will need to change on the Gen I if there is a risk of spinning which it sounds
like there is!
There are quite a few of us hillclimbing without modifying the gear train including people running 1500cc derivatives.
[Edited on 13/4/11 by Rustybin]
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ffrgtm
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| posted on 14/4/11 at 12:37 PM |
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Thanks for the info guys! Think I will go with a gen II then. What's this about spinnin? The gen II requires no modifications then?
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ffrgtm
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| posted on 14/4/11 at 12:38 PM |
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oh and fwiw the gen II has a slightly larger output shaft
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Rustybin
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| posted on 14/4/11 at 01:14 PM |
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quote:
Originally posted by ffrgtm
What's this about spinnin? The gen II requires no modifications then?
The starter clutch on the Gen I would break if you spun and the engine was contra-rotated i.e. you didn't get the clutch in quick enough. It
could be modified to Gen II spec (the give away being a green label on the starter) which doesn't suffer the same problem. Personally I think
the Gen II with upgraded clutch springs should be good to get you going. Where you want to modify to after that is all down to aspiration and depth of
pockets.
Best of luck.
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Chet
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| posted on 14/4/11 at 03:02 PM |
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FYI-
The Busa starting system was actually changed in 2003 not GEN II. The 2002 and earlier engines can and should be updated with the 2003 parts.
Chet
[Edited on 14/4/11 by Chet]
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