General bike design..
Discussion
I done automotive engineering design years ago,and I'm always thinking on how to improve things,in my character now..
Anyway,Ive never mentioned it to anyone,so this is a first so will you guys let me know what you think..
Take an in-line 4,4 exhausts sticking out the front,then going under(usually)the engine.Carb/injection and filter behind the engine under seat..
On the surface this seems a little ineffiecient to me,and easy to improve...,(or I AM a thicko
)
If you reversed the design of the engine,4 pipes comming straight out the engine under seat/mudguard a'la ducati 916/996 etc,no ugly exhaust spoiling lines,the carb/injection/filter at the front of the bike,making the most of the air intake ( x forced induction ),and because theres no exhaust under the engine,engine can be dropped a few inches,helping to lower centre of gravity.
so all in all,better handling,better performance,better fuel economy,better looks..
what problems would you envisage ? , or any ideas you guys have had to add ?
cheers..
Wayne
>>> Edited by wayne_uk on Sunday 4th July 21:23
Anyway,Ive never mentioned it to anyone,so this is a first so will you guys let me know what you think..
Take an in-line 4,4 exhausts sticking out the front,then going under(usually)the engine.Carb/injection and filter behind the engine under seat..
On the surface this seems a little ineffiecient to me,and easy to improve...,(or I AM a thicko
) If you reversed the design of the engine,4 pipes comming straight out the engine under seat/mudguard a'la ducati 916/996 etc,no ugly exhaust spoiling lines,the carb/injection/filter at the front of the bike,making the most of the air intake ( x forced induction ),and because theres no exhaust under the engine,engine can be dropped a few inches,helping to lower centre of gravity.
so all in all,better handling,better performance,better fuel economy,better looks..
what problems would you envisage ? , or any ideas you guys have had to add ?
cheers..
Wayne
>>> Edited by wayne_uk on Sunday 4th July 21:23
Main problems,you'd spend all day cleaning out sensitive things like the air filter/fuel injection system being so vulnerable at the front end,hot arse anyone?Lots of heat deflection between said arse and exhaust would be crucial,i personally think over the years some exhaust systems make a bike,looks wise:-)Many great minds have gone together to bring about the basic bike design,and as you can see most engine layouts of modern bikes haven't changed for years,its mostly cosmetic/weight changes have come about to improve things,making things lighter and faster seems to be the main perogative these days:-)
I believe the Petronas FP1 in-line triple (www.fp-1.com/) has it's engine 'reversed' with the cylinders inclined backward so that the injectors are in the airbox and exhausts straight out the back.
Also I understand that the engine even runs 'backwards' not sure what (if any) advantage that gives though - but it does shoot flames out the exhaust when on the overrun.
I seem to think that there is (was?) a US made motocrosser which had the engine in 'backwards' but can't remember the details.
edited to add: more info here www.beaudrymotorsports.com/cgi/bmsmerge.pl?fp_fp1.txt
>> Edited by cazzo on Monday 5th July 00:37
Also I understand that the engine even runs 'backwards' not sure what (if any) advantage that gives though - but it does shoot flames out the exhaust when on the overrun.
I seem to think that there is (was?) a US made motocrosser which had the engine in 'backwards' but can't remember the details.
edited to add: more info here www.beaudrymotorsports.com/cgi/bmsmerge.pl?fp_fp1.txt
>> Edited by cazzo on Monday 5th July 00:37
Basically it is a problem of packaging - trying to get it all into the space available is not efficiently possible.
Lowering the engine in the frame may lower the bike c.o.g. but does not take into account the rider. The relative height of the engine affects the handling by pushing the front along under braking, reducing grip and feel of a 'higher' placement which adds to the weight transfer onto the front tyre. Also by placing the engine lower you reduce the available lean angles.
Exiting the exhausts near the rear shock serves to heat up the damping oil and reduce efficiency and consistency of damping. Also an inline 4 is rather wider than a V configuration where this is often employed, making the area around the riders legs wider and reducing control as well as adding to rider risk of injury. Given the placement relative to the engine would also impact on the frame design at this point.
Any of the above affect the siting of the petrol tank. Honda tried moving it under the engine on their GP bike (1983?) which used this reverse-engine philosophy, but found it altered c.o.g. too much and was less predictable as the c.o.g. altered as the tank emptied.
Spinning the engine in reverse has dynamic effects which mean it is not widely used and the Petronas team have had to work hard to counter these effects. Principally the gyroscopic forces of the rotating crank mass (with all the bits) has a tendency to lift the front under acceleration beyond that of a forward spinning engine. It also reduces the engine braking effort and apparently can be felt whilst trying to turn under braking as well, as these forces try to keep the machine more upright.
Lowering the engine in the frame may lower the bike c.o.g. but does not take into account the rider. The relative height of the engine affects the handling by pushing the front along under braking, reducing grip and feel of a 'higher' placement which adds to the weight transfer onto the front tyre. Also by placing the engine lower you reduce the available lean angles.
Exiting the exhausts near the rear shock serves to heat up the damping oil and reduce efficiency and consistency of damping. Also an inline 4 is rather wider than a V configuration where this is often employed, making the area around the riders legs wider and reducing control as well as adding to rider risk of injury. Given the placement relative to the engine would also impact on the frame design at this point.
Any of the above affect the siting of the petrol tank. Honda tried moving it under the engine on their GP bike (1983?) which used this reverse-engine philosophy, but found it altered c.o.g. too much and was less predictable as the c.o.g. altered as the tank emptied.
Spinning the engine in reverse has dynamic effects which mean it is not widely used and the Petronas team have had to work hard to counter these effects. Principally the gyroscopic forces of the rotating crank mass (with all the bits) has a tendency to lift the front under acceleration beyond that of a forward spinning engine. It also reduces the engine braking effort and apparently can be felt whilst trying to turn under braking as well, as these forces try to keep the machine more upright.
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