variable valve timing
beef_bourito
12-22-2005, 02:23 PM
Has any bike got some variable valve timing like vvt, vtec, mivec, etc?
If not, is it at all possible to get a honda head to fit on a bike, or is it at all possible to modify a bike head to fit a car I4 vtec system?
If not, is it at all possible to get a honda head to fit on a bike, or is it at all possible to modify a bike head to fit a car I4 vtec system?
BP2K2Max
12-22-2005, 04:18 PM
Ghetto-z
12-23-2005, 09:08 AM
... a honda head on a bike... or the entire intake system from a car with variable valve timing... have you ever looked at an engine?!
jeffcoslacker
12-23-2005, 09:56 AM
Just loosen up your cam chain tensioner, and you'll have variable valve timing...
beef_bourito
12-23-2005, 11:43 AM
well, just the head, for the vtec or whatever, but the intake would probably have to be custom. i was wondering if they were at all similar in size and bolt holes, i'm guessing not.
jeffcoslacker
12-23-2005, 09:18 PM
It would be easier to just build a bike around a Vtec car motor (ala BossHoss w/chevy motors) than it would be to try to "reverse engineer" a bike engine to include that system.
Not just that the castings are totally incompatable, but a pretty high level of computer control specific to the design of the motor is required also...
Not just that the castings are totally incompatable, but a pretty high level of computer control specific to the design of the motor is required also...
beef_bourito
12-23-2005, 09:22 PM
oh ok, i was just wondering. don't you think it would be smart for companies to incorporate their vairable valve timing systems in their bikes? wouldn't it provide more power and a broader torque curve? does anyone know if there are any plans of companies incorporating it in their sportsbikes?
Also are those systems restricted in motorbike races? if so, that might explain the unwillingness to put it in.
Also are those systems restricted in motorbike races? if so, that might explain the unwillingness to put it in.
jeffcoslacker
12-24-2005, 02:19 AM
I'm sure it will become common on bikes, engine management computer systems for bike motors might need to catch up in sophistication first.
I don't see why it wouldn't be allowed in competition, but I don't know much about those rules.
Besides the performance boost when it kicks in, a system like that is preferable in a car because it allows it to have emissions compliance across a broad range of conditions and engine speeds, where a performance cam that works well at higher RPM produces a dirty, fuel-sucking and unstable idle at the idle speeds we expect from cars, especially with an automatic transmission.
Bike motors by comparison can idle higher, don't have to adhere to emissions standards so closely, quickly spool through the lower RPM range to get up into the powerband of the cam, can be kept in that powerband with closer ratio gears, fuel economy off powerband isn't a real big concern, etc...less real gain to be had for the complexity involved.
I don't see why it wouldn't be allowed in competition, but I don't know much about those rules.
Besides the performance boost when it kicks in, a system like that is preferable in a car because it allows it to have emissions compliance across a broad range of conditions and engine speeds, where a performance cam that works well at higher RPM produces a dirty, fuel-sucking and unstable idle at the idle speeds we expect from cars, especially with an automatic transmission.
Bike motors by comparison can idle higher, don't have to adhere to emissions standards so closely, quickly spool through the lower RPM range to get up into the powerband of the cam, can be kept in that powerband with closer ratio gears, fuel economy off powerband isn't a real big concern, etc...less real gain to be had for the complexity involved.
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