hi, i was just wondering what difference the valves on an engine make...e.g. if a car had a 12v engine, and another car exactly the same had a 16v engine, what would be different about them in the engine, more power maybe? or top end speed, better acceleration...i don't know.
Thanks
dumb question, but newbie @ work
Moderators: daewoomofo, Moderators Group
dumb question, but newbie @ work
like the lanos
Re: dumb question, but newbie @ work
Better airflow.lanosguy wrote:hi, i was just wondering what difference the valves on an engine make...e.g. if a car had a 12v engine, and another car exactly the same had a 16v engine, what would be different about them in the engine, more power maybe? or top end speed, better acceleration...i don't know.
Thanks
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PrecisionBoost
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The Valvetrain is usually dependand on the cams.
For example... a single overhead cam engine such as the 1.5L Lanos will typically have 8 Valves where as a dual overhead cam engine such as the 1.6L Lanos will have 16V.
The 8V SOHC will operate both the Exhaust and Intake valves off of one cam shaft.
The 16V DOHC is much more tuneable since the Exhaust valves are run off one cam and the Intake valves are run off the other.
With an 8V there is no way to change the valve timing unless you get the camshaft reprofiled ( cam lobes are built up and or ground down for new configuration)
With a 16V you can use adjustable cam sprockets to change the timing of both the intake and exhaust valves.
Usually the manufacturer sets it for good fuel economy so you can typically pick up a few horsepower by carefully adjusting the cam timing on a dyno. (this should only be attempted if you know what your doing)
So a 16V will have higher flow numbers but having two cams will also make more horsepower.
In the lower RPM levels flow levels are not as important.... it's usually in the higher RPM levels that you run into flow restrictions.
In this way a 16V will usually make more power in the top end but it will be fairly similar in the lower RPM to that of the 8V
8V cylinder heads try to make up for the flow difference by using large valves but this can add weight to the valvetrain and make it run at a slightly lower Redline.
I think Audi or Volkswagen has a 5 valve per cylinder engine.... not sure if its for intake or exhaust....but cramming more valves into a given spot will make the valves smaller which is good because they are light but bad because they don't allow as much airflow per valve.
Overall the 16V is currently the primary design of auto manufacuters... they can get good gas mileage and good top end power.
For example... a single overhead cam engine such as the 1.5L Lanos will typically have 8 Valves where as a dual overhead cam engine such as the 1.6L Lanos will have 16V.
The 8V SOHC will operate both the Exhaust and Intake valves off of one cam shaft.
The 16V DOHC is much more tuneable since the Exhaust valves are run off one cam and the Intake valves are run off the other.
With an 8V there is no way to change the valve timing unless you get the camshaft reprofiled ( cam lobes are built up and or ground down for new configuration)
With a 16V you can use adjustable cam sprockets to change the timing of both the intake and exhaust valves.
Usually the manufacturer sets it for good fuel economy so you can typically pick up a few horsepower by carefully adjusting the cam timing on a dyno. (this should only be attempted if you know what your doing)
So a 16V will have higher flow numbers but having two cams will also make more horsepower.
In the lower RPM levels flow levels are not as important.... it's usually in the higher RPM levels that you run into flow restrictions.
In this way a 16V will usually make more power in the top end but it will be fairly similar in the lower RPM to that of the 8V
8V cylinder heads try to make up for the flow difference by using large valves but this can add weight to the valvetrain and make it run at a slightly lower Redline.
I think Audi or Volkswagen has a 5 valve per cylinder engine.... not sure if its for intake or exhaust....but cramming more valves into a given spot will make the valves smaller which is good because they are light but bad because they don't allow as much airflow per valve.
Overall the 16V is currently the primary design of auto manufacuters... they can get good gas mileage and good top end power.