VW Performance Autotech Sport Tuning Camshafts — Volkswagen Bora MkV

31 Май 2015 | Author: | Комментарии к записи VW Performance Autotech Sport Tuning Camshafts — Volkswagen Bora MkV отключены
Volkswagen Bora MkV

Camshaft Design

The camshaft an important role in the SportTuning of water-cooled VW. The correct application of design will ensure a balance between drivability and


Race cams normally rough idling characteristics due to the overlap required for high rpm Street cams generally use a duration and keep the lobe spread apart to prevent too overlap. Too much overlap on injected cars equipped Lambda is especially bad. can cause the airflow sensor to up and down, forcing the system to in either direction in an attempt to the CO in check.

Diagram #1 explains happens to the fuel mixture cam overlap causes both and exhaust valves to be open at the time. Some of the mixture into the combustion chamber is out of the tailpipe when the overlap is The loss of partially burnt increases hydrocarbon emissions generating the low-end power for the street. However, a little can help scavenge the mixture the combusition chamber on normally vehicles. This is where the technology plays an important in today’s cam design.

The duration of a cam is measure in degrees of on a circle when the valve is off its seat. An example would be a cam 225 degrees of duration at .050. is a portion of a 360 degree circle the valve is lifted at least inches off its seat. The longer the the more chance of the intake and lobes both being at the same time (overlap).

Another factor affecting is the distance between adjacent peaks. This is referred to as a center. Simply stated, it is the of distance in degrees of rotation the peak of the intake lobe to the of the exhaust lobe. The closer the centers are to one another, the more Fuel injected Volkswagen run best on 110 to 115 degree lobe Racing cams are on the other end of the and run as close as 102 degree lobe creating very rough characteristics.

The base circle of a cam is the of the heel dimension. Base on cams may vary depending on design features in the cylinder Such things as valve length, valve seat (how far down the seats are set in the chamber), grind on the valves and thickness of the lifter/cam follower, of the bore in the cam towers, and the basic of the cylinder head casting are all The base circle diameter of a solid lifter cam is between and 1.500 inches. On the hydraulic cam the base circle is between and 1.336 inches. The top of the hydraulic is approximately .0825 inches to the cam centerline than the solid

A smaller base circle can the valve train dynamics running. If a cam, such as a has a reduced base circle, the cam becomes more sharply This can lead to harsh and closing of the valve, and may even the lifter to skip off the cam surface high rpm conditions. High or harmonic valve spring may result from these

A quick and easy way to measure the of a short profile cam is to subtract the of the base circle (B) from the of the lobe height (A) using a set of or dial calipers.

An example: A) 1.919

minus (Line B)

Cam Lift =0.423

Both and exhaust profiles should be because there may be a difference in the and duration of each respective (referred to as an asymmetric cam). quick method of measurement is not accurate on racing cams. durations can cause inaccurate at the narrowest point of lobe. In case, the only accurate of measurement is by using a dial and a set of V blocks for rotating the cam, or a cam measurement device.

Perhaps the most important to remember when searching for perfect camshaft is this: be mislead by the numbers! The lift and of a camshaft are not the only features make a cam behave the way it does. like ramp profile, center, and nose shape all a cam’s behavior. It is virtually to determine exactly how a cam will or where it makes power, by looking at the numbers. Ultimately, all of a design aspects play a in how it will perform.

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