cam options

[-Bruce-]

ast 1 spec

power band 2000-6000
valve lift 10.55mm
duration 270 deg

does not realy look that great ben, well not what im looking for.

bruce

[benji]

hmm, i must of been thinking of a different cam

[Snowface]

the ast range of kentcam is designed for use with carb's on the vauxhall 8v engines.

The NVO51/61/63 etc are for injection. Not sure about mappable injection though.

Someone on here said they fitted an ast2 to their GSI and only got 2bhp more.

[Stuart]

indeed, some lairy cams can send "stationary" pulses of air back up and they can stop at the air mass meter and effectively cause the flap to close

[DrivingSpanner]

ummm, this is generally when you have a cam with a fair bit of overlap and you are still using a plenium chamber.... a big problem with the rover k series...

[DrivingSpanner]

the reason that a 'wild cam' can sometimes (or all the time depending on how much overlap) be rough at idle or low revs is because of the overlap, when the inlet and exhaust valves are open at the same time you will get scavenging, where inlet gasses go out the exhaust valve, this helps remove all exhaust gasses, at lower speeds this is a fairly large percentage of the air going into the engine, resulting in starvation.
some of this can be helped with a mapable ecu but does not cure the problem, it will generally 'clear' at slightly increased revs because it can now breath properly because the engine speed has increased and is therefore pulling more air through the engine meaning that as a percentage, less is lost from the 'scavenging'.

More overlap = more scavenging = more airflow = more power

generally increasing valve lift will not increase the power of an engine unless it is already scavenging more than can be inhailed/ exhailed throught the available opening, at wich point larger valves would usually be needed also

[j1400]

Unless it's a turbo cause then your duration is limited but lift isn't ::

[DrivingSpanner]

ha, think ya clever do ya, well it still applies, ah but without overlap you will end up with exhaust gasses left in the engine which will reduce its efficiency and hence power, everwondered why a WRC car sounds so shit when they first put there foot on the throttle at lowrevs even with antilag?
Plus with a terbo the thing that will generally limit the amount of overlap is actually that you have to have a plenium chamber.

Duration = overlap = scavinging = airflow = power