Well I bought a '03 silverado with the 5.3L and I'm thinking of putting a turbo set up on it, well I called comp cams ans they told me to run a reverse duration camshaft. From what I have know to be true is that for any forced induction (including nitrous) you want to run more duration and lift on the exhaust side of the cam, also spread out the LSA to the 112-114 range. Anyways, if anyone has any ideas on why a reverse pattern cam would wor kbetter please fill me in! thanks

Later
Rassan

Isn't it something about the sooner you open the exhaust valve, the more pressure there is on it and then you are shoving it out that much faster too which accelerate's exhaust gasses better????

Which helps spool up the turbine wheel better??

pdq67

Turbo cams normally have a longer intake duration and a shorter exhaust duration , and useually a fairley wide LSA.

With a turbo you dont want or need much in the way of overlap....

While it is somewhat questionable as to how much actuall " Crossover " flow from the intake side through the chamber and out the exhaust dureing overlap on a N/A engine.....

You do not want that to happen much with a Turbo engine.... A turbo that is produceing Boost would actually force air through the chamber and out the exhaust dureing overlap.... When you are produceing boost a fair amount of A/F mixture could go right out the exhaust ...therefore produceing less HP and a loss of heat to spin the turbo... So by reduceing the overlap you actually would produce more boost.... At least in theory...

A typical turbo cam would look something like this...

intake... .440 / 268 / 216
Exhaust.. .420 / 256 / 204
114 LSA.

Looks similar to a Performer cam wit the intake/exhaust values swapped for one another and ground on a 114LSA.

Interesting.