It was your use of words is why I call you out. I've seen other members criticize you of the same occurances.

This is exactly what I mean. You have never been more incorrect. Obviously you have never swapped cams in a car. When you put a high performance cam in the inherit nature is a lopier idle. Ask ANY engine builder.

Supercharged cars aren't supposed to have a lopey idle? You need to go to the drags or classic car show!

http://www.youtube.com/watch?v=6JKJXWO6yF8

 

we are not talking about drag cars, this is a street car.
from what I understand it's the lobe overlapp time which dictates if a cam is going to have a lopey idle.

And our NA cams are more agressive when compared to boost cams, because the NA cam is using the scavenging effect to increase cylinder fill of the air/fuel mix, by allowing the exhaust gasses to pull a low pressure point on the cylinder. This increases the velocity of the incoming air into the cylinder. much like a two stroke motor.

On a boost cam, it has less overlap version than the NA cam because, the super charger is feeding the cylinder it's air/fuel mix, so there is no need to have a the cam which creates the scavenging effect.

now if you put the NA cam in the superchaged engine, you will be loosing cylinder pressure because of the overlap of the NA cam with leave the exhaust valve open, thus letting the undurned pressurize air/fuel mix to blow out the exhaust manifolds.

NOw why does my N/A M112 motor, idle smooth as silk at 500rpm, while this guys SC m112 sound so lopy at 500rpm? Maybe he has a vacuum leak.? because I know the boost cam will not creat a lopy effect, the schricks cams do have more lift, but they are a custom grind and are not listed in their catalouge, which also makes me wonder about the design or if this guy has the correct cams installed.

 

The link you posted above had this info in it:

"If I remember correctly they have 2mm more lift on the intake and ~.1mm more lift on the exhaust. The cams also had very faster ramp rates and more duration."

 

Faster ramp rates and more duration with slightly higher lift will usually result in more overlap or create it if it wasn't there to begin with.

The C32 video sounded very mild to me. Very streetable. I suspect that at another 100 RPM higher it smoothes right out.

Again, this is the nature of more aggressive cams.

I too would be curious about dyno numbers before and after with just the cams changed on a stock motor. Then a before and after with the Schrick cams and stock ECU to a tuned ECU. Then with a bigger pulley... then another ECU tune... etc.

Baby steps ... I've seen this done by a tuner before and he logged all the changes.

Modern engines RARELY have big increases from a single mod. So I would expect that the Schrick cams would be no different.

Cheers!

EDIT: Posted by HDDP in another thread. (I presume by mistake )

The specs for the OEM cam are:
Lift @ Lobe / Intake 6.59mm / Exhaust 6.73mm
Lift @ Valve / Intake 9.8mm / Exhaust 10mm

The Specs for the Schrick Cams are:
Lift @ Lobe / Intake 7.25mm / Exhaust 7.25mm
Lift @ Valve / Intake 10.8mm / Exhaust 10.8mm

 

A supercharged road racer would sound very similar only without the big scoop hanging out the hood. The point of that video was to show you that a supercharged cam CAN have a lope contrary to what you believe since that is what the debate is all about.

Yes lobe separation (not lobe overlap as you called it and it is measured in degrees not time) is the primary factor in a smooth or rough idling engine. Lift and duration also play a part in this too.

If there was a vacuum leak the car would be running terrible and would probably trip a CEL.

FYI your car is idling too high if it is at 500RPM when its up to operating temps. Pay closer attention to the tach. Look at the attachment, the line at idle is more like 225-350 RPM.

 

OK, sounds cool then, somebody post some dyno before and after runs. Iwill have to check my rpm again when fully warmed up, that picture looks a little low almost stalled, was that car tuned or something?

 

We can only count on our members testing. Even at a shops cost it gets very expensive and time consuming just to prove a point, and it doesnt always increase sales proportionately. After intake, pulley and ecu the cams seems like one of the next logical mods to me. Still waiting to see what the LET headers do...

 

We are working on the headers now.....stay tuned!

 

I don't think so man.. I drove my car for 30 minutes, and it won't drop below 500rpm, your info is incorrect

 

It isn't my info, the line is screen printed right on the tach face and it clearly isn't in the middle of the 0 and the 1. It is below the half mark which means what Max?

 

that probably means the minimum stall speed, because at 250-300rpm my engine wants to die.