Cam Shaft Tech (duration)

[JOHNZAZA]

I have a cam question for everyone. The original cam
shaft in a 3.8 turbo motor has more duration on the exhaust
than the intake. so why would cam makers make cams like

210/205 or 218/214 or 206/206


Every cam for turbo motors that ive seen for small block
applications run bigger exhaust than intake.
To me that would make sense.

Why build cylinder pressure if you dont have enough head bolts
to keep the head down anyway.If the motor is forced induction
then should the cam be

205/210 or 214/218 or 206/208

does anyone run a cam like this or similar?

please respond with some insite

THANKS TURBOBUICK PEOPLE.

 

[WarpSpeed]

I'd agree! Since the air is forced in, and "naturally aspirated" out, it seems to me that all the help you can give the exhaust would help,,, seems GM thought that too.
I run the 204 214, which also has more exhaust lift than intake(450-490, I think it was) Runs good too.

Also, IMO, alot of duration is not needed on a mostly street driven car, as it raises the power band,, and lets face it, ya don't drive around at 5000 rpm on the street everyday....

 

[JOHNZAZA]

Whts your combination and how fast are you runnin?

 

[WarpSpeed]

I only got 2 runs before they "removed me from the track, roll bar? )

 

[turbobitt]

To say the exhaust gas is normaly asperated out is an incorrect statement. It is much easier for the piston to drive the exhaust gas out then it is for the turbo to push it in.(especially on small ports). Also the exhaust is working against turbine back pressure that is at least eqaul to boost pressure . There is not much to be gained(if any) by making the exhaust side bigger in duration but only could hurt things by increasing pumping loss because of increased time cylinder is exposed to exhaust back pressure.
Allan Gorneault

 

[KWIKR 1]

I've resarch and read all the arguments .and I just recently installed a SP 204/214 car in a new rebuild due to the cost factor. I orig had a Crane roller . And all I can say this cam feels great with my combo . I am total pleased with it . And would consider it in any other rebuild I may do in the future . I'm not a cam tech expert but I know this cam works well . Great bottom/mid and pulls like a train on top . A real sweet spot in the mid/top area . the only problem I'm having is finding a road long enough to be able to dial my car in . It may not work on paper but it sure works in my car and feels good on the butt dyno . Go figure .


** TRY IT - YOU MAY LIKE IT **

 

[REDS HOT AIR]

they do em backwards to keep these cars from being so fast..

i've been pushing the 204-214 cam for a while now and everyone who has trie it likes it

now im going to a 208-224 cam and see what happens.

 

[49-blues]

red-who makes the 208/224 sealed power?

 

[bruce]

Duration is but one piece of the puzzle.
While folks want to talk duration, what really get critical is overlap. In a N/A engine you might be dealing with 6 PSI of back pressure, in a turbo application you can be looking at 40. With that much back pressure, the engine does ALOT more self EGR'ing then what's wanted. Yes, you want some effects from self EGR'ing. Some, not alot.

Trouble is it's hard to design a cam like that.

 

[REDS HOT AIR]

Originally posted by 49-blues
red-who makes the 208/224 sealed power?

Schneider Racing Cams

 

[JOHNZAZA]

well i think im going to change my cam and go with
something like that.
maybe i won't blow as many headgasket's .



thanks for the input guy's

 

[Mr URL]

Originally posted by REDS HOT AIR
Schneider Racing Cams

My buddy has that cam and just flatted exhaust lobe #3 the other week after 6,000 miles.

 

[motorhead]

Just out of curiousity... could you run the 204/214 cam in a basically stock engine & combo like mine?

We have all heard the testimonials that the stock cam can go 10s... but, more lift is more lift... and who really feels that 15 yearold technology still cuts it?
We aren't still running stock chips, are we?!

 

[WarpSpeed]

EldelBrock makes the 204 214 also.... it does work in our motors.