Help me understand camshafts

[Jerryl]

I have looked at Hyd roller cams and have seen a few options.
(Picked a few examples);

More intake timing - Example - Weber 212/206/111LSA /0.503/0.496 lift
More exhaust timing - Example - FTS 206/210/110LSA / 0.516 lift
Single pattern - Example - Weber 206/206/109LSA / 0.496 lift

I realize that the timing of the events have a lot of effect, as well as the porting, efficiencies, etc, but these cam event timing specs are not listed.
What I am trying to understand, is why some have more intake timing than others.
Cam techtips

More tips

So I guess my question is :wink: ;
For a 231CI 6 cylinder turbo changed motor, which philosophy do you subscribe to and why?

 

[street6]

I'm by no means a cam pro however to pick a proper cam one must acknowledge first which combo/parts & use (street or track) will be utilized. heads? turbo? converter? etc...

IMO- Roller cams are the way to go. They provide less friction and eliminate flat tappet camshaft lobe wiping.

 

[Jerryl]

I'm by no means a cam pro however to pick a proper cam one must acknowledge first which combo/parts & use (street or track) will be utilized. heads? turbo? converter? etc...

IMO- Roller cams are the way to go. They provide less friction and eliminate flat tappet camshaft lobe wiping.

True, so let's say you have the turbo and converter matched (Call it TE44 and 2800 stall for example).
Do you think it changes the requirements as far as "more intake vs exhaust lobe duration"?

 

[street6]

Well, to answer your question I think it depends on who you ask. Split cams have been discussed in several different threads if you do a search. I began reading up on this topic after purchasing a built 109 block with a 205/222 roller cam which looked odd to me. Regarding the turbo buick cars I have read that more intake duration is good b/c exhaust back pressure is usually two times your boost pressure and since the exhaust is under more pressure (back pressure) it required less exhaust duration for the spent gasses to escape the cylinder. However......I have also read that more exhaust duration is needed on turbo cars b/c the intake is being forced in (under boost).

If your looking to purchase a cam I would contact one of the reputable buick dealers (Anderson Performance, DLS Engine, Weber Racing, etc.) and get their opinion. Your goals for your car will have alot to do in deciding on which cam to use.

I would say a majority of mostly street driven cars on here stay under a 212 intake. Good luck, and let us know what you go with.

 

[Jerryl]

Well, to answer your question I think it depends on who you ask. Split cams have been discussed in several different threads if you do a search. I began reading up on this topic after purchasing a built 109 block with a 205/222 roller cam which looked odd to me. Regarding the turbo buick cars I have read that more intake duration is good b/c exhaust back pressure is usually two times your boost pressure and since the exhaust is under more pressure (back pressure) it required less exhaust duration for the spent gasses to escape the cylinder. However......I have also read that more exhaust duration is needed on turbo cars b/c the intake is being forced in (under boost).

If your looking to purchase a cam I would contact one of the reputable buick dealers (Anderson Performance, DLS Engine, Weber Racing, etc.) and get their opinion. Your goals for your car will have alot to do in deciding on which cam to use.

I would say a majority of mostly street driven cars on here stay under a 212 intake. Good luck, and let us know what you go with.

Thanks for the reply.
I have drawn “My own conclusions” :tongue:
The Buick Engineers made many correct decisions in the mechanical arena with these cars/motos, and the stock cam biased the exhaust side in both duration and lift.
So, I am going to run with that philosophy ............. at least in my head.

 

[SPOOLFOOL2]

I figured that one may be better geared to someone that wants performance, but still needs to pass smog. Be interesting to find out.

 

[gnxtc2]

You also have to look at flow numbers of the heads and plan accordingly.

Billy T.
gnxtc2@aol.com

 

[Jerryl]

You also have to look at flow numbers of the heads and plan accordingly.

Billy T.
gnxtc2@aol.com

Billy, I agree.
I am no expert, but I would think you also need to look at the headers, intake, turbo back pressure @ XX boost, etc.

But here is the question :biggrin: ;
At what intake/exh flow ratio do you start to make the change?

 

[Jerryl]

Well, after I dusted off the cobwebs of my memory bank , I remembered this thread. This is like the ultimate cam thread I found.
http://www.turbobuick.com/forums/turbos-turbo-related-parts/144094-boost-vs-back-pressure-3.html