Dual pattern cam for turbo app

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I did a search and could not find anything definitive on this subject.

With a turbo you mostly overcome intake deficiencies.

Exhaust side becomes burdened with turbo back pressure as well as the deficiencies in the log and smal valves.

Has anyone confirmed the benifits/detriments of a longer duration?
Would larger ex valves be enough to cause a change?
Would both be the ultimate turbo system enhancement?

Still planning 99% street driving, 2v carb, auto trans. mild gears. Rice eater in nature.
 
TYPICALLY..........

Nitrous and mechanical supercharged engines need a dual pattern cam with MORE exhaust duration than intake duration.

Turbo engines need LESS exhaust duration than intake duration.

My next engine will use a straight pattern cam. Close enough.
 
Thank's !

I found an article in a 2000 issue of Car Craft that said the same thing. Just read it this morning.
 
All of it and more.

They even said you were going ti use a standard cam in your build LOL

Seriously the article was about cam selection, and had a question concerning S/C, nitrous, and turbo cam specifics.

Ken Duttweiler called out twin TO-4's for a 350chebbie. He said to select a cam with 15-20 degrees short on your desired operating range
( I assume RPM ) with a 114 deg LDA installed at 110 deg intake centerline. He also said beef your intake valve springs and use "killer" pushrods for the exhaust side.

Those spec's are for a V8 so I don't see much help on the LDA or intake centerline install.

What this explains to me is how you are squeezing the power out of the one barrel. According to the basic information it appears to me that the stock cam is a pretty good turbo unit. I think it will drive up that wall you are hittng at 5500 rpm if you go for a little more duration on your next cam. Question is how high do you want to rev it?
 
Howard":3fqthncg said:
1) Those spec's are for a Vee-Eight so I don't see much help on the LDA or intake centerline install.

2) I think it will drive up that wall you are hittng at 5500 rpm if you go for a little more duration on your next cam.

3) Question is how high do you want to rev it?
Click to expand...

1) an engine doesn't care if it has 1 cylinder or 12, you are only firing one cylinder at at time.
V 8 or 6 doesn't make a difference on basic cam theory.

2) The smallest straight pattern cam FSPP offers is a 214*/214* at .050" lift.
I got that one.

3) as high as it takes, doesn't matter to me as long as it holds together.
 
StrangeRanger":18xlsh5s said:
Isky makes turbo specific cams
Click to expand...

Yeah, that's a little smaller. I could have a custom ground but don't want to shell out the $$$$.

I'll stick with the one I have.
 
Crane says their 2030 for the SBF is suitable for turbo and blower applications. It is 216°/220° @ .050" on 112° LCAs. Your cam is milder than that so it should work nicely
 
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