I've been searching and cant find a definitive answer. What lobes does everyone recommend for FI applications. From what I've found, XE, HUC, EHI, LXL, and EPS lobes work well (less aggressive ramp rates for more valve control). I want to build a street car and want the springs to last a long time. this is for a 347 with 317 heads, LS6 intake, F1A procharger.

So i guess that the questions are:

Why is one better than another?
What do our cam gurus use?

 

What have the cam grinders proposed???

 

Everyone suggests something different. I'm trying to learn and would like to know why one would be better than another. I don't like throwing parts at my car without knowing why theyre choosen over something else.

 

211/230 .558/.552 122.5 LSA

run the LS9 cam. you need a 1x sprocket, LS2 front cover, and a conversion pigtail but with all that and LS9 springs its still under $400.

GM uses it in the supercharged 6.2 ZR-1 so it should be nice in a procharged 5.7 F-Body

 

G5XB for a supercharged car...they do very well!

 

the aftermarket must be able to make more power without having to worry about emissions. Besides "throw XXX cam in it" doesn't help me learn why it is better than another. Can you tell me why that cam would be better than something like the EPP Blower cam?

That cam has been around since 2006. Have there not been any lobe design advancements since then? what lobes does that cam use?

 

i was simply going off of "street car" and "long lasting springs" its a factory cam from a supercharged car is the only reason i offered it and its 1/4 the price of another cam. the EPP is a beast of a cam tho. a buddy of mine is using it and it has great power N/A also

 

Doesn't that cam use XER lobes? They're very aggressive from what i understand which makes good power but is very hard on your valvetrain. Maybe Bob@Brutespeed will chime in on that.

 

There are a lot more variables than just forced induction.

A lot more...

 

Just go with a blower cam, that's why the various companies call them that. That ls9 cam package is the way to go if long lasting stable valvetrain is your chief concern.

 

I like to let the boost do the work and I avoid high lift. Mostly I use XE lobes with no more than 6* overlap on the street.

 

Care to elaborate?

I've read that XE lobes are good. I guess that I'm trying to learn why an XE lobe would be more favorable over say an LXL or EPS lobe. What effect would going with more than 6* of overlap have?

 

i went with lsl lobes.. from what i was told by my tuner, they are pretty fast but not too hard on the valvetrain. i am running a larger lift cam tho

 

High lift will make it harder to control valve-train and since incoming charge is pressurized, it is not necessary to open the valves more than needed.

 

When I'm choosing lobes for FI I grab several lobes from different families I like to use and I compare them for the given application against each other @.020, @.050 and @.200. If I have valve lift curve charts for those lobe families I compare under the curve area with major and minor intensities and then with lobe lift, tappet lift and closing/opening rates.

Depending on the supporting valve-train modifications such as valve weight, rocker weight, rocker ratio, push rod diameter, push rod wall thickness and lifter type will determine how aggressive the lobes I use will be. At the same time the application itself such as the engine specifications like compression, stroke, bore, rod length, intake runner cc, exhaust runner cc, intake and exhaust valve diameter, intake manifold type, primary diameter, collector diameter.... is it a roots blower, centrifugal blower, single turbo, twin turbo or screw blower. How big is the blower, how big is the turbo(s) etc... If it's a street car whether hydraulic or solid I take into account mileage a year the customer puts on the vehicle so that they get a reasonable life out of their valve-train components, mainly valve springs.

Then depending on how much I have to compromise on all of the above will start that process all over again. So there really are no cut and dry instances where finite rules apply.

Selecting lobes for a cam are all a big compromise in the end as to what you can get away with and what needs to be accomplished. That said I don't like super aggressive lobes on hydraulic roller stuff, and reserve them for solid rollers in certain situations. They work very well when planned for and around with stout parts, but if you don't build for it and decide one day, "I'm going to use the most aggressive lobes I can, because I can" will normally end up not getting you the results you had wished for.

I know this doesn't answer specific instances, so if there is a combination in particular you have in mind don't be afraid to ask.

 

But what of those things would make you choose say an XE lobe over an LXL lobe? or an EPS lobe over an XE? Not asking anyone to spec a cam at this point because the heads aren't ported yet so i dont have flow numbers.

 

Ramp design is more important than the lift max. We run the higher lifts with less duration.
I like the lsl lobes. Timing is good and controllable without over springing them.

 

Valve-train weight, cylinder pressure, rpm range, mileage.

 

So the titanium spring kit, shifting at around 7k, and wanting a long life out of the springs on 20lbs of boost?

 

Ok ,,,,,I hear You saying You want to learn ,,,,,,,,,but asking poeple on here for answers to You're questions would take maybe 1000 years to get answered . Have You read the stickies at the top of gen3 internal engine ? There is quite a bit of information about what You're eager to learn about ,,,,,,,also I would suggest Google-ing about cam lobes and intake opening/closing events and exhaust open/clos and center-line over-lap ......etc ,,,,,then if You come back on here You can ask specific questions and then maybe You'll know enough to spec You're own cam/lobe if You study enough first . The info is there , You just need to find it . Also Car Craft ,,,,,,,,and Hot Rod mags and others like Them are a good place to search cams and cam results real world .