04Crew

Just what the title says. Is there anything that specifically makes Comp's XFI "Exhaust" lobes specific to the exhaust? In other words, why wouldn't they work on the intake. For those of us running single springs (and not wanting to push our luck) they seem like a nice comporimise in lift. They have a little more lift than the XE/XER lobes and a little less than the XFI "Intake"/LSL lobes.

Beaflag VonRathburg

iTrader: (176)

XFI lobes are not specifically exhaust lobes. I've seen quite a few cams that are XFI / XER setups.

SweetS10V8

iTrader: (4)

Yup, they are simply families of lobes that people mix and match the way they want.

Theres even LSK lobes....

04Crew

Aparently my original question wasn't clear enough. I am well aware that the XFI lobes are a family of lobes and that technically you can use any lobe wherever you want. However, there appear to be XFI "Intake" lobes and XFI "Exhaust" lobes. For example, the 230 XFI "intake" lobe has a lift of .612 and a 280 duration at .006. The 230 XFI "exhaust" lobe has a lift of .604 and a .006 duration of 282.

http://texas-speed.com/shop/item.asp...d=898&catid=44

So, I ask again, is there anything particular about an XFI "Exhaust" lobe that makes it more suited to the exhaust (versus the intake)?

SweetS10V8

iTrader: (4)

I understood your question perfectly, you didnt understand my answer apparently.

So I answer again, They are families of lobes. Nothing is specific to intake or exhaust, they are simply a lineup of lobes that people mix and match. Some lobe families are more aggressive, some have lots of lift, they are just different.

They just list what lobes are being used because there is most likely a 230 in almost every family, so they just tell you what "230" lobe they are using. A lot of people use a different lobe family on the intake and another lobe family on the exhaust.

For example a 230/230 cam. It could be a 230(XE) on the intake and a 230(XER) on the exhuast. Its simply a way of letting you know what your getting.

Old SStroker

04Crew, your question was a good one.

One possible reason for labelling lobes as "intake" or "exhaust" is lobe asymmetry. IOW, the opening and closing flanks of the lobes are not identically shaped.

This might pose the questions: "Why asymmetrical lobes?" "Why should intake and exhaust be different?"


Jon

NightTrain66

iTrader: (7)

They could call it an exhaust lobe if it closes slightly slower from .025 to .006 or .001 lift and allows the exhaust valve job to last longer since it will see alot more heat and abuse.

They could call it an exhaust lobe if it has a lil more aggressive lobe once it gets moving since the ex valve is lighter than intake valve and they feel the weight difference allows this motiona nd still remain stable at a given RPM with a given spring pressure.

I have seen either one of these reasons for a lobe being an "exhaust" lobe. I am not familiar with every plot on the XFI lobes and a call to Comp would let you know the real reason if you talk to the right person there. If you talk to the wrong person you could get all types of answers.

Lloyd

04Crew

Old SStroker - thanks. That is the kind of answer that I was looking for.

Anyone know if the Comp XFI "exhaust" lobes are asymmetrical and thus more suited to the exhaust cycle?

04Crew

Nighttrain - Thanks for the info. I thought about calling Comp but figured that I would just get some guy that would want to push one of the shelf grinds on me or at best give me his best guess regarding the XFI lobe design.

NightTrain66

iTrader: (7)

there ya go, OldStroker beat me to it and used less words explaining it.

He even ended with a question to make you think one step further. . . lol.

Hopefully this info helps a lil.

Lloyd

99Bluz28

iTrader: (35)

I was interested in finding out the difference also.

Go to INFORMATION, Catalogs Online, and click on Cam lobe Master Catalog, then go to page #15.

http://www.compcams.com/DefaultWide.asp

This is on page #15:

"the exhaust lobes have more area under the curve, for better
exhaust flow"