What effect does lobe seperation have on cam characteristics? The cam I am looking at has 110 LS but I see that most people are running 112-114. I have a 99Z28 A4 that I am about to do a head/cam package on and need a little info. Thanks.

 

Higher lobe sep (114 LSA) will idle better, and more the powerband up slightly. Lower LSA (110) will chop like a lumberjack at idle, surge and stall and act shitty around town, but will offer a little better cylinder filling which gives a little more midrange torque.

Most people with a 6 speed go with a 112, as 6 speeds are less tempermental than automatics at idle, and the manuals can use a little boost in the midrange (makes them a lot more fun to drive). Automatics have torque converters, so midrange torque isn't as big of a deal. Lots of automatic guys go with 114, but some go with 112 as well. 112 can be made to idle, it just takes a little more tinkering or custom tuning in most cases.

Then some people go with 111, 113, 116, etc. A higher number will typically have a smoother idle, everything else held constant.

J.

 

Thanks for the info. The problem I am having is that I will be running 1.8 roller rockers so I have to keep the advertised lift in the .52X. All of the cams I have found with .52X lift have almost stock duration. The only one I have found with the duration I am looking for has the 110 LS. Please help me find a cam with .52X lift and 225-235 duration @.050

 

Comp Cams allows you to pick any 2 lobes and have them ground on any LSA you want. The biggest lobe they have with .52X lift is 218 duration. Before I committed to a lift of that height, I'd do a search and try and find out what lift cams people are using with 1.8 rockers and stock pistons.

Here is a chart from MORE Performance.
http://moreperformanceinc.com/custcam.htm

J.

 

Do not compare LSA's of cams that are not otherwise identical.

 

I am running a comp 228-234 with a 510 on both sides with a 114 ls.With head and cam headers and pully I am at 400rwhp.I make alot of power up top.

<small>[ April 15, 2002, 10:33 PM: Message edited by: I follow no 1 ]</small>

 

Have you already purchased the rockers? If not, have your lift ground into the cam. It'll be a lot less expensive. For example: if you're running a .525" lift cam on 1.7 rockers, when you use the 1.8s you'll end up with a .556 lift. Have CompCams custom grind your cam with .556 lift on 1.7 rockers, and you won't have to buy the rockers.

'Los

 

If your not running open headers 90% of the time i wouldnt use 110*LSA cam, i chose a 112*, but dynos show littl;e difference to a 114* with other cam specs the same, i would go for a 114* if i were you, i run a M6 trans. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

 

Thanks for all of the insight. I already have the 1.8 roller rockers so that is what I will be running.

I Follow no 1: What is the part number of the cam you are running?

 

I can give you part # but it is a custom grind.
I havent seen anybody with the same grind post on this site.

 

Thanks to everyone that replied. I ordered all my stuff yesterday. If the results are good I will spread the info otherwise I may just keep my mouth shut to avoid the ambarassment.