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> CAMS (which), 2.0 Euro P/C Weber 40's
seanery
post May 21 2003, 06:59 PM
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Take your time to fit your other cars' schedules.
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McMark
post May 21 2003, 08:52 PM
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What about split duration cam? The 494 is lookin' like a great cam for street use, but I wonder if a split cam would be better. Does choosing the split duration depend on the volumetric efficiency and flow number of the head?
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seanery
post May 21 2003, 09:10 PM
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way over my head, what is a split duration cam?
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Mockmaw
post May 21 2003, 09:45 PM
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The Eagle cams are intriguing.. anyone want to share an anecdote about their experience with any of the Eagle products?
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McMark
post May 21 2003, 09:56 PM
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A split duration cam has different lobes for the intake and exhaust. For example, you could have the intake of the 494 (0.465 by 288 degrees) and the exhaust of the 86a (0.435 by 290 degrees). Or any other combo. Logically, it makes sense because intake tracks and exhaust tracks have different needs in terms of valve action. So it gives you a deeper level of control. Of course, diagnosing what level of valve action you need is the tough part.
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seanery
post May 21 2003, 10:02 PM
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sounds like a lot of 'figuring' for a street motor. Is it done mainly for race engines?
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McMark
post May 21 2003, 10:38 PM
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For a guy like me, I do a lot of armchair engineering and, good or bad, I'm willing to spend the money to build an above average engine. So if I can find a place to test my heads on a flow bench, I'll do it so I can better choose a cam. Ever since I've started working on cars about 3 years ago I've been voraciously devouring every bit of auto knowledge I can. So I suppose a split duration cam would be most often discussed in race engine circles, but isn't really that far off for the informed hard core hobbyist.

On a side note, I was just sitting here thinking about cams and wouldn't it be great to be able to test how cams would work on a dyno before even contacting WebCam to choose your grind. All we have to do is engineer some heavy duty solenoids that would bolt on in place of the rockers, and then write a computer program to interface with the solenoids so you could change lift and duration "on the fly". Hmmm. It all seems so easy... (IMG:style_emoticons/default/blink.gif) (IMG:style_emoticons/default/wacko.gif)
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Mockmaw
post May 21 2003, 11:41 PM
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While we're that far, why don't we just rig the solenoid setup to work in the engine all the time.. infinite variability. Cadillac is doing this/working on this, no?
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Brad Roberts
post May 22 2003, 12:07 AM
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As far as I know.. you can't do split duration on any VW cams. Two valves share one lobe. Something like number 1 intake shares a lobe with number 3 exhaust (I'm guessing here) I forget which ones share which without looking at a cam in a engine half, but I do know they share lobes.

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McMark
post May 22 2003, 12:39 AM
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The do share lobes, but it's intake - intake, not intake - exhaust. There's four lobes on the cam, and they line up with the rockers in the head which is exhaust - intake - intake - exhaust. So on a split duration cam the two out lobes would be the same, and the two inner lobes would be the same. The WebCam page lists a 0.500 284/300 250/260 163/86b cam, for example.
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Brad Roberts
post May 22 2003, 12:43 AM
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I'm not sure what split duration would gain us.. but Dema Elgin will grind you anything you want on a stock core.


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ChrisFoley
post May 22 2003, 05:22 AM
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Jake Raby has been using split lift/duration cams for a while now. He designs them on his engine analyzer program.

I have an 86a cam in the engine currently in my race car. It makes good power from 4400 to at least 6200 rpm. I have had it up to 6800. Apart from a compression increase the heads are bone stock.
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MJHanna
post May 22 2003, 09:07 AM
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I've got an 86 B in my 2.0, but its got some major headwork. (IMG:style_emoticons/default/aktion035.gif) Lot of good mid range torque to get you out of corners. (IMG:style_emoticons/default/mueba.gif)
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Bleyseng
post May 22 2003, 09:14 AM
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Chris, do you have a dyno sheet you could post? Love to see it on paper to see actually what the power curve is.

Jake Raby has been using the split cams to get more power and cooling. If I recall a longer exhaust duration to help the exhaust flow and it helps to cool the engine some. The bottleneck on the type 4 heads is the exhaust port with its 90 degree turn so anything helps the flow over stock.
Geoff
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Dman
post May 22 2003, 10:04 AM
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I am running an 86a with webber 40's, stock heads and heavy valve springs. I am very happy with it, It is totaly streetable and idles fine.

Like Chis says it realy comes alive above 3500 RPM, you can get to 6 in a hurry.
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seanery
post Sep 7 2003, 08:18 PM
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OK, so everyone who was involved with this thread, what lifters are in there? And why aren't you having the problems that others have had and others fear?
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Gary
post Sep 7 2003, 08:55 PM
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Haven't hopped on this thread yet, but OE lifters from pelican. No problems in nearly 20k miles.

Using an 86a on a 1911cc motor, 8.5 CR, 42X36 valves, mild port and polish, 40 mm Dells.

Which cam depends on the use. If I were to pick again for a street motor, I'd probably go for the 86. I spend less time 3500-6000 than I do 2000-4000.
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ChrisReale
post Sep 8 2003, 01:08 AM
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I thought about Web Cam for my rebuild, but they were back ordered to hell....so I went with stock cam and lifters. No problems yet, and I have driven the piss outta the car. Funny, all the reputible builders in my area said web cams were not necessary, and none of them even consider them during a type 4 rebuild. Not that that says anything...????? All this talk about the lifters failing would make me go caramic all the way. The 4400 would more than make up for itself in the future as far as headaches were concerned
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redshift
post Sep 8 2003, 01:14 AM
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Can we talk about something else?

(IMG:style_emoticons/default/wink.gif)

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ChrisReale
post Sep 8 2003, 01:51 AM
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QUOTE(redshift @ Sep 8 2003, 12:14 AM)
Can we talk about something else?

(IMG:style_emoticons/default/wink.gif)

M

Every time this comes up its like taking one straight to the gut huh? (IMG:style_emoticons/default/barf.gif)
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