16 V cam specs

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16 V cam specs

Post by dirtytorque on Thu Jul 09, 2009 1:05 pm

Not just lift and duration,more interested in intake/exhust centre lines and lobe seperation angles.
for the usual culrpits.

9a/kr/abf.


Anyone got anything hidden facts useful websites etc?

thnks

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Re: 16 V cam specs

Post by mrbeige on Thu Jul 09, 2009 2:59 pm

try [You must be registered and logged in to see this link.]

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Re: 16 V cam specs

Post by dirtytorque on Thu Jul 09, 2009 3:28 pm

mrbeige wrote:try [You must be registered and logged in to see this link.]


didn't see anything cam specific ?

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Re: 16 V cam specs

Post by mrbeige on Thu Jul 09, 2009 5:07 pm

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There is a bit in there Smile

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Re: 16 V cam specs

Post by ctwg60 on Thu Jul 09, 2009 7:07 pm

You have a spare head don't you rob? Get hold of some cams and measure them yourself. I can send you the digital gauges if you want or send it all over to me and I'll do it. 9a cams have ridiculously low lift don't they??

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Re: 16 V cam specs

Post by dirtytorque on Thu Jul 09, 2009 9:08 pm

ctwg60 wrote:You have a spare head don't you rob? Get hold of some cams and measure them yourself. I can send you the digital gauges if you want or send it all over to me and I'll do it. 9a cams have ridiculously low lift don't they??


Right,i'm going to take you up on that.
Will need to get hold of a selection of cams.
Then I'll send everything up.Really interested to know.
abf/kr's and some 9a's


yeah 9a's 9.0 mm lift I think from memory.

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Re: 16 V cam specs

Post by ctwg60 on Thu Jul 09, 2009 10:41 pm

Cool. Look forward to it. Smile

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Re: 16 V cam specs

Post by mrbeige on Fri Jul 10, 2009 8:29 am

I'd definitely be interested in the results too Smile Good work guys

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Re: 16 V cam specs

Post by dirtytorque on Fri Jul 10, 2009 3:13 pm

mrbeige wrote:I'd definitely be interested in the results too Smile Good work guys


Have you got some KR cams we can borrow?I need mine atm.
If so I will pay postage costs to send them to Chris.
thnks.

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Re: 16 V cam specs

Post by mrbeige on Fri Jul 10, 2009 3:47 pm

dirtytorque wrote:
mrbeige wrote:I'd definitely be interested in the results too Smile Good work guys


Have you got some KR cams we can borrow?I need mine atm.
If so I will pay postage costs to send them to Chris.
thnks.

I should have yes, I'll have a look when I get home Smile

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Re: 16 V cam specs

Post by ctwg60 on Fri Jul 10, 2009 4:01 pm

mrbeige wrote:
dirtytorque wrote:
mrbeige wrote:I'd definitely be interested in the results too Smile Good work guys


Have you got some KR cams we can borrow?I need mine atm.
If so I will pay postage costs to send them to Chris.
thnks.

I should have yes, I'll have a look when I get home Smile


So we just need a set of ABF cams and we are set! Unless you want 9A's doing also??

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Re: 16 V cam specs

Post by dirtytorque on Fri Jul 10, 2009 5:12 pm

ctwg60 wrote:
mrbeige wrote:
dirtytorque wrote:
mrbeige wrote:I'd definitely be interested in the results too Smile Good work guys


Have you got some KR cams we can borrow?I need mine atm.
If so I will pay postage costs to send them to Chris.
thnks.

I should have yes, I'll have a look when I get home Smile


So we just need a set of ABF cams and we are set! Unless you want 9A's doing also??


yeah,just for completeness.
I have some in the post.
May go and get some abf's tomorrow.

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Re: 16 V cam specs

Post by mrbeige on Fri Jul 10, 2009 7:59 pm

Right, I've defo got a KR inlet and both 9A inlet and exhaust. Ready if you want them.

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Re: 16 V cam specs

Post by dirtytorque on Sun Jul 12, 2009 8:07 am

Collecting reasearch data on cams in one place..


Narrow lobe seperation angles are only beneficial with combinations that have the exhaust side of the engine optimized. With long tube headers of the correct diameter, if they are run open or with an extremely low restriction exhaust system, the high velocity exhaust gas is able to produce negative pressure in the exhaust port near the end of the exhaust stroke. When that is happening it's often beneficial to narrow the lobe seperation angles which in turn creates more overlap and allows the intake port to be exposed to this negative pressure for a longer period of time. This counteracts intake reversion and actually helps to get the intake charge moving in the right direction before the piston starts down the bore. However, if the exhaust system isn't optimized the negative pressure isn't there. Instead there is backpressure, which has the opposite effect and actually creates reversion in the intake tract. With that in mind it's not hard to see that under those circumstances that less overlap, which is created by widening the lobe seperation would be better. Widened lobe seperation cams also open the exhaust valve sooner, while there is a little more pressure in the cylinder which produces a more violent initial blowdown and helps exhaust flow, which of course would be beneficial in a restricted system. As well, most wide lobe seperation cams are usually run in an advanced position to get the intake centerline angle at approx 110 degree ATDC for best torque. This also opens the exhaust valve sooner which helps exhaust flow. When all of these things are considered it's not suprising that your engine with stock manifolds will respond well to a cam with wide lobe seperation angles.


EFFECTS OF LOBE SEPARATION ANGLE
LSANARROWWIDE
Intake OpenEarlierLater
Intake CloseEarlierLater
Exhaust OpenLaterEarlier
OverlapMoreLess
Cylinder PressureGainLose
Idle QualityWorseBetter
Idle VacuumLessMore
Torque CurvePeakierFlatter
Peak TorqueMoreLess
High RPMDrops OffHangs On

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Re: 16 V cam specs

Post by mrbeige on Sun Jul 12, 2009 9:00 am

Now that is very interesting Rob. So, if you were to increase the lobe separation on a N/A 16v, and thus reduce overlap, you need to change the exhaust manifold to provide less back pressure. So with that in mind a set of ABF cams on a N/A 16v with an optimised exhaust manifold would be best. I'd love to get some back to back tests on a dyno to see the effects of all this.

So how will all this apply to a force fed engine. Back pressure seems to be key when determining overlap. I suppose on a superchaged car, the above would still be applicable, but then with a turbocharged car, where the turbo acts as a restriction, you'd want more overlap, and thus a set of KR cams would be better.

You could also use a set of vernier cam sprockets to help reduce/increase lobe separation and thus overlap.

I love stuff like this. I think I'd like to get vernier cam sprockets, just so I could fluck about with it.

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