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16 V cam specs

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16 V cam specs

Post by dirtytorque on Thu Jul 09, 2009 6:05 am

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 7:59 am

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 8:28 am

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 10:07 am

Cylinder head stuff

There is a bit in there Smile

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Re: 16 V cam specs

Post by ctwg60 on Thu Jul 09, 2009 12:07 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 2:08 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 3:41 pm

Cool. Look forward to it. Smile

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Re: 16 V cam specs

Post by mrbeige on Fri Jul 10, 2009 1:29 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 8:13 am

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 8:47 am

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 9:01 am

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 10:12 am

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 12:59 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 1:07 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 2:00 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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Re: 16 V cam specs

Post by dirtytorque on Sun Jul 12, 2009 11:17 am

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mrbeige wrote:
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.

Million dollar question. Smile

I may have figured wrongly but I think that the kr and 9a cams have the least amount of overlap.In fact using the 1mm lift numbers they have negative overlap numbers i.e the zaust cam is closed b4 the intake starts opening.

The overlap on the KR cam is -6 degrees the 9a -4 degrees where as the abf has +2 degrees of overlap.

The 9a has the lowest lobe seperation angle(LSA) of 107.
The ABF has a LSA of 109 and the KR has a LSA of 111 degrees.

The ABF has the most lift however,then the KR and then the 9A.
The 9a's cam is generally agreed to give the 9a a torquier feel low down.

I still don't think that there is a radical difference between the ABF and the KR,but the ABF does seem to be the best all rounder.
The 9a should have the most low down grunt but not a very flat curve,where as the kr's and ABF's should be better in this respect;not tailing off as early as the 9a cam.
I'd like to try the 9a to see if it improves low end torque although the short durations and low lifts will probably hamper performance too much.


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.

I think the thing to note is if your cam grind will have intake/zaust overlap due to narrow LSA/long duration you need to have as little back pressure in your exhaust system a possible to enable good scavenging affect and not to havof overlap.e reversion effects hampering perfomance.With a restrictive system you don't really want alot of overlap.

Just a case of if your start with head modifications you have to make everything else is in order first.


For intake valves:
Lobe Center = [Iopen+Iclose+180]/2 - Iopen

Iopen = angle the valve opens BTDC

Iclose = angle the valve closes ABDC (after bottom dead center)

And for exhaust valves:
Lobe Center = [Eopen+Eclose+180]/2 - Eclose

Eopen = angle the valve opens BBDC (before bottom dead center)
Eclose = angle the valve closes ATDC

For example, using numbers from Suzuki's SV650, the intake cam's lobe center is:
Iopen = 28

Iclose = 62

Lobe Center = [28+62+180]/2 -28 = 107 ATDC

The exhaust cam's lobe center is:
Eopen = 43

Eclose = 24

Lobe Center=[43+24+180]/2 -24 = 99.5 BTDC

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Re: 16 V cam specs

Post by Toad on Sun Jul 12, 2009 12:20 pm

Rob, I'll email you my spreadsheet weapon shortly...
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Re: 16 V cam specs

Post by dirtytorque on Sun Jul 12, 2009 12:32 pm

Toad wrote:Rob, I'll email you my spreadsheet weapon shortly...

thnks. Smile
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Re: 16 V cam specs

Post by dirtytorque on Sun Jul 12, 2009 1:11 pm

To make things interesting an example of a VW supercharged engine.
Yup the good ol g60.
Cam duration breakdown measured by Chris directly from the g60 bump stick.
using the above formula and Chris's figures..


specs and at 1mm of lift they cam out at

IVO 10˚ BTDC
IVC 30˚ ABDC
EVO 50˚ BBDC
EVC -10˚ ATDC (or 10˚ BTDC)

ID 220˚
ED 220˚

These give an intake centre line of 100 degrees
zaust centre line of 220 and so a Lobe sep angle of 110.

Does anyone know if the limited engine used a KR cam????????
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Re: 16 V cam specs

Post by ctwg60 on Sun Jul 12, 2009 2:15 pm

I've been majorly p1ssing about with DD2003 and I've found for a generic 16v head and a G60 that longer exhaust duration and quite conservative intake duration gives good low end torque at little expense of top end. Obviously it's all theory. LSA was 110˚!!! ID 246˚ ED 268˚ ICA 107˚ ECA 114˚overlap 36˚ this is all seat to seat stuff or near as damn it!!

These where specifically worked out for Rob's engine and CR.

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Re: 16 V cam specs

Post by mrbeige on Sun Jul 12, 2009 2:34 pm

Chris, do you reckon you could do a dummies guide to DD2003?

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The good lady wife's Golf VR
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Re: 16 V cam specs

Post by ctwg60 on Sun Jul 12, 2009 3:16 pm

Mmmm not sure, just ask when you get stuck the biggest tripping points are trying to figure out how to represent a G60 in the FI section and trying to figure the cam lobe aggressiveness, but the program can help you out if you have seat to seat (0.01mm) and 0.05" (1mm) durations. The G60 cam I measured came out at 2.4 on a scale of 1 to 6. Head flow figures are also an area that can trip you up I've been using flow files from JP.

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