HKS Vcam Step Pro Issues

[joshuaho96]

On 5/17/2022 at 8:40 PM, The Mafia said:

Okay, so changed the valve springs and the VCT works as it should now (nice and responsive at idle). 

125psi springs were just too heavy for it. 

I have heard that when people have put heavier springs in the Barra those have stopped working too. 

Currently running HKS springs. 

I recommend lighter springs 90psi would be pushing it. 75psi or below will be my safe estimation.

(Please bear in mind your RPM targets, cam selections, etc). It's a careful balancing act. 

This is actually the first time I've ever heard of this. 

[Butters]

So when kelford say - 80lb seat pressure at 39.10mm installed height

 

Should be good ?

[Komdotkom]

That's interesting, thanks for posting the outcome.

[Dose Pipe Sutututu]

On 18/05/2022 at 1:40 PM, The Mafia said:

75psi or below will be my safe estimation.

Then you face another problem with valve lift when big boost/rpm are introduced

[Piggaz]

On 19/5/2022 at 9:45 AM, Dose Pipe Sutututu said:

Then you face another problem with valve lift when big boost/rpm are introduced

Spose it has to be application specific.

Youre not going to run 140 lb springs on a basic setup that runs twins and will rev to 8000 rpm and you’re not going to run 50 lb things on an 8 second thing that spins to the moon with turbos the size of a small planet.

[Dose Pipe Sutututu]

FWIW in my pleb motor shit box, I have 80 lb springs in there, I suspect any softer it would valve lift with the boost it sees.

I can't imagine @The Mafia's setup being anywhere near pleb level.

[Komdotkom]

Talking about valve springs in these terms is problematic. Valve spring pressures are measured at the seat, and on the nose of the cam (max cam lift). Two different springs with the same seat pressure don't necessarily have the same pressure on the nose, and vice versa. Like spring rate vs wheel rate when discussing suspension = apples vs oranges

There are so many factors to valve float, seat pressure is barely half the story. Heavy springs will generally help with valve float but they are not always the best way to skin that particular cat and always cost power.

[Dose Pipe Sutututu]

On 19/05/2022 at 12:40 PM, Komdotkom said:

Talking about valve springs in these terms is problematic. Valve spring pressures are measured at the seat, and on the nose of the cam (max cam lift). Two different springs with the same seat pressure don't necessarily have the same pressure on the nose, and vice versa. Like spring rate vs wheel rate when discussing suspension = apples vs oranges

There are so many factors to valve float, seat pressure is barely half the story. Heavy springs will generally help with valve float but they are not always the best way to skin that particular cat and always cost power.

Very fair points as well, I suppose this is why talking to an engine builder with decades of RB experience helps.

I pretty much just took guidance from whatever Alex at Birrong Automotive recommended.

[The Mafia]

On 19/05/2022 at 9:59 AM, Dose Pipe Sutututu said:

FWIW in my pleb motor shit box, I have 80 lb springs in there, I suspect any softer it would valve lift with the boost it sees.

I can't imagine @The Mafia's setup being anywhere near pleb level.

haha details. What engine / cams / turbo / boost / power are you running? 

[Dose Pipe Sutututu]

On 20/05/2022 at 10:12 AM, The Mafia said:

haha details. What engine / cams / turbo / boost / power are you running? 

Pleb setup lol.. just a 2.5L with cheapie forged parts (CP Pistons, Manley H beams), 264/272 9.6mm w/ VCT retained, planned 2bar, GTX3576R Gen2 with divided 1.01, Sinco TS manifold.

Need to book a dyno to tune it when I have time.

[RB335]

I also have Vcam Pro and my engine builder advised to stay upto 80 pound valve springs for it to work well

[burn4005]

HKS suggest upgrading the valve springs for the Vcam Step 2 or step pro kits.

anyone know what the seat pressure of the HKS springs are? I can't find any info.

I've got kelford beehives at 105lb seat so it would be interesting to know if this rules out Vcam for me.

[The Mafia]

On 27/07/2022 at 11:37 PM, burn4005 said:

HKS suggest upgrading the valve springs for the Vcam Step 2 or step pro kits.

anyone know what the seat pressure of the HKS springs are? I can't find any info.

I've got kelford beehives at 105lb seat so it would be interesting to know if this rules out Vcam for me.

Hey mate

HKS springs have a 55psi seat pressure. We measured them ourselves when installing them. 

Your 105lb Kelford Springs will be too heavy. Vcam won't work until over 3000rpm.

JUN springs are 65psi and I recommend those. I would have used them now that I have the HKS springs. 

This is just a guess too - but I think about 75psi would be the limit for a Vcam. 

The Vcam was worth it though. Car had about 1000rpm more usable powerband down low. comes on boost a lot more savage now too, and that is with the BW EFR 8374. I just installed a 8474 so I'm keen to see how that performs. 

 

[Butters]

going to be interesting to see how my kelfords 80lb go, cars running but yet to see dyno

[bigboss59400]

On 7/27/2022 at 3:37 PM, burn4005 said:

HKS suggest upgrading the valve springs for the Vcam Step 2 or step pro kits.

anyone know what the seat pressure of the HKS springs are? I can't find any info.

I've got kelford beehives at 105lb seat so it would be interesting to know if this rules out Vcam for me.

Funny I ask that to HKS last week, they said 55

[Butters]

Well got my VCAM wired in today.   Seems to be no issue activating it at low RPM/idle and this is with the kelfords 80lb springs

. 

Still yet to get on dyno but this is a nice relief. 

[The Mafia]

That is a good test and thanks for letting us know. I will go heavier when it's all apart again. 

[Butters]

889 rpm and 22 degree advance

 

Sorry for the potato pic, its a screen shot of a video.

 

Edited August 20, 2022 by Butters

[The Mafia]

This is the purest form of Skylines Australia. Proper data straight into the SAU encyclopaedia. 

I wish I knew this when I installed mine. Could have saved a lot of time and $$ and used heavier springs. 
 

Thanks so much for the information. 

[The Mafia]

Butters, how does it drive? Can you feel your foreskin starting to peel back when its coming onto boost now? 

(I have to ask because mine got snipped 😢 )