HKS Vcam Step Pro Issues

[Butters]

On 8/21/2022 at 7:18 AM, The Mafia said:

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 😢 ) 

 

lol that is an interesting way to describe ......

 

Car is still not tuned yet, this was setup step prior,  so hopefully in a couple of weeks time i will have a dyno graph. 

[brian_s30z]

I'm glad the issue was resoled by changing the valve springs. I hope to have my VCam Rb26 240z this week, but need help on wiring. The solenoid is not polarity dependent, but the cam position sensor is... 

Does anyone know which lead wire is Signal Ground and SPI (shielded cable) . Haltech ECU. 

I have a yellow wire with black stripe and a solid yellow wire,. 

[r32-25t]

One with with the black stipe is earth (signal) and the plain one goes to power 

[believer]

Hi guys,

Sorry to butt in and take it slightly off course, although still on the VCAM subject. 

I had VCAM put into my Tomei 2.8 bottom end and I struggle to take off because the engine has very little torque caused by VERY low dynamic compression at 60psi. But once off the mark and especially on boost, the engine rev happily all the way to 8000rpm and makes 630hp at 20psi of boost on E85 at the rear hubs.

Has anyone had any similar experience or any suggestions on what might cause this low compression at low rpm?

I am in the process of converting it into a 8hp transmission and with this low torque, the engine would not even stay running until the throttle is opened to more than 30% and then I loose all vacuum. 

[GTSBoy]

Surely the cam timing is set to something stupid at low RPM?

[The Mafia]

1 hour ago, believer said:

Hi guys,

Sorry to butt in and take it slightly off course, although still on the VCAM subject. 

I had VCAM put into my Tomei 2.8 bottom end and I struggle to take off because the engine has very little torque caused by VERY low dynamic compression at 60psi. But once off the mark and especially on boost, the engine rev happily all the way to 8000rpm and makes 630hp at 20psi of boost on E85 at the rear hubs.

Has anyone had any similar experience or any suggestions on what might cause this low compression at low rpm?

I am in the process of converting it into a 8hp transmission and with this low torque, the engine would not even stay running until the throttle is opened to more than 30% and then I loose all vacuum. 

I would be looking at the tune mate. How do you know that you have such a low dynamic compression? 

I had to dumb mine down because it was too jumpy when taking off (too much torque). 

What ECU? Do you need help with the tune? 

[believer]

I am using Motec M150.  I am not working on the car myself actually.  My workshop is giving all these info, they are quite reputable in the industry and are very familiar with Motec and RBs and have done a few big setups with VCam and single turbo on RBs.  In fact, they built and tuned my engine from day one.  But they are stumped with my engine at the moment and cannot work out how come the compression is so low with the VCam. They told me that they have now swapped in some Kelford cams (without the VCam) and can achieve around 130psi compression and the low end torque is better, but now the engine is doughy as.  It boosts and peaks at more than 1000rpm slower, with twin HKS GTIII RS, it doesn't get full boost until over 5000rpm.
I have always thought the VCam was a bit disappointing at the low rpm. To a point I had to ride the clutch a fair bit to get up a small hill from stand still.  That was when I had a clutch.  Now changing to a 8HP, I don't have that luxury and this problem has become a major issue.

I am beginning to think the VCam never work since the day it was installed.  Maybe it was just sitting at the most advanced point, that is why it went good at top end but very ordinary at the bottom.  Therefore, with the help of the Holinger 6 speed and paddle shift, as long as it was moving, it drove pretty good.

Edited yesterday at 12:20 PM by believer