Jump to content
SAU Community

HKS VCam Step Pro + Carillo Pistons - 9.5:1 - Has anyone does this before?


Recommended Posts

Hi Everyone

I'm in the process of building my RB28 engine and I have basically got everything here ready to be assembled. Currently have an extensively modified head (Shimless buckets, 1mm oversize valves, ported, clearanced, springs, Kelford 272, 10.25mm lift cams. 

Pistons are CP Custom 9.5:1
Crank is a 2.8 Stroker. 

I want to fit a HKS VCam Step pro with the 264 / 10mm lift. 

I'm aware that the HKS VCam kit needs the HKS pistons that have a larger valve relief to obtain 50 degrees advance. 

I've spoken to someone that has done the CP + VCam Step Pro and they said they got 32 degrees of advance before there would be clearance issues. 

So, my question is pretty simple - Has anyone does this combination before and can confirm this? I would be pretty happy with 30 degrees advance because that is still a decent gain.

We would be installing a stopper once we know how far it can be advanced. 

Thanks in advance for any information.

Can’t just put larger valve reliefs in the slugs? So many factors come into this and really can’t be answered without the donk being assembled and measured.

- head been decked?

- block been decked?

- rod to stroke ratio…

- gasket thickness?

- depth of relief

- valve size

Measure it up and work backwards from there. There isn’t ANY other way to know.

I would be disturbing the structure of the piston by doing this. 

The HKS VCam was a late choice. I know, bad idea but It's apparently been done. Just can't run the full amount of advance which I'm okay with. 

On 10/11/2021 at 8:13 PM, The Mafia said:

I would be disturbing the structure of the piston by doing this. 

The HKS VCam was a late choice. I know, bad idea but It's apparently been done. Just can't run the full amount of advance which I'm okay with. 

You could always ask CP how much valve relief you can mill into the pistons before it's a problem. I know some tuners out there mill valve relief out of the stock pistons to get the full 50 degrees of cam advance on an otherwise stock engine.

I've been thinking about this. If a Step1 kit can go onto a stock engine and move to 30 degrees advanced, I think a Step Pro should be able to do relatively the same because the CP pistons will almost be the same valve recess area and piston to quench area. 

I should be able to get about 30 degrees out of the 50 degree kit which will be still a significant upgrade. 

The engine builder is going to measure everything up for me and see how much advance I will have. 

Except step 1 is 8.6 mm of lift and pro is 10.0mm or whatever it is, Plus the different ramp rates and durations of the cams.

So many variables. Can’t compare a factory engine to your built one as so much can change.

Step 1 moves 90-120

Step 2 moves 75-125

Pro moves 80 - 130

Another variable.

Yeah we thought about that too. Sorry I should have mentioned that in my post. Once we have built the bottom end and have dummied up the head we will have a better indication on how much piston to valve clearance we have. 

I'll make sure I post the results so there are answers. It's always good to know this stuff. 

  • Like 2
  • 4 weeks later...

okay, so I had issues with sourcing a 0.8mm Apexi head gasket and purchased the Nismo 0.9mm gasket. 

Careful measurement with the engine dummy assembled showed that with these particular pistons, and Kelford 272, 10.15mm lift cams, at 35 degrees advance I have 2.15mm clearance from the piston at the closest point of the valve lift. 

The pro cams have slightly less lift at 10mm.

A pro kit will work fine locked out at 35 degrees or less. 35 degrees is still a massive gain to be had. 

  • Like 1

I did a Step II with 9:1 comp pistons and there was a good amount of clearance, the go was to mock it up and advance the cam 50 degrees one way see if engine is still non interferance and then 50 degrees the other way and repeat on the stand I was not going to risk guesswork at all

Yes now I have Vcam Pro going for 10:1 comp pistons and the go was to get custom pistons made with a dome shape that doesn't interfere where the valves normally travel to

Edited by RB335

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Yeah well per the video it took 15s for the stock unit to start up....even if I give it a few seconds discount for starting that is at least 12 sec before you get a reverse camera if you are trying to leave a park.  The android unit is way faster, but 2016 for the stock unit is a long time ago in consumer electronics
    • Yea that’s why I said ima test them with multimeter and see the reads.
    • Only at idle. Isn’t a problem when rev it seems.
    • @Haggerty This seems silly to ask, but are you confident in your ability to tune the Haltech?  
    • Next on the to-do list was an oil and filter change. Nothing exciting to add here except the oil filter is in a really stupid place (facing the engine mount/subframe/steering rack). GReddy do a relocation kit which puts it towards the gearbox, I would have preferred towards the front but there's obviously a lot more stuff there. Something I'll have to look at for the next service perhaps. First time using Valvoline oil, although I can't see it being any different to most other brands Nice... The oil filter location... At least the subframe wont rust any time soon I picked up a genuine fuel filter, this is part of the fuel pump assembly inside the fuel tank. Access can be found underneath the rear seat, you'll see this triangular cover Remove the 3x plastic 10mm nuts and lift the cover up, pushing the rubber grommet through The yellow fuel line clips push out in opposite directions, remove these completely. The two moulded fuel lines can now pull upwards to disconnect, along with the wire electrical plug. There's 8x 8mm bolts that secure the black retaining ring. The fuel pump assembly is now ready to lift out. Be mindful of the fuel hose on the side, the hose clamp on mine was catching the hose preventing it from lifting up The fuel pump/filter has an upper and lower section held on by 4 pressure clips. These did take a little bit of force, it sounded like the plastic tabs were going to break but they didn't (don't worry!) The lower section helps mount the fuel pump, there's a circular rubber gasket/grommet/seal thing on the bottom where the sock is. Undo the hose clip on the short fuel hose on the side to disconnect it from the 3 way distribution pipe to be able to lift the upper half away. Don't forget to unplug the fuel pump too! There's a few rubber O rings that will need transferring to the new filter housing, I show these in the video at the bottom of this write up. Reassembly is the reverse Here's a photo of the new filter installed, you'll be able to see where the tabs are more clearing against the yellow OEM plastic Once the assembly is re-installed, I turned the engine over a few times to help build up fuel pressure. I did panic when the car stopped turning over but I could hear the fuel pump making a noise. It eventually started and has been fine since. Found my 'lucky' coin underneath the rear seat too The Youtube video can be seen here: https://www.youtube.com/watch?v=uLJ65pmQt44&t=6s
×
×
  • Create New...