Head gasket? WTF

[Dose Pipe Sutututu]

12 hours ago, admS15 said:

Mine only makes around 150kw at 4k rpm and is lazy with low end torque, peak torque comes in around 5k + but does get to the peak kw figure, makes 312. 

Wonder if your VCT is setup properly on the Adaptronic? 

Send me your map.

[admS15]

Pretty sure vct is setup properly. On from 1500 to around 5-5200.

I'll send you the map when i get a chance to get to the pc.

[Slap]

would have thought vct should start to kick in as boost does bout 2200-2500.

Maybe 1500 is ok

i havent played with vct.

 

Why does it end at 5200?

[GTSBoy]

15 minutes ago, Slap said:

would have thought vct should start to kick in as boost does bout 2200-2500.

Maybe 1500 is ok

i havent played with vct.

 

Why does it end at 5200?

Stock range is about 1700-5400. It stops at that rev point because when it is on the valve timing it creates suits lower revs.

You don't want it coming on as late as boost does, because a street car actually spends a lot of time at <boost threshold and you want the VCT to be available to help out and actually get you up to boost threshold.  It's also got a TP threshold on it so it doesn't actuate unless you have enough throttle/load.

[Slap]

Ah ok. I gots it.
So it needs to back off as boost comes on.

Stock range is about 1700-5400. It stops at that rev point because when it is on the valve timing it creates suits lower revs.
You don't want it coming on as late as boost does, because a street car actually spends a lot of time at

[GTSBoy]

3 hours ago, Slap said:

So it needs to back off as boost comes on.

Hmm, not really.  It's pretty well independent of boost - more just a case of being advanced intake valve timing in the lower half of the rev range (where it improves torque) and retarding it again in the top half of the rev range (where it again improves torque).  It is off/retarded at idle/crawl revs because it is better for emissions.

Having boost probably helps up high in the rev range.....but there's not really a lot of difference between VCT on DE and DET engines.

[Dose Pipe Sutututu]

4 hours ago, Slap said:

Ah ok. I gots it.
So it needs to back off as boost comes on.

You back it off as you reach max torque for your RPM range.

Generally the easiest way to dial in VCT (this is how I do it) is do 1x run with VCT off and 1x run with VCT and overlay the torque curve. Where they intersect is an ideal RPM where you disable VCT. I find (based on my personal experience on dynos) most motors will happily take more timing as switch off VCT.

[admS15]

When pulling everything apart, i noticed the exhaust cam out by 1 tooth to the right. Whoever put the timing belt on 7 years ago set it like that.



My question is, should i set it up like that considering the tune has been done with the cam in that position?

Is that 1 tooth advanced or retarded and what effect is it having on the power curve?

Thanks gents.

So I finally got all this back together today. Decided to set the cam timing back to zero but threw on an adjustable cam gear just in case weird stuff started happening. I set it all up with an oem belt using the line markings on the belt lined up with the markings on the timing cover making sure it was spot on. I spun the motor over a few times, checked everything lined up again and then took a pic.

In the pic it looks like it's a tooth advanced again, it's actually not. It's an optical illusion, if you drew a line on the belt it would actually line up with the marks correctly. So that solves that mystery, cam timing was correct all along.







If you draw a line between the 0 and 2 on the belt you can see the nark does actually line up on the correct tooth.




Couple of pics of the head as received back from its birthday. Apparently was in pretty good shape, is now as good as new.








Block cleaned up






New oem head gasket, arp studs, nsk idler and tensioner, new tensioner stud and spring, exh manifold studs, yokes and nuts, cam and crank seals completes the service. I also fitted a gmb rb30 water pump. I opted to use the gmb as that is what was already in it, it never leaked and water temps never went over 90 even after 20 minute track sessions. I modified the pump so i could fit a stud on the hole that didn't line up being an rb30 pump.




Also received my turbo back from hypergear with a new exhaust housing and bigger wastegate puck. Didn't take a pic but it looks pretty much the same.

So that concludes this drama. That was a hell of a lot of work. Shame it didn't really need to be done but at least everything is now in excellent shape and i shouldn't have to touch anything for a long time. Fingers crossed..