Rolls

there is your problem, one lean injector probably = a hole in your piston if comp is that bad with oil in it. A decent tuner should have picked up the detonation though and needing more fuel than normal to compensate for 1 cylinder barely firing. I'd be asking them what knock detection equipment they use and if they say none you ask for nothing less than a refund.

If boost is held constant then the best performance tune and the best economy tune will be the same. Down low you'll have as much timing and as lean as it can handle eg off boost and with O2 feedback, up high you'll spend 2% of the time there if it is daily driven so it doesn't really matter how it is tuned. Ask nistune themselves who they recommend to tune it.

as nismoid said, buy a rips motor all done, you know it will work, less time wasted spent building it, they make amazing power and make it down low, they hold together and you can't go wrong. if you pay someone else to do it there is no guarantee they won't f**k it up as a lot of places have slap dash warranty and if it breaks then you are shit outta luck, that and the 3L will make more power down low, they will pick a better turbo combination as well. http://www.ripsracing.com/products.html $19k for their 900hp motor all done, all you need then is to spend the remaining 20k on driveline and making sure the rest of the car can handle it, could go a smaller turbo for your required 600hp and make it even more responsive.

Could it be a leak in the turbo seal causing air to get into the system? check the exhaust doesn't have coolant and isn't steaming. Other option could be air has got into the system during installation, leave it idling for a few minutes until the thermostat opens up and see what happens, you won't kill anything at idle. This is assuming the foam is just air and not the coolant mixing with oil or something else.

Yeah I was of the opinion a twin charged system would be even better than a compound turbo because no matter how small the first turbo is a super charger is still going to come on faster and give better throttle response, then you have the big turbo in both systems for the torque high in the rpm range.

Are you ever going to overlay the various turbo dyno sheets for us to see? Comparison is still very hard to do for your products and I am quite confused where they all stand against each other. Identical turbos one with the ceramic bearing vs the standard bearing would be great to see overlayed as well. Status should have all the data saved so it should be very easy to compile.

exactly, end of the day I'm confident that even some of the cheaper oils will still provide good enough protection for my motor.

Just go to autobahn and buy any of their $50 mufflers if you want noise, it isn't like it is going to sound any different.

Interesting, perhaps the cooling channels restrict the expansion.

Surely their expansion properties are not that much different? Does anyone have them, I'm curious. I'm sure they vary a bit but surely you'll still need a larger clearance than stock pistons.

it will still be noisier as you have to run a larger clearance, can probably get it pretty quiet though.

it has nothing to do with the brand it has everything to do with the fact they are forged and the clearances you use. You can minimise slapping by running as tight clearances as possible but the only way to avoid it entirely is to use non forged pistons, so no they will still slap.

why is that?

Get rid of the bleed valve and get an EBC, eboost street are around $400 and very good, as good as any of the other brand name ones for $600+ You could also try reducing the line size on the bleed valve, the mechanical ones often spike if they have more than 10cm of line on them, when I first got my first turbo car it had almost a metre of line, spiked to 16psi then dropped to 10 on the lowest setting with a turbo smart one, cut the lines right back and it got a lot better but still spiked. EBC is the only way to go, a stock GTR controller should let you run 10psi quite easily and this is all you want to run max anyway if you dont have supporting mods, if you do then EBC it up.

If you are getting boost spikes with no boost controller it wont help, it is your gate setup that is causing it, boost controllers can only make the boost come on faster and higher, cant lower it or make it slower. What are you currently using for boost control and what is your turbo setup?

This is neat for people who want to be able to change easily between the two. Good work.

np let us know how it goes

Don't ever put it back on, there is no need for it, all it will do is make you need a retune, stocker is good for over 300kw and loads of boost

Thanks for the figures but how did you come up with that? Surely it is entirely dependant on tyre size and diff/gear ratios?

What rpm is the power/boost hitting hard, and to what rpm does it hold the power for?

also if piston slap is the issue a rebuild will make it worse as almost all forged setups have some piston slap.

Doesn't stop it being decent evidence though. edit: Funny picture to ease the tension

I really doubt it, even if you ran a 25w-50 mineral oil in your skyline sure it would be ever so slightly more sluggish but it wouldn't be 'running not right' after 3000kms.

When you throttle off you lose all exhaust gases (basically) so any force acting on the blades is now essentially gone, hence it is not an issue, if you continue to apply exhaust gases and the flutter continues (real surge) then yes you will cause the turbo to shit it self, different conditions and causes though. The stresses are so small they are negligible, there are more forces put on it during normal operation at full throttle (massive speeds and temperatures). Some great examples of why this is negligible force is the ford sierras that ran equivalent for 650 1/4 races and 6 hours of constant track work with 36psi and NO BOV if they thought it would improve spool time, throttle response or turbo life they certainly would have fitted them. There are examples of VL turbos doing 300,000kms on the standard turbo with no BOV and no issues as well in that thread if you feel like reading it all.

by nice you mean bad don't you? lol how much worse is the fuel economy, do you have figures?