Lithium

With decent tyres really with that power you should be solidly into the 11s

Indeed, those trap speeds are much more like what one would expect from those power levels... for the sake of interest, what kind of blow of valve is this car running?

Quite strange issue, seems you have had a few mysterious power limitation issues over time with this project. Fingers crossed the HTA plays ball more enthusiastically - when is it due to be tuned?

LOL! Not doing well at distracting myself. There is no way I'd try and convince someone on one of those for this setup

Not really any point putting a massive flowing low mount turbo on that manifold, the manifold will probably be the choking point. As a scary aside, I have a feeling I have heard of people putting FP3794HTA turbos with internal wastegate housings on XR6 Turbos. They are pretty much the same frame as a GT30/35R but are good for a kosher 1000hp+ at the engine on E85. Mental.

Apologies that I don't follow these threads too closely - what is the general consensus on the OP6 housing allowing in terms of flow? I would be surprised if it would even allow a GTX3071R to be utilised properly. Is this case one where a GTX3067R might be worth considering?

Gotta keep talking so I remember to breathe, and not post in other threads asking annoying questions

Reaction time isn't going to affect your time. Interesting enough your time seems VERY similar to my first ever outing on my GT3076R with a soft tune in it - 14-15psi, 270kw @ hubs (equate to around 245ishrwkw on a DD?) did a similar time and trap speed on street tyres. What boost, and type of dyno was that on? Here's a link for the dyno plot and time slip from back then: http://www.dragtimes.com/Nissan-Skyline-Timeslip-13888.html

Shit, that's not cool Sorry to hear mate.

In my "if I had all the monies and all the time in the world to throw around playing with cars" world I'd do a comparison between a GTX3582R, FP3586HTA and a PT6262 - I think on this kind of setup all three have varying strengths which could equate to a hell of a rapid car. The PT6262 definitely gets overlooked in lieu of it's bigger siblings when it clearly has epic potential, but in saying that there are a lot of other turbos out there which will give similar (+/-) results which are completely overlooked as a result of hitting the market in the right way at the right time.

Ryan - it was directed at you

Is that with an EFR9180?

Oh yeah forgot about that, he didn't share much publicly other than it didn't work out. They are capable of a LOT of power from all I can tell, and sound like they don't give that much (or anything) away to smaller turbos considering the power they are capable of. Doesn't hurt me in the slightest that you are ill informed, I have a bit of manflu so probably quite short with my response - so don't take it the wrong way. Also don't take it the wrong way that I have no compulsion to try and justify myself in a thread that this would be going off topic on.

You are so transparently poking that the poke is hurting my eyes - stop it. There isn't much point debating it either, the other transparent thing is you must have an idea about something but no idea what you are talking about if that is your stance. Go learn more about rod/stroke ratios, head flow, and general tuning and do some research on what people have got out of various RB variants yourself before making blanket statements, then when you make a statement you might come off looking a bit more informed and a bit less like someone who has blindly swallowed some marketing propaganda. To answer your question, I've seen next to no EFR9180 results on ANYTHING yet. The only results I have seen have been on 4cylinders, and there is someone I know of getting near having one running on a 13B - I am not even aware of anyone with a build intending on putting an EFR9180, the few that were keen lost interest after waiting about a year and it has since been probably another year or so before they have actually starting dribbling into the market. I for one will definitely update this thread if I catch wind of that situation changing. I don't expect to see any form of EFR9180 RB30 doing good at 9000-10000rpm, whether overpriced OS RB30 or an OEM RB30 based setup as the EFR won't supply enough for a 3+litre with decent VE spinning at those rpm under any respectable amount of boost - which is good really, means they are 1000hp capable without needing to thrash the shit out of them.

Given that the topic of momentum in the complete opposite direction to what we desire is being discussed as a result of compressor stall - I am guessing my suggestion that some of these "straight line" performance figures being lower than expected from the given dyno results being a result of the lack of blow off valves on the cars in question causing the turbos to lose WAY too much shaft speed on shifts and spending excessive (compared to if they had a functioning BOV) time building the correct momentum up again to provide the target boost level in the next gear is plausible?

What I meant by that comment is they put a Toyota V8 into a Nissan chassis when the Nissan brand has far better and easier to acquire V8s - for the sake of purity as well as performance I thought it was a weird way to go. Agreed with a 6.2+ litre V8 not needing turbos to get the performance, and they probably fit nicer... but turbo V8s definitely tickle my ticklish bits and the idea makes me happy.

Oh yeah, All theory, of course. GTScott - be very keen to hear the results if you do some testing, or at least if you guys do the brake loading test what your thoughts are.

No - just gives you an idea (if you think about it a bit) of how much of a difference in shaft speed would be required going from full boost, full rpm to "no surge" with a closed throttle then back to full boost, mid rpm. Going by this GT3071R compressor map a GT3071R on 17psi on an RB25 would normally operate at an absolute minimum of around 105000rpm to supply full boost at any point in the rev range - going up to >120,000rpm at redline... so maybe around 20,000rpm variance in shaft speed for the full boost operation range. Shutting the throttle off will make it charge to well <60,000rpm and then when you get on the throttle again it will have to add at least (at a guess) 50,000rpm in shaft speed again. Not sure how the differences would be with a functioning blow off valve and without, might have to trawl around and see if anyone has tested it with a blow off valve and a turbine speed sensor - or even just tested boost recovery with and without a BOV.

The types of surge you are describing are just far less violent surge than if you close the throttle. I know how you are looking at it, but it seems a bit like serious denial or something - surely you can see it is the same thing, just a very extreme version. With a turbo there is no solid barrier to provide compression, it relies on aerodynamics to create a higher pressure down stream of the compressor - and assumes that the design of the overall system will ensure that whatever is downstream of the compressor will "accept" enough air to allow air to flow through and out the compressor to allow it to pass more air through it. If whatever is down stream doesn't flow enough at a given pressure you get a bit of a surge noise, which can get as bad as shown in that clip - depending on how bad it is will essentially cause how abrupt the noise is. In the case of closing a throttle it isn't so much that downstream of the compressor isn't allowing enough air out of it to work right, there is NO airflow out of it. This pushes the compressor HARD into its surge line, the pressure ratio will be enormous and the flow will be miniscule - the compressor will have no option but to try and go to an rpm which matches that flow rate, and quickly. The only reprieve is the engine isn't pumping at full load and therefore trying to keep the turbo pumping back up again - it will just decelerate under an extreme surge condition until it is no longer surging... make it no less surgey, it just at least has an out.

Goes like stink, very cool on not an overly large turbo

That is close enough to my theory to roll with. Ever brake boosted? Ie, roll along at a set rpm - lean on the throttle and lean on the brake, just enough to stop the car from accelerating so to load up the engine enough to bring up boost without accelerating away... good for rolling races etc. Try brake boosting in 4th gear (or whatever gear is safe for the rpm and conditions) then letting off the gas, see if it surges. Now go as low as possible before it doesn't surge when you back off the throttle - between engine rpm and the gauge pressure you are running at that point to not surge you should be able to get an idea of how much lower the shaft speed is relative to the engine rpm and gauge pressure you would have been running at 7000+rpm and full boost. After that, then consider the amount of rpm the engine will be spinning at in the next gear and how quick the turbo would need to be spinning (relative to the "minimum surge" test) to supply the target boost pressure at those engine rpm and how much acceleration it would need to do to get there. I haven't, and can't do that test - so I'm not sure what to expect but I'd be surprised if you needed to go much (or at all) over 2000rpm/2psi to make surge against a closed throttle audible.

I don't know for sure, I am not enough of an animal to do that to a turbo so haven't tried the difference but I am picking there is a lot of deceleration when that happens. That will definitely be costing response, how much I don't know... but when you consider how much effort goes into improving response (manifold design, ball bearings, wheel design etc) by increasing the rate the rotating mass can accelerate it seems a bit redundant if you are actively decelerating it again by shutting the door on the pump whenever you aren't at full noise. The fact the surge noise goes away is because the compressor has slowed down enough that it is no longer surging when flowing down a path which will accept less air than the lowest surge line even mapped... Which can only mean the compressor must be back to cruise equivalent rpm at best. If that is right, the turbo will be spinning slower than if you just cruised at set rpm then stepped on it... I don't know for sure but I would expect the response lost to be measureable.

Was wondering if that was it, sounded that way. Be very interesting to see if the performance improved without it compressor stalling on every shift....

Was wondering if that was it, sounded that way. Be very interesting to see if the performance improved without it compressor stalling on every shift....

If it needs to go to over 8000rpm it is pretty bad, sounds like it takes a while to come on in first gear but hard to tell. What blow off valve is that?