Dale FZ1

It's all about the shape of the torque curve, as much as the area under it. The 2wd ECR chassis/drivetrain was more or less intended by Nissan engineers to cover ground/distance quickly and easily for an "average" driver. Lurid smoky corner exits might be spectacular but aren't the fastest...

Exactly what sort of high flow is it? ie. who did it, and what core has gone into it? Using RB25 housings won't be the real issue on lag - the size + trim of impellers will though. If it's a Garrett core into Nissan/Hitachi housings then there will be ID tag numbers visible. They tell the story on what spec impellers you have. If you can find them, post 'em up.

Can the Apexi software log data? With a wide band input FCLogit is just unbelieveably good ie. fast and consistent AFR, and user friendly.

Pretty common problem Tighten up ALL your hose clamps on the intercooler piping. Not hard, won't take long, costs nothing. If that doesn't work start thinking about gaskets.

Ok, I'm a little ignorant of what the options for Cefiro is too... Is this a FAQ? Come on guys, an 040 is not that hard but just looking for options. Is there a bolt-in (ie. drop-in) assembly as per the R33?

Are GTR rods the same length? ie. no probs with pushing the pistons higher/lower in their bores?

I run a Skyline. The Laurel belongs to a friend. Just done a 040 into the Skyline and was looking to see if there is a direct drop-in for the Laurel to avoid fiddling around. Nothing listed with Nengun or Greenline in Nismo or Tomei for this model. I figured there would be some knowledge about. Has anyone done a pump into Laurel?

As per topic, what is the most common/effective replacement fuel pump to feed a hungry RB20DET when the original is on the way out? Want something that will go in without too much trouble, and must be an in-tank. Skyline unit, or Bosch 040?

I'm getting about 80 on normal commuter running. Not surprising given the std cooler is basically regulating temps similar to the coolant. Higher ambients 35+ it will hit 90-95 More spirited on-road running with rpm and/or boost it will sneak up to 100 if the run is extended, but come back to 85-90 after buttoning off.

Quoteable quotes: Where did they (cops) come from? How did they know I was driving here? Honest, it wasn't me If you've got a good thing, best not advertise to the world.

Well the peak numbers look pretty good Sam. Congratulations. You may be aware of another GT30 thread been going for a while. Can you enlighten us with the CHRA numbers off the ID tag on your unit? And how are you finding it drives with the mods?

I recognise those pics. Running at the moderate boost levels that either can supply, I'd say it's less the case that the RB20 won't hold boost, than it won't push as much air at the same boost level. ie. less power capability. The pics show how/why.

Haven't gone through the exercise of finding out. Any reputable Garrett seller would be able to give opinion and price on the job. Note I'd only ever looked at it as a way of getting that 52T comp with a matched housing mated up to the GT30 turbine. as Disco has pointed out, budget can kill some ideas. I take it that you are questioning the ability of a ported shroud to decrease lag? If so, then I'd like to know too. Ported shroud is used to combat surge. I suspect there is a bit of bling (wank) factor involved at times though, with evidence of HKS using a ported shroud compressor on the small GT2530 KAI, which to my knowledge uses the same cartridge as the original 2530 - itself not known for surge probs on a RB.

Yes, thanks heaps. Definitely clears a few issues I was trying to sort out in my mind. Seat of the pants, is yours comfortable to roll on the throttle @ 2000 and expect it to just drive progressively faster and faster, or does it come on like a firecracker somewhere around 3000? I'd take it that once the boost is in, you've got it so hang on for the ride Any word from Trooper about his setup?

I interpret this as saying once you target performance outcomes for a RB25 that is beyond the capabilities of a GT28 based unit, and want a GT30 that you should crack the engine open, look at porting, cams, and manifolding to make it all work together? It would take some really careful thought and matching of parts to get an engine that can still respond down low while delivering the top end clout that all that heavy breathing hardware can provide. I recall some threads probably back in 2004 that indicated guys were doing the extra engine work once they were targeting beyond about 260-270 odd rwkW. Maybe they were onto something. Hopefully Mafia's 0.63 housing will give a reasonable compromise for street use and the odd drag. Can't wait to see his thread updated, with pics BHDave and al r33 can you add to this, especially re transient boost response? Are you running internal or external gates, and/or engine mods with those setups? This whole GT3076 thing is giving lots of food for thought.

Read this thread: http://www.skylinesaustralia.com/forums/in...=127600&hl= Your search function would have found it. CHRA is 446179-5031, 48T GT2871R. Early boost, fairly quick response and highly satisfying.

This is one upgrade that's been worth the wait, to see how it all comes together. I don't know of any other SAU members who've gone down this exact path yet, so it is a ground breaker. Hopefully it does give satisfactory (there's that term again) bottom end response with the sort of knock free top end pull that the TO4S based hi-flow seemed to have a problem delivering. Maybe a fresh thread Jono, with the background and some impressions on what this specific upgrade is like on the road?

Disco I tend to agree on many points you've raised here, but my overall view is that if you want a mechanically stock RB25 to be lively down at 2500 then you're going to need a GT28 based turbine with its quicker acceleration. It seems as though once you get a GT30 60mm turbine driving things, its higher moment of inertia and the physical difference in housing size dictates that the effective torque range WILL be higher up the range. You may well move through the boost threshold at 2500, but it will start cranking real grunt somewhere around (above) 3000. The payoff is in unchoked flow through and past 7000. So the effective powerband is pushed further up the range. Very selective choice on spec though, can yield satisfactory (a nebulous term that one...) off boost performance. Going for an earlier responding unit, I'd suggest that a 0.63 turbine is a must, combined with either that 52T / 0.54 A/R comp from the GT3776, or the 56T / 0.50 GT3071R. My calcs reckon each would be surge free, but the 71mm needs another 12000 odd rpm to deliver the airflow at the top end. Both would also offer the least amount of resistance to acceleration for the flow capacity. If I was to choose, and it could be done for a reasonable $$ then it would be to use the GT3776 0.54 comp assembly with the 0.63 IW turbine housing. Fairly well matched for flow on both sides, and the comp flow map is available. Beats a lot of guess work. For the extra flow capacity, the 56T GT3076R would be a goer, at the cost of transient response and higher boost threshold against the other two. Then you'd have to choose power vs response and maybe go with the 0.82 turbine in order to take advantage of the comp flow. In any case though, a 53.8mm turbine will just get up and boogie earlier but also sign off earlier. The "windmill" idea is attractive but I suspect you can't have it both ways using conventional (non variable) technologies. As an aside, I'm still very happy with my little highflow; very torquey and responsive right down low but flattens off about 5800 like a stocker. Quick and easy to drive on-road but maybe a bit light-on for the numbers for those who are interested in numbers. Just my thoughts.

AWD2Go, I assume you've changed manifolds with this particular upgrade? I noted the Garrett GT2871R housing - 5 bolt discharge, which would also mean a T25 flange. That turbine discharge looks quite good - and points to why external gated units tend to have much less probs with back pressure with that expanding taper immediately after the rotor.

How so? Why will an engine with management system designed to have an AAC regulate air flow under closed throttle idle properly without that device fitted? Is it commonly eliminated, and why do the factory engineers deem it necessary? Not looking for a debate, just some info to increase my knowledge and understanding. cheers

I know a bloke with GT3076R 56T and a 0.82A/R housing on RB25. Probably won't be long before he's got it fitted and running to his satisfaction. Wait and see how it goes - I believe it will be a very handy device for his requirements.

Is there one around?

Looking for a good condition unit with mesh grilles intact.

Looks just how it should be - a couple of blokes in the shed knocking some Frankenstein together. Interesting to see the progress, and interested to see how it runs. Keep up the work.

Here's a pic of relative sizes of the RB20 + RB25 compressors. Size measurements reasonably accurate too. The impellers are possibly unique to Nissan/Hitachi as Garrett GT sizes are 54, 60 and 71mm. Even if the impellers were the same, compressor maps involve measurements using specific housings. cheers Dale