whatsisname

You can actually buy mechanical fuel pressure bleed kits. See here - http://www.horsepowerinabox.com/mall/fs05.asp However this is very crude (yet effect) way to improve the A/FR's on boost. The system has no feedback. So a conservative approach is best. Mind you, considering your engine is running @ worse than 10:1 up top, there's plenty of room to move! Much better to try & score a second hand Unichip or S-AFC (~$400-$500). I'd also get a second opinion on the A/FR's. Just to make sure the dyno info is accurate.

Nothing wrong with granny shiftin'

Mike, Your A/FR curve on WOT is very very rich in the top end (above 100km/h on the dyno run) I'm fairly sure the Dyno Dynamics A/FR software only reads to 10:1. So the flatline you see from 100km/h & above isn't a true reading. In other words something more like 9:1 A/FR. That's bloody rich! Bad for power, economy, health of engine internals (fuel washing oil off the bores), plug fouling, the list goes on..... I'm guessing you don't have any form of ECU management. The dips in the power curve look like the factory ECU is pulling timing, & most probably causing the overly rich mixtures as well. You could advance the base timing as a slight work around, at least until you get some control over the ECU. What mod's does the car have currently? I'm guessing it has FMIC? Matt

rev, Did you do the flywheel upgrade on its own, or did you fit your upgraded clutch & flywheel at the same time? Is it possible the new improved clutch could've helped the ET drop slightly at the same time?

Al, Attached below are the A/FR's on my current tune (WOT of course). As you can see from the dyno sheet a reduction in fuel (throughout the whole rev range) shows we still some fuel left in reserve. The biggest limiting factor is the amount of boost. Over 17psi will regisiter "max duty" on the Microtech. I still use factory injectors, a bosch '044 pump & rising rate reg (~65-70psi fuel pressure on boost) I could push pressure even higher but I'd rather what till internals are done & bigger injectors go in. Japanese factory injectors are very good at handling high f/pressure. As much as 90psi has been pushed through stock injectors without failure (long term)! If the remaining fuel system is up to the task then no prob's Just look at the Nismo 550cc'ers that Gibson Motorsport used in the ATCC R32 GT-R's. Up to 128psi f/pressure! Big Bosch pumps, twin fuel systems & a mechanical pump gave the total fuel system plenty of ability to cope with the demand 128psi would need! Nismo 550's obviously use good solenoids. A variable rising rate reg (VRRR) is just that. It allows a base variable adjustment plus a greater than 1:1 increase ratio (i.e 1.7:1 - every 1psi boost gives 1.7psi f/pressure increase). A standard reg will give a 1:1 rate. Large HP goals - no better way to go about it than larger correctly sized injectors. Medium HP increase - a good pump & VRRR is not a total "band aid" appoach. If applied correctly.

My eyes hurt!

Sounds like fun Is it still FWD or has it had a full AWD conversion?

Oil capacity for the RB25DET is ~4.3L (with filter) From experience & also according to the manual.

Yep Muck. New, rebuilt or replacement turbo.

SBCS

Joel, I got a good price But they don't retail for much more anyway. This is basically the same kit - http://www.horsepowerinabox.com/mall/ck06.asp Ring ACS/Xtreme & get a quote for the 1050kg pressure plate kit. I'm hoping the ET will come down by @ least 0.1sec

I run a 9 puck ceramic cushion button single plate with a 1016kg pressure plate (had it tested). Heavy on the leg - yep! I needed to get both master & slave cylinders full reco'ed to handle it! Driveable - easy as pie. Doesn't mind a you giving it a bit of slippage. Hasn't slipped on me yet. Clutch kit cost - $720 The stock GTS25t pressure plate is supposed to be rated @ 800kg according to a few local websites. I've since been told this is incorrect & it is actually 650kg!? If so 1000-1100kg is a decent upgrade!

Motul (300V) or Redline are expensive but well worth looking into.

In the case of the R33 GTS25t my best guess is that the Nissan engineers set the RB25DET engine up to run conservatively rich? That way they ensure maximum engineering tolerance & protect the cars warranty. Why not run a lower comp ratio & boost level instead? The RB25DET is designed to have good off boost response & decent top end power (above that of the RB20DET), something that both the aforementioned changes would've hurt. Further to the above - Now add lower octane Aussie fuels & modifications such as large FMIC, & the ECU does it's best to run rich as hell! More relevant to the thread topic - My car had just on a 50rwkw gain after fitting a Unichip. Before/after, same dyno, all within a few hrs. This gain was from the combination of modifications I'd performed, but until I had some control over the ECU it just got richer & richer (in the 9:1 range!). So yes, in some case a 100hp gain from just a 'chip' is possible (not on it's own though).

I'd put money on it that your turbochargers exhaust wheel is now somewhere within your exhaust system (lodged in the cat) or possibly gone completely if you don't run a cat? The much louder exhaust note would be due to the fact there's nothing much left in the path of exhaust gases to quieten it down. It would take a monumental exhaust manifold leak to lose ALL boost, so you can count that one out. Not to mention the noise from the leak wouldn't sound like any exhaust I've ever heard. I've heard a nasty RB25DET exhaust manifold leak - horrible chuffing/screeching noise If the shaft/bearing assy is still intact (no reason for it not to be) then you won't see any smoke out the exhaust. As Secoh mentioned, get it checked asap! If the compressor wheel is unbalanced & has send fragments through the rest of the IC piping (tends to happen if the turbine isn't there anymore) then it won't be good for your IC, & even worse, engine internals!

Yeah I know Did the easter shopping with missus thing (was in TTP car park ~1pm too!) Pic's look good.

Hey Erica you sure it's 'TRUST FARQN'? I though TRUST's new aero parts division was 'TRUST FARKIN', formally known as 'GRACER' Incidently, my Exhaust system is 'TRUST FARKEET' I was bored ok

All valid points Roy. If anything I would say the Microtech is.... maybe a little less tolerant. All sensors need to be operating 100%; it needs a very good voltage supply & so on. I know of the odd Microtech authorised dealer that I wouldn't go near with my LT12! Just because someone is very familiar with a product doesn't mean they'll put that knowledge to best use, ALL the time! - Unfortunately Maybe we should amend the old saying, "the best ECU in the world is only as good as its "motivated & dedicated" installer/tuner. I have no experience with the MT series of Microtech ECU's but I'm tipping that the laptop software upgrade has made the LT series noticeably better. Cheers, Matt

The price I paid for my LT12 & handset (including tuning) was quite a lot less than any 2nd hand PFC & commander deal I've ever seen! I won't give the price I paid, as I was asked to not to. Microtech's going out of tune? Sounds a bit like the old Unichip fallacy. I had a UC too, & it NEVER did any of the things people claimed 100% they did. Explain to me how the numbers punched into the ECU can 'go out of tune'? Unless the fuel pressure is altered, a sub system is changed, or a sensor gives intermittent readings I see no way the ECU will start changing the mapped timing & inj MS numbers? As for losing 20rwkw on the dyno? Many things can cause a large drop (or increase) on dyno runs. I'd have done a bit of investigation as to why rather than just put it down to the ECU going out of tune. Closed loop - yep the Microtech range doesn't "currently" utilise CL. If your tuner can, then the fuel & ignition mapping will give very good economy anyway. Just working on WOT, idle & a few points in between isn't what I'd call a tune. Using the laptop software & matrix mode to the full potential will give very good results. It will never be as good as a well tuned CL ECU but 50kms per tank difference max. Someone mentioned Microtech's being voltage sensitive. This is very true. It pays to have a decent battery. I've very happy with my LT12 Microtech. I've had it running the show on my car for ~ a yr now & it's not looking like going out of tune yet At the end of the day it's good to see we Aussies have a wide range of ECU choices. After all we do lead the world aftermarket ECU industry. Nothing wrong with the PFC at all but it too has limitations. Although with the laptop software about to become readily available in OZ it'll remove some of those limitations. Cheers, Matt

Microtech ECU's are very straight foward as far as aftermarket ECU's go. That said I haven't played around with many of the settings on mine. Tim & Martin did a damn good job Mine's an LT12. I also run the LT series 2 line handset - get one of these! Have a read here - http://www.microtechefi.com/mt_ltseries.asp

*in my best upper class english voice* Jolly good show ol' chap! errr.. chapess? Frightfully sporting of you I'd say.

I'd put money on it not being far from the truth though!

Hmmm I'd be really careful guys! Image it - Erica gets slapped straight back on a defect! Take care out there.

Wouldn't suprise me @ all Matt. Being easter & all. The revenue raised from an easter "road safety" blitz would've already been accounted as part of the annual state budget.

Enrico, Just jumpin' in before Martin gives you the full info. I'm "fairly sure" you CAN'T do the same straight swap from R33 GTS25t to R32 GTS-t ECU. This is partially due to the VVT on the GTS25t. I do recall reading about the ability to use the Z32 300ZX ECU though! As it has VVT.