Gradenko

pawson, the O2 sensor is screwed into the dump pipe right after the tubo. Don't assume its the O2 sensor straight off, it could be anything from incorrect heat range spark plugs to the thermostat. What sort of problems are you having?

The O2 sensor is also used during a cold start, at least it is once the sensor heats upto 800degC and starts operating. So a slow reacting or broken O2 sensor could cause the car to stumble and feel slugish while the engine is warming up.

My thoughts... Prefer Redline Lightweight Shockproof myself. Or genuine Nissan for less. Bosch fuel filter 0 450 905 002 is bigger than standard, has better flow and fits the factory bracket.

Pretty big improvment in the mid-range there, even bigger than 80hp. Looks like 100hp at 6000rpm! The factory ecu is an evil, evil thing. Kept the afm I hope?

YEE-HAA, I haven't looked at a RB30 O2 sensor myself, but I remember reading that its different from the RB25's in some way. Either thread type or number of wires coming from the sensor.

Pretty much the same assumption I was working under, that it should be able to hold 450hp - like a stock plenum - before having problems. But then RNS11Z wondered in with his modified factory plenum putting out a lot more than 450hp... Its interesting that each runner in his modified plenum flowed more than a factory plenum. Any internal plenum mods, RNS11Z, or just a relocated throttle body? JimX, its the exhaust manifold itself (head to turbo) that may be causing problems, not the post-turbo exhaust. But wrap your dump anyway, it will make a difference in other areas . Finally, Sydneykid. I largely agree with your last post, with only this to add as an advantage for the modified plenum: no heatsoak from radiator or cam covers. You'd have to weigh up how much power you'd gain from colder air vs how much you'd lose from certain cylinders running too rich. I've made my choice .

Which just leaves heat soak from the cam covers to deal with. If you don't want to modify your plenum, then Sydneykid's piping route is the best way. Just forget the bling look and insulate it! Aluminium alloy is cheaper by the metre but more expensive to work with (needs a TIG). Regardless, it's the only thing to use.

I just came back in from giving up. The freaking thing is well stuck in my aftermarket dump. It'll unscrew a couple of turns and go no further. I think I'll leave it to some one with the skills and tools (I only had a non-metric spanner in that size!).

int21h, I just bought a Ford EL oxygen sensor (Bosch 13950) for $95 from Schultz Auto Electrical in Willetton. Didn't try anywhere else so I don't know if theres any cheaper in WA. There must be another Nissan with the same connecter, wire type and thread as the R33's O2 sensor. Would save time with re-wiring. Can anyone with Maxima's or Pulsar's check it out?

Sydneykid, come on, 1jz and 2jz engines fat and unresponsive? The early 1jz's were simultaneous twin turbo'd, not the clumsy sequentional style of the 2jz. The 1jz's made 70% of their max torque by 3000rpm, and they sure didn't feel lethargic to drive. Sure, Toyota may have run them rich from factory, but can't the same be said of the RB25? (Yes!) Its the same story for most late model turbo cars, run them rich and save on warantee repairs. Actually, I remember accusing Nissan of hiding flaws with factory plenum by running the engine overly rich in another thread - you're borrowing my ideas Sydneykid I don't mind restricting this conversation to Nissan inline 6's, but it is interesting to note that Nissan used the crossover plenum design on fwd ca18det's and then switched to a forward facing deign for rwd ca18det's. They had no problem changing the design for little else than packaging purposes. With the issue of volume between valves and throttle body, I'm not entirely sure it's an important point. Heres a quote from Roy in a previous thread: Using common sense, cylinder 4, 5 & 6 only have to look to the end of their runner for a fresh breath of air. Add forced induction into the equation and the distance between throttle body and intake runner should become a non-issue. I really have no experience with valve to throttle body distance and its affect on throttle response. Any references to published work? With the issue of tuning so that some cylinders run rich while others make power, is this really all that different from factory plenum? If, for arguments sake, the modified plenum is indeed affecting distribution, running clyinders rich and robbing me of horsepower, I would consider it a fair trade off for the driveability and power gained from cooler intake temps. Wideband O2 sensors in each runner and an ecu that can trim indvidual injectors would be nice (even with the factory plenum), but I'm just looking for a driveable street car, not something to extract every last 10th from. As an aside, I'm a fan of the gts-r's exhaust manifold too. PM me if you know of any used ones or aftermarket replicas around.

I do have a dyno graph with power and boost on it, but I'm not going to show it. Nothing more confusing than people trying to compare rwhp, so I'm making a stand against it. :)Besides, the graph tells us nothing about part throttle or low load situations. I've already mentioned that it makes 13psi by 2700rpm, full throttle in 4th gear on the dyno. I don't have a "before" graph to compare it to.

Sydneykid, a lot of your points are valid, but simply aren't a factor with a carefully designed factory plenum mod. Which is a major reason why I chose to stay with the factory plenum (albiet modified) rather than go for a full custom job. I also kept the standard throttle body. I haven't come across any problems yet. Note, even with the factory plenum, certain cylinders show signs of leaness. You've suggested in the past that water cooling issues has some part to play in that. The poorly designed exhaust manifold may also contribute to the rear cylinders running hotter. I don't think its fair to blame known problems on this plenum. If that was the case, shouldn't I have lost power? Keep in mind that for all intents and purposes, the plenum I have is the same as what Nissan deisgned with regards to runner lengths, runner diameters and plenum volume. All I've improved on is the throttle body location. Comparing modified factory plenums to enormous volume, short runner, custom plenum's just isn't right. In my case, I changed nothing but the plenum and turbo-afm pipe. Intercooler was already in place and if anything, the current tune is a little more conservative than the last (ie. not on the bleeding edge). I was mindfull of this even when I had the original intercooler piping done. All the alloy piping is no larger than 63mm and the factory L pipe is 65mm to the match the throttle body inlet. For anyone installing an intercooler and using sanely sized piping (please let me know if mine isn't), a modified plenum saves a lot of volume in comparison to the stock one. Of course, individual throttle bodies is the pinacle in achieving perfect throttle response (although BMW's infinitely variable lift valves goes one step further!), but how many people are going to pay for the privallege? The basis of your point (distance from valve to throttle body) apply's equally to all front facing plenums, not just our cut'n'shut specials. Mistubishi, Toyota and Nissan have no problems using front entry plenums on their engines. Sorry, but its not a valid "against" point. Would Mr Gibson not be working within class restrictions? Its possible that changing the plenum volume or structure was not allowed by regulation. He may have found (like I have) that a front facing plenum is a better choice given the reduction in heat soak and length of piping to the throttle body.

Hear, hear! I'll get the billet, steve, you organise the rest .

rbs13, if I understand you correctly, moving to a side entry plenum from the drivers side will interrupt runners 3 &4, radically changing their effective length and flow potential. I'm sure a car could run with this setup but Its not something I'd be advocating.

SLY33, as far as testing goes, no, it hasn't had a wide band O2 sensor stuck in each exhaust runner (who can afford that?), but it has been tuned as best it can. I can't prove that the rear cylinders aren't running lean, but I can assure you that its running safe afr's (overall), has no sign of detonantion and is a better running engine than before.

rbs13, thats the single worst idea I've heard in a while. BOOSTMEISTER, if you read my 2nd post again, I explained why flow of individual runners means nothing (or very little) in real world use. Strich9ine, total cost would go like: labour to remove plenum $80 to mod $85 & $15 for genunine Nissan plenum & throttle body gaskets. (Or make your own, I did). labour to refit The rest, ie, silicon connectors and intercooler piping, would have to be done anyway. The only fidldy bit is how you want to mount the bov. I asked for it between the ic and tb and I wanted it to recirculate air back to the afm-turbo pipe (plumb back). That increased costs a bit, but I'm happy I have a non-stalling car that is free of bov sounds (the rubber plumb back piping seems to have dampened the noise). With the cut down stock factory L pipe, I was suprised they used it but the rational is that its 90 degree bend is a far gentler radius than what they could achieve with alloy donuts. And, the factory pipe already has a bov mount and mount for idle solenoid air feed, so there's less labour charge if they use it. The throttle cable had to be custom made at $70, but it appears that if the throttle plate was mounted so that the tb linkages are on the drivers side, the original cable has enough length to reach it. Just remember to specify "linkages on the drivers side" when you have it made and it should be fine.

AeroGrace, I installed the plenum myself and Global Motorworks did the piping and finish work with assistance from Perfomanze and SST (all in the same complex). Despite the controversy surrounding the modified factory plenum, everything I've looked at says it shouldn't be a problem. I've yet to run temp probes to individual exhaust runners to check for lean running, but my tuner is confident with the result. As for power loss, although I cleaned the injectors and replaced the soft afm-turbo pipe at the same time, I'm fairly sure the plenum didn't lose power. Or so my passengers tell me. As T0nyGTSt mentions, there can't be anything fundamentaly wrong with the front facing design if so many OEM's are using it. When I first got the plenum, I spoke with a head porter about having the plenum flowed. He explained that since we can only flow one intake runner at a time, the final result means nothing as in practice all 6 are pulling air from the plenum at the same time. Air reversion (caused by valves shutting) travel back to the plenum as a wave and interact with other wave fronts causing high and low pressure areas. Very difficult to simulate and measure. A flow bench will tell you the max flow potential of each runner, but not the flow distribution to each runner. Skyrine-Dave, you are right in that the flow characteristics are different. I believe the reason for the factory design, as brought up in that other thread, is for packaging purposes. A cross over pipe is the shortest route to the stock intercooler in the guard. Any consideration to air distribution can be summed up by the picture attached of a stock plenum: yes, the throttle body does open up straight into runners 3 & 4. I like some of the aftermarket designs, but I wanted to keep the same plenum volume and runner length as I had (stock turbo, remember), and spend as little as possible. I don't really want to turn this into a "how to design the best plenum" thread, just wanted to offer an alternative.

Updated, and come on, I know some one wants to change back to a airbox or do the front facing plenum mod .

JimX, I bought the plenum used, but my mechanic tells me he would charge ~$80 to mod one.

Whats your power goal? If anything, it may be too large.

And another pic.

Otherwise known as the cut'n'shut special The front facing plenum has been the subject of much discussion on the forum, and the modified factory plenum is surrounded with its own stigma. I set off to install my own modified plenum to find out if it was a good idea or not. Firstly, have read of this thread if you haven't already. Specifically my posts starting from here. Pre-requisites for this mod: You have a front mounted intercooler. You have a stock turbo or aren't currently making more than 500hp (reported flow limits of factory runners). Some sort of engine management. The aim of the front facing plenum is to gain throttle response by cutting down the number of right angle bends in intercooler piping and lowering the volume of piping involved. Reasons for modifying factory plenum instead of going full custom: Idle solenoid and a/c compensation all intact. Nissan would have tuned the intake runners for max torque at low/med revs. Exactly what we want and would be hard to improve on. Plenum volume isn't so large as to cause response loss with our stock turbo. "What about airflow distribution?", everyone asks. I haven't noticed any problems with airflow. Some inaudible detonation was picked up on at the top end, which needed base timing retarded slightly, but theres no evidence its caused by the plenum. A different person tuned the car this time around, so it could come down to something as simple as tuner sensitivity. Also, ye ole 5 knob s-afc isn't the most articulate ecu inteceptor. Of course, its early days yet, so I'll report any problems as they happen. Improvements to throttle control were picked up on straight away. Previously, holding the accelerator pedal at a small throttle opening would see the car accelerate linearly unitl it got onto boost when it would rapidly accelerate. This meant constant modulation of the throttle if you only wanted linear off boost acceleration. With the new plenum, I can actaully hold the throttle constant and keep the engine just off boost indefinitely or press a little harder and hold it at a different boost level. No more creeping acceleration syndrome. I used to have an interesting problem where if I was hard on the accelerator and lifted off slightly just as it came on boost, there seemed to be a massive reversion in air and the throttle would snap shut. This made the car jerk about and was't comforting in the least. Anyone else felt this with a fmic? Well, its gone now. Absolutley perfect control at all loads and throttle points. Another improvement is with throttle response, an amazing difference here. Its not going to rival a current model LS1 for crispness, but it is a hell of a lot quicker to come on boost. You can be accelerating gently off boost at about 3000rpm and simply twitch your right foot for it to come on full boost in an instant. Full throttle in 4th gear on the dyno saw full boost (13psi) come on by 2700rpm. Best way to descibe it is that it feels like a (slightly) bigger cube turbo engine. I won't give any dyno figures (because its completly irrelevant), but after long periods of driving, there is a huge difference in the seat of the pants feeling. Previously, the alloy piping would heat soak and rob quite a bit power. With the new shorter route, intake piping is only luke warm to touch (as opposed to bloody hot previously) and it makes a difference on the road. I've since wrapped the pre throttle body piping in insulation to further reduce heat soak from the radiator pipe. If anyone has any questions about the install, ask away . If anyone in Perth has the extra long fmic piping and wants to see what all the fuss is about, pm for a ride. Heres a pic of the previous setup. http://www.skylinesaustralia.com/forums/at...=&postid=516510 And attached is a pic of the current setup.

I think a vanilla Clubsport is $60k. The only HSV's the ~$50k range are the utes.

The Y series HSV's are a whole lot better than previous generations. I drive a R8 regularly and like it. If your 25t is stock, the VY HSV will out accelerate and out handle you. But don't worry, a few simple mods will see you laughing .

You guys seen the Murclieago R-GT pics on PF? Carbonfibre, now thats an outfit. http://board.performanceforums.com/forums/...readid=67161807