thehelix112

SR20DET for $150.. can't go far wrong there! Hopefully that'll be the end of your gearbox woes. Look forward to pics. Dave

Cool find Justin. Google says they're around 21lbs? Thats only a lb or two heavier than the Rota RB in the 17x9.5 size I think? Dave

Shika805, emwhyr0hen would be flattered you've got his car as your avatar. Dave

Haha. Dave

Nice. I was waiting for it when I saw that Audi billboard. Dave

Whittie, http://www.ozdat.com/forum/viewtopic.php?f=8&t=6393 Is a sans-pics tutorial I wrote a few years ago re the SR box onto L. Its incredibly simple. Will take you less than an afternoon. It also includes part numbers for the bearings required (the hardest bit for me when I was doing it). I used a S14 SR20DET box that I got for $500, so I can't correctly say if the gearboxes are different between DE and DET. I'd pop over to nissansilvia.com (and probably regret it) and have a search for differences. I seem to recall d0ritf0 guys swapping in SR20DE boxes when they break theirs due to the likelihood of them being in being less abused. Also have a look here: http://www.ozdat.com/forum/viewtopic.php?f=8&t=6340 . Despite me not knowing what gears are what (whoopsy), the figures are accurate, and its clear that the C box's gears are significantly larger. Have you wacked one of those thermo sticky things on the side to see how hot the box is getting under racing conditions? Maybe a thicker/different gearbox oil as has been suggested, or a transmission cooler, is in order. Also, why was your engine builder dictating the oil you run in your gearbox when you have a gearbox guy? Sounds like a cop-out on his part to me. Dave

You could get some from coleman in the appropriate size and PCD I'd think. http://www.colemanracing.com/catalog/index.php?cPath=28 Dave

A 300zx does not have a L6 engine. Dave

John, I believe thats true of inerter-based dynos like dynojet, but not true of electromagnetic resistance chassis dynos like dyno dynamics. Dave

Mongo, How does it make it unusable? Are you saying it makes it more difficult to take off/easier to stall because there is less energy in the rotating mass? If so, couldn't you just put more energy in the system by revving the engine a bit higher? But I guess that means that you then have more slip in the system, and more flip == more friction. Dave

http://www.taylor-race.com/add.cfm?id=5520 Innnteresting! Cool site. Dave

Made a little bit of progress on getting it all back together yesterday. I pulled out the old 3.54 diff, and cleaned up the cover and all the rear sub-frame for installing the 4.11. I painted the rear subframe black, but left the rear diff cover bare alu. I also got the local auto shop with a hydraulic press to push the pin out of one of the rear strut stub axles, and then dropped off the strut for the other side to them as that one doesn't want to budge either. So I assembled the coil over for the one that I got back. Here is the left rear coil-over installed. And here (not really visible) is the cleaned up rear subframe including new bushes in the moustache bar. So all that remains is the final coil-over, bolting the cover onto the 4.11 diff when I get a new gasket for it, reinstalling it, and then bolting up the rear lower control arms. Oh and greasing the front tie rod ends and ball joints, and an alignment (and perhaps corner balancing). Hopefully not too far away. Dave

Xnke: nice. Sounds plausible to me. I wonder if there is any good (read: cheap DIY) way of detecting such a thing? I have DIY detonation detectors (earmuffs with hose attached to copper pipe bolted to the block), I wonder if it'd be possible to hear this. I'm thinking unlikely over the valves slamming closed all the time. Gira, are you willing to share any more details about the oscilliscope + accelerometer setup you're going to use to try and identify this occurring? Dave

Greg, Yeah I didn't think the twisting would be causing enough deformation to rub out the bearings, but I don't understand enough about harmonics (amongst other things) to comprehend why the crank would be whipped about as you suggest (and is evidenced by the worst bearing wear occurring in the middle). Or how to fix it. Makes sense that the more time you spend at the natural frequency (harmonic frequency?) of the block the larger the oscillations will be and the more deformation will be involved. I can only think that its the load on the front by the accessories and/or dry sump thats keeping it from being terrible there as well. Does someone understand why/how the twisting deformation transforms into deformation along the axis? Dave

http://www.circletrack.com/techarticles/ctrp_0504_engine_balancing_tech_terminology/piston_rod_crank_balancing.html For those now going ``wtf is mallory metal?'' Dave

4mm out of the flywheel flange? Any ideas why that would help? Dave

Thats pretty interesting as I thought (can't remember where I read it) that the crankshaft oscillations due to harmonics would result in the twisting of the crankshaft along the main axis. I also thought I remembered that the twisting would be greatest at the front, as the rear (flywheel + drive) is what is resisting the torque, but perhaps in your race motor you are running a large dampener + dry sump thats adding a bit of load to the front and reducing this factor. So perhaps thats why the twist is greatest towards the middle of the crank, also, perhaps the twisting is deforming the crank so its less than perfectly round, which, depending on your clearances (race motor so I'm assuming they're larger than stock), could perhaps be causing interference to the bearings. Isn't it true that you can determine the engine harmonics on a dyno simply by looking at dips in the power curve? I heard rumours that V8SC engines in oz the crankshaft harmonics were almost a 20hp drop. Dave

http://hyperphysics.phy-astr.gsu.edu/hbase/mi.html#cmi Note the radius is always squared. E.g. Radius1 = 40, I1 = M1.1681 Radius2 = 20, I2 = M2.400..... *2 as there are two smaller turbos: I3 = 2(M2.400) = 2.M2+800 So lets say the larger turbo wheel weighed twice as much as the smaller: M1 = 2M2 so I3 = M1+800.. which is definitely less than I1, which = M1+1681. Lots of assumptions, but hopefully that makes sense. Re bearing friction, http://www.roymech.co.uk/Useful_Tables/Tribology/Bearing%20Friction.html offers a couple of equations for this, but both of them are linearr with regards to diameter. Therefore as the diameter increases, so does the coefficient of friction for the bearing. But thats kinda besides the point as chances are relatively good that you can get two turbos with very similar sized shafts, and hence very similar sized bearings. All this is starting to get very complicated. A large factor in the bearing friction is the axial or radial loads. I think the axial load in a turbocharger may be quite high, but how does this change between two turbochargers? Are two smaller turbine housings producing the same axial loads on two shafts? Head hurts, stopping. Dave

Looks interesting. Nice idea. Dave

So just did some more research, the NT-01 comes out to be the cheapest comp tyre for me. Pretty cool. Thanks for the heads up. Dave

Mannyvig, Did you have the direzza z1 star spec or the direzza dz101? The former performed much better than the latter in tirerack's test (and is in the Extreme Performance category versus the Ultra-High Performance category). Just clarifying. The NT01 sounds good, but treadwear of 100.. it doesn't sound like its likely to fulfil the OP's request of 1200mi round-trip. I'm currently debating between the direzza z1 star spec and the kumho xs. Tirerack hasn't reviewed the kumho XS yet, but hopefully they will soon which should give a little more info upon which to make the decision. Dave