Drax240z

Personally I would refuse to sell it to them. We has a similar case up here with a Supra MkIII that was highly modded. The young kid who bought it killed himself in it about a week later. It was a real shame, because the seller was very upright and honest with the the kid about what needed to be fixed/changed before serious driving (the rear tires in this case) but the kid didn't heed his advice. Ended up hydroplaning off the road while excessively speeding and hitting a barrier. The seller wasn't a happy camper after this, and the family of the buyer wasn't too happy with him either. It's tough to say no to someone when they want your car, but in this case I think you can justify it. He will destroy it.

The 3.1L we just build REALLY responded positively to the switch from 32mm to 36mm chokes. Plenty of bottom end (much more than the 2.8L with 32mm) and of course top end gains as well. We're going to be mucking some more with the jetting on this car once we have our wideband. (end of the month) I'll try to remember to post the results to this thread.

Yeah the seals are totally fine. I am not sure what is up with the first engine that we used them on... it still acts like it has some top end oil leaking, but I don't know why.

http://www.modern-motorsports.com That should take care of that question! (oh yeah, a search would have yielded the same results for you and saved me my time...)

Of course, with a engine build like that you might be in another league than most of us turbo guys. Nice setup!

I don't think you are going to break anything actually... unless you drive like Norm! Not sure where the misconception comes from that superchargers create all this torque... yes more than the same NA engine, but if you want torque, take a look at a turbo dyno sheet sometime. A supercharger might have more torque below ~3000rpm, but low RPM torque isn't what will break stuff, as it will often only be ~75% of the maximum torque the drivetrain will see. Pound for pound a turbo is going to create more torque than a supercharger. (if all else is equal of course) There are enough high torque turbo setups running around here on stock drivetrain components, that i think you can get a significant baseline from those people of what the weak link is. Many of those people aren't breaking anything. Don't get me wrong, I love the idea, the execution, and I can't wait to hear testimonial on how it runs. I just think that some of you aren't entirely grasping how a supercharger effects engine output.

Interesting topic. My dad was a cop for 29 years and has permanent hearing loss in his left ear from driving around with the window down all the time in the cruiser. This occurred over a 10 year span or so. Just some proof that even small noise levels over time can have a very negative effect.

Rick the 3.1L with ford seals runs perfectly at this point, and it has about 700miles on it. The customer is really pleased with it and can't stop talking about how nice it is. Since about 10 seconds after the first startup it hasn't smoked at all. On a side note, that engine is super nice to drive, and I found myself doing excessive speeds without realizing it... not a problem I have with my turbo engine. (though I am making much more power) Somthing about the linear power delivery and the balancing just makes it a car that needs to go fast!

An interesting notion DAW, I will look into that!

Speeder this engine has Nissan valve seals. (actually they are Felpro now that I think about it) There is no oil in my intake tubes. However, I figure it is just as likely for the turbo to leak on the exhaust side as the intake, and I believe this is what is happening. I suppose I should swap turbo's with another I have at the shop and verify. (ugh, what a bear that job is)

So John C, any chance of you disassembling your Quiafe and taking some pics of the wear on the housing and the helical gears for us?

When turning the car, the two axles move at different speeds (obviously) and the axles are directly linked to each center gear via a spline. So the 2 gears need to move at different speeds, the bushing in the center allows minimal friction between these two side gears... With too much friction here you'd end up skittering like a locked diff would. Also as best I can recall the side gears are free to move slightly, and would only constrained by the backlash on the helical gears (and the case itself) if not for the thrust bearings and washers. So Jon you are saying the friction between case & helical gear is where the majority of the loading comes from... Fair enough, but I would think in that situation, the case would become a wear item. (it is hardened cast iron mind you) I can't see a lifetime guarentee given if the case (the main part of the Torsen diff) was a significant wear item. I know that if you want to replace the gears/bearings/shims in your torsen you can buy the parts off the shelf. If you want to replace the case, you need a new diff! Due to the nature of helical gears though, there must be axial loading on those gears, and as a result there is likely friction between the end of the gears and the case. Some more pics of the torsens I found on my HDD: If you are wondering what I'd doing with the milling machine... well... don't ask.

Ooooh, I got it! BMW Isetta with anything greater than 3L displacement.

19psi at the turbo, stock turbo... I wonder if the blade tips are supersonic or how close they are? Instead of a jim wolf setup, why not just buy an SDS for less, and then you can modify your maps as you like, and as you make future engine mods?

Yes my stock turbo of unknown age (likely ~120,000miles) may be going, or it may be top end on my fresh engine. Symptoms are similar to valve seals leaking, blue smoke on decel, and if I sit idling for a while then rev it I'll get a fair bit of smoke too. Oil consumption is occuring now too. I am sure someone here has had an oil seal go on a turbo before, are the symptoms similar to what I describe? Intake side seems quite clear at this point. I'd hate to think my valve seals need to be replaced after 5500miles.

A cut away view of a torsen: 3 washer packs, one on each end of the main splines, and 1 in the middle, seperating the 2 axle splines. Each end 'pack' has a needle bearing and a thrust washer, while the middle pack has a hardended bronze bushing and thrust washers. (barely visable between the 2 helical gears on top)

Timing depends a lot on the specific qualities of the engine, however, mildly build L-series engines seem to respond well to 10-14* initial, and around 36-38* total. In my experience only the (low compression) turbo engines really work well with 20* or more initial timing. Try backing off your timing to 12* initial. (with vaccuum advance disconnected) Varify that as you rev the engine the timing is advancing, you should be at about 36* advance at ~3000rpm.

F1 used viscous diffs up until 1998 apparently. Again you are assuming there are no needle bearings between the gear and the case. Both Torsen units I have had apart had these bearings to reduce the friction caused by sideloading the gears. I am still not sure what you guys are talking about when you say 'preload' in the Quaife. Are you equating this to TBR? All gears have friction, and all friction creates heat. Same deal goes in a regular open differential. Answering my own questions here, if it goes open too easily than the TBR is too low for your application. I couldn't figure out any way a Torsen type diff could slip without having sheared the teeth off the gears. The difference is that the quaife isn't worn out, it is just not adjusted correctly for the given application. Once it's adjusted correctly you can forget about it except for an oil change here and there. (hence the no adjustment mumbo-jumbo... should read: "needs no adjustment after it has been adjusted correctly") Did you happen to ask about a R200 unit as well? Those prices seem quite reasonable and don't correspond with what I've been told by my suppliers.

How's F1 for serious racing? Yup, they use viscous differentials believe it or not. I can't really comment on the why, other than to suggest that it might be stated somewhere in their rules only passive or reactive differentials are allowed. The Quaife: Not sure what to make of this, but I am a bit lost. I was under the impression (and I've had a couple Torsen's apart before too) that the differential action was simply a by product of the backlash in the gear system. Adjusting TBR on the particular units I've used basically was only available through shimming of the helical gears, and running a different viscosity fluid. [EDIT:] I've found my point of confusion, the diffs I've used had needle bearings to reduce the friction between the helical gears and case, some older model Torsens didn't use this. As a result, you could raise TBR by replacing needle bearings with steel washers of a similar thickness [/EDIT] So the torsen is essentially a locked diff until you hit the torque bias ratio. If you exceed the TBR then you will get slip, which is exactly how you manage to turn without the locked diff skittering effect. If you are getting slip in a high speed corner as john was, isn't it simply a matter of adjusting the TBR as necessary? As for price difference between Quiafe and Torsen, the quiafe comes from england... and they also happen to make a drop in unit for the R180 & R200's. Low production numbers, high exchange rate and significant shipping costs would be my guess as to why the quaife costs more than a Torsen unit. However, there are no Torsens for the Nissan diffs we use, are there? (or any nissan diff's to my knowledge)

Or as Reg Reimer had on both his 1 lap of america cars... "Technology is the only replacement for displacement" I of course do have other options available to me, a 2.9, 3.0, 3.1L depending... I could build a higher compression 2.8L and go with that too. In all these other cases the rod/stroke ratio isn't as favorable though... I suppose this arguement is a bit academic until I (or someone else) builds it and tries it. I would think the long rod engine I speak of would be quite a good combo for a high revver all out hp NA engine, at the sacrifice of torque. (which doesn't really appeal to me) I might just build it on a whim to try it out. I was hoping that someone else had travelled down this path and could shed some insight though. Interesting that the dimentions are so similar to the RB however.

John are you taking into account the recent price hike from Quaife when you say you can get them for $1200? Or do your suppliers have stock left from before the price hike? My (one) supplier changed the prices significantly lately to reflect the chances in pricing from the source... Or so I have been told.

Might as well throw this up on this thread as well. Subaru R160 is the same case as the 510 R160. (except it is LSD) I don't have an R180 here to throw in the mix, I just gave all 3 away last week. Note the differences between the R200's.

The R200 out of the 240sx is physically much larger than the Z31 or S130/S30 R200's. I actually don't have any R180's to throw into this comparison.

Given all options, the Z31 R200 is easily the cheapest. Next choice is the Nismo unit for $700. Then you're looking at R230 conversions which (with CV conversion) will be $1000+. Then a quaife.... $2000.

Pressurize the intake system... not the engine.