TimZ

Thing is - it doesn't run hotter. At all. In fact, my cooling system now works as well or better than it ever has. I am running the stock viscous clutch fan and the LD water pump, so that is probably helping a bit, but I now have far fewer problems with the coolant temps climbing above the 195 degree setpoint than I ever have.

Only if you can keep it from spot-boiling, which appears to be difficult on an l-series head. If there is a vapor barrier between the fluid and the head it doesn't matter what its specific heat is. I've been using the Evans NPG-R for two years now, and it works really well.

That works - I was concerned that you were going to shut off the pump with a thermostatic switch, which IMHO is not a good idea, although I've seen it suggested several times.

If I read that correctly, it sounds like the fan and pump turn on and off at the same time - is that right? Are you leaving the fan on all the time, or turning the pump off with the fan when the engine coolant temperature falls below some setpoint?

Aww mannn... Wonder how much the upgrade will cost?

That's a really clean car you've got there - it should work really well for you. Now get it in out of the snow for Christ's sake!

Agreed - I seriously doubt that anybody would be able to detect a difference from either method - I just bristled a bit at the notion that setting the valves cold is "lazy" and "inferior". No, the smaller cold spec is correct. Think of it this way - as the metal in the head gets hotter, its molecules move faster and get farther apart, hence the expansion. Everything gets farther apart, not just select parts of the head. So, for instance, any holes drilled in the head also get bigger (not smaller), since all of the metal circling the hole has to get farther apart too. Same can be said for gaps and clearances in the head - so long as the whole head heats up at roughly the same rate, and the expansion coefficients for the parts of the head are not vastly different, then everything gets farther apart.

How do you know what the temperature is for each valve when adjusting them hot, and what that spec was supposed to be? At least if the engine temperature is stabilized, the temperature is the same from start to finish. I guess if I'm going to go to the trouble, I'd rather have the valve-to-valve settings consistent and just worry about being in the ballpark for the absolute measurement rather than the other way around. I just don't think that there is any real extra "accuracy" to be had from adjusting hot, and more potential pitfalls. Nothings going to break if you are a thou off in any case - Nissan spec'ed it both ways, so do whatever makes you happy.

The problem I have with it is that people automatically assume that it's more accurate because everything is at "operating temperature", when in reality the engine is now changing temperature (and actual clearance) the entire time you are adjusting the valves. Working faster just says to me that you are spending less time per valve ensuring that you have a good lash setting, so what exactly are you gaining? I believe that you are more likely to get repeatable results valve to valve when adjusting cold, since the engine temperature has stabilized.

As I recall, the main thing we were looking at in this thread dealt with method for decreasing the pressure drop across the intercooler core for a given amount of airflow. The effect this has on efficiency is twofold: First, you maximize the amount of core being used, thus maximizing the amount of cooling surface area available. Second, for a given amount of boost in the intake manifold, the turbo has to create lees outlet pressure, so the air going into the IC is cooler to begin with. That's an interesting aspect for discussion, but I don't think the software that Jeff is using is designed to actually look at the thermal transfer properties of different core shapes. Perhaps there is something that could be done there, but I think that that type of analysis would be even more involved, and you'd need some pretty advanced models of the heat transfer interface (cooling fins, both heat transfer and airflow models, and much more) that probably don't exist with enough fidelity to be useful for everyone (i.e., conclusions for one core might not be applicable for another, and it would be really difficult to know what is applicable and what is not)

I don't understand - could you be more pacific?

That is what I did when I was using a stock manifold. It seemed to be the best solution to me, although I don't think anyone will be able to give you more than anecdotal advice. I did go the extra step of ceramic coating the bottom half of the manifold to reject IR radiation from underneath while allowing heat to be dissipated from above.

Open Triples definitely sound great, but after having run open triples, blow through triples, single throttle EFI turbo'ed and ITBs turbo'ed, I'd have to say that you'd be hard pressed to hear the difference in the blowthough triples setup vs a "standard" turbo EFI setup. Also, setting up the triples for blowthrough operation is not trivial, and not the same as open triples. Getting decent power isn't that hard, but normally simple things like drivability and throttle response can be pretty challenging.

Just out of curiosity, were you guys using the Nissan Comp special bolt and extra thick crank pulley washer by any chance? It has a step in it that is supposed to register the washer in the bore of the damper. Problem is they made the stepped section a bit to deep and it bottoms on the crank snout a few thou before the shoulder of the washer grounds to the damper. While the washer keeps the damper captive, this make it impossible for the washer to apply any clamping force on the damper at all. The damper can thus walk on the snout and eventually fails. I ruined two stock dampers before figuring this one out - milled the step down on the washer and have not had a problem since. I was pretty sure I'd posted on this before, but I couldn't find it when I searched - sorry if this was your issue.. Here's a pic of the bolt/washer:

I forgot to mention it when I first read your response, but thanks for the quick reply - it was very helpful.

Just to be clear, does anybody know if the rotor mounting surface is also moved out by 3/4", 35mm, or some other amount? I realize that the rotor spacers were stated as 35mm, but it's not clear whether this is purely from the hub offset, or from a combination of the hub and the Z31 rotor. From eyeballing the pics above it appears that the two hubs are roughly the same distance from wheel mounting surface to rotor mounting surface, but its hard to tell for sure.

Well, one end of the spring is stationary (the end with the spring washers), but the other end moves with the valve assembly, so its mass is significant to this exercise. Since one end moves with the valves and the other doesn't, only half of the spring's mass counts as moving mass. This is exactly the same way you measure the spring's contribution to the unsprung mass in a suspension, btw. I guess that was what I was getting at - the spring's moving mass does make a significant contribution to the total moving mass, and there's no point in measuring everything else with hyper accuracy and then ignoring the spring. Now as Tony already pointed out, this extent of accuracy is way more than what is needed to keep the valves from floating at RPMs that are far higher than most are likely to be able to use, so the conversation is pretty much academic at this point.

My take on this is that if you are going to go to the trouble (and it is a LOT of trouble!) to "balance" the rocker's to within a gnat's behind, then you must take the unsprung weights of all of the moving parts in the assembly into account (i.e. the rocker and everything that moves with it - retainers, lash pads, springs, valves), or the exercise make no sense whatsoever. This would be akin to spending $4000 per corner on the lightest suspension parts available, and then using 50lb steel wheels, each from a different car. After re-reading your post, where you mention balaning the rate of return, you would have to take these additional weights into account in order to achieve this. Really this has much more to do with reducing valve float uniformly across all cylinders than anything else. The only effect that this can have on the reciprocating balance of the engine is from the decreased force required by the cam to overcome the rocker's inertia and move the rocker up and down. Since we are only changing things by a few grams here, this effect is hugely drowned out by the friction presented by the valve springs pressing the rocker against the cam lobe. If you are only going to spin to 6000rpm anyway, then you probably won't see any benefit from doing this, but if you want to regularly go higher in the RPM range, then it starts becoming more and more important.

Thanks, Tony, for that indelible mental image. FWIW, every cam I've used had the lugs.

...And of course VW already did something along these lines by arranging two VR6's in a conventional "V" to make a W12 that takes up roughly the space of a V8, in case anybody wanted to talk about something that you could actually put your hands on...

Yes - I am... http://forums.hybridz.org/showthread.php?t=140128 In the time I have been running E85, I have had to make a couple of adjustments - I've had two Walbro pumps fail, and have replaced my dual pump setup with a big single pump from Fuelab that is rated for methanol/Ethanol use. I'm not going to be terribly quick to attribute this to the E85, though, as there is a documented issue with Chinese Walbro copies being on the market, and the failure rate of these pumps seems to be pretty high regardless of what fuel was being used. They are said to be indistinguishable from the real thing, so this could easily be my problem, as I did get a pretty good price on them. Also, there are several people that have reported using the Walbro with E85 and no issues, so who knows? Just didn't want to keep beating my head against the wall with that pump. Also, my other pump, purchased from Kinsler (I believe it's a Bosch) was folding up just fine. Also, I had been using a pair of Barry Grant screen filters at the pump inlet, which are supposed to Clear Anodized. Givenb the amount of pitting I've found inside the housings, I'm thinking maybe Clear Anodozed = Not Anodized. Getting a Single Fuelab filter to match the pump...

Take a look at the flow vs. pressure chart for the A1000 - as I recall it flows a sh#tload at 43.5 psi, but it drops off pretty dramatically after that. Here's a chart: It's probably still enough, but probably not by as big a margin as the 43.5psi numbers lead you to believe...

+1 Just remember to pull the spark plugs first- you won't go anywhere near that amount of torque to turn the cam

The Dynamat stuff looks great, but it doesn't seem like something you'd want for a track car - I'm assuming from the mention of a 5 point harness that you plan to track it, or is that for looks?

Well, look at the bright side - blu240z had to have been using the search function to have found this post in the first place, and that's still a good thing.