TimZ

If you want dynamically adjustable cam timing, I would think it would be much easier to make a replacement for the chain tensioner that could dynamically change the chain length on the drive side while maintaining tension. Take a look at Lockjaw's tensioner setup (maybe Lockjaw could post a pic to save people from seaching 8) ) and then think having the whole thing on a worm gear slider with a stepper motor...

Here is a better link: http://205.243.100.155/frames/shrinkergallery.html They mention that the magnetic field is strong enough to erase your credit cards if you are standing anywhere near it...

Just stumbled over this... http://205.243.100.155/frames/shrinker.html I'm thinking blueovalz will appreciate this...

Just to add to what Scottie said, it's also worth noting that as you try to move the powerband upwards in a turbo motor, it gets harder and harder to find a cam profile that works effectively, especially since we don't have the luxury of separate intake and exhaust cams or variable valve timing. Turbo engines don't like alot of valve overlap, so the old na tricks just don't work. If you want to raise your torque peak a lot higher rpm-wise, plan on trying more than a couple of cam grinds before you find one that works for you. It most likely can be done, but this is not a trivial matter, and you'll have to decide what compromises you can live with.

Your suspicions sound basically correct. If you have a speed-density system (MAP sensor), then ANY time you change the ve curve (it's really a curved SURFACE, not a line, and definitely not a single number) you will need to recalibrate the fuel delivery table(s). I'd be careful about trying to shortcut the tuning process by wholesale leaning out your fuel maps. I'm not exactly sure what you have available to you with the DFI, but if you can datalog, that would be how I'd go about figuring out how to change the fuel delivery tables. Don't just guess - that's for people with carburetors.

Okay, regardless of whether it's sane to destroke your motor, I'd just like to mention one thing - You don't HAVE to buy a kit to get forged pistons. In fact, I don't think that "kit" is saving you much (if any) money over having pistons custom made to your specs. Also, I personally don't think a piston "kit" is a terribly good idea for an engine this old, simplly because you don't know (at least not without measuring) how many times the block/head has been milled, or the head reworked (changing the combustion chamber volume), so your compression ratio estimates could be quite a bit off, or worse yet, the pistons could end up riding above the deck at TDC. Also, you'll be stuck with whatever type of piston they give you, which may not be ideal (for example, a dished piston with a closed chamber head would be a dumb idea). If you spec your own pistons and do the appropriate measurements on your block and head, you can get exactly the compression ratio you want. You could even spec the pin height to allow longer rods than the L24s. I think there was an I4 L-series with an even longer rod, or you could have those made to spec, too. If the "ready made" pistons were a whole lot cheaper I could understand the logic to trying to make them work, but in just about every case I've seen for the L-series engine, they aren't. Oh - one other thing... Copper Head Gasket? Really? Who makes that? Maybe I just haven't been paying attention since I have a head gasket solution already?

Here are a couple of pics of mine : This is gonna look like Fred Flintstone's car with the ribs at the drive-in... :shock:

A couple of things that I can think of... If you have greater oil capacity and assuming it's properly baffled, you should be able to keep oil at the pickup for a longer period of time under high g situations (cornering, braking, accelerating). Also, since there is more oil, you will have a longer "grace peroid" until you overheat the oil during 'high stress' conditions. Since there is simply more oil, it takes longer to heat it all up. The downside here is that it will also take longer to warm up to normal operating temps from a cold start.

Most of the reasons that the 260Z is "less desireable" have to do with the performance of the powertrain in stock form, since it had the very early emmsions control stuff on it. If you are planning on a modified powertrain anyway, then none of that stuff is of any consequence. If you can find a nice example, I wouldn't hesitate to buy a 260Z.

ummm, not to be a pain in the ass, but 1g acceleration equates to approximately a 9 second quater mile...

If it's plumbed in a similar manner to the stock EFI, then yes it will cause a vacuum leak. On a speed-density type EFI it doesn't matter, since the system just measures manifold pressure and doesn't care where the air came from.

Yep - the stock ones will work just fine.

Yes you should definitely have check valves for both the brake booster and the vacuum accessories. The stock check valves will suffice.

I'm assuming from your post that you already have it apart - is this correct? If not there is a tool that is specifically designed to block the chain and tensioner so that you don't have to take everything apart - it costs something like $10 from Motorsport Auto.

It's not an issue of how much the valves open - rather it's an issue of when they open relative to the position of the piston in the bore. Changing the distance between the cam centerline and the crank centerline (i.e., deck height, head thickness, cam tower shim) has basically the same effect as a stretched chain - as the distance from the cam to the crank becomes shorter, the cam timing becomes later than it would normally be (retarded). This type of error can be seen using the timing marks on the cam and thrust plate. Changing the relationship between the cam and the valve (i.e., cam tower shim, cam base circle, lash pad thickness, valve installed height, etc) has the effect of changing the angle at which the rocker nominally contacts the cam lobe. This effects how early or late the cam lobe starts acting on the rocker, and can go either way (advanced or retarded). It's important to understand that this type of error cannot be detected with the timing marks on the cam and thrust plate, as these errors are introduced "after" the timing marks. The timing marks are still very useful for knowing whether you are in the ballpark, but do not tell you the whole story. Finally, valve lash generally has the effect of slightly changing the duration of the valve opening - as the lash gets looser the valve both opens later and closes earlier. To answer your first question, unless the head/block were milled to the extent that the chain tensioner can no longer keep the chain tensioned, not having the cam towers shimmed should not hurt anything, so long as you can find a cam timing that works for you. At this point it's doubtful that you would know how much to shim the towers anyway.

The stock EFI has always been this way - in fact, most mass aiflow type systems are this way. Pulling the dipstick or opening the oil filler cap lets unmetered air into the intake via the PCV system. The reason air gets in is that the PCV system uses manifold vacuum to try to maintain negative pressure in the crankcase. If you create a leak via the dipstick for example, this translates through to the intake manifold, and the additional air does not go through the AFM.

I'm confused here - when did this happen? If the engine is pressurized, then why does pulling the dipstick cause a vacuum leak?

Are you sure that the regulator is working? Seems like that MSD pump shouldn't be able to overwhelm the stock return line by that much. If you are sure that the regulator is working, then the proper solution would be to upsize the return - choking off the supply kind of defeats the purpose of upgrading the fuel system.

IMHO, painting is for iron parts to keep them from rusting. I think an aluminum trans case looks far better unpainted, although the polish and clearcoat idea sounds pretty appealing. Of course you can always argue that the polishing was to eliminate places for stress fractures to start, thus strengthening the case... (that said, I did powdercoat my vavle cover...)

Oops - missed the crossover... The regulator comments still apply, though...