JMortensen

Here's a bit from "Tune to Win" that explains why vertical load (weight or aero) is necessary for traction: It goes on from there, and the book is worth reading. The point is you do need some weight on the tires to turn the car, but Z cars have more than enough weight on them to turn, so we're generally trying to make them lighter and reduce weight transfer to keep that weight on the inside or rear tires depending on whether we're turning or braking so that they can contribute a larger percentage of the work to the whole. As Smith says on the next page:

Haven't seen that myself in probably close to one hundred autoxes. Maybe you could give me an example. So you're saying that ON THE STREET there is a car that has so much rear weight bias and so little weight transfer that you need to step on the brakes to get the car to turn? Again, never seen it. Do you have an example of this? It seems that some of us already have. Well, not rear engined, but rear biased. It isn't done just to improve the braking though. It also improves traction coming out of the corner. Can you give me an example HOW other areas might suffer? I used to be a Porsche mechanic, and my boss raced and quite a few of our customers raced so I was involved with setting up a number of them for racing, corner weighting, alignments, etc. I never saw or heard of any of them fixing a push by stepping on the brake. We used to put a hell of a lot of caster into the 911s though. 911's do require careful throttle modulation because of their rear weight bias and even more so on the older ones with the semi-trailing arm rear suspension. Weight transfer is weight transfer whether it be lateral or longitudinal. When you step on the brakes, it's longitudinal. Well since we're on a Z forum, let's apply these ideas to that platform and suspension. Remember that the wider rear tire thing was a response to you saying that you'd need a wider front tire to get more traction if you had less weight transfer to the front (which again doesn't make too much sense).

Six Shooter, you're saying some things that run against the prevailing wisdom and you're not backing yourself up very well. "Because I know what I'm talking about" is never adequate here. Some examples of your questionable comments: One of the hardest things for me to learn about road racing was that you CAN'T coast into a braking zone and be fast. You're either on the gas or the brake 99% of the time. Every once in a while you might find a turn that requires a slight breathe on the gas pedal, but NOBODY who is racing is going to be letting up on the gas and not hitting the brake and going faster for doing it. Above and beyond that, weight transfer to the front happens when you hit the brakes, but that means that the front brakes do a lot more of the braking than the rears do because the weight transfers OFF of the rear and then they can't put in too much braking effort without locking up. If you have a heavy rear end (like pretty much any mid or rear engine race car) then you can apply more overall braking force because you can use the rear wheels for more braking than you would otherwise be able to. Rear weight bias is why the 911 is so legendary for it's awesome braking. Do you have an example where handling was degraded just from lowering weight in the chassis. That would be a new one on me. Everything I've ever read says that the lower the weight the less transfer to the outside wheels. The less transfer to the outside the more traction the inside wheels can use to increase overall grip. Again, backwards from the normally accepted ideas, just like your braking theory. Which is why race 911's always have much wider rear tires than fronts and the older air cooled ones had something like 38/62 weight distribution. Sorry, but none of this stuff adds up. I didn't get into the Subaru mounting specifics because this handling theory stuff caught my eye first...

You can go to any machine shop and they can order you up some generic valves if you don't want to spend the money on the SS ones. I think there was a guy in OR selling SS valves super cheap. A couple guys were going to buy some and test them out, I don't remember ever hearing about them again...

This got me curious so I just weighed a gutted stock door without hinges and with the interior area where the door panel covers mostly removed and found that with some bondo but without paint they're about 17-18 lbs. Under 10 lbs would be a pretty significant weight savings.

Now that was cool!!! That was better than the dude jumping the canal.

I'd shave the head and do the N head valves if you're running it NA. 8.8:1 compression is pretty low, and then if you want a thinner headgasket I'd use the HKS metal gasket.

Ron IS Searchy... He's "working" on it...

Looked pretty bitchin to me. Nobody around, rail looked safe, kid did a big ass wheelie. What's not to like here? On a semi-related note, here's an even younger kid having fun at a much smaller wheel. 6 year old tearing it up in a souped up 24V Power wheels Jeep. Not nearly as exciting, but it's amazing how a 6 year old can countersteer and all that, where I had friends who were 20 and didn't know how to react in similar situations in real cars...

Poly on the front, rubber on the rear. You might loctite the nut on next time.

I think guessing at the pad thickness is risky. Is Comp using new cam billets or regrinding? What's the base circle? How do you know if his valves have ever been cut or if his seats are sunk into the head a bit? You might have a vague guess as to what size lash pads are necessary, but it's easy to guess wrong if anything has previously been done to the head. One of the threads I linked to previously has specific instructions about cutting up a feeler gauge and using the pieces to measure what thickness you need so that you can order the correct lash pads the first time.

Read these threads THOROUGHLY. It might also be a good idea to buy the How to Rebuild Your Nissan/Datsun OHC Engine and How to Modify Your Nissan/Datsun OHC Engine books before you proceed farther. http://forums.hybridz.org/showthread.php?t=111523 http://forums.hybridz.org/showthread.php?t=112184 http://forums.hybridz.org/showthread.php?t=108398

Did you actually read the rest of this thread?

It sounds like you're confusing cam timing and ignition timing. Cam timing is often 4 degrees advanced on aftermarket cams, there is a sticky in this forum about degreeing your cam and setting cam timing correctly. Ignition timing should be in the mid 30's at full advance for best power with a normally aspirated engine. The way to check it is to rev the engine to 3000 or 3500 degrees and then check the advance. This is easier to do if you have a timing light with an advance function, you set the light to 35 degrees and then line up the timing mark at 0. There are two lockdowns for the distributor. The obvious one is has the 10mm bolt, but there is also another one on the distributor which uses an 8mm bolt. If both of those don't get you the advance you want then you have to pull the oil pump and move the shaft that connects the distributor to the oil pump one tooth. Moving the shaft is not hard to do but it's easier if you have two people. Get a manual if you don't know what I'm talking about here.

Should be a ton of threads on this subject. You'll need to search to find the info you're looking for. EDIT-Also your title is not very good. I'm going to change it from "My planned setup" to "tires for ZG flares and stock springs". Always make your title clear enough so that people can get an idea of what the thread is about without having to open it.

You understood wrong, but let's not get into that one again. Search here or the web at large for "quench" and read for a bit and you'll see that the closed chamber has higher compression but is less likely to detonate.

No, but I think you could cut the threads on a 12mm bolt on a lathe.

There's been a heck of a lot of talk about most of these subjects in the past 3 or 4 weeks. I think the only thing you need to know is that the ZX stuff won't work. Aside from that where you choose to go from there is up to you. Search and read and you'll find info on every single part you're considering.

Good point. What you did was pretty ingenious.

That's what I would expect too, so long as the dowels are still there to locate everything. You'd want to copper coat each piece so you don't get leaks between, but still as everyone seems to agree, pulling it apart to clean in between the layers is probably a waste of effort.

Your main limitation as I see it is the stock ECU. I think you should get rid of that before doing anything else. Once you have some sort of aftermarket programmable fuel injection or even SU's or triple carbs, then I'd suggest a slightly larger cam and a different head gasket (go HKS if you want the 1mm gasket for the compression boost). I think you'd do fine with that head on 93 octane.

9.5 * 25.4 = 241mm. So theoretically a 245 would be about right for a 9.5. You have to consider the ACTUAL width of the tread as John said. What it says on the tire has little relationship to what the actual width is.

Good to see you here again Dan. I think when I used the term "bleeding compression" it was in an attempt to convince Mack using his own terminology. I think that's a really bad way to think about what is going on when you install a larger cam. I think "dynamic compression ratio" is much more accurate, but Mack seemed to be saying that a larger cam was a sacrifice because it "lowered compression", and that post was an attempt to try and convince him he was wrong. http://www.empirenet.com/pkelley2/DynamicCR.html As stated in the above article dynamic compression ratio is effective over the entire rpm range, just as static compression ratio is. In that sense the cylinder is again "bleeding" compression all the way across. The difference is that at high rpms VE goes up due a combination of air flow in the intake and the later closing of the intake valve and the resultant cylinder pressure is higher, even though the dynamic compression ratio is still lower. That's when you're "on the cam" as you said. I agree with your last point about sacrificing the lower rpm power for upper rpm gain, although I'd say that a medium sized cam might do better than stock over a very large portion of the rpm range than the stocker. The stock cam is designed for emissions and efficiency at low rpms where most engines spend their lives. As it ended up he was arguing that he shouldn't be increasing the size of the cam because he was using stock FI. Later in the thread he conceded that the stock EFI does suck. Not to pick on Mack any more here but there are actually a group of people here who are fascinated by what they can do with stock compression, or a stock cam, or a stock head, or a stock intake, etc. I just don't get the fascination with this. I see no point in hamstringing yourself so you can claim that you've made the most of a shitty situation. Make the situation better and make the most of THAT situation. I just don't get the "Look at the shine I put on this turd" contingent.

If you've gone to the trouble to install the LS1, it shouldn't be too much effort to put a set of wheels and tires on it to put the power down. I'd put a 195 or a 205 on a 7" rim generally speaking, and that isn't nearly enough tire for your usage.

I agree. I'm thinking that the strut tops are the thickest metal in the whole unibody. These bars bolt straight to the strut top, so you're basically relying on the tube itself. So long as the tube thickness is reasonable that bar should be plenty sturdy. I've installed "harness bars" in 911's that were not nearly as robust as this thing is, and they were specifically sold for the job of attaching harnesses. I don't think I'd attach my harnesses to a bar with small rod ends like the MSA bar or anything like that, because then the rod end is the most likely potential failure point, but in my opinion this one should be fine.