burninator

Thanks, now I guess I have to decide on a path to take. I want to buy some of the stuff without having to pick it up all at once. Maybe I should think about just picking up something less expensive and save a few bucks for more upgrades later. But I'd feel like I wasted money on something that wasn't what I ultimately wanted.

I have been planning for a while to get Koni Yellows and coil-over springs probly in something like a 275/300 rate. Right now I'm running stock struts with cut stock springs. My car is stripped down and weighed at the divisional autocross last fall at 1998 lbs, but slightly lighter now after a bit more weight reduction. I don't have any other mods. I am planning to keep running in prepared class, but my car is way underprepared at the moment. I had an instructor (at the Evo school) who drove my car last year tell me the first thing I should do is get new struts, but I'm not sure he knew I'd go with such stiff ones. Anyways, the whole project just isn't in my budget right now (stupid bad economy). I'm wondering.... how would it be to run the Konis with the stock (cut) springs? Or are they too stiff for those springs? What are the downsides of running a stiff strut with light springs? For the record, I'm just spent 2 hours searching and didn't really find what I was looking for. It's possible that I just suck at searching though.

Most people shoot for a pretty flat AFR curve, but OEMs and people who are tuning for mileage may tune for different AFRs in different areas. I believe common wisdom is that NA engines produce best numbers at 13.2 and FI engines a bit richer (something like 11.5 or 12 depending on who you ask). You may be able to make more power (especially on an FI engine) by running leaner, but it's not safe for your engine to run too much leaner. And in my experience a few points doesn't make a huge difference in power.

My first instinct says that it's going to have poor balance if you mix and match. Without knowing more about the damping characteristics of all the shocks it's hard to say for sure what it'd be like. I think you'd probly be better off sticking with the same shocks all the way around.

One thing I'd point out is that even on a motorcycle the lean angle is affected mostly by steering input and not by the rider's shifting weight. If you don't believe me check out "A Twist of the Wrist II" you can get it as a book or DVD https://secure.echoalley.com/superbikeschool/store/ On a motorcycle you counter-steer into the turn which causes the road to exert a force on the front tire which causes the bike to lean. Keith Code (wrote the book and runs the Superbike school) even went so far as to build up a bike with an extra set of handlebars with throttle and break controls on it that was attached to the bike separate from the steering system, using those bars your leaning on the bike could not directly cause steering input on the fork. What they learned was no matter how much you lean or shift your weight on the bike it hardly turns the bike at all. The bike has too much mass and stability (from the gyroscopic motion of the wheels) to be strongly affected by your tiny little mass shifting around. On a four wheeled vehicle designed to be leaned into turns it may work differently. Looking at the videos on the 4MC site linked above he maneuvers the "bike" just by leaning, but he is moving very slowly and it may not work the same when you going faster. I just thought that was worth a mention. With something like a race car a huge deal would be the amount of ride height a system like that would require. And with the amount of compliance in a system like that you'd have huge amounts of squat and dive without specially designed linkages to reduce that, but those are not without penalty to performance. The F400 is cool, but I don't like the extra weight and complexity it has. I wonder even if active camber like that would work as well on a race car as it would on a street car. With a race car you can run much higher spring/damper rates and more static negative camber. In the end it may not be worth the added weight having that kind of thing on a race car.

Yeah, we were doing about 45mph in that corner. So some aero might come into play at higher speed, but my car doesn't have any aerodynamic aids except an MSA type 1 airdam (I think it's a little better than the factory valance). For some comparison, my friends 911 was pulling about .5 Gs higher with the same tires (just a bit wider). I'm usually on the outside bumpstops in any kind of sweeper, so my inside tires probly weren't doing much to help.

I've heard that quite a few of the nationally competitive autocrossers are starting to data log, but in my admittedly short experience with data logging I'd have to say in an autocross situation I don't think it's particularly useful. I could never find the time to really look at the data, maybe if I had more help I could have used it to make line adjustments. I really can't imagine using it to setup a car. You don't get enough runs on a particular track configuration to really tell what would have changed on account of your setup. Like I said though, my experience is with autocross. On a road course where you can get a lot of laps in a row and the track is always setup the same I think it would be great.

I have some G-force data from a TraqMate logger at an autocross. I have stock dampers with cut springs in a stripped out 240 that weighs a little under 2000lbs. My tires are Nito NT-01Rs (I think you'd consider them a semi-slick). I was reaching peak Gs in the neighborhood of 1.15 Gs and sustained Gs of about 0.95 Gs. Obviously your results may vary depending on the track surface and setup.

As far as I know any aftermarket steering wheel will work you just have to buy an adapter to fit it and there are only a few kinds of adapters. From the product description it appears that you need a Nardi compatible steering wheel hub adapter to make this one fit. Check ebay.

Probly, I dunno... There are lots of threads related to this subject.

I'm not sure about hp loss, but with respect to strength angle cut gears have wider teeth and engage more gently with multiple teeth engaged at once, but straight cut gears are usually made with fewer and thicker teeth and can be made stronger that way. Angle cut gears also transfer some force sideways which may add to friction and/or transfer stresses to other parts of the transmission. I've heard of split transmission cases that were blamed on the sideways load on the gears.

I agree with your example but disagree with your conclusion. We may just have to agree to disagree on this one. Inertial losses are a component of tototal drivetrain loss, it's not all one or the other. Nobody would expect the dyno number to change by doing anything to the non-drive wheels. I think what matters is power you can put to the ground and lightening drivetrain components does produce a measurable and useful change to the power number on an inertia dyno. I understand that on a non-inertia dyno those changes wouldn't be seen, but that's just a case of needing to know what your dyno is capable of measuring. And people who use inertia dynos need to be just as aware to avoid misunderstandings.

I think that for the most part it's guess work, but for what it's worth I think 4.5% is quite low. You can't use johnc's results as a judge of drive-train loss because even different chasis or engine dyno's will report different power to the wheels by as much as a few percent. The results aren't comparable at all. Another thing is what MAG58 said about light weight components (CF drive shaft) not making a difference in power output is plainly incorrect. A drive shaft has to be accelerated just like the gears in the transmission. It has mass and a heavier one will be harder to accelerate and give more drive-train power loss. If you have access to a dyno (and I'm not sure it will work with all dynos) one thing you can do it run your car up and then put it in neutral and let it coast down by itself (don't apply the dyno brake) for a while before stopping the run. This should give you a negative power curve. That would give you an estimate of the amount of power your drive train leaches. This is not exact because not all of your drive train is still spinning in neutral, but it would give you an idea. If your dyno uses the rpm signal to calculate power it won't work, and if it uses rpm to calculate torque then that won't work either (most I think only use RPM for one or the other). Next time I get my car on the dyno I'll try it. Won't be untill after I swap the engine though.

As long as you stick with the L28 in FP there isn't a whole lot you can do that would bump you out of class. You can't build an entire new frame, but you can do just about anything to the suspension. Just keep it over minimum weight.

The 240Z, 260Z, and 280Z are all listed on the same line in the rule book. That means that the engines are swappable between them. Basically the only thing you lose is you have to add a little extra to the minimum weight for the larger engine. Any other engine (SBC, LS, L28ET) would put you in XP provided you don't have to modify the firewall to clear the engine. I am putting an L28 in my 240 this winter and the only reason I'm moving to XP is because I'd have to add about 200lbs to my car to make minimum weight, and I don't want to do that. I'm not trying to win my class, I just want fast raw times.

I don't recall what exactly fixed it. It stopped running at all a while later. We regapped the contact breaker (they go out of adjustment faster than I'd have guessed) and replaced all the plugs with a hotter plug and that did it.

After reading it again, that doesn't even make any sense. I don't know where you got this from, but in the situation described the "absorbed load" from the extra 550lbs of resistance would have to be added into the total power. This is definitely true of how it works with Dynojet dynos, and I'm sure is also true with Mustang dynos. To prove this you can take a Dynojet with a drum of known mass and do a run, then do another run with the load control set to a certain %braking. If you did this the runs would show the same power and torque, but the second run (with the added load) would have taken longer. This example seems to be trying to say that both dynos would have given the same power which is simply not true. If the mass of the drums was the same and the time taken was the same, then the one with the extra load would show more power. This is another example of someone who doesn't know how dynos work trying to slam a brand with false information.

Hearing people slam Dynojet Dynos get's old. I think there is a lot of misinformation out there. People have a reasonable theory of how they think power or torque is calculated, but its normally just something they heard from a guy who heard it from a Mustang sales man. A lot of the things people like to pick on Dynojets for (like not having load control to tune certain parts of the map with) are about dynos and software that is pretty old by now. There have been Dynojets available with load control for years now and they work well. DynoJets measure horsepower and derive torque from that. Loaded Dyno's have a load sensor, and actually measure the torque being applied to the drums (it's a little 5volt reference load sensor). Horsepower is then derived from that information. Torque is an actual force (like gravity), where as Horsepower by definition is a derivited of torque (work over time). Statements like that are fairly inaccurate, and only serve to discredit Dynojet unfairly. For starters, Dynojets (in inertia only mode) only measure acceleration. The drums have a known mass that can never change. As we all should know Force = Mass * Acceleration. If we know the mass and we know the acceleration we know the force, it's as real as it gets. From force, torque and power are calculated. Saying that because torque is actually measured with a loaded dyno makes them better is just false, and makes it sound like Dynojet doesn't measure anything and just pulls the numbers out of the air. Here, I found this link to a paper. Yeah, it's written by a guy from Dynojet (the VP of Dyno Sales), but he's not just some sales guy, he actually knows how to tune cars. I think it offers valuable info (some of which I repeated here). http://www.fmjmotorsports.com/link/Truth_Lies_Dyno%20Runs_Final.pdf And for people who still believe that Dynojets always make more power than any other brand or whatever check this article out: http://www.modified.com/tech/modp-0909-awd-dyno-comparison/dynojet.html They tested four different brands of dynos and the Dynojets that were in the test were neither the highest or lowest. Sometimes cars are the things that aren't repeatable or consistent. There are hundreds of factors that can make a car show a different power number from day to day, even on the same dyno. Modern cars with fancy computer controlled maps are notoriously bad about this. And just saying a Z06 didn't produce the same numbers on several different days means nothing to anybody regardless of the dyno they were on. And yes, I'm sure there are even cases of 400 hp cars that are faster than 425 hp cars on that were both measured on the same dyno, there is more to life than peak numbers. Dynos are a tuning tool only. Nobody should be comparing different cars on different dynos and bragging about which peak numbers are best. If you need work done, by all means pick a dyno shop that has the tools you need to do the job you need done, but don't rule out all Dynojet dynos because somebody on the internet said they sucked. And I don't expect anybody to pick them because I said they were good. If you think you need load to hold the car in an area of the map to tune, then find a shop with that. Also, check out what they have for air circulation. You need a lot of cool fresh air and a good way to get rid of the exhaust. And most importantly you need a competent honest operator. End Rant.

And the ones from 935 motorsports are up to $399 for a pair now. This might not be the right place to ask, but this thread seems to have worn out it's original use. Since the subject of the shocks came up... What kind of spring rates are appropriate for these shocks with the stock valving? I'm looking at getting them for my autocross car along with a coil over spring setup. It's a dedicated stripped out race car, so streetability isn't a factor.

The reason your car doesn't turn off is probly because you put in a newer alternator with an internal regulator and your car has an external voltage regulator. Same thing happened to me, something is backfeeding into the sense line so the alternator never quits powering the car. Try looking at the bottom of this page: http://www.atlanticz.ca/zclub/techtips/alternatorswap/index.html You'll probly have to disconnect the regulator according to their instructions and then splice in a diode on the sense line. Hope that helps.

No. That's not how carbs work. They are not electonically controlled so the MAF signal would have no place to go and nothing could be adjusted by it. In a sense carbs are already controlled by the air flow mass, as the more air goes through them the more fuel it takes with. It's just that the jet/needle sizes don't work exactly right at all flow rates.

Cool, thanks for the advice. I'll pass it on.

I hope this is an acceptable place to post this question. My friend needs to know a good way to accurately measure the distance that a piston sticks out of the deck at TDC. Sorry, it's not for a Z-car that is why I wasn't sure if it could be posted here, but I didn't know where else to ask. The engine is a Renault turbo diesel out of an '87 Jeep. There are apparently 2 different head gaskets it could use depending on this measurement. According to him there is no way to know without measuring it (no markings on the engine). Info on this engine is hard to come by.

If your talking about the spring on the slave cylinder, you probly don't need it. I replaced my slave cylinder a few months ago and with the spring attached the clutch felt weak no matter how many times I tried to bleed it. I took the spring off to check something out and the push-rod slid out a bit and the clutch felt great. Car has shifted fine ever since. That spring was overpowering the slave cylinder and apparently isn't needed.

Sorry I guess looking back I should have made it more clear. I am running SUs, stock air box, and stock horns. The loss is backed up by multiple runs and is not due to heat soak. I appreciate all the advice, I am the one asking the question afterall, I just didn't think the AFR was different enough with or without the airbox to say a lack of tuning caused it (especially where the power dip occurs). I beleive I have the car as lean as it will go at my altitude (~5000 ft) without getting new needles and/or nozzles I guess I might have to get some to see enough difference in the air-fuel ratio to see a diffence in power. As far as stiffer springs in the dashpots, I was thought it was the other way around. Heavier springs may cause the needle to sit further in the the nozzle, but the air is moving faster and the venturi affect causes it to pull more fuel and actually richens it up. Thats what I read, and I have a few runs to back up this theory. I started out with no oil in the dampers and stock springs, now I'm acutally running it with no springs and ATF in the dampers. I did quite a bit of testing and it did improve the AFR. Thanks for the input.