Flexicoker

Removing the flanges of the I-beam shape is the most inefficient way to remove weight. I would strongly suggest not using that part if that is where you removed material. https://en.wikipedia.org/wiki/I-beam#Design_for_bending

One other thing I'm unclear on with such a setup is if the PTT organic discs are marceled, and if they are does that cause any engagement issues? You've only got 0.030" of allowable pack wear so if the marcel uses up that much you'll be reducing clamp load and potentially have a long engagement window. I don't have enough experience there to say but it might be worth asking if the organic discs are still an option for you.

Most of these small diameter clutches (Tilton/Quartermaster) are hard to drive because of the sintered metallic material. If it's that coppery coler, it's going to be hard to modulate regardless of clutch diameter. I have driven a 5.5" 4-plate with a special lining (designed to slip) and a 5.5" carbon-carbon 3-plate and both were easy to modulate. To the point that having very little inertia wasn't a problem. If you're replacing the discs, remember that you'll need to ensure the total stack height is the same. If I recall correctly, you can take a 4-disc tilton/quartermaster basket, and make it a 3-disc organic using the .2" thick PTT discs and be really close to the original stack height. I think this would be a sweet setup, and I plan to do a 5.5" version for my car in the future. I was quoted $430 for the 5.5" organic 3-disc pack. I think super low inertia makes for a really fun car to drive. Don't forget, you'll need an annular release bearing for most of these clutches.

I just installed a set of these. Unfortunately it's been years since I've driven my Z so I can't give you a great comparison. I lost 2 radiators in the past due to fan contact during aggressive braking and downshifting with stock mounts, and was always unhappy that nothing stiffer and captured was available off the shelf. The parts are nice quality, but I had to clearance my drivers side mount a little to avoid contact with the steering shaft. Driving around with the hood off it definitely appears that there is almost no movement of the engine. Can't really comment on responsiveness or NVH... The car was a loud, rattly, POS before the mounts so I don't think they made much difference there =) I'm happy with my purchase.

That sounds amazing. Great job!!

Anyone know where I can find one 0.06mm (0.002") under rod bearing? I am having a difficult time tracking one down. Alternatively, what is common practice when going 0.25mm undersize? My crank guy was concerned about the case depth of the journal, and was suggesting that I might have to re-harden with that much of a cut. I haven't heard mention of that elsewhere, and my understanding is that the induction hardening process used produces case depths on the order of millimeters and would be plenty deep to cut .25mm without re-hardening. Thanks for any advice.

That sounds nice! Can't wait to hear more.

Ya, limit airflow. Trying to cut 100hp via timing, fuel, etc. is going to be difficult and potentially risky. You could waterjet cut some thin sheetmetal restrictors to go between the carbs and the manifold, or between the intake and the head. This will probably be the least obvious as you're not going to get a big change in engine sound like you would with timing or cutting spark to cylinders. This will take some trial and error to get exactly what you want.

This is so cool!!!

This is where the magic's at: http://en.dmgmori.com/blob/176078/01e15b6a1ada509cb34fa169fafaed17/pl0uk14-lasertec-additive-manufacturing-pdf-data.pdf https://www.youtube.com/watch?v=s9IdZ2pI5dA

This company offers products that will directly print casting tools: http://www.zcorp.com/zcorp/casting-material.html This place offers some cool materials which we have used for functional prototype turbo car intake manifolds as well as functional aero bits on racecars. They've turned around parts for me in less than a day. http://www.crp-usa.net/crp-usa-mooresville-north-carolina/ The racecar I'm working on now uses SLS stainless steel exhaust manifolds, pretty neat parts.

My new racecar: If you look at 1:47 you can see the air wand assembly which the mechanics use to drop the car gently. I don't know what pressure they require since I'm not a mechanic and don't actually touch that thing. They do use the big nitrogen bottles since that is what is distributed at the racetrack which they also run the air tools, wheel guns, fill the tires etc. so not all of that volume is required for the jacks. I would think you could use a smaller bottle without issue. Some teams use jack stands that slide around the air jack shaft. We use wooden blocks of different heights. The sequence for raising the car up high is to lift it up with the air jacks, then slide the taller wooden blocks under the frame rails. Then the air pressure is released, and they slide slightly shorter blocks under the air jacks, and then lift it up again. From there they put jack stands under the frame rails, and that is the height they use to work underneath the car. As others have stated you never never ever get under the car with just air jacks. Even in pit lane the blocks go under the car if someone has to get underneath.

This is really amazing. Are the ports more like the Honda or the Goerz-Paeco head?

d3c0y, Impressive motor build! Thanks for sharing

A tight fitting wheel liner/fender closeout could make some big gains, but you might not see them in a non-rolling road wind tunnel.

Stock diameter ones are =)

bump =)

The motor in question is from a 1981 2+2, however as far as I'm aware these particular flywheels are the same for any 6-bolt crank flange L-series, including the 4 cylinders.

Like this: http://www.quartermasterusa.com/qm/datsun-5-5-l-series-6-bolt-94-tooth-flywheel.html Anyone have a used one?

If you get in touch with a place like Taylor Race Engineering (disclaimer: I used to be employed there doing just that) They will ask you for the necessary measurements and can design/manufacture something for you. Important things are lining up the ring gear with the starter, and designing a clutch release system with the proper overall height. Someone like Aasco could probably do the same thing. With the correct measurements up front you should not need to create a prototype. http://www.taylor-race.com/

That is a really good explanation. There is definitely no "magic" in the helical LSD's like people make it seem. Mathematically they operate the same as a clutch style LSD, there is a locking torque between the 2 axles that is proportional to input torque. What you'll see looking at data from a racecar is that the outer wheel speed will be a little higher right before the apex (travelling a wider arc), and as soon as the driver applies power the inside tire will spin up a little (or a lot at high drive ramp angles). Then as the driver rolls on the throttle and straightens the steering, the vehicle weight transfers back to the inside and the wheel speed difference will start to reduce until there is an abrupt point where the diff locks and the inside tire slows down to match the outside. That point is where the clutch locking torque (proportional to input torque from the motor) exceeds the torque difference between the wheels. At zero input torque and zero preload, both diffs will be totally open. Although, off-throttle the motoring torque pushes against the coast ramp or pushes the planet gears in a Quaife in the opposite direction and create a locking torque. Here is a good paper on differentials: http://www.optimumg.com/OptimumGWebSite/Documents/DifferentialAnalysis_BertaReport.pdf

This is a great article, although I disagree with this statement: I have seen enough to data to suggest that many tires work the other way around; lower peak slip angle at larger tire normal loads. BTW: John, are you going to be at the IRL race in Sonoma next weekend or the ALMS race at Laguna in a few weeks?

I designed some of the throttle linkage for that. It is a really sweet bike.

Just buy one. Flywheels can be subject to some huge forces at high RPM, and after doing analysis on several different lightened flywheels I can tell you for a fact that it is very easy to take off material in such a way that would make it very dangerous. I would not trust one that someone just machined down without doing analysis first or tested afterwards.

my experience has been that powdercoating is quite a bit more durable then paint. Another option would be zinc-dichromate (gold) or black zinc plating