Dan Baldwin

FWIW, I've seen an L-series motor (mine) gain 20hp by retarding the advance from 45deg to 35deg. I bet there are as many Z's out there that are losing power due to too much advance as there are losing out due to too little! Like an idiot, I had just set mine to ~20 at idle and figgered I was done because I couldn't detect any ping. Little did I know I was robbing myself of hp and running the risk of high-rpm (harder to detect) detonation. I've also been to the dyno and LOST 18 hp by running VP11 fuel, vs. 93-octane pump. I got 8hp back by advancing the timing from the 34deg (lowest advance that didn't hurt hp on 93-pump) up to 39deg with the VP11, but still didn't make as much as I did at 34deg on 93 pump. Go figure... Pete's 164rwhp stock-cam/stock-N47 head ~9.8:1 CR build indeed has to be retarded to 26deg to run pump fuel without pinging. But my then-10.35:1, then-stock-cam/stock-N42-head 3.1 liter, ran at 10static/35total without pinging. When I put a cam in, I was able to advance it to 20/45 (FOOLISHLY going by the "advance it til it pings, then back off a bit" method, see above) without detectable ping, though I think it must have been detonating at higher-rpm as it was costing me quite a bit of hp. ANY motor will lose hp with too much advance, regardless of fuel, CR, quench, etc. Juggling any or all of these variables around will no doubt change the optimum ignition advance. Like Mack says, it's worth it to determine what's best for YOUR engine at the dyno. IMO, it's best to run the least advance you can without hurting torque/hp production. Last time at the dyno I made the same hp/torque with from 34 to 38deg advance, so I keep it at 34-35. My .02...

Whoops, missed the L26 bottom end. L26 has ~8.3:1 CR, IIRC, with a 47.8cc head. With the 53.6cc P79 head, CR is ~7.7:1! N42 (square exhaust ports like you have now) will bump it to ~8.8:1. Or you could shave the P79 and shim the cam towers. Either way, on that bottom end, you'll be fine on 87-octane pump, so a bit of silver lining...

If you want to know what's the best stock head for your application, I'd say a 280Z N42 or N47. Your motor *should* have flat-top pistons, with the 280Z head you'll get 9.8:1 CR. No problemo on high-octane pump gas. The N47 has the same round ports as your '81 P79, so with that one you can keep the same exhaust manifold. My .02 only!

I did what katman sez above, simple 1/8" plate on top of the frame rail, long bolts up through, tightened with nylocks. Been there since ~1996. Many many track days. No problemo! No welding required, even a moron like myself was able to do it:)

Camber is maximized when the control arm is perpendicular to the strut, not when it is horizontal. Lose the spacers and I *promise* you more negative camber:)

Lose the bump steer spacers. Unless the car is really REALLY low, they take away negative camber. I didn't miss them any when I got rid of mine. Slotting the shock towers got me .5 deg negative. Definitely worthwhile for the price (if you don't mind a little butchery!). Eccentric Al/delrin bushings might get you another .5 deg, some anyway. Stock front sway bar, maybe? Ultimately I lengthened my front control arms 9/16" to get more negative up front. With that and slotted towers (and polyurethane bushings) I'm ~2.25 deg. up front. ~1.8deg. in back. Minimal toe-out up front, ~1/16 toe-in in back (Al/delrin bushings). With this setup I had to get rid of the rear sway bar to make it neutral. All is not ideal, as it picks up the inside front outta low-speed corners, but it is pretty fun and reasonably fast:)

Congrats! With that approach, your mods will INCREASE your braking distances significantly. Even under 1-g braking, there's still on the order of 30% of a Z-car's weight on the rear tires. Biasing braking "all to the front" will lock the fronts prematurely and limit your absolute capacity for deceleration.

I've had very good success with Bridgestone S-03 Pole Positions in that size (225/50-15). Have even won time trials on them vs. Kumhos and other DOT race rubber when my Hoosiers were corded! I wouldn't bother with all-season tires if there's zero chance you'll be driving in snow. Summer tires grip mucho-better-o.

Trying to brace to the firewall would be problematic, once you get around the vac booster, you're pretty far removed from the line of action of the force on the piston. I don't like the bolt head in this particular instance, I'd rather see a spherical button, with maybe .015" static clearance. I would be surprised if the Z32 has enough firewall flex to warrant this. Like I said, I've only heard of it on 914s. A quick search yielded this GRM archive: http://www.grmotorsports.com/archives/914.html Holy crap, that's ugly! I totally agree. You can get a HELL of a lot out of stock brakes with appropriate pads and fresh high-temp fluid. And if a brake setup has not been developed and tested by qualified automotive engineers, I wouldn't spend money only to find out the balance is ruined, or risk structural failure of a bracket or such. Generally I recommend against brake mods (other than pads and fluid). If a hp mod goes wrong, so what. If a BRAKE mod goes wrong....

That "fix" would be welcome on my 240! My M/C moves at least 1/8" with my foot hard on the pedal. This solution may appear crude, but should be effective. I hear tell a similar fix is very common on 914s/914-6s. Why they couldn't get the caliper bracket machined to correctly locate the caliper on the rotor is beyond me. I kind of like to use hardware that I KNOW has been proved by engineering analysis and testing, anyway.

1800# is a LOAD (force), not a STRESS (force/area). Depending on the wall thickness, stresses in this plenum could well be in the range where fatigue is a concern. Quick and dirty FEA shows ~7800psi near the welds with 1/8" wall, at 20psi. In the heat affected areas, the yield strength of 6061-T6 could be down around 15ksi, so fatigue could be a real concern. Garret, what's the wall thickness on this plenum? You might consider having the plenum heat-treated to get back to T6 properties. Of course they failed at the welds, that's where the stresses are greatest and strength is the least! Such failures ARE because of the design of the tank! In which case you have to go with a much thicker wall than would be required with a round plenum.

Long/short: If this device keeps the chain stable at 9k, at reasonable levels of pretension, then obviously my reservations were unfounded! Jeff, are you using one o' these? I've never stroboscopically checked my cam timing accuracy at 7.3k, but with the stock guide it does make good reliable power up there. Of course, I doubt if I would notice even +/- 3 degrees with my measuring methods... A question: Does everyone install the stock curved guide with the chain pretensioned, or leave some slack?

Needless to say, I'm VERY interested in following the development of this 9000rpm 14.5+:1 CR monster L6 development! Totally different world from my 11:1 7300rpm application. If the Kameari chain tensioner controls the camchain oscillations at 9000 where a properly set-up stock-type curved guide won't, I'll be among the first to laud it here.

My only argument for the L-series tensioner is that it has worked for myself and others up to pretty high-ish rpm. I always thought crank torsional stability became the limiting factor at rpm ~8000+ anyway... FWIW, a solution for noisy cam chains that is regularly implemented in motorcycles is to do away with the oil pressure tensioning and replace it with a mechanical screw-tensioner (still operating on the stock chain guide). 13,000?! That's certainly impressive, if true, but of course overkill for any L6 I'm aware of! I would still be very interested to see what the required chain tension is compared to a curved chain guide. That'd be swell! In truth, it looked to me like a solution to a problem that didn't exist. But of course if they were running into destructive instability problems at (presumably) very high rpm and very tight piston/valve clearances... It *seems* to me the better solution would be a mechanical screw-type tensioner for the curved guide, though. That would *I think* require less chain tension. In any case, I'm not having any reliability problems at usually 7000rpm, sometimes up to 7300rpm for a few timed laps. But of course there are applications that go well beyond that, but still the ones I know of still use a stock-type curvedguide. I would of course be very interested to see any test data if available. yr. devil's advocate,

Heh heh! Dude, jump right on in! Since the tight side motion was noticeably reduced, the chain tension must have been greater. Coupla questions: how much chain tension is too much (causing increased wear and/or frictional losses), and how much motion is really a problem vs. what appears to be a problem? If you ask me, what is important is whether or not the "solution" does indeed provide increased performance (or performance potential) and/or reliability. I'll agree with that statement. My personal preference is to conservatively stay with the setup that I have seen on more factory-developed high-performance applications. I would suspect that WHEN the camchain does begin to move around with the Kameari setup, it would go unstable very quickly and violently. rpm at which this would occur would be highly dependent on pretension, which of course it has already been stated would have to be checked and maintained.

No evidence that this setup is better in any way is presented anywhere in this thread. [edit: I also readily agree that no hard evidence is presented in this thread that this setup is WORSE in any way.] BTW, EVIDENCE means that with an otherwise identical car/setup, this device demonstrably improved performance or reliability or both. That it has been used successfully by a race team is not evidence that it is better than a stock setup. It is evidence that it does perform its function under race conditions, which is surely a good sign. Unfortunately, you're absolutely right that in order to sell hop-up parts to a public that has no capacity for scientific reasoning, there is no burden on any aftermarket supplier to provide any real evidence of actual benefit. I have given my *impressions* of this setup, I have not done any kind of real analysis. I have presented my impressions FOR WHAT THEY ARE WORTH (which should go without saying). Obviously, I'm not a big fan of the concept, but I have NOT made up my mind. I am totally open to any and all evidence one way or the other.

ZERO evidence has been shown of ANY benefits from using this setup. If there is any, present it. All else IS hype. As for being condescending, I don't mean it that way. But in the immortal words of Randy Newman, "I'm not saying I'm better than you. But maybe I AM." Ok, ok, now I AM being a jerk... Please believe that all the dick-headed things I say and the asinine way I present them are actually intended in the MOST light-hearted way!

Of course I understand how it works. I also understand why some might think it's a better solution. And I understand why it's NOT a better solution. There is a long length of chain on the "slack" side that is unsupported between the tensioning pulleys. The ONLY thing to control it is chain TENSION, and a lot of it. I believe having the chain follow the curved guide under lower tension is a better solution. There are very BIG inertial forces acting on the chain. It is heavy, and it is MOVING, and being asked to follow a very, er, "interesting" path. The chain STRETCHES. Particularly at high rpm, when the valvetrain load is greatest. The stretch induced by valvetrain load equates to reduced tension on the slack side. I.e., more tension required. And no matter HOW much tension you put in it, it will move around. Having a long unsupported length of chain means one of two things: Big pretensioning load, or uncontrolled chain motion. Dude, a length of chain, which has considerable MASS, and zero bending stiffness (in one direction anyway, and one is all that's needed), under tension, with absolutely NOTHING preventing even first-mode oscillation *IS* (figuratively) a twanging geetahr string! Lesse, if you constrain it on both sides halfway between the two tensioning sprockets, you can either cut the chain tension or increase the rpm. Constrain it again at 1/4 and 3/4 length, and again you can reduce tension and/or increase rpm. Continue ad infinitum and you end up with with zero tension and with physical lateral support (i.e., a GUIDE) for the chain all along the slack side. Make a big inside curve out of it and you actually make the centrifugal acceleration of the chain reduce the drag against the guide. Voila, now you have a single big curved guide and next to no tension required on the slack side. And that's what you find on ANY well-developed high performance engine that uses a cam chain. What we're considering are ways to control the cam chain at high rpm operation. Same issues in a superbike engine and in the L6. I'm just pointing out that a curved guide on the slack side is a workable and efficient solution that is utilized in high-rpm high-performance applications. And tensioning sprockets with NO guides and straight-line chain paths is NOT a solution that's utilized in the most demanding modern applications. I think the more pertinent question is why you'd be so eager to believe they've come up with something novel and inherently better despite not having the resources to develop and test it. Whether or not the company's big or small is not pertinent to whether or not the design is a good one or a bad one. BUT, if I have fundamental problems with a design idea, if it came from Yamaha or Kawasaki or Nissan i'd at LEAST have some reassurance that an army of engineers developed and analyzed it and that an army of technicians tested it. In this case there are no such reassurances. Therefore I feel it to be my duty to speak up about my misgivings. Look, it's human nature to root for the little guy. I LOVE to see valid technical advancements come from the little guy. But the actual usage conditions aren't going to take it easy on this component just because it was developed by a small company rather than a huge company. The design has to stand up on its own merits regardless of where it came from.

In the world of structures, NOTHING is "fixed". Metal stretches, parts deform. The higher the rpm, the greater tension in this tensioner is going to be required with this setup to keep that chain from whipping all over the place. Greater tension = greater friction and greater wear. I'd MUCH sooner modify the existing curved-guide setup than go for this arrangement. If this were such a great idea, you'd see similar arrangements on superbike engines. But no, you ALWAYS see curved guides on well-developed high-performance engines. With a timing BELT, this is the way to go. With a heavy chain, I don't think it is. Here's an image of the chain guides on a 13,000rpm Kawasaki ZX-10R motor: http://www.ronayers.com/fiche/400_0572/tensioner/tensioner.bmp And here's the setup on a 13,750 rpm(!) Yamaha R1: http://www.ronayers.com/fiche/501_2451/camshaft_chain/camshaft_chain.bmp Both these bikes make on the order of 160rwhp out of 1000cc. I'm sure this company means well, but I'd put my money on Kawasaki's and Yamaha's engineering and development over Kameari's when it comes to designing a camchain layout that maximizes output and revs and valve control and minimizes losses. Obviously, I don't like this design, but this is my engineering judgement. Do what you will, of course!

Without the curved guide, chain whip should be WORSE with this setup. Think about it, between sprockets it is TOTALLY free to TWANG like a GEEtahr string. It would require a lot more tension to keep the mass of the chain under control. The curved guide prevents "whip" with relatively little tension. Looks like a bad idea to me.

Yup, I've got a set of 45mm OERs w/ 39mm venturis on my 3.1 liter. Bought them used, came off of a 3.1 liter in Japan. I'm using Mikuni PHH air jets and 102/221 (small round) Mikuni motorcycle main jets, readily available for $2.50 ea. at most motorcycle dealers. Emulsion tubes? I dunno, that may require a trip to Japan or something. Webers and Mikunis "much better looking"?! Bwahahahahah!

.040 is FORTY over, not four over. As in, forty thousandths.

JMort, "Backing off the timing really hurts power,..." This isn't always true, and for a lot of Z's I bet the OPPOSITE is true! I know YOU know what you mean here (backing off timing from OPTIMAL hurts power), but a lot of folks will read this and assume more advanced timing is always better. I once ran a stock 240Z distributor at 18 deg initial advance because I thought it was "better". It may have been better down low, but above 3000 rpm I was LOSING power because the max advance was up around 43deg! Anyway, I just like to pipe in to let people know that the idea is to set timing for maximum power, and not to just set it as high as they dare, or advance it 'til they get ping and then back it off a smidge. Anyway, sometimes backing off timing HELPS power, and advancing it HURTS (which you know, I know!). Iskone, Come to think of it, the cam may be 305 rather than 310 duration. And that's at zero lift, not .050". Anyway, yes it has become something of a dedicated track car. About the only street driving I do with it is to and from the track. I do go to tracks hundreds of miles away, though.

Regarding timing, I always seem to hear the "more is better"/"run as much as you can" approaches being preached. In my *limited* experience, you can run the timing too advanced and lose a lot of power even with no pinging. On more than one occasion I've gone to the dyno with too much advance and made more power by backing it off. My philosophy is to back it off until it starts to hurt power. I've found my engine makes the same power from ~34 -38deg total advance, and loses power on either side of that range. So I keep it set to 34/35 total.

11:1 is pushing it without a huge cam. I'm running 11:1 on 93 pump, but with a ~310deg/.550" cam. If you're really at 11:1 with a Felpro + .020 shim, then a 2mm HKS gasket would put you at 10.5:1, a bit more realistic. I dunno of two Felpro's is a good idea. Didn't Norm try that once?