johnc

The only valid comparison is stock for stock. Once you get out the CNC mills, the carbide bits, the flow benches, etc. all bets are off. There's too much variability. Both are good head designs and a properly modified high performance L6 will make lots of power with either head. Any differences in power have more to do with builder variation then any inherent "betterness." But, no one will listen to that arguement so... I return you now to the group engineering masturbation thing still in progress. Aren't you guys a bit chafed by now?

Just keep your eyes and ears open and your heads down.

I'm not clear on what you're cutting and moving. Are you talking about the front or rear struts (or both)? If you're talking about the front, the whole strut and spindle are essentially one unit and its important to retain the geometric relationship between strut top mount, lower control arm mount, and the ball joint/steering arm. You might be able to put a small curve in the strut tube but then getting the shock inside would be tough. FYI... the shock fills up most of the length of the strut tube. If you're talking about the rear, again you need to retain the geometric relationship but you don't have steering to worry about. In either case you're talking about a significant redesign of a critical part of the suspension. How wide a tire do you want to fit? BTW... I'm moving this topic to the Suspension section.

I'm not clear on what you're cutting and moving. Are you talking about the front or rear struts (or both)? If you're talking about the front, the whole strut and spindle are essentially one unit and its important to retain the geometric relationship between strut top mount, lower control arm mount, and the ball joint/steering arm. You might be able to put a small curve in the strut tube but then getting the shock inside would be tough. FYI... the shock fills up most of the length of the strut tube. If you're talking about the rear, again you need to retain the geometric relationship but you don't have steering to worry about. In either case you're talking about a significant redesign of a critical part of the suspension. How wide a tire do you want to fit? BTW... I'm moving this topic to the Suspension section.

The floor pans of a 240Z are pretty flat to begin with. What causes front end lift on the stock 240Z body is air packing up in a high pressure area under the front of the car. What causes lift on the middle and rear of the 240Z body is the curved upper surface (in comparison to the flat lower surface) creating a low pressure area similar to an airplane wing.

Try pricing Inconel. A 4' x 8' sheet of .062 Inconel 625 was $1,300 last time I checked. I have no idea what the tubing costs. The newer metals are pretty intersting, but as long as what you're using is stable at typical exhaust gas temps (1,200 to 1,700) then you probably don't need to spend a mint. Unfortunately, at those temps your best "cheap" choice is the 321 stainless James mentions or well coated steel.

None have Positraction. Positraction is a brand name for a General Motors clutch pack limited slip differential (LSD).

My reference to the high end engine management systems was in relation to some pretty radical NA engines. The 3L in my 240Z starts after exactly 4 complete engine revolutions (programmed that way), idles all day cold or hot at 1,200 rpm, has excellent driveability, and would work fine as a commuter engine - except that is has no flywheel and needs 110 octane leaded fuel. It also has 13.6 to 1 compression and a pretty radical cam. Do I think a 230 hp NA L6 can be made to work woth the stock Bosch L-tronic fuel management system. Absolutely. Has anyone done it? I don't know. It would take a lot of research and you'll probably be swapping in some components from the BMW implementation of L-tronic. Come to think of it, I seem to remember someone modifying the VG30 engine managment system to work on the L6. Does this ring a bell for anyone here?

The issue with Ti tubing is price and getting it bent. Figure about $100 per pound for 6a4v. Ti also has memory, so you have to overbend it by about 25%. It takes a lot of trial and error with a mandrel bender to get it right. Ti elongation is similar to 304 stainless (about 25%). Ti fumes and dust, like any metal, can be toxic in large quantites, but with adequate ventillation you shouldn't have to worry. Welding it requires purging of the tubes, a big gas lens, a trailing cup behind the TIG torch, and a lot of Argon gas. Any color in the base metal or the weld besides silver or a light straw and the weld is contaminated. Even in a low stress application like an exhaust you will get failure at the point of contamination from carbide precipitation at elevated exhaust temps (over 800 degrees F). Ti and C have an affinity for each other. In use, Ti tubing turns a dark brown, just like stainless, Inconel, and Monel. So, it may look cool when its new, but after about a couple months it will look like most any other header. I suggest you try stabilized 321, 347, or 348 stainless or Inconel. Those are the tubings of choice for lots of high end race cars.

Devil here... > Therefore, the overlap and the intake valve > closure point have a larger effect. Once the > engine is running, there is some momentum to > the intake charge, which allows some of > that "pressure" to stay in the combustion > chamber when the intake valve is still open > after the piston starts rising from BDC. At > cranking speed, as soon as the piston begins > rising from BDC, some of the charge is pushed > back out the intake valve until it closes, > (which by some areas I have read, is effective > at about .050 lift). But, conversly, your are not exhausting the cylinder as effectively so some residual "charge" remains that would normally be scavanged by the header and exhaust system. Does this offset what's lost by leaving the intake valve open longer? Maybe to some degree but I don't think anyone has the numbers. For those interested in the numbers, sticking a 'tater in the exhaust tip would pretty much eliminate the cam from the static compression test. This thread does help to point out that static compression numbers are useful for comparision over time for your particular engine (a quick check of wear) but appear to be useless for comparison with dissimilar engines.

A rebirth of the High Horsepower L6 discussion... There are a few folks on this board who have built 450+ horsepower L6 engines. I and others are very interested in hearing the merits of turbo, N02, or both in these applications. Technical discussion please. No morals, no judgements...

There are a couple that run occaisionally at Cal Club SCCA events here in Southern California. Sam Strano of Strano Parts ran a 280ZX Turbo in ASP for a number of years.

Well... Let me be the Devil's advocate. While I agree that overlap will have some effect on a static compression test how do other aspects of a cam design effect static compression tests at low cranking speeds?

In the past, high horsepower normally aspirated engines were tempermental, mainly because the fuel and ignition management systems were not sophisticated enough to manage high compression and high overlap, long duration cams. Modern fuel managment systems (Motec M48, TecIII, etc.) can make these engines very manageable and easy to live with - as long as you're willing to buy "good" fuel.

Ian, Go back and read the HybridZ homepage and also read the thread about the origins of HybridZ. Regardless of your opinions on the merits of the swap, its inappropriate to call it "rediculous", an insult to the car, or refer to it as a "rice-out" on HybridZ. HybridZ History

The only sure way to verify the rear gear ratio is to pull the diff cover (12mm socket) and look at the ratio stamping on the ring gear.

Quartermaster multiplate 5.5" with no flywheel.

If its for a street Z then anything sold from MSA is fine. The most important thing with any header you purchase is to port match the header to the cylinder head. The smoother you can make this transition area (including the gasket) the better. The are some rumors out there that a certain design produces more torque and another produces more high rpm horsepower. The real answer is: it depends on your specific engine and its current state of tune. The only way to know is to do back-to-back tests on YOUR engine.

That's interesting. Hopefully there's someone I can talk to who has used it before. Considering the sway problems I had trailering during the OTC this might be a solution.

I only use anti-sieze on fasteners that will see corrosion or lots of heat cycles, are made of dissimmilar metals, or that tend to get removed and replaced a lot (like wheel studs.) Otherwise, I just make absolutely sure the fasteners are in perfect shape and are spotlessly clean and dry. I do not use oil or WD40. I do use blue Loctite on many suspension and driveline fasteners.

GT2 race motors occaisionally see 9,000 rpm and thus have a need for valve springs that stiff. L6 engines that are kept under 7,500 rpm work fine with stock valve springs and can even be made to work very well with valve springs 25% less stiff then stock. I don't know for sure if the stiff valve springs are the cause of your problem, but I do know the stiffer valve springs are not helping your engine at all. In fact, they are robbing you of torque because of the effort needed to compress them. A turbo motor does not need stiff valve springs or radical cams (which might require the stiff valve springs.)

I have not heard of anyone doing this swap. You can be the first, go broke, then write a "how to" book.

I forgot how I stumbled across this site, but I'm glad I found it - rational people and intelligent discussion. I do post on zcar.com from time-to-time (still a great general purpose Z site) and I try to do it in a thoughful manner, but I still tend to piss people off over there. Mostly the guys who are convinced [insert odd modificaiton here] is the only way to go.

Increasing front track with by 24" will be a huge job. You can't accomplish this with wheels spacers or wheels (who sells a 12 or even 6" long wheel stud?) You will have to relocate the entire suspension outboard by about 10" on each side. You'll also need a different steering rack, steering shaft, custom anti-roll bar, and the services of someone who is an excellent fabricator. It can be done, just be prepared to invest a lot of time and money.

235 normally aspirated rwhp for under $5000. That's a pretty good price.