katman

Unlikely that any aftermarket cam is really going to beat the stock one over 2-6000 rpm, that's just too big a range for most "performance" cams. Without elaborate head work and increased compression to go with it, its also unlikely any cam will get you more than 10-12 hp, and with some loss of driveability. The original engineers just weren't that dumb.

Sunbelt Performance Engines, Suwanee GA, 770) 932-0160.

Which brings up a point. A large combustion chamber (low CR) boosted to the same pressure as a small combustion chamber (high CR) contains more fuel/air and hence more power. The desire for a high static CR motor is for off boost driveability, me thinks.

The only real way to go is to get the idle smooth, which is usually kinda rich because of the nature of L series combustion chambers and intake tract, and use a wide band O2 sensor for everything else. After hours and hours of needle shaving and experimentation you'll discover that a) carbs suck, and over 4000 rpm the only way to affect the mixture on an SU is by changing the exaust system since the needle is already out of the jet. No substitute for a dyno day with the right instrumentation. Best of luck.

I think 75-76 is pretty much a bolt in except for the size of the return line. 77-78 was a totally different shape. Those cars had a raised deck in the rear and you'd be pulling out the Sawz-All.

Uh, for street racing I recommend you stay out of my neighborhood. But seriously folks... If your drag racing requires an NHRA approved cage then the S&W and the Chassisworks cages are fine like I said. They meet the rules and make a good seat belt anchor. Fortunately you don't crash much in the kind of drag racing we do with our Z's so the safety aspect is moot. They are probably safer than nothing, but are extremely heavy (and raise your CG) for the protection they provide. Basically they weren't engineered by anybody that knew very much about structures. Competitive road racing requires an SCCA ITS type cage, some of which are better than others, and none of which can be had for $299. For time trials and such whatever meets the rules of the club should suffice, depending on how much risk you're willing to take. Usually just a rollbar with a handy place to locate the shoulder belts, like a Kirk or Autopower. I don't mean to sound negative, but in this case you get what you pay for. Like I stated in my first post, it depends on what you need as to whether or not the S&W cage is a "good" cage.

If you are trying to meet NHRA rules and don't care about handling or safety, these are fine. If you are trying to meet some other sanctioning body rules, or are actually trying be safe for road racing, they suck. If you are just trying to look cool, well they're cheap.

Way ta go, Danno! Now we need to get that Isky valve relief cutting tool so you can get some valve clearance so we can time that cam properly. That, the mixture, and some 1-5/8 headers with 2-3/8 collectors and we'll get you to 250 rwhp with huge midrange. When you moving back to the Bomber Plant?

The 10hp number, like most of Rebello's (where the rumour started) hp claims, is exaggerated. On an actual engine dyno in back to back tests for an ITS L24 (as previously described by John C.) the N36 makes no more than 2hp in some parts of the rev band, less than a E88 in others. On a modified engine of some sort I'd be surprised if it ever amounted to more than twice that. In Dynamation simulations at Sunbelt, and what a few years of dyno testing ITS motors has showed us, the short manifold on carburetted L series motors really limits the gains that can be made on either side of the cylinder (exhaust header and intake manifold). Injected motors, depending on the plenum, usually have longer runners and are more successful at intake/exhaust tract tuning, IMHO.

Hey Bob. I have a Gleason Torsen from about 1984 for an R200, still in the box. I'll check it, but I think that's about normal. Let you know in a few days after I get up to the shop.

I've seen sketches of these and can't figure out what good they are or what exactly they're supposed to make stiffer or stronger. I ain't gettin it, but I could be stupid, wouldn't be the first time. Yeah, yeah, I still owe us a computer model of an early Z unibody. Lost the old one, got the new one in CATIA but not in NASTRAN yet, been busy. I'll get to it.

Stock thickness for L series heads was 107.9mm or 4.248 inches

It wouldn't be legal for ITS racing, and for any other class you pretty much are competing with a fabricated sheet of aluminum for $15. I'd consider the CF at it's price or the fiberglass at its price if they had a glovebox and provisions for all the stock stuff to go back in and were trimmed to final dimensions. A commendable endeavor none the less.

I think the Jag has steel or cast iron liners for the bores, and ends up being a pretty heavy mill. The BMW is nikasil treated all aluminum block so it's substantially lighter. The width is an issue in both cases. For the Jag with stock induction arrangement where the intakes go outboard overtop the valve covers it won't fit. You have to make something else or go vertical like the picture in the previous post's link. BMW probably same way. The Jag's been done so I imagine the bimmer could be done too. All it takes is money, time, and a torch. Do it, it'd be an 11 on the "cool" meter.

I have a subscription, but don't tell any of my road racing buddies...

I'd do a leakdown test to see if you need rebuilt. Factory engines were usually good for a couple hundred thou, and I've tested one at 365,000 that was still only 6% or better leakdowns. Chances are new rings on old pistons and bore won't make that any better, as the piston ring lands is what goes first. If you need pistons then that means you need rebored, and now you're talking real money to get machine work anything close to factory quality. My vote would be get the fuel management, boost control, and all the other subsystems working on your new project and then run it till it blows, then spend the $8k it takes to build a real longblock for a 15psi boost application. Best of luck.

Ditto Johnc's answer. But when it moves it's built for corners. Anybody can drive a straight line....

Well that depends somewhat on the application. If you are racing in a particular organization then you obviously have to meet their rules (SCCA, NHRA, HSR, whatever), which may or may not meet other criteria like safety. But some things to consider: If I was doing a "cage" for a street car only that did autocross and some track days with a sanctioning body or club which required a rollbar but didn't require a full cage, my primary goal would be safely mounting a 5 or 6 point belt system and keeping the weight to a minimum so as not to influence the rollover and handling characteristics of the car. Keep in mind most of the material in almost any cage or rollbar setup will be above the vertical CG of the stock car, so a cage hurts handling to some degree (not to mention acceleration). Also, ignoring the mass (which I personally cannot), almost anything you do will be better protection than the stock car unless it's design is just so bad it adds elements to the interior of the car which will actually hurt you instead of help you (not out of the question BTW). I'd use 1-3/4 OD by 0.095 wall DOM tubing between the rear strut towers to loop the belts to, and put in a short main hoop as far outboard as I could get it mounted to the forward side of the rear wheel well. I'd put in a horizontal in the plane of the main hoop at shoulder level for the belts to ride over, and a short section on each side from the top outboard corner of the main hoop back to the strut towers for some stability. This setup provides almost no additional rollover protection from stock (no diagonal in the main hoop plus the wheel well deforms), no additional side impact protection, but is light and stable for mounting belts to keep your arse in the seat for autocrossing and having fun. For actual crash safety for street or racing you should build to SCCA rules. Some elements of a safe design for the 240/260/280 unibody would be (assume all tubes 1-3/4 OD x .095 wall DOM mild steel, all attachments to the unibody have .120 plate): 1. Main hoop at the bottom intersects the rocker beam at the wheel well and is gusseted vertically to the wheel well (which shears the load to the vertical beam at the end of the tranny tunnel. Wheel well can take shear but not a punch load like in my street hoop). The mounting plate here has to be formed funny because there's several surfaces of the unibody that come into play here, it also covers up the seat belt mounting hole so that has to be drilled out ahead of time. The tube does not go to the floor, it sorta runs out in the rocker. At the top the main hoop is just forward of the trim piece that contains the interior light. Just under the rear quarter window there's a boss in the unibody for a tooling hole or interior screw (can't remember which). This is where another slight bend occurs so the hoop can follow the contour of the car. The main hoop should almost touch this boss, like 1/2 inch clearance at most. The main hoop will have an uninterrupted diagonal from the top just above the drivers right ear (just inboard of the end of the radius for the upper left bend) down to the intersection with the rocker or floor on the passenger (left) side. Then you need a horizontal to stabilize the intermediate bend at the aforementioned boss and the main diagonal, from one side to the other split at the main diagonal. Need one more horizontal at the top of the tranny tunnel to stabilize the bottom of the hoop and help get side impact loads to both sides of the car at once (load distribution). The cages that run a diagonal into the tranny tunnel may as well stop them in thin air because the tranny tunnel not only folds up if you try to push on it but it also usually splits in a big T-bone type accident. For SCCA you'd also need to integrate the seat back and headrest supports in here somewhere. You can make a cage heavy enough to not collapse in a rollover without using a diagonal, but it's stupid. To support the top of the main hoop in a fore/aft direction for the case where your rollover also involves an element of fore/aft motion (which is basically always), I run a tube from the middle of the upper main hoop bends to the strut towers as far outboard as I can get them, and then a horizontal tube between the strut towers (if rules allow, in SCCA ITS they don't so I weld a tube to the two previously mentioned). Better would be tubes from middle of the upper main hoop bends all the way back to the taillight area, brushing the strut towers along the way, but I haven't had need to do it this way lately. 2. Door bars. An "X" gets you more torsional stiffness whereas "NASCAR" style mutiple tubes bent out into the door skin gets you way more T-bone protection. What happens at their forward connection at your feet is critical to either one being anything other than the waste of good tubing. The floorboards and the stock unibody's ability to shrug off a T-bone in the vicinity of your knees is this car's weak point. Cages with a forward down tube (the one that runs along the top of the windows, down along the A pillar, and to the floorboard near the door hinge area) which attaches to the floorboard only nearly always punches thru the floor in a rollover and ALWAYS collapses into your shins in a side impact. Z's are just wimpy here. The forward down tube should blend into the rocker panel at the forward opening of the door. This keeps it out of the way of your dead pedal. Too far forward encroaches on that. The forward down tube has about half of it stopping on top of the rocker and the inboard half continuing to the floor. Nice big mounting plate here integrating the rocker and the floor. Carry a tube to the firewall from the forward down tube running just above your toe when it's on the dead pedal. Shuold hit the intersection of the vertical portion of the firewall and the slanted portion (important). Now then, you need a horizontal about 1/4 inch above the tranny tunnel from one downtube to the other (if rules allowed I'd gusset this horizontal to the tranny tunnel). This helps distribute the side impact again to both sides of the car to spread out the loads. A horizontal tube above the dash is another waste of tubing (because the downtube just folds inward from the doorbar loads with the horizontal up high). Of course lots of padding on my tube or you'll break your shins. The key is to get the side impact loads into the firewall on their way to the engine (the big mass providing the M part of F=MA) at the same time maintaining the integrity of the capsule where your feet and legs are. As a point of interest, a Z will tend to split the floor and tranny tunnel right about your right thigh and hip and I've seen collateral damage (injury) from this before. Hey Pete, they split on a 45 degree angle more or less just like the classic shear failure! A single tube serving as a door bar from the main hoop down to the floor will just fold up the floor without all this other stuff relating to the forward down tubes. Not that that's any worse than stock, it's just not significantly better. Now you have a foundation for the door bars. Maybe a later discussion, have to get back to work. As I've said before, a good description of the load paths (what causes the loads and where they want to go to be reacted) with pictures of a good SCCa type cage is in an old Z Car Magazine article on building an ITS 240Z. I can scan this in if there's somebody I could email it to that could post it somehow. Lots more details to work out for a good cage, but this is a start. The S&W and similar cages are NHRA approved I believe and that's why their wall thickness (and hence detrimental effects on handling to some degree) is so big. The Z unibody is the weak link, how any cage is integrated, and WHERE exactly they're integrated is very important for a road race type application. Most of these aftermarket cages will give you a good spot for seat belts (albeit a heavy way to do it) but little else IMHO. Hope this enlightens a bit.

Perfect? Did you want a cage for looks or a cage for safety? Is there a particular type or class of racing you're trying to meet or just for street?

Keep in mind big brakes do no good with crappy tires. JohnC was right, until you can stop 20 times from 123 mph to 47 down a hill at turn 10 at Road Atlanta with 225 series Hoosier's at race temp, you haven't explored all the capabilities of a stock system. Big vented disks are nice, but most street folks are tire limited.

The forces due to engine torque are the same. What is different is the amount of vibration (and the resulting forces) applied to the chassis AND the internal engine parts. Not usually a static strength problem, but often a fatigue concern. And every race car I ever worked on with solid mounts shook the hardware loose from one end to the other on a regular basis. Just something to watch out for.

Uh, nope. Me thinks the ITS 240Z that won the ARRC the last 2 years would qualify as being "driven hard" on a track that hates brakes, and it is still tire limited after 30+ minutes. But you're right that X-drilling would kill it. I should hope you can outbrake any ITS Z with the 200SX. Lower CG, lighter weight, and slicks, right? That said, I'd use Mike's setup in a heartbeat if I could. It would actually be cheaper long term than any ITS setup that's being driven at competitive times, and could be streetable at the same time.

Yeah John, I wanna see too. Spotwelds versus seamed, same problem as fastened versus fused when it comes to modelling. As we say in our best Colonel Klink accent, "Vee haf Vays". Pete hits on a phenomenon I too have seen, having repaired countless wrecked race cars and having cut up an entire HLS30 into wittle bitty pieces, which is that the spot welds don't rust but the region around them does. This would be typical of the technology available at the time. Any protectant on the parts before welding is cooked off, and any treatments after welding don't quite wick down between the parts at the spotweld. Sad, but true. John's statement that seam welding might restore strength lost due to age has merit and it does relieve some of the stress around the spotwelds where the rust is most likely to have started. Pete, I'm sorry to hear you're only 40. I'm 43 but don't feel a day over 39.

Good grief. Ignore this one. Netscape and SGI Octane 2's just don't get along...

Dang Pete. You're even older than me! We still had some card decks when I started but I didn't have to use them. I had a teletype daisywheel hardcopy terminal that we thought was the cat's meow, until we got a bona fide CRT. Monochrome of course. These kids today, just don't know what goodies they missed. The ole UNIVAC had a 36 bit word which I always liked for scientific work. 'Course the Cray's had 64 bit words but they were a pain to talk to.... FEM will be in NASTRAN, so Femap will read it in, yes? I ain't including the spotwelds, this is an "airframe level" internal loads model, local stresses we'll have to do by hand (keeps the riff raff out of the stress analysis business), but overall deflections and gross stresses no problem.