katman

The race cars were ITS or EProd. In ITS you can't cage forward of the firewall but you can have a strut bar (as long as it only attaches at the shock towers, no triangulation). Not really any difference in the rates we ran with the shock towers tied in to the cage on the EP car verus not as on the ITS cars, but I will say between 350 and 400 hard to see any difference on the ITS car proly due to the flexibility of the unmodified chassis. IMHO what gets you in a non caged car isn't a 300#/in spring, it's the shock loads necessary to control it (not to mention the shock $$$). We never found any added fun over the aforementioned 185 lb/in springs on a street car, and have had gobs of fun (and I'm talking about rolling out of the seat LMFAO type fun) on the track in cars that were in the 115-145 range. This with drivers used to the race cars. Now if you want to discuss my humble theories on spring rate as a function of driver experience....

"Chet Whittle [sIC- Wittel] was very successful running without a rear anti-roll bar on many tracks back east. He did run springs up in the 350 lb. in. range (and higher on some tracks). Generally, the more spring you run the smaller your anti-roll bars need to be." JohnC recalls correctly. In the southeast we were blessed with several new tracks (Kershaw, VIR, Barber) and several repavings (Road Atlanta, Roebling Road, Charlotte). On smooth tracks I always preferred big spring to big bars to maintain compliance with the inside tires. We almost never had a rear bar on and in fact our front bar, a custom 4130 hollow, was only about the equivalent of a 15/16ths solid. In our case, spring rates in the 350F/285R and 400F/350R worked best to get the power down. I dare say our suspension package (shocks, springs, bar, alignments, "tweaks") was "HOOKED UP" like no other, as back-to-back ARRC victories attest. BIG CAVEAT: Over the years I've come to the conclusion that front to rear spring rate balance you need is very sensitive to roll center (function of ride height- more sensitive the lower you go, not too sensitive at streetable ride heights) and how many low speed corners your track has. At Mid Ohio for instance, a 240Z wants a lot more rear spring than we run at RA. You end up with asomething more along the lines of the "west coast" setup- 250F/300R or something like that- opposite in balance and softer than what we run on the higher speed tracks. And then there's this: On street cars that we've also done driver's schools or other track events with, we've had extremely fun setups with 115F/145R and a standard combo of bars (say 1"F, 3/4R, mounted in poly), and also a 185F/185R and solid mounted bars 7/8F, 5/8R. Same drivers as with the ITS car, same amount of balance and fun. Bottom line, YMMV. Regarding 3/16 toe in the back, I'm afraid I'm from the "low drag" school. I always preferred to find other ways to make the car handle without pointing the tires somewhere other than straight. With our "east coast" setup on the ITS car we did need to run about 1/8 toe out in the front to help turn in on slow corners like 7 at Road Atlanta, but could always make zero rear toe work everywhere (on a street car that retains some rubber in the rear you still want a smidgeon of toe in to control trailing throttle oversteer). And as far as droop limiters- anything that's non-linear in a race suspension can't be good. Y'all are scaring me... Hope that helps.

They sure are pretty pieces, but I'm still not sure I see what the fascination is with being able to adjust the length of my primary front suspension geometry driver and shortening the length of my TC rod. I guess one could make a case for the ease of gaining adjustable camber this way versus camber plates, but potentially having control arms at different lengths I just don't get. Maybe I'm missing something....

Regarding the weatherstripping- We recently finished a total resto on an original owner 1971 and started with the factory door weatherstrip, now only available for 280Z's but it still fits. Way too thick. Les Cannaday at Classic Datsun fixed us up and the doors close great.

Just a data point: On our race L24 ITS engines we tried a crank scraper once at Sunbelt. Lost 2 hp. However, after the tests we decided we might have had too much oil on the pan so we didn't totally blame the scraper and ran out of dyno time before we could reconfirm. To do it properly, the scraper needs to come within .030 to .050 of the reciprocating assembly and be stiff enough to hold up to the windage. Then, to mount it somewhere, oil pan or cap bolts, such that the clearance is repeatable, is no small job. Sounds like a great idea but it takes a lot of time to get it right.

"I read in how to modify your nissan/datsun OHC engine that it would be a good idea to sand and polish the block interior to remove casting-sand residue, and then paint the inside. Waste of time, or worth the effort???" Waste of time. We occasionally will grind down a particularly bad casting flash, but otherwise extremely little to gain.

Just what I love, good ole butt dyno numbers to prove once again that headers make huge increases in power!

The "Curmudgeon"! You truly do know him. I won a lot of races with his engines, but alas, I found that my drivers could not win a race if I didn't enter- because I was waiting on Don to finish a motor. He builds perhaps the greatest motors nobody ever gets.

400 RWHP? Now we're talking turbo cams, not NA. In which case stock is fine. Another innovator Tony left out of his dissertation is Don Potter, builder of Frank Leary's "Giant Killer" turbo Z's that regularly beat Electramotive and BRE back in the day. Sadly, Frank was killed a few years ago in a private plane crash as he and Don were beginning to discuss restoring Frank's car for vintage racing. Potter, who was on a first name basis with Ed Iskederian and Harvey Crane, has forgotten more about L series cams than either of those guys. Don's also the one who took over FAR performance from Dolf Von Kersten (sp?) and turned it into D.L.Potter Engineering. However, I'm not sure Don is in business anymore. Tony is right when he hints that most aftermarket L series cams are copies of copies of somebody's mod to an original BMW grind. I'm a Sunbelt fan myself, because I know they've done the most recent original development.

Heck, I've owned a Bridgeport. I wish I had a wife that wanted one!

Hey Bryan, my offer still stands if you don't sell them this time. And I'll let them be used as a pattern.

The last season season we ran "Big Orange" in ITS used 400#/in front and 350 rear, with the equivalent of a 15/16 bar up front, no bar in the back. John's structural assessment is right on all accounts as usual. We got away with it because we had a very effective front strut bar, very efficient cage, no structural compromises to the basic unibody (dents, rust, corrosion, etc.), and custom adjustable remote reservior shocks. We also had very light wheels and tires (Hoosiers) and overall front end weight was less than stock. The low unsprung weight is important because is reduces your shock loads.

In the tension side (driver's side), I've bored a hole completely through the rubber and both plates right at the stud which attaches the engine mount blockto the front crossmember. Then, with a long bolt, put a poly washer and a metal washer on the engine side of the flat plate part of the mount (the piece with the two treaded holes) and bolt it all to the crossmember.

'Tis also what 2 time ARRC ITS winning 240Z of Chet Wittel had. You sir, are a freakin' genius!

Malvern Racing and D.L.Potter Engineering have both done roller rocker cams for the L series motors. You have to have a lot of money and even more time before you call either one of those guys. I'm a big fan of the cam work that's been done recently by Sunbelt. They've figured out how to reduce the valve spring harmonics, reduce the spring load, and still keep the rocker on the cam lobe. Not quite as low drag as a roller rocker but way more "free" horsepower (i.e. the kind you get by reducing drag, it's been said it eats up 75hp at 5000 rpm just to drive the camshaft on a Z) than a 25 year old Schneider grind.

4.248-4.164 = .084, that's why what's left of the combustion chamber looks like the E31 chambered E88. Hope you have some thick lash pads to chose from and some slots in the curved timing chain guide to take up the slack.

On several L series road race engines I've been responsible for we always achieved better driveability, more consistent power, and a better overall "demeanor" with a big balance tube or bona fida plenum, even with itb's or individual carbs. I don't see how in operation, when you actually have to accelerate a car and not just a freewheeling engine, that a single throttle body like johnc's would have any disadvantage as far as "throttle response" to itb's. They sure look cool though...

"I want 100 watts but only have enough money for a 40 watt bulb. Is there a cheaper way to get 100 watts?"

Well what it is'nt: Stahl, MSA, Pacesetter, Rebello, Rallyesport, NISMO, Doug Thorley, Clifford Research, Anti-Reversion, BRE/Interpart, or Sunbelt. Could be custom. You'll pick up some hp if you get rid of the Chevy red engine paint too.

And the specs are "the lift seems higher than stock" ???? Sorry, not much to go on. Any writing on the back of the cam?

A lab quality burette (which is what you should be using, check Fisher Scientific) will cost more than the shop should charge you for measuring the chamber volume on 6 chambers. Good grief. The volumes "look" smaller than an E31? Do they know some E88's have E31 chambers? Have them cc it so there's no doubt. Ballpark is every .010 you shave reduces the volume by about 1cc on the '72 version of the E88. The head would have been 4.248 to 4.253 thick stock.

The original Tilton style are still available from Don Oldenburg at Design Products Racing, Carerra used to have cheapo's, but as much as I hate their shocks, the Ground Control plates do the best job with the spherical thrust plate. Best design I've ever seen for a Z. EMI Racing (our own John Coffey) has them too but I can't comment on their design.

That is some beautiful work. I kept searching for a picture of the seats installed relative to the main diagonal. There's one picture near the end with the doors on and it looks like the driver is a good foot+ in front of the main hoop, which makes the side bars way longer and less stiff than they need be. They sure are worried about the back half of the car, and it doesn't seem like they're too worried about a side impact at the door. Nice work, but not the way I'd do it. But I might not have all the appropriate info to pass judgement.

Or, for people like me whose PC is not worthy, for about $3.97 you can get the DVD and watch them on the BIG screen in Dolby Digital 5.1 Surround! Just go to the bmwfilms.com website.