johnc

You'll get much better technical support and service with Taylor. I've not had good luck with Quaife USA. I did buy my first Quaife diff from them but they couldn't answer my questions when I tried to order a Quaife sequential 5 speed. Craig Taylor is a wealth of knowledge and his team is very helpful. I don't know if the California sales tax vs. shipping from Texas are a wash.

> I wouldn't be too concerned about a 1/16" here or there. Pete, Sometimes I worry about you...

Mike, I'm going through hell with my e-mail, so your reply is here (sorry HybridZ folks)... Congratulations on placing second a Cal Speedway. I was there for a few hours Saturday BSing with Doug, Wayne, the Schley's, Pmum, and Erik. The Schley Viper was being tested for a bunch of aero changes and I stopped by for a bit to see how it worked. My wife was driving at an autox practice in the west lot of Cal Speedway and I was in town for 42 hours. When you get your shocks fixed you should be able to hang with the M3s except on the longer straights. Regarding the Quaife diff: order it from Craig Tayor at Taylor Race Engineering in Texas (800) 922-GEAR (http://www.taylor-race.com) and have it installed by Jerry at Unitrax (http://www.gearedbyunitrax.com) in Anahiem. The diff should be $895 and Unitrax will install it, replace the bearings and seals in the R180, and check everything out for about $380. If you've got a 3.90 R180, use that, otherwise intall it in a 4.11 and be careful with top rpm in 5th at Willow. Regarding the engine - what's said above is correct. The L6 bottom end is hell for strong as long as you keep the rpms under 7.5K for stock rods. Also, the F54 block is not needed until you get horserpower levels over 400, and even then a few guys run 450+ horsepower with the N42 block. Spend your money on engine preparation as opposed to "trick" parts. Johnson Machine in Monrovia knows L6s and is a good machine and build shop. Dan Baldwin on this board (and many other lists) is making plenty of power with an engine similar to what you are building (Dan's is a 3.1L stroker - not worth busting your budget right now). He regularly smokes (and occaisionally gets smoked by) Porsches and M3s on the east coast. The only ways to ruin a L6 engine are to: 1. Overheat it. 2. Run it lean or detonate it a lot. 3. Over rev it (keep under 7.5K with stock rods). 4. Run it out of oil (Accusump, Comp pan, etc.) I suggest you run a 50/50 fuel mix of 91 octane and VP C12 to eliminate detonation and allow as much timing as the engine likes. Sorry for the post here instead of a regular e-mail.

Many times racers will spend hundreds of hours trying to find another 5 horsepower. This seemingly irrational behavior is driven by the requirements of a restrictive ruleset and the advantages that even small gains provide on a racetrack. What I find funny is that a lot of the things racers determine filter out as rumors of some kind of secret "trick" that street racers absolutely need to go fast. There are really no rules when building a street engine. Take the time and figure out why racers are hunting junkyards for some elusive intake manifold, rare cylinder head, "special" camshaft, etc. You'll probably realize that you can accomplish more with less time, effort, and dollars because you don't have to fight some obscure rule about "stock" parts.

Although I don't have any hard numbers, I witnessed most of a series of chassis dyno tests spanning about 5 days the looked at a number of changes for ITS L24 engines. Again, these tests were conducted to determine horsepower and torque gains for engines built to SCCA's restrictive Improved Touring rules. The rules essentially dictate the following for our discussion: 1. No internal engine changes from stock (stock cam, valves, ports, pistons, etc.). 2. Stock, unmodified (except for port matching 1" in) intake manifolds. 3. Stock, unmodified (except for needles and jets) SU carbs. 4. Unrestricted headers and exhaust. Within those limits it was found that the N36 manifold was marginally better then the others that were legal for IT. The 10hp number is an exaggeration. Small ignition timing changes to the engine produced more horsepower then the manifold swap. There was also some arguement that the N36 manifold was illegal in ITS on a 240Z so the engine in question ran E88 manifolds - and won the divisional and regional championships 3 years in a row.

Don't rely on movies for information about committing a crime. Every vehicle has its ID number engraved onto the body in at least one place. Newer vehicles have the ID numbers engraved in multiple places. On the 240Z its on the firewall near the master cylinder. You can swap ID plates around all you want, but the sharp cops know where to look for the "real" ID.

All its takes is a California Highway Patrol officer to look at the firewall near the master cylinder and your friend and his customer goes to jail while the cops investigate a possible stolen vehicle. The CHP knows where to look on every vehicle for the permanent ID number and its how they catch a lot of chop shops.

Normal. The allowed tolerances in the R&P and the diff are probably adding up.

280Z companion flanges have 27 internal grooves to fit the 27 splines on the 280Z stub axle. 240 and 260 stub axles and flanges have 25.

A simple way to check on your engine's "state of tune" as delivered by the factory is to calculate its horsepower per liter and compare it with one of the industry best - the Honda S2K engine. Honda S2K engine - 240hp / 2.0 liters = 120hp per liter. Dodge Viper V10 - 500hp / 8.3 liters = 60.25hp per liter. The above would tell you that there is much more room for improvement in the Viper engine then in the Honda engine. For comparison, a 5.7 liter small block Chevy would have to be making 684hp to match the Honda and the Viper would have to make 996. For the Nissan L28 we have different horsepower numbers, but let's use the most optimistic one: 170hp / 2.8 liters = 60.7hp per liter. That will tell you that there is a lot of room for improvement and you can also brag to your friends that the Datsun makes more horsepower per liter then the Viper. You ultimate goal would be 336hp for the L28 to equal the horsepower per liter of the Honda. So far I don't think anyone has achieved that in a normally aspirated L28.

I think the answer we're all trying to give is: "It depends..."

> So what your saying is, if you haven't done > any porting, polishing, and enlarging of the > valves, then you should stick with the stock > cam? Basically, yes. In a stock L6 the cam and port flows are reasonably well matched. Remember, what we are trying to achieve is velocity, not ultimate port flow. If we can reduce mixture dillution through better scaveging and/or reduced reversion we increase power. When you change the cam what you're trying to do is get more mixture through the engine. The cam (assuming its well designed) will do its job correctly but now the ports, valves, and combustion chamber act as a bottleneck. This keeps the cam from realizing its potential. Now, I'm not saying swap back to the stock cam. What you have is a good cam. I would start thinking about simple porting work. If you haven't already, port match the intakes and the exhaust to the head. Get a subscription to Circle Track Magazine and find the back issues that talk about beginner and budget head work. The basics apply equally to Chevy and L6 heads. Its not rocket science, just take your time and practice on a junkyard head.

I hate to say it again, cuz its been said a million times: You have to look at the engine as a system. The stock L6 cam in a stock, unmodified head is a very good match. Witness lots of ITS L24 engines that make 170hp at the rear wheels and close to (but not over) 200hp on very accurate engine dynos. Swapping cams in an L6 without doing head work is basically a waste of money. Again, ITS L24 engines with stock (but well matched and assembled) internals, headers, SUs make at least 15 more horsepower then the two engines mentioned above. Your cams are not the issue.

My wife says I'm acute. Or she did many years ago...

If you are talking about a racing center lock then I haven't heard or seen anything. It would probably have to be all custom, including your wheels. BTW... have you ever worked with center locks before? Hopefully you know they require special impact guns that cost at least $750 each and the cheap ones will require that you buy two, one for left hand thread and one for right hand thread. The good ones that can turn either way are close to $2,000. You'll also need about 500 psi of Nitrogen or compressed air to run them. Just some tips from a tire man at various ALMS races...

If money is a concern, you'll get more bang for your buck by spending the stroker money on a good turbo setup. Combining a stroker and turbo together in one motor tends to really increase costs.

Obtuse is my middle name..

The pinion gear turns once and the ring gear turns .2564. Smaller gear turning bigger gear means less turns for bigger gear (gear reduction). It also means greater torque multiplication, which a reciprocating engine needs.

The shop's are right, at least from their perspective as businesses. This is a wild ass guess on my part, but I figure it would take about 175 hours to get the RB engine into the 240Z. That includes design, fabrication, installtion, wiring, plumbing (fuel, oil, coolant), and hundreds of other small things that pop up. So let's figure just the labor charges: 175 hours * $60 per hour = $10,500.00. Are you willing to pay that (and remember that's just labor charges)? My guess is that you are not and the shop owners figured that out pretty quick. If you are willing to pay that money, go back to the shop that you feel will produce the highest quality work and convince the owner that you have the money and the patience needed. Again, business exist to make money. They need to bill 173.2 hours each month for each technician. If they can do that with 1 big job or 5 smaller jobs, normally they prefer the smaller jobs because they get paid quicker (5 payments in a month instead of 1) and the risk of non-payment is spread over 5 jobs instead of 1.

Not true. 120 mph tops, on a really good day, for pretty much any stock 240/260/280Z. My ex-BSP 240Z would run 135 with a 3.54 rear gear.

I've always been skeptical too, but then I'm used to Zs with roll bars and cages. I can't recall the last time I drove a basically stock 240Z. Ooops! MSA autocross! I drove a few of the student's nearly stock 240Zs. Unfortunately, I wasn't paying attention to chassis stiffness or response.

The top speed issue is not important. I was just trying to provide a little insight into what torque really is. My little scenario has never and will never exist in the real world. Vehicles A and B would most likely have some driveline and chassis optimizations done to make best use of their particular engine. Or, vehicle B would protest vehicle A's engine...

Although I left out some details that Bob added, in essence both cars should have identical performance on a race track. A higher crank rpm allows a race vehicle to run a lower (higher numerical) rear end gear giving a better torque multiplication at the tire contact patch. Ideally a race car is geared to be rpm limited in top gear at the end of the longest straight. That's one of the big reasons NASCAR Winston Cup motors are turning 9,000+ rpms. I started thinking about this after watching the Pocono race where the 12 car ran the entire track in 4th gear with an incredibly low rear and the engine hit 9,400 rpms entering turn 3. That pushrod motor lasted 500 miles and they almost won the race. It also helps explain why a low crank-torque engine like the Honda S2K engine can do so well on a race track. BTW... a WC engine has a power and torque curve very close in shape to the Honda S2K engine. The WC engine just hits higher peak numbers because of its greater displacement.

Assume a couple mythical engines... Engine A makes 292 ft. lbs. of torque from 6,000 to its 9,000 rpm redline. Engine B makes 339 ft. lbs. of torque from 3,000 to its 6,000 rpm redline. Engine A runs a 4.11 rear gear. Engine B runs a 3.54 rear gear. Both are in identical chassis and both have identical trans gearing with a top of 1:1. Both cars have an identical rpm limited top speed of 150 mph. Both have have identical traction limits, both vehicles are absolutely identical including having Schuey as the driver. Using the information presented here, what are your answers to the following questions: 1. Which one puts the most torque to the ground? 2. Which one would be faster around a racetrack? Hint: Latest issue of Circle Track Magazine, page 56.

The problem with changing the oil in a shock is that it affects everything (low and high rebound and low and high bump). Its a good cheap way to stiffen up rebound, which is what most cars need to help handling, but you'll end up with stiffer bump which just makes the ride harsher.