Leon

Quick update: Went to the dyno on Saturday, 8/20/11, and did a baseline run with a bit of exhaust testing. You can read my analysis here. Quick plug: the shop I went to is Dito's Motors in South San Francisco. Nice shop, David and Robert are cool guys and they have a nice dyno (load-bearing "Dynomite" with 4WD rollers available). Everyone wants numbers, so here they are: 121hp @ 5200rpm and 136lb-ft @ 4000rpm. I came in hoping to be over 100hp so needless to say, I was very happy with the numbers as they verify that my un-jetted Webers are close and the ol' L24 is doing okay. As I was removing the exhaust I snapped a stud at the manifold-to-pipe connection. I tried like hell to get it out to replace it but it wasn't budging. I had a few headers sitting around so I decided that it was time to use one, even though I hadn't planned on it. I removed the intake and exhaust on Sunday night and installed my Nissan Motorsports header. The install went well, I just had to remove two bolts from the steering coupler so I could get the shaft out of the way and it slid right in. One collector is very close to the floor (couple mm's) but it should move away as the engine spins. On Monday (yesterday), I drove it to a local exhaust shop to get twice pipes built off the headers. The Z sounded like a ground-pounding race car and, unfortunately, I forgot my ear plugs so it was quite a ride to the shop! Also, my Momo hub adapter came in yesterday so when I get the car back I can mount my new-to-me steering wheel. I got a very good deal locally for a 350mm Momo Race. Can't wait to have the Z back!

I bought a wheel locally and the adapter just came in yesterday, so I'm all set!

What he said. Clean up the pulley and you should see the mark. Alternatively, you can use a piston stop. (1) Gently rotate the engine til it hits the stop, (2) mark the pulley where the pointer is pointing, (3) rotate the other way to the stop, (4) mark the pulley again. (5) Put a mark dead center in between the two that you just created and that will be TDC.

I've always liked the body style. The box flares just do it for me! The 944 was almost my first project, until I got pulled into the Z world.

I'll quote my first post: Inspect first, and if they fail inspection then either rebuild or buy new. Download the FSM.

Did you put a timing light on the #1 plug to see if it's timed correctly instead of guessing? You can just move the spark plugs around the distributor to where #1 fires at the right spot. Makes sure to keep the firing order correct (1-5-3-6-2-4).

Sure you can try, but it won't do anything for you if your seals are leaking...

I would inspect your clutch slave and master cylinders, both are simple. You may need new ones.

I would definitely go R180 STi with Coffey's axles as far as LSD goes, but that will be over $1000. As Mortensen points out, $500 is nothing as far as suspension goes. It's more like ~$1000 for a basic setup (shocks, springs, bushings, ball joints, tie-rods, etc.) and up if you're going with coilovers (I would for a track car). If the engine has good compression, I'd leave it alone and focus on the rest of the car. Maybe freshen up the cooling system, make sure the carbs are good and do a general tune-up. I do think you can go cheaper on the wheel/tire combo depending on wheel size, maybe $1000 or so if you go for something like Rota or Sportmax.

However, some cars are more maintenance intensive then others. When you have to do the timing belt/water pump or clutch you may be in another mindset! I've considered getting a 944 many times, but the parts cost and maintenance schedule (timing belt every 30k miles?) have kept me away. No doubt, they are great cars, but I prefer the S30. Although the 944s were galvanized so rust is much less of an issue, and that is a very good thing. I think if someday I find a nice, well taken-care of 944 I may just pull the trigger anyway! I'm such a masochist...

Very nice job Mike, I love the attention to detail and functionality! Any plans for a splitter and/or undertray?

Great Scott! You're correct that it's 1.21GW, but I was going off of TD's post . I should've quoted him... Edit: quote put in above!

Dyno Testing a 260Z This is an analysis based on my dyno testing from yesterday (8-20-11). Test Parameters The reason for the testing was that I wanted to log a baseline for my 260Z before going further with more engine modifications and to make a comparison between different configurations. The baseline settings are as follows: early 260Z with 1972 L24/E88 that was installed by the previous owner triple 40DCOE-18 Weber carbs with K&N-style filters, not jetted yet, just bolted on and sync'd Cannon long-runner manifold stock exhaust manifold to single 2.5" crush-bent pipe stock cam and internals refreshed cooling system with aluminum radiator, new water pump and hoses heater loop is blocked off at both ends Mobil1 synthetic 10W-30 in engine, Redline 75W-90 in transmission (GL-4) and differential (GL-5) MSD coil, NGK plug wires The two pipes to be tested: \ Test 1: Long 2.5" pipe with straight-through muffler in the rear Initial Thoughts and Numbers: I know actual dyno numbers don't mean a whole lot but I came in thinking that I'll be happy to break 100hp! The Z feels very torquey and quick but we all know that the almighty butt-dyno isn't very representative of reality, so for all I knew I could've been making 85hp... I was also pretty convinced that I would not be over 120 hp as the carbs are not jetted and I have not even touched the spark timing. However, according to the dyno that day, I am making 121 hp @ 5200 rpm and 136 lb-ft @ 4000 rpm! At the very least, this indicated that my engine is fairly healthy and that my tune is not completely off. A happy side-note but we're here for comparison purposes not peak numbers. On to part two! Test 2: Stock downpipe, cut after the merge Results SOLID lines are long-pipe runs DOTTED lines are short-pipe runs *Note: there are local peaks at about 5850 rpm, and they are there for both runs so it very well could be due to the tune. The long-pipe made slightly more torque on the top end, but the short-pipe made more low-end torque. Analysis On the surface, the results look counter-intuitive. After all, shouldn't a short pipe be better for top end and a long pipe better for low end? How about the "mechanic" that's been "doing this for years" that says "well son, when there's less backpressure you lose all yer low end torque. You need some backpressure." Well in this case, running it with no muffler and a cut after the merge increased low end torque. So please, get any thoughts of backpressure out of your head when speaking of exhaust tuning. In fact, forgot the word completely, it is not a very useful term in the exhaust theory glossary, besides wanting as little of it as possible. The results come out as expected after you look at the differences in the two pipes. The critical difference between the two being the length of the secondaries before the merge into a single pipe. Take a look at the second picture from the beginning of the post, showing both collectors. Take note of the differences. The long pipe exhaust merges the secondary pipes quite a bit earlier than the short pipe, meaning that the short pipe secondaries are actually longer. Thinking back to wave tuning, whenever there is a discontinuity in a pipe (e.g. a change in pipe diameter or merge), the compression wave coming from the open exhaust valve gets reflected back as an expansion wave. A tuned length of pipe allows the expansion wave to travel back to the exhaust valve just before it closes, further dropping pressure in the cylinder. This draws out more burned exhaust gasses as well as draws in more air-fuel mixture during the valve overlap period (scavenging). Keep in mind that a tuned length is only good for one engine speed. As pipe length before the discontinuity (merge) changes, so does the time it takes for the wave to travel out the exhaust valve, down the pipe, reflect and come back to the exhaust valve. A shorter pipe before the merge decreases the length of time it takes for the wave to reach the exhaust valve, therefore it is more efficient at higher engine speeds. The opposite is true for a longer length of pipe before the merge (longer wave travel time = lower rpm efficiency). This test also shows that a single 2.5" pipe is ample for my L24 spinning to 6000 rpm, because it essentially mirrors the short pipe and actually outperforms it at high rpm. The large diameter pipe allows for the collector to do its work without hindering performance post-collector. Conclusion and Discussion The results nicely agree with the exhaust theory that we've covered in this thread. If I took the long pipe with the muffler and cut it after the collector, it would perform better, but the difference would likely not be discernible. On the other hand, if the pipe coming off the collector were smaller than 2.5" then pumping losses would begin to climb and performance will decrease across the board, especially at high rpm since frictional losses in a pipe increase with the square of velocity. In the near future, I am having twice pipes made and I'm curious as to the effect of keeping the secondaries separate. It may cause a small hit in performance, judging by how much of an effect moving the secondary merge point had, but carb and spark timing tuning will be a much more drastic change. I broke off a stud at the exhaust manifold-to-exhaust connection point, and although there was no detectable leak, I may just put on my Nissan Motorsports header and build the pipes off of that.

2.88 gigawatts!!!

Good call jhm! Looks like it's a TVR 2500M: Looks like it's an early '70s TVR body with TR6 drivetrain.

BMW Z3? It's probably 30 or so years older than the earliest Z3, very likely a '60s era British sports car. My first thought was Lotus Elan but that doesn't quite fit the bill. You have me curious now, looks like some searching is in order...

Well there's your problem... Take this as a lesson learned and move on, and at least this lesson is a relatively cheap one.

http://xenons30.com/reference.html

Braden's book has some rough sizing guides. You'll likely find similar stuff online. When I have my book on hand, I'll try to dig up some equations for you. But before I do, you must get me... a shrubbery. Here's something you can find from a quick google search: http://cnx.org/content/m37431/latest/

The procedure to check timing is the same whether it's a Datsun, Volkswagen, Ford or Volga. Newzed makes a great point: buy a general automotive repair book and self-educate.

Sounds like stivva's Z but I think he changed his paint scheme since then. Here you go: http://forums.hybridz.org/index.php/topic/87272-post-pics-of-your-zs-here/page__st__320

Thanks! It's funny how we've taken a similar path with our cars as well! Since I have the 240Z sitting on stands, I've been thinking of what to do with it. LSx? Maybe... The plates were there when I got the car. They block off the bumper shock holes as you've said, purely cosmetic.

Or you can put in 6 EGT sensors and get a 6 actual numbers that can be data-logged instead of a purely visual and subjective reading. It would presumably be cheaper than 6 colortunes and 6 cameras as well.

It would not be wise to remove the booster from a system designed for power brakes. Your pedal ratio will be too low, and there will be a considerable increase in pedal effort. This is dangerous. You don't like pedal travel in your brakes? Would you rather have almost zero pedal travel?

Jetting your carbs takes experimentation and will be tough without a dyno or at least a wideband 02 sensor. As I said, there are books on this, e.g. Braden's book, that have some rough guidelines for setting up your carbs. You can try to order a few different sizes to try to match them up to your engine. The carburetors function the same, whether it's an L20 or L28. Read the sticky!