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Arne, I hear what you're saying. I can only take your word for it about the "quality" of the standard US spec Z cars you guys have over there. The standard exhaust system on my 280 was of the single outlet variety, so improvements over this was fairly easy to achieve. the pipe diameter was 1 3/4 inch with a small resonator and a large rear muffler. I have owned other Cedrics that had the 'better' dual outlet cast exhaust manifolds with two pipes running along till about the crossmember before they joined back into a single system. When I had this system replaced on another car a long time ago, I found that one of the joining pipes was so badly welded (by the factory I might add since this system was virginal...first time replaced) that three cylinders would have been working a lot harder than the other three to get the exhaust out. As you can see from my own personal experiences with L28's and Cedrics, a good exhaust system is worth its weight in gold in the performance stakes. Cheers, Mark

Steve, I added the dyno sheets to the discussion because I wanted to show people how much potential there was in improving the performance of a stock l28 engine. I have no personal experience with modifying L24's but how different can they be to what is essentially a fundamental performance upgrade? If dyno sheets exist for L24's before and after an exhaust upgrade I would love to eat my words! Cheers, Mark

240zman, I think you missed the point of what I was trying to point out here. Many people have claimed that there is little point in adding a performance exhaust to a stock engine. My claim is that this is just not the case. My original spec L28s (single carb!) engine ran a Hitachi 2 barrel carb from the factory. Rated HP is 139HP at 5200 rpm. This is what Nissan claims for that setup. The figures are also for an automatic trans car where there is about 10% driveline loss over that from an equivalent manual trans car. You do the maths and see what is works out to be. I can assure you that the engine was running very well at the time of the first dyno run since my father and I had been owning these types of Nissan cars since 1971. Sure, it doesn't make me an expert but at least very familiar as to how these cars should be running. Naturally, twin su and injected engines are going to make some more power than a stock L28 with a single two barrel. Cheers, Mark

A few years ago I began a series of modifications to my L28S to improve its performance. Along the way, I decided to dyno each modification to see what effect my modifications had on rear wheel horsepower. One of the first things I did was to replace the standard 2 barrel carburettor with a 4 barrel Holley. Then I replaced the entire exhaust system and installed a set of headers and a 2.5 inch pipe including two mufflers because I wanted the exhaust note to be quiet but free flowing. I've included the dyno graph that shows these two mods. If you look carefully in the shaded part, there is a line that represents the addition of the Holley carb. Not a huge improvement as you can see. This showed me that the engine was consuming as much air as it could but something was holding it back from producing more power. The other line is the result from changing the exhaust. To say that a performance exhaust is worth very little in extra power on what is, essentially a stock motor, rubbish. Maybe it's got something to do with the majority of guys running the twin carb setup, being of a dual plane arrangement as compared to my single plane Holley setup that might end up producing different results for different engines. All I can say is that the 'wow' factor, in this case, was huge. At the time, I hadn't really known about the twice pipes exhaust setups. Once I found out about them, I did some research of my own and read Morrisons and Smiths book titled 'Scientific Design Of Exhaust and Intake Systems' where experiments by these fellows concluded that the twice pipes are indeed the best setup for inline engines with a firing order of 153624. When it comes time for replacing my exhaust, I'm going to run a similar design on my L28. It's just that I didn't know about it at that time otherwise my car would have this system on it now. Cheers, Mark

What a great summary Daniel (240Zman)! There isn't much more to add to this except that I have used the Crane Cams XR700 conversion kit and had great success with it. It was the first unit that I used to replace my stock points setup which were regularly mucking up. I too am running a 280ZX electronic distributor with an MSD 6BTM which has a rev limiter as part of the unit. This is an advantage in that it prevents an engine over rev. by dropping out random sparks to the spark plugs. Different 'pills' are available so that you can determine how high the rev. limit is set. The other advantage of using the MSD in the ignition setup is that there is a whole range of products that can be used with it. I bought a window switch so that things can be turned on and off via the 'pills' that you install into it ie water injection,intercooler fans, water pumps etc etc etc. Have a look at the MSD website or order a catalogue and have a look. The book is a great read and will teach you a little more about ignition systems and what's out there. Cheers Mark.

I've recently acquired a CAS setup for the L series L28 engine. I'm looking to replace the sensor with a new one. (part number 23731-V0801, made by Hitachi in Japan.). I'm also considering an alternate sensor to use as a substitute if the original ones are NLA. Can anyone help me out? Cheers, Mark.

I think that, in most cases, the standard exhaust system is usually pretty, well, standard! Press bends on the smallish diameter pipes with very ordinary flowing mufflers and exhaust manifolds means that it isn't very hard to improve on this as far as performance is concerned. Anyone who says that you need a cam change before an upgraded exhaust is fitted has rocks in their heads! There is no point improving the breathing capacity of the engine via a larger camshaft until the exhaust can flow adequately! Get the exhaust first, then the cam.

I have an L28 that runs a Holley 465 on an Arizona manifold imported from the USA. Bought it off ebay. I also have a Clifford 4 barrel manifold for the 4bbl conversion. Very different results from each of them. The Arizona is a torque manifold by design. The Clifford sacrifices low speed torque for a lot more power up top all else being equal. Admittedly, the Arizona 4bbl needed a lot more 'tuning' of the carb to get it working right, but it's worth the effort. I have played around with different sized carbs too, one being a spreadbore vac secondary 650, an annular booster square bore vac sec 600 and the 465 and they are all reasonable performers. The best for low speed torque is a close run between the 650 (small primary throttle bores) and the 465. The 600 produced the most power on the Clifford manifold. The 465 on the Arizona produces a low speed torque monster with a stock cam when the cam is also advanced (positition 3 on the stock cam sprocket). This is how my car is set up at the moment. Throttle response is excellent with the 4bbl setup and economy isn't half bad either. Like I said, it takes time to get it right but the results are there if you're prepared. BTW, I also recommend some mixture metering device to see where your mixtures are at. I use the Innovate wide band O2 sensor thingy. Best tuning tool I ever bought. Check out my engine and car on youtube. (Dyno run Datsun 280C). All the best with your 4bbl project. Mark.