The Exhaust Debate

[Weasel73240Z]

Yikes....I came on the board to help me decide what kind of exhaust I want to put on the 73, and I got a popsicle headache. I use the board alot for help, but I don't think I've ever read so many differing opinions on a Z subject.

It seems there are a bunch of options for around $200 - $250 out there, which is about my exhaust budget. I'm most interested in performance, with sound a distant second. My 73 is very low miles, de-smogged with a rebuilt set of 71 roundtops. Otherwise everything is stock.

I was thinking about the MSA twice pipes, or the Black Dragon Monza exhaust. Any other, better, options in that price range for my car? I can't wait to read the responses.

[xray]

I did a bunch of searching as well. I think on a stock engine you'll see little improvement over the baseline exhaust manifold, except for the aesthetics, and only when the engine is more significantly modified will you see substantial performance improvements.

That didn't stop me from dropping some $$$ on a new exhaust, though. Coated headers, 2.5" stainless etc. Why? For me, it looks good and that's what I wanted. May net me a couple extra HP, but to me that's gravy since I doubt I'll feel much difference in 5 HP for street driving. Until I decide to modify the engine...

Racing's a different story, and beyond my knowledge base....I'm sure you've seen some of those threads since you've been searching.

Buy what you like!

Steve

[LBO730]

Same as what Xray said. I had a jet hot coated header, 2 1/2" ss pipe with a 3 chamber flow master on a mildly cammed, otherwise stock engine. The sound was perfect, HP gain is neglegible like Xray said for street driving.

Just my .02 worth. Good luck!

Bryan

[240ZMan]

When I picked up my 73, it had the stock L24 and a monza exhaust. I have to say that exhaust sound was sweet. It had good bass, and almost none of the harshness that most comes with most "performance" exhausts. It was definitely not too loud.

I currently run the MSA dynomax muffler with their header and 2 1/2" pipe on a modified L28. Sound is good, but nowhere near as refined as the Monza was.

For a stock motor, the Monza would be my first choice by far. Plus the 2 tips coming out the back, stacked vertically, looks nice to my eye.

[d240zx2]

Back when dirt was new, I installed headers on my '70. They were smogged (couldn't get the other kind then) so I plugged 'em with NPT brass plugs. They're still there. The header was a three-into-two system and I ran dual exhausts out the back, centered, just like the old Jaguar XKE's used to do. Loved the sound. It says "Get ready!"

I've retained the old "mufflers" and installed stackers out the left side. See comparative photos. The sound is still the same, but it now looks better and more complete.

[glistx]

I just added a Flowmaster 40 series muffler to the stock exhaust (haven't dropped the other motor with headers in it yet) and am really happy with the sound and the throttle response. Call me crazy but I swear I feel a difference, as you should I suppose when going from a muffler with literally a 1.25" outlet to a 2.5".

[Sailor Bob]

I like the over and under pipes.

[ozconnection]

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

[240ZMan]

Ozconnection, thanks for sharing the dyno sheet. From you description above, I'm guessing that the bottom curve was taken with the 2 barrel carb (not sure what that is - we didn't get any 2 barrel carbs here in the US) and stock exhaust, and the top is with the holley 4 barrel and upgraded exhaust. I see you gained about 35%, but when I convert to HP I see that you had ~ 80 whp before, and ~105 whp after. Many others have posted that a stock L28 (with twin SUs or FI) will put down ~120 whp. I'm not trying to "rain on your parade", but unless I've missed something, your original configuration had some serious issues and was not representative of a properly tuned stock engine.

[Arne]

He's down under. Their dynos measure power in kilowatts, not HP. A kW is larger than an HP. I don't know the ratio, though.

[Mr Camouflage]

Nissan didn't create all L28's equal. The 280C was probably rated at less power than the L28 fitted to the 280Z & ZX. I say probably because I'm not sure on the figures for that car, but the L24 fitted to the C110 Skyline was around 20HP less than the same L24 fitted to the 240Z.The C110 also used a downdraft 2 barrel carbie.

I would guess that the heavier cars engines were tuned for more torque at the expense of maximum power.

Edit: Yes good point Arne. 80 kilowatts = 107 HP

[Arne]

He's down under. Their dynos measure power in kilowatts, not HP. A kW is larger than an HP. I don't know the ratio, though.

Edit - Upon review, it looks like Daniel was already doing the kW to HP conversion. My bad.