Thanks for the very informative page, although I think you misunderstood me--I did not state clearly enough. I meant I will probably remove all the plates and the endplate and everything and just run it open like my other car. You're right, just 'removing all the disks' (leaving the endplate) would no doubt create a bit too much backpressure. I'm dynoing Tuesday and might play around with the backpressure a bit. One of the main reasons I went 2.25 is so I could run it wide open. I think 2.25 is perfect for N/A Z motors (yes, save all your flames--I've read it all). I am guessing 18 plates would be very near wide-open in terms of amount of backpressure produced.

steve

Interesting that

I am running a lightly modified L24, mild cam, 6 into 1 header, triple webers and 280 distributor (nearly 180 at last dyno visit)

I have just moved from a MSA 2.5 inch "turbo" system (yes we get them in the UK) to a custom stainless 2.25 inch with a single "straight through" rear box and square tip -- I will bet on a buggers bum that my RWBHP has gone up, the car feels generally more torquey and pulls far better from low revs, I have also lost a misfire I had at around 5.5 - 6K.

Oh and the exhaust note has changed from a harsh wail to a more colourful deep "TVR" tone -- (not that you guys know what a TVR is) which is far less wearing on a 40 year old set of ears.

So in my very humble opinion I also feel that a 2.25 is better suited to a "street" L series

So in the immortal word of the human torch FLAME ON

Hey, we know what a TVR is. I may have only seen a few in my life, but I have driven a speed 6, a griffith, and a speed 12 on Gran Turismo 3. Okay, I was lame...

Nice one

It sure would be nice to get some mp3's up so we could hear the different combinations. I am sure it would help a bunch of us save money and get it right the first time.

Still looking for the right combo...

inline6

I have a 20 second clip of me revving my car a bit on my phone and let random gear heads i run into listen to it....

Originally posted by v12horse

speed 6, a griffith, and a speed 12 on Gran Turismo 3.

I sold all my TVR's and bought Skylines!!!:classic:

Chris

Well people argue that 2.5" exhuast is perfect for a Z.... but here is my conclusion about my research on Z's...

For mainly stock or light modifications the 2.25" exhuast is ideal.

For modified or medium modifications the 2.5" exhuast is perfect.

For TURBO or highly modified Z's the 3" exhaust is even better.

Here is a baseline 240Z.... Dyno chart

1971 L24 stock bottom end, approx. 150K miles

E88 cylinder head, fresh valve job, shaved 0.025 inches. Otherwise stock.

MSD 6AL ignition, Pertronix Ignitor, MSD 8mm wires

Stock Rebuilt Distributor - stock advance curve.

Stock SU carb.'s, N-27 needles

This is how much more HP you get from Rebello or Nismo headers

*Almost nothing but a cool sound

This is for a 2.5" exhuast compared to a 3.0" exhuast

and finally.... an AIR CLEANER will actually improve your peak HP!

Awesome post!

Those are the first dyno sheets I have seen on this forum!

Thanks for the very informative page, although I think you misunderstood me--I did not state clearly enough. I meant I will probably remove all the plates and the endplate and everything and just run it open like my other car. You're right, just 'removing all the disks' (leaving the endplate) would no doubt create a bit too much backpressure. I'm dynoing Tuesday and might play around with the backpressure a bit. One of the main reasons I went 2.25 is so I could run it wide open. I think 2.25 is perfect for N/A Z motors (yes, save all your flames--I've read it all). I am guessing 18 plates would be very near wide-open in terms of amount of backpressure produced.

steve

Hi Steve,

I have been doing some research on exhaust systems for my track car. I have a '71 than I am putting a stock '83 L28 into. Have had the intake ported and polished, but that about it, so far. This car will be used for NASA HPDE's, open track days, High Speed AX and still has to be civilized enough for the street (no trailer, have to drive to the track).

So far I have bought a Pacesetter Header with Jet Hot coating. My initial plan was to go with 2 1/2" pipes and end in a turbo muffler. Saw you post and found it intriguing about the tuneability of a Supertrapp.

Did you get to the dyno? I would love to hear your results. From the date of this post, you must have some experience with the system by now. What do you think of it?

Thanks,

Marty

Steve probably won't answere because he's long gone from this site. Mr. McConnell is over at 'West Coast Z Racer' which is a yahoo group site that I occaisionally browse. He's been gone from here since late '04. Couldn't take the crap here is more or less what he says.

Stephen,

Thanks for the heads up. Too bad. It seems like we have been losing a lot of knowlegeable members in the last year or two.

Anybody else have experiece with Supertrapps?

Marty