Stainless steel headers, exhausts and JDM twin-pipe mufflers.

[Sean Dezart]

In 2020 I will have been producing performance exhausts for 10 years !

Firstly, I would like to thank all my loyal customers over the years to make this happen and I’ve been rewarded in return by having many of you as friends. I’d also like to thank all those Z-professionals and track, rally and hill-climb competitors who continue, respectively, to sell and exploit my parts !

To celebrate this I’ve produced some exclusive super-goodies which I’m including as gifts* with each 2020 order and so as to be clear :

Silencer, muffler order = free keyring (your choice)

Manifold/header order = free T-shirt (quote size ‘L’ or ‘XL’)

Complete kit = free 10yrs keyring and T-shirt (quote size ‘L’ or ‘XL’)

These items may also be bought seperately with worldwide shipping** included in the prices below :

Keyring 10 yrs : us$11

 Keyring Z profile 50yrs : us$15

 T-shirt 50yrs : us$23 (two sizes only ‘L’ and ‘XL’)

*so long as stocks lasts !

**I will group ship so as to reduce the overall shipping cost. Obviously if bought as an extra and included in an exhaust order, there will be no shipping cost ; so less expensive !

Please contact me via mail (or PM) for any enquiries : seanz@wanadoo.fr

So, Merry Christmas and I wish you all a happy and above all healthy New Year with new Z (and ZX) adventures ! 

[Sean Dezart]

Now available, sizes S, M, L XL and XXL.

[AK260]

Frenchie, I hope you don’t mind me commenting here - happy to delete if you object.

 

Before buying Sean’s full Race / Sport system, I ran the MSA header with 2.5” back to a turbo muffler on both my L26 and it’s replacement hot L28. Due to a shotgun sounding misfire I managed to utterly blow the baffles and Sean very kindly and speedily (at his cost!!) sent me his Classic muffler to help me out of a hole and able to get to an event I really wanted to go to.

 

 

The classic is a straight through (spot the Z I worked hard to get into the pic!! [emoji12])

 

 

I was absolutely jaws on the floor at how much power had previously been left on the table. She now rushed to 6.7k RPMs rather than topping out at 5.6k ish. I like the classic raspy sound of the turbo muffler however this one is deeper and more TVR / V8 burbley. But the system as it was still droned like hell between 2.2-3krpm and was exhausting on the motorway.

 

I then bought Sean’s full race / sport on the same engine and set up. The quality is great.

 

 

Here’s the headers side-by-side for comparison - a very sexy beast!!!

 

 

 

The fit under the car is tight but a near tailored fit. Don’t have a decent photo to show except the one below. At first I was worried about how close to the gearbox it was but NEVER has there been a single clonk even with some serious thrashing on bumpy fast country roads.

 

 

The power at the top end just opened up to another level - I’ve had to add a limit on my 123 ignition at 6.8k rpm as the engine now sprints into the mid to high 7k region and I don’t want to bust something as I’m not running forged pistons and rods. I rarely need to cross 6k - unless I want to really upset an N/A 911 or Impreza STi! ;)

 

The sound is very nicely muted below 3.5ish maybe 3.8k rpm but anything over that is totally grin inducingly vocal! With the windows down and over 6krpm with a barrier or wall on the driver’s side, I dare say it’s a bit of a nascar howl! Absolutely ZERO resonance or drone on the motorway now or where it existed on the old system.

 

Here’s my first drive after fitting (headphones on, sound up) ...

 

 

Here’s a much longer one with some thrashing and some cruising while I was tuning carbs (yes that AFR was all over the place with the wrong needles). The window was slightly open so the iPhone microphone struggled a bit to capture the fullness of the bass in the sound track ...

 

 

My buddy (same orange car as Sean’s pics) with an L26 has the exact same package but with a JDM muffler. Driving our cars back to back was a hoot and showed that on the smaller engine the JDM was louder at the top end than the classic muffler on mine with the bigger engine (he’s running a 275 degree cam I think versus my 270) - a bit raspier on his and bassier on mine. He has a beautifully progressive power band with this set up.

 

 

I did, for personal reasons, want to see if I could make her a little quieter and Sean being a beautiful gentleman (no matter what they say [emoji12]) has kindly sent over the track muffler to test. Sadly I’ve been utterly buried for the last few months and not had a moment to do anything but store it or even to be able to see my car! It’s a straight through but with a much bigger box than the classic so it should be quieter but flow the same. Will report back once I get her on.

 

[grannyknot]

1 hour ago, AK260 said:

Absolutely ZERO resonance or drone on the motorway now or where it existed on the old system.

That's interesting, opening up the system decreased the drone. I have been fighting drone for yrs now and all my efforts seem to do is move it up or down the rpm range.

[AK260]

That's interesting, opening up the system decreased the drone. I have been fighting drone for yrs now and all my efforts seem to do is move it up or down the rpm range.

Well my friend, my original system didn’t have the centre resonator - it was merely 2.5” pipe back from the MSA collector to a Magnaflow turbo box (and later the Z-Story classic muffler) at the back. Apparently this is the classic hot-rod setup that the PO had installed. I merely ceramic coated the lot.

Sounded way louder and more aggressive with delicious popping sounds on the overrun. Sounded very race car like, but alas, the droning drilled into your brain when cruising in 4th/5th between 50-70mph and became unbearable for anything more than 5 mins.

The popping sounds are still there but a lot less anti-social and more like someone remembered to put the lid on the sauce pan while making popcorn. On the old system and with the L26 she would even shoot out a two foot yellow flame when coming off the power at 6k RPM! Scared the b’jeezez out of me and impressed the driver of the TR6 following! ;)

I know little about exhaust design but I would say that Sean’s centre resonator and it’s position along the system greatly eliminates the drone. I believe it has a lot to do with the length from the collector to the tip of the muffler and the frequency of the reflected waves along the length of the line. The expansion in the resonator takes the energy out of it and the position changes the standing wave frequency (or something like that). Also, the whole thing essentially being a wind instrument means that changing the primary diameter and lengths + change of metal type from mild to stainless steel is likely to change the frequency characteristics yet again.

I imagine Sean has been experimenting with getting it all to work together as a system.

[Sean Dezart]

16 hours ago, grannyknot said:

That's interesting, opening up the system decreased the drone. I have been fighting drone for yrs now and all my efforts seem to do is move it up or down the rpm range.

Exhaust drone, anyone can google it to know the cause but it IS sound freqencies not only from the exhaust but combining with tire noise vibrating up through the chassis too. This is why it's only heard/felt at highway speeds. The simple addition of a resonator eliminates this by allowing the gas to expand therefore altering the freqencies. But a resonator does much more. Not only does it curb the dBs leaving the rear (still plenty loud if wished !) but it encourages exhaust chamber scavenging (again, please Google it) to help release more torque and power. Alis' swap to my Race-Sport header obviously helped enormously combined with the 2x secondary pipes becomming 1x as far back as possible (the rear of the gearbox in fact) so as to prevent any suck-back of exhaust gases up the pipes again towards the head.

Each cylinder sends gas pulses down the primary pipes and behind these pulses are vacuums that help suck out the next detonation point gases and so on and so on. These pulses are to be encouraged and therefore the exhaust gases to be stablised -  whilst not losing any gas velocity.....so not too big a diameter pipe, not too small with room to expand just after the 6 become 2x3 which become 2 and finally join to 1x.

What surprises me is that MSA and before them d*** Barbour (perhaps others) have been selling these straight-tru pipes for decades telling people that they're performacne exhausts when in fact they're just the cheapest mock-ups they can find to sell on !

The 6-1 header is particulary awful at producing exhaust drone and killing any power gains an attenttive owner might have invested in his engine......so long as it's noisy - the client will feel fast and be happy. Just like sticking on a cherry-bomb muffler to a 50cc m-bike and feeling like Evel Knievel....

hot damn - is that his Z ? https://www.banpei.net/2009/04/07/popular-bosozoku-cars-nissan-fairlady-s30

[240260280]

I recall the drone in my MSA "Turbo" 2.5" exhaust  to be max ~ 2400 rpm.

The straight pipe from the header to the bend at the rear axle would be ~ 2.1m. 

This would be ~ 60Hz from 6 sources at an average exhaust gas temp of 300C

 

 

[Sean Dezart]

Latest exhaust batch - Spring 2020

 My latest batch has arrived and shipping has begun for paid-up orders. If you have reserved parts with a deposit, I invite you to complete your payment so I may also ship yours.

 I'm very satisfied with my new header flange allowing easier fitting and tightening against the engine head plus larger porting for better performance. Lastly, it's lighter - saving nearly 1/2 kilo (1.1lbs) !

 Don't forget when ordering that now I stock new valve-cover bolts and inlet/outlet stud kits - both in stainless steel, reasonably priced.

 I also offer a choice between two gasket versions : Stock ‘A’ for carbs and Efi ‘B’ with injection cut-outs – please specify which when ordering

[S30Driver]

Any news on the availability of the downpipe for those of us who have opted to keep the stock manifold and not go with headers at this time?

[Jason240z]

how many hundreds have you sold now Sean?  Thats a lot of boxes!