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Author Topic: Exhaust downpipe rules compliance
Aaron Bailey
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Year : 1990
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We are in the process of finishing up our 1.6 and the one thing holding us up is the exhaust downpipe. The current one off the car had the mounting flange cut off for an aftermarket catalytic converter. We are wondering if it would be rules compliant to mount to this with a slip fit or if we need to find another downpipe with the flange on it. If anyone can help that would be great!

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Aaron Bailey
#15 Spec Miata
http://www.aaronbaileyracing.com

cam Verified Driver
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Related question, the flange on my downpipe is slighly warped, thus causing an minor exhaust leak. Is this repairable? Can I just cut the flange off and use a slip fitting of something like that?

TIA for your feedback

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Blake Clements Verified Driver Series Champ
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Guys, I wouldn't do it. It may not be legal/illegal, but many times downpipes are checked in tech for modified welds, ground welds, etc.

--------------------
Blake Clements

PhillipsRacePrep/SP Induction Systems/East Street Racing/MiataCage.com/Carbotech/WBR Graphics

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Aaron Bailey
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In that case, does anyone in SFR have a stock downpipe they would be willing to give up? PM me if you do!

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Aaron Bailey
#15 Spec Miata
http://www.aaronbaileyracing.com

Mike C Verified Driver Made Donation to Website
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It must be stock. You cannot cut or alter.

They rust like crazy and are brittle from the factory. They are cheap enough to buy new.

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Mike Collins
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d mathias Verified Driver Made Donation to Website
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Mazdaspeed sells them. (Mr. Collins beat me to it)

OPM AUTOSPORTS INC Verified Driver Made Donation to Website
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There is no performance advantage but you can in no way modify the downpipe. They are cheap and used ones are easy to come by.

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-Tom Fowler-
OPM Autosports / SMAC MEMBER
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TimBuck Verified Driver Made Donation to Website
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Rust? what's that?

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Tim Buck

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Mike C Verified Driver Made Donation to Website
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quote:
Originally posted by TimBuck:
Rust? what's that?

Its an east coast thing

You wouldn't understand

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Mike Collins
MEATHEAD Racing
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W. Bonsell
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Somewhat of a related question....what is the deal with the heat shield. Mine keeps rattling like crazy. I have had it welded once and it is loose again. Must it be retained or can it be removed. And is its' purpose to protect the starter from excessive heat?

Thanks
-------------------
Bill (WA)

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William Bonsell
SCCA/ICSCC #26
SM/ITA

Jerry Cabe Verified Driver Made Donation to Website
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I'm reasonably sure that there are several individuals out there that have dozens of downpipes from when they were flowing them looking for that little advantage. [Big Grin]

Just keep asking.

Jerry

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Just driving SM until the F-1 car is ready.

tony senese Verified Driver
Phew, that was close!

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The heat shield can be removed. Up here where I live, the rust usually removes it for you. I had the same problem you did, and the first time I removed the tranny, I removed the heat shield.


12.6 Exhaust System The stock down pipe must be used. However any single exhaust pipe may be used, providing that it has a maximum outside diameter of 2.25 inches (+ 0.0625 tolerance). The stock muffler may be retained, discarded, or replaced with any other muffler, providing that it serves no otherpurpose than to quiet the exhaust. All exhaust must exit aft of the rear sub-frame. Stock exhaust heat shielding may be removed.

--------------------
Tony Senese
SM#99
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davew Verified Driver Made Donation to Website
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Do not remove the heat shield. It may be legal but you will cook your right foot without it. Use a simple radiator hose clamp around the pipe where the welds are broken. Fixes the buzz without baking your toes
Dave

--------------------
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Rich Verified Driver
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What dave said. Spend some pennies and buy a new one from Mazda and they come with the shield on them. I had one with no shield for a while and got 2nd degree burns on my foot from it, even with reflective tape and insulation in the footwell.

A slip fit isn't legal, it needs to be the factory part in its entirety.

--------------------
Rich Wiese

Spec Wrecker Ford

Sphinx Verified Driver
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quote:
Originally posted by davew:
Do not remove the heat shield. It may be legal but you will cook your right foot without it. Use a simple radiator hose clamp around the pipe where the welds are broken. Fixes the buzz without baking your toes
Dave

+1 Ask me how I know? Car i have was missing its heatshield when I bought it. Cooked my foot the first qualifying session in the heat.

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Sphinx Racing
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Sphinx Verified Driver
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quote:
Originally posted by Rich:
What dave said. Spend some pennies and buy a new one from Mazda and they come with the shield on them. I had one with no shield for a while and got 2nd degree burns on my foot from it, even with reflective tape and insulation in the footwell.


LOL! Exact same experience, reflective tape and burns! Yea, I can laugh about it now.... [Smile]

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tony senese Verified Driver
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I guess I must be going to slow to heat up my foot.....

--------------------
Tony Senese
SM#99
2008 NASA-NE SM Champion
NASA-NE SM Director
2008 PRO-IT SM 3rd place
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andrew_anderson
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maybe asbestos shoes?

--------------------
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Rich Verified Driver
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quote:
Originally posted by andrew_anderson:
maybe asbestos shoes?

Shoes just keep you from catching on fire, they still transfer plenty of heat.

--------------------
Rich Wiese

Spec Wrecker Ford

Drago Verified Driver Made Donation to Website Series Champ
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I had the value pipe on my 94 and w/o doubt your foot will not make it less the heat shield of some sort... If the intimidating corners dont get your foot off the gas pedal, the heat will. I remember it being so bad I would push gas pedal with my left foot on straights. [nope]

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Jim Drago
East Street Auto Salvage
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EAST STREET RACING

cam Verified Driver
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Instead of starting a new thread, thought it better to add to this one.

Does the stock narrow band air/fuel ratio need to be connected for the car the run properly at the track? I know it affect street/low speed driving but how about those times when we are not WOT (hence not in close loop mode) at the track?

Since I just ordered a new stock downpipe, will I need to weld in a new threaded port for the wide band or can I just use the factory header port and toss the factory narrow band?

TIA

[ 11-24-2008, 02:37 PM: Message edited by: cam ]

--------------------
"The problem with Socialism is that you eventually run out of other people's money."
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Rye
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I don't believe that you can legally alter the downpipe anyways, so I would install your wideband bung further down stream.

Richard

JD Morris Verified Driver Made Donation to Website
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Cam-

I'm pretty sure a new Mazda downpipe has an additional O2 bung in it so you'll be all set. I installed a wideband in my car and ran without the narrowband sensor in testing and the car is unruly when you're going between off and on throttle, even if you attempt to avoid maintenance throttle altogether (which doesn't work well, at all).

JD

hoverducky Verified Driver Made Donation to Website
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You can legally add a bung to the downpipe for a wideband sensor. Instrumentation is free.

Now whether or not it is legal to have the bung welded in and plugged when you aren't running the sensor is an interesting question...

For that matter is my installed-but-not-yet-wired temp sensor legal?

Scott

GROOTS
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Does anyone know the answer to this question. Can I run the INNOVATE air/fuel sensor in my car in a race. And can we install the bung in the downpipe. How far into the pipe should the sensor protrude ??

--------------------
JEFF GRUTER
SM #48
EXCELL MOTORSPORTS
PARAMOUNT TOOL & EQUIPTMENT http://www.ptetool.com/

pat slattery Verified Driver Made Donation to Website
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Mazda sells a down pipe with a second 02 sensor bung installed. Works great.

Pat

--------------------
keeping the faith for the 1.6

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Muda Verified Driver Made Donation to Website
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Jeff, since my LC-1 is in there I won't protest you.

Vick or Tony might. [Smile]

--------------------
Muda Motorsports
"We're all here 'cause we're not all there."

breathesfire Verified Driver
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quote:
Originally posted by pat slattery:
Mazda sells a down pipe with a second 02 sensor bung installed. Works great.

Pat

I assume this is a downpipe from an OBDII car? What years are compatible with the 1.6?

Thanks,
Pete Maerz

pat slattery Verified Driver Made Donation to Website
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Its legal on 1.6 also.

Pat

--------------------
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johnh23
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this might be a stupid question but i just bought a springfeild dyno exsaust do you have to get a new downpipe for the rear o2 sensor or can you leave it out

David Dewhurst
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GCR - 538 Point 3.

The post catalytic converter oxygen sensor may be disabled, replaced, relocated, or removed:

--------------------
Have Fun [Wink]

David Dewhurst
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johnh23
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im trying to install my exsaust and it is on a angle does the new downpipes compensate for that or do i have to move pipes around to make it fit

JIM DANIELS
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quote:
Originally posted by johnh23:
im trying to install my exsaust and it is on a angle does the new downpipes compensate for that or do i have to move pipes around to make it fit

Should bolt right up.

Assuming you do not have a CA emissions car, it will bolt right up.

johnh23
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IT JUST SEEMS TO BE ON A ANGLE AND HITTING THE TRANS TUNNLE

Rob Burgoon Verified Driver
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quote:
Originally posted by johnh23:
IT JUST SEEMS TO BE ON A ANGLE AND HITTING THE TRANS TUNNLE

Welcome to the club. Make sure your motor mounts are intact and then take it to a shop and have it rewelded at the correct angle. My springfield dyno exhaust had the same "not even close" fit.

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Bellwilliam Verified Driver
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+1 here. SD exhaust "not even close fit" club.

Keith in WA Verified Driver Made Donation to Website
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I found I could get SD to go from not fitting well at all to dead on. It doesn't appear to work for everyone but I found a lot of variability with the way I could get it pointed too far up, down, right, left or just right with some patience by just twisting and giggling (the exhaust that is).

--------------------
Keith Novak
(Will work for tires)

Motor City Hamilton
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Same here. SD exhaust angle was way off. The explanation I received is that there seem to be a couple of different down pipe angles from the same Mazda part number on the 94-97s. Some cars it will bolt right up and others it won't. SD said they were considering selling a unit with the front flange tossed in the box for your local shop to weld up. They sent me a new flange and I had a local shop line it up.

johnh23
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Yes i got a new flange in the box with the exsaust i guess i have to realine it myself to make it work thanks guys

   

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