Exhaust restrictor on a N/A car - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


General Miata Chat A place to talk about anything Miata

Reply
 
 
 
LinkBack Thread Tools
Old 03-05-2014, 07:07 PM   #1
Junior Member
Thread Starter
 
Join Date: Jan 2014
Location: Tulsa, OK
Posts: 46
Total Cats: 4
Default Exhaust restrictor on a N/A car

So I just got a 1.8 into my 91, between the donor chassis and my car I was able to cobble together a continuous piece of pipe, but that's about all I can say for it. The cat's internals were fractured and fell out all when I took it off, the stock muffler is full of it's own rusted out guts and the rest is a patch work of pipe, but the bastard runs again!

I'm working on piecing together a DIY turbo, but in the meantime I need an exhaust so i don't sound like I a civic with a test pipe.

Can I go ahead an build a 3" exhaust so that I'm set when I turbo it and run a 2.25" restrictor at the header/cat coupler? I've seen it used to fix boost creep, but this is stock and I need to maintain back pressure. Will a single plate be enough or a couple waste of time? I don't want to buy resonator/mufflers twice.
jj1000 is offline   Reply With Quote
Old 03-05-2014, 07:28 PM   #2
Elite Member
iTrader: (1)
 
Leafy's Avatar
 
Join Date: Jun 2012
Location: NH
Posts: 9,093
Total Cats: 90
Default

Back pressure is the enemy always. Velocity is what most mistake for backpressure. In other words. The 3 inch without the restrictor will make more power and torque everywhere than the restrictored exhaust.
Leafy is offline   Reply With Quote
Old 03-05-2014, 08:10 PM   #3
Cpt. Slow
iTrader: (25)
 
curly's Avatar
 
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 12,110
Total Cats: 518
Default

I think he means for pre-turbo. To keep sound and riceness to a minimum.
curly is offline   Reply With Quote
Old 03-05-2014, 08:16 PM   #4
Junior Member
Thread Starter
 
Join Date: Jan 2014
Location: Tulsa, OK
Posts: 46
Total Cats: 4
Default

Quote:
Originally Posted by curly View Post
I think he means for pre-turbo. To keep sound and riceness to a minimum.
This. I was reading about spec miata exhausts and they said that 2.25 was a good spot for hp/tq naturally aspirated.

I only want to do this once though, that's why I'm hoping I can do a 3" and make due while I collect parts. I just had to run to walmart and the sound makes me cringe so I have to do something about it soon.
jj1000 is offline   Reply With Quote
Old 03-05-2014, 09:56 PM   #5
Senior Member
iTrader: (3)
 
Join Date: Dec 2008
Location: KY
Posts: 700
Total Cats: 51
Default

Leafy is right. Smaller pipe is good for N/A because it keeps exhaust velocity high for the full length of the exhaust and helps cylinder scavenging. Putting a restrictor in won't create the same effect, since exhaust velocity is still going to drop immediately after the restrictor. Just build your 3" exhaust and run it without a restrictor.
jpreston is offline   Reply With Quote
Old 03-05-2014, 10:10 PM   #6
Junior Member
Thread Starter
 
Join Date: Jan 2014
Location: Tulsa, OK
Posts: 46
Total Cats: 4
Default

ok I see what leafy is saying. Im just going to use some stuff I have laying around and make it work until I can utilize a full 3" system.
jj1000 is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
elesjuan's mediocre 95 Miata adventure (google fiber edition) elesjuan Build Threads 8 02-16-2016 09:36 PM
Turbo 1995 Miata Low mileage Clean Tekel Cars for sale/trade 29 02-05-2016 05:16 PM
FS/FT: 03.5 Mazdaspeed Protege leatherface24 Cars for sale/trade 15 10-16-2015 12:35 PM
Anything To Gain from Using Piggyback on N/A car? 2000SE ECUs and Tuning 5 09-08-2015 12:30 PM
New here, saying hi, here's what I'm workin with. SuperSneakySecretSquirrel Meet and Greet 5 09-06-2015 09:30 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 08:31 AM.