Miata custom exhaust

I think I need another advice guys. The car in question is a '94 1.8 Miata. Since I've now bought an RB manifold the remaining part of the exhaust needs addressing too. The car is mainly used on tracks and what I want to achieve is minimum restriction and minimum weight. Noise is less important, but of course a nice and not too loud tone is better than a fart cannon sound. Off the shelf systems seem to be good for noise and restriction, but not so for weight.

I'm thinking of different ways to make it and would like to hear your thoughts about them.

A couple of notes:

I believe that RB manifold internal diameter is 60mm so I will use the same diameter stainless piping for the rest of the system. No catalyser will be used. The car is naturally aspirated.

To better explain my questions I've made this fantastic diagram with different parts marked with A, B and C (plese ignore the yellow marks).

Option 1:

A - a straight-through muffler like this one

B - straight pipe

C - straight pipe

Option 2:

the same as (1) but with an additional small diameter straight through resonator at B or before A.

Option 3:

A - a straight-through muffler like this one

B - straight pipe

C - a boy racer style muffler similar to this

Option 4:

A - small diameter straight through resonator

B - straight pipe

C - a straight-through muffler like this one

Options 1 and 4 would be the lightest but I'm concerned they will be too loud as in too loud even for track.

Check out spec Miata exhausts. They're not terribly loud and pretty lightweight.

http://www.mandrelbendingsolutions.com/servlet/the-822/1999,-2000,-2001,-2002,/Detail

I personally can't stand the rasp of the typical SM exhaust. Considering this one as an alternative.

Get a bunch of resonators instead of straight pipes and maybe a straight through muffler if it is still too loud. Maybe a side exit at point "B" if you can get away without a full sized muffler

And or run a little larger diameter exhaust for most of the length of the exhaust and narrow it at the exit to whatever diameter the motor does best with. I think that could help with flow and sound

Spec Miata exhausts seem to do right what I want from my exhaust, thanks! I've checked a couple of videos on youtube showing how SM sounds and it isn't too bad. Single muffler center exit it will be then.

I am also exhaust shopping for my 95 miata.
I need to keep the converter though.

So far I have been leaning towards the Flowmaster Hushpower 819110 system for $309

I want something streetable that can make sound for bigger SCCA SOLO events.

Aparrently it weights less than 20lbs.

Really open to other options, that mandrelbendingsolutions system looks good, other than deleting the converter.

DaveEstey wrote: Check out spec Miata exhausts. They're not terribly loud and pretty lightweight.

That's complete opposite of everything I've read and hear (they are lightweight though)

OP, look into an ENthuza exhaust for your car.

I have an MBS exhaust on my '97 Miata. It's the one they used to create their pattern. As quiet as any exhaust at idle (got out of sticker that way recently), though it is a bit loud under load. Still, I recommend it.

MattGent wrote: http://www.mandrelbendingsolutions.com/servlet/the-822/1999,-2000,-2001,-2002,/Detail I personally can't stand the rasp of the typical SM exhaust. Considering this one as an alternative.

MBS is great to work with. Local to me. Good folks (owner is a FWD VW drag racer, so he would fit in here).

so just how loud is this compared to something like the springfield dyno SM exhaust. their video makes it seem pretty loud still

The Spec Miata Springfield Dyno exhaust is LOUD and obnoxious. Not streetable. However, it is a good starting point for a semi custom job. Most of us have a local race shop add a second muffler at the rear of the car when we visit tracks with lower sound restrictions.

Find yourself a local Spec Miata shop and they can probably fab the rear part pretty ea$ily for not too much $

http://www.saferacer.com/springfield-dyno-spec-miata-exhaust

I've been curious about that Mandrel Bent Solutions exhaust but don't know anyone running it nor have I seen dynos but its probably not too different HP wise from the SD exhaust.

I've always wanted to incorporate a dirtbike style baffle into a car exhaust. Weight savings and quieter than straight piping.

I drove a truck to the muffler shop today with a hot rodder special steel wool packed headers. He was like high five, no tickets for you. I coiled up a piece of wire in a spiral then fed it into the exhaust leaving about a 8in straight piece bending the end over the lip of pipe. Then packed it with steel wool. Put door screen over it and hose clamped it to get it to the shop 40 miles away.

If that works I'm convinced about any kind of baffle will work to tone one down.

There are a couple Spec Miata exhausts out there that advertise being able to meet the 90 db Laguna Seca sound limit without losing power -- if you want quiet then that's probably not a bad place to look. These guys list one for a 1.6, dunno if they have a 1.8 version or not.

http://www.hartzelautomotive.com/racing.asp?sSection=racing&sPage=spec

How is the mbs on the highway? ~4000 rpm constant load 80 mph ?

MattGent wrote: How is the mbs on the highway? ~4000 rpm constant load 80 mph ?

Dont want to derail the thread but ... did you go to FAU and drove a black Talon TSI?

J

MattGent wrote: http://www.mandrelbendingsolutions.com/servlet/the-822/1999,-2000,-2001,-2002,/Detail I personally can't stand the rasp of the typical SM exhaust. Considering this one as an alternative.

Update: blew the transmission in my car, as part of repair I figured I'd have the exhaust out so might as well replace it. Had also burned up the cat when a coil went bad.

Went for a Raceland header and the MBS exhaust. The MBS is a quality piece. Fit great, good looking welds, includes 2nd O2 bung, and hardware & gasket for the front flange. Bolted right up to the Raceland. It is not a polished show-car exhaust but that isn't what I was looking for. It does fit with a hidden hitch receiver as well.

The raceland header EGR fitting still doesn't quite line up correctly (as claimed in more recent reviews) but I was able to get it in with a minor squabble.

It is about as loud as I could bear on the street. My car is no longer a daily driver. It has little to no raspiness, but a deep loud grunt. On the highway, it is reasonably loud under steady-state at 70-80 / 4-4500rpm, and really pipes up if you tip in the throttle at all. It sounds entirely appropriate at the track, and made the track night feel like more of a racing experience. I'd like to say it feels a bit faster but hard to say with the butt dyno, the car is still slow in a straight line. I probably wouldn't want to daily with this exhaust, at least for the highway.

Overall for $160/header and $260/exhaust, around $500 after shipping, its a good value that won't give me a headache. If I get a few free minutes will snap some pics and video.

SpecMiatas are the only cars that I've heard at the track that I'd want a set of ear plugs.

They are light, but usually loud.

You will want a muffler and a resonator. Also exiting past the limits of the car with a turn down will help reduce drone and diffuse sound.

Future data point: My Racing Beat header and Hytech exhaust weigh 29lbs combined.

I somewhat doubt it'll be quiet, though.

turboswede wrote: SpecMiatas are the only cars that I've heard at the track that I'd want a set of ear plugs.

Many (most?) of them use the Springfield Dyno exhaust. This MBS one is much more mellow than that. It has a larger muffler, but does not include a separate resonator.

I would add anything with a rotary, and F500, to your earplug list.

MattGent wrote:

turboswede wrote: SpecMiatas are the only cars that I've heard at the track that I'd want a set of ear plugs.

Many (most?) of them use the Springfield Dyno exhaust. This MBS one is much more mellow than that. It has a larger muffler, but does not include a separate resonator. I would add anything with a rotary, and F500, to your earplug list.

Obviously it depends on the event/location. Growing up with an Uncle and his PP GT3 RX-3, i appreciate a nicely built rotary :)

When you're following a Spec Miata on track, you can tell exactly what they're doing with the throttle at all times even if you're wearing a Peltor with soundproofing. It's not going to land on my list of "best exhaust sounds". I'd be wearing earplugs.

Personally, I'd take another 15 lbs to make the car sound good. The weight's in a good place and a loud/nasty exhaust will really affect the way you feel about the car.