Designing my own NA exhaust - project.

[synXero]

Decided I'm unlikely to be able to bag myself a TRD or similar exhaust within the next few weeks... So I'm going custom.

Not being one to waste an opportunity I've taken on a bit of a design role. I'm presenting two options. Firstly a very replica twin exit TRD looking exhaust, as the more plausible and easy dome back up:




Second a more interesting and unusual exhaust, that I know you will give me hell for.


The idea is a split backbox, quad exit active exhaust that kicks in under WOT. This should avoid most motorway drone, give a dynamic effect, and personally I feel it's a nod to the tech of the beams engine. I'll be aiming for that mechanical howl that the E92 has from its splendid V8, and though it won't be anything like it from. 4cyl, it's going to be fun seeing what I get.

Many more sketches and such to be done. Consider this a project.

[thomp1983]

my powerflow exhuast is twin silencer boxes with single chrome tips ill grab you a picture later ive been looking into the cost of replacing the boxes as the link pipe between the two is breaking and i may just replace the boxes instead of rewelding the one, the boxes in aluminised mild steel (dark satin finish) are about £50 or about £80 in stainless so not too pricey, you may be surprised how much chrome finishers are though

chris

[dan4]

I think you are wasting your time?

The TRD one looks stock with different tail ends and the split box idea im sure ive seen on ebay. Its going to sound the same as any other na mr2...

[synXero]

Doesn't mean it won't be a laugh. I need a new exhaust anyway, and I don't want eBay build quality or predictability. I don't want boomy or droney or raspy either. Custom it is.

[MR2O12]

I read reviews saying the beams has a distinctive noise.. so should sound great!

[RikH77]

i think a decat will take away alot of the "note" anyway and sound boomy regardless of engine 2-4k revs

in terms of the TRD have a look at my thread as it just looks like the rolled mongoose i have but with satin back box chamber.

custom single exit i had a quote of 350 for one fabricated from zorstec in W Yorkshire

[Ryan S]

stick with it man, the problem i think you may have is that, no matter what you come up with, it will most likely have been done before

i'd try and look at as many exhausts as you can, the other thing is, you've no idea what it's going to sound like until it's finished.

let us know how you get on, watching this with interest

[Donato]

Look forward to seeing the progress!

Hope you get exactly what your after or other wise there wouldn't be any point in going custom.

Is it worth getting a price for it first? If it does come astronomically dear, then maybe you could get a brand new TRD exhaust?

Good luck!

[priusmr2]

I'm developing my own exhaust. I bought a cheap ss system from ebay with 76mm pipes. I put in some silencers at the end to reduce the low noise. Now my brother is welding 76mm pipes into a 300 catalist because it is a decat and without a catalist it does not go throught the dutch MOT. the 200 standard catalist will not fit because it is way to long and the replacement is only 200mm long. I hope i can show you the pics as soon as it is put under the car.

[Rosssco]

Just take it to a good exhaust fabricator and tell the what style and type of sound you are looking for and let them make something for you. AAS in Newcastle have a good reputation with some of the Twobrutal guys at making very good quality systems exactly to the owners tastes.

If you've ever seen inside the rear silencer section, you'll notice it's a combination of different pipe lengths, baffles, chambers and sound absorbing materials, so exhaust flow is not as simple as purely in and out of exhaust gases.

[thomp1983]

here's a couple of pictures of mine, there not great as it's currently in bits whilst im fitting my v6 engine.





here are the boxes im thinking about using to replace the 2 pictured,

http://www.ebay.co.uk/itm/Jetex-Univers ... 43aa162084

i know from using a jetex setup on a redtop nova that the sound won't be 2 different to the current powerflow boxes, if anything it'll be a touch quieter but as it'll now be attached to a v6 and not my original n/a engine that's probably not a bad thing

chris

[Loque]

Like the idea.

[synXero]

Thanks.

Thomp - looks really interesting man. Those boxes are a bit grotty! Get the, polished pronto!

I have a price and its within the realms of acceptability to me, in return for a project where I get to specify what I want. Plus if it all falls through and is too ambitious, I'm happy to go with a TRD style replica, as I can't find the real thing

[Herts66]

You probably know all this already but the exhaust gases will take the easiest route or shortest path put so you need to balance the lengths and pressures in a twin/quad outlet system.
Also silencers generally work by obstructing flow by baffles or in line attenuation on straight through silencers. This adds back pressure or resistance to flow and absorbs power. Bends also absorb power and silence.
Aim for smooth flowing design with minimal bends (like the 180 off the cat) and any bends should be mandrel bent to preserve pipe diameter rather than kinked.
A good exhaust fabricator will help with his experience of what is appropriate and tweak the final version.
Think about how you will control your active part and what it achieves. If it doesn't shorten the route or relieve pressure the effect is probably nowt.
Sound like a great project though.

[4ndee]

+1 id be tempted to remove the cat and go stright into the box from the centre pipe but obviously it will be louder.
I woiuld try go into the centre link pipe of the back box and it would brance into each side then have a dual tip

[4ndee]

[Herts66]

Yep - then starting to look just like a turbo mongoose or japspeed apart fro the 'T' being more restrictive than a 'Y'.

Maybe the active part could by pass the silencers altogether?

[synXero]

Been looking into active systems and also inner structure of a silencer. I'm an architect in training so this is so up my street!

I'm definitely sold on the visual of the quad exit IF I can get nice proportion. Set about some measurement today in the p1$$ing rain... 1100mm between stock exits, silencer is 800mm wide and at least 200mm tall, depth tbc. It'll be a precise art getting the look right with the curves kept gentle.

Taken on board the points about Y over T, and equal length exits for pressure balance and optimisation. Ill be into the realm of scale drawing soon and back with a new proposal!

Been thinking about practical ways to move the weight inboard, to aid general mr2 weight dynamics. It's such a short system though, it's hard to get any realistic looking benefit.

[dan4]

Active exhaust and worrying about weight are you seriously worried that much about it, you will probably end up with something worse than the stock system

Why not just get a stock system if you like the sound and remanufacture the tail pipes to suit?

[Herts66]

I think you will struggle with space to build in two active outlets and two norms and two active ports will be extra heavy and extra complex.
A two tailpipe system with one silenced and one active (silencer by pass) would be much simpler?