[P0knfp]

Yeah, I was wondering, would anyone happen to know the size of the piping to da muffler of an NA Supra? Is it 2 1/2 or 2 1/4? Cuz I want to get an aftermarket exhaust. Just a universal exhaust for now. But im also wondering which is better to do. A straight pipe to da exhaust and taking out the two resonators or leaving them on and just change the muffler. Which would any of you guys recommend. I also dont want my car to be hella loud.
Thanks

 

[Yonaga]

It's 65mm, which is 2.55 inches. A 2.5 inch generic should fit because the boltholes are almost invariably elongated on after-market products. If you live in California, you might want to check into smog and noise regulations before you do too much.

 

[BlackSupra93]

if the piping sizes are different how do they match up> i wanna put a super drager on my na...will that just bolt up?

Bob

 

[Yonaga]

I think the Drager is 85mm. This will attach to the back of your cat, or "test pipe" if you remove the cat. The Drager will be a lot bigger than the stock header and cat setup. You can get a turbo cat with 76mm openings vs the NA's 65, but even this is not as big as the Drager. The Drager will definitely be louder, but I am not certain it will result in much more power than an 65mm NA exhaust. I think the Drager will bolt on all right, because as I said the holes on the attachment flanges are elongated for just this contingency. You will need to center the gaskets: you may want to use O-ring copper, to get a good seal.

Contrary to popular misconception, you don't need any backpressure to run the engine; but if you put an exhaust on (everyone who is not running on a track has some kind of exhaust) you have to consider the flow of the gasses through the piping. There is a value known as the Reynolds number which applies to all fluids flowing in a pipe; I am familiar with this for water flow through sewers. Basically there is an optimum pipe size to minimize turbulance and maximize throughput. Because the calculation is cumbersome for exhausts with bends and different sizes, the best "advice" is don't do too much to disturb the flow. Consequently, I don't think you will get much HP advantage unless you increase the size of the entire exhaust, including tuning the headers. But it will be louder.

 

[*wishlist*supraTT]

drager 2 is 85mm and drager is 95mm... i have a little question about this that was never answered on the other thread... i am wondering about the piping... the stock exhaust has 2 pipes that join at the muffler... many of the turbo exhausts have just one large pipe, some straighter than others... i got the drager 2 which is one 85mm pipe... what is the reason for the stock exhaust being the way it is (2 pipes)? and does one larger pipe give the same effect as the 2 pipes?

 

[Yonaga]

I don't know why Toyota ran the two cast-iron extension pipes off the mainfold. Since Toyota "wrap" the pipes in insulation, I can only guess this provides some "header-type" harmonic tuning. I think on the stock turbo the gas runs through a single cat, so the downpipe is a replacement for that. The gas is already combined to get past the turbo's blades so splitting it again in any meaningful (harmonic) way might be difficult.

I think since there are twin pipes on the NA, there must be a reason, or big-T would have used a single pipe which would have been cheaper to cast.

 

[ThomsonCharm]

I remeber hearing or reading somewhere that they did that because it gave the effect of dual exhaust without having to have two mufflers and that is also why the stock outlet is so huge compared to many other cars. Dont know if this is true or not but i remember hearing it somewhere.

Later

 

[Yonaga]

You could talk me into it. We should also consider that the NA fires the cylinders one at a time, and the turbo fires them in pairs: there is not as much volume of exhaust coming down the pipe(s) at once. I wonder if NA-->T find they get more or less spooling because they are still running off the NA distributor? Maybe I'll start a new subject

 

[*wishlist*supraTT]

i hear that the na-t spools faster than the tt. not sure of the truth of it though.