Up pipe, Down pipe, Exhaust?

[kimokalihi]

I bought a 2K mile TD04 turbo and I'm awaiting it's arrival. Meanwhile I was thinking maybe I should think about the exhaust now.

I was planning on buying a magnaflow or borla hush muffer used on NASIOC but I have yet to find a single one in the last couple weeks. All I see are EVO and STI mufflers. Or full exhausts or catbacks, no mufflers by themselves. Then I was just going to take it to a shop and have them bend me the whole 3" exhaust.

Should I upgrade my up pipe? The car came with a 3" downpipe but I don't know what brand it is. How about a high flow cat?

Any suggestions?

[kimokalihi]

Another question. Should I put a cat on this car or not? Does it need one? I live in a county where they don't do emissions testing.

[kimokalihi]

What do you guys think about this muffler
[/url]http://www.magnaflow.com/02product/shop ... d=7959[url]

$160 shipped ebay or just about any online magnaflow retailer.
http://cgi.ebay.com/ebaymotors/MAGNAFLO ... 0292662727
[/url]

[GeneralDisorder]

I have a catless 3" turbo-back on my 91 SS and it works excelent. It's pretty loud but it has a nice deep tone to it. I can't compare power-wise to the stock stuff as my car came to me with the 3" half-installed on a half-installed engine so I just finished the install of both at the same time. I have been told by other's that it's good for around 10 to 20 HP though as the stock pipes are quite restrictive. I do have the complete stock exhaust in my garage (came with partially assembled car ) and compared to my 3" system it looks tiny and I wouldn't doubt the power increase claims I've read on replacing it.

Don't do anything with the up-pipe or headers. The up-pipe is the same part used on the STi's (identical part) and is capable of handling 300 HP. Aftermarket headers (unless you spend a ton of coin) are largely worse flowing than the stock units and the testing I've seen shows they hurt performance more often than not.

GD

[93forestpearl]

^ For the most part, unless your setup is big enough to actually utilize an aftermarket exhaust manifold. If you are going to replace the manifold, you should go to a twin scroll setup anyways.

[kimokalihi]

What's a twin scroll setup?

[GeneralDisorder]

What's a twin scroll setup?

"Twin Turbo"..... although a scroll compressor is an entirely different beast from a turbo compressor (otherwise known as centrifugal compressor). But scroll compressors aren't used in automotive applications except for possibly some exotic Air Conditioning pumps.

GD

[kimokalihi]

Now I'm really lost. I've never heard of a scroll other than back in history class learning about the egyptians and their papyrus paper.

I'll look it up on google.

[93Leg-c]

You can search NASIOC. Here's a couple of threads:

http://forums.nasioc.com/forums/showthr ... twinscroll See post #15 for hp/tq.

http://forums.nasioc.com/forums/showthr ... twinscroll Pics of new parts.

[kimokalihi]

How did you guys learn so much about this stuff? Was it all on message boards? I spend countless hours on these boards trying to soak up all the info I can but a lot of it is difficult to understand just by reading. It's not my style of learning. I'm hands on. I could pick this stuff up 10X faster if somebody were to explain to me in person what it was or better yet show me everything on the car and learn from doing it.

Too bad I don't know anybody around here who's into building engines.

I'm gonna go cut a hole in my hood for my WRX scoop!

[93Leg-c]

I learn a lot of things by reading but I really like it when I can be shown in person by someone who really knows his stuff.

BTW, twin turbo is not the same as twin scroll. Twin turbo means having two turbos like the jdm twin turbo Legacies. One turbo is a smaller one for quick spool and the second turbo is for higher rpms. There's usually a "hole" in the power band where the smaller turbo is maxed out and before the larger turbo can kick in and pull strong.

Twin scroll is one turbo with the uppipe having two "runners" or pipes. One guy with a twin scroll setup said it's like driving a NA car, meaning no turbo lag but power from almost off-idle. Another guy on NASIOC said he ran mid 12's with the twin scroll setup and exhaust setup only (I don't recall if it was a 2.0 or 2.5 block).

I haven't been looking but does anyone on legacycentral have a twinscroll setup on their ss or TW? I thought I read somewhere that it couldn't be installed on our cars but I don't see why it couldn't be done (just need $$$ and some fabrication, I would think).

[kimokalihi]

I see. Well I didn't get the hole cut out but I'm ready to. It was too loud and it was 1:30 in the morning so I'll do it tomorrow.

Twin turbo is what I've got. The 95 JDM twin turbo motor with VF13 and VF14 turbos. But I'm gonna be using a TD04 with only 2k miles on it. That is, if I can get this motor in and all the hoses and everything hooked up. I'm really don't know where they all go so I hope I can pull it off. Otherwise I'll have to find someone on here locally that can help me out.

[93forestpearl]

How did you guys learn so much about this stuff? Was it all on message boards? I spend countless hours on these boards trying to soak up all the info I can but a lot of it is difficult to understand just by reading. It's not my style of learning. I'm hands on. I could pick this stuff up 10X faster if somebody were to explain to me in person what it was or better yet show me everything on the car and learn from doing it.

Too bad I don't know anybody around here who's into building engines.

I'm gonna go cut a hole in my hood for my WRX scoop!

I've been a car guy for about 15 years, and have learned by doing and some from reading. Message boards can be hit or miss and there often a lot of misinformation out there. The best way is to stretch yourself a bit, because you'll never know if you can do something until you try.

Twin scroll is one turbo with the uppipe having two "runners" or pipes. One guy with a twin scroll setup said it's like driving a NA car, meaning no turbo lag but power from almost off-idle. Another guy on NASIOC said he ran mid 12's with the twin scroll setup and exhaust setup only (I don't recall if it was a 2.0 or 2.5 block).

If it is on a small turbo, it may drive like an N/A car. Twin scroll just cuts down on the lag. Its more helpful on our turbo Subarus since the exhaust manifold is so unequal in length.


Think of it like this. I'm using periods to represent exhaust pulses. This first series is what the stream of pulses is like with the factory exhaust manifold arrangement:

.. .. .. .. .. .. .. .. .. ..

The pulses are grouped together due to how unequal in length the manifold is, and that is why we have the rumble that we do for a four cylinder engine.

When you pair the proper cylinders together, 1-2 and 3-4, have an equal length for the runners, and use a twin-inlet turbo, the pulses hitting the turbine wheel look like this:

. . . . . . . . . . . . . . . .


With the more even distribution of energy hitting the turbine wheel, it will ramp up it's speed faster and require less energy to do so.

I haven't been looking but does anyone on legacycentral have a twinscroll setup on their ss or TW? I thought I read somewhere that it couldn't be installed on our cars but I don't see why it couldn't be done (just need $$$ and some fabrication, I would think).

A friend of mine was running a GT3076 with the twin-scroll .78 A/R exhasut housing. It spooled up a hare before my GT2871R.

He used an eBay manifold that paired the proper cylinders, was pretty much equal length, and ran the two runners right up and combined right before the subaru turbo flange. He just lopped it off and ran the two runners to the turbo.

[93Leg-c]

Dan, good explanation of the exhaust pulses! And you're right about the size of turbo being used on a twinscroll setup too. And, the pics are great!

[RJ93SS]

that makes sense, what would the cost be on that exhaust manifold?

[93forestpearl]

You can find them for $200-300 on eBay usually. Sometimes less if you are dilligent enough about it.

[RJ93SS]

hmmm

[kimokalihi]

Very interesting, thank you.