legacycentral bbs

Alright I've got a 92 turbo and have a couple mods done nothing to major, My next step i was going to do is 3' exhaust all the way back and custom downpipe, but i wanted to do a FMIC very bad as well, what do you think is the better choice and power gain? i was wondering what all you other people have done to your 92 turbos and in what order how much gain in HP you've gotten out of it and baic shit like that, thanks any input would be greatly appreciated and if its a ton of stuff please e-mail me at Subleg4@yahoo.com

Please feel free to use the "search" feature of the board as well as the rest of the internet. Answers to your questions have been covered many times over.

Hate to be a dick, but it's there for a reason.

3" turbo back first for sure, then boost to 11 psi, that will put you in the 210-220 hp. If you want more power then go for a saab 900 or better yet WRX top mount. Then any sort of FCD and boost to 15 psi. This will get you into the 250-260 hp range. Want more power. then you'll need a larger turbo, or a standalone ECU (let you control fuel, timing etc), and fuel system upgrade.

Mark,

I have never failed to be shocked by getting rid of the stock exhaust on a turbo car. Have not done it yet on the Legacy but will soon. You are going to want the exhaust before you can get too much through the FMIC anyway.

LegacyT wrote: Then any sort of FCD and boost to 15 psi. This will get you into the 250-260 hp range.

I think that might be kinda optimistic don't you? I mean 100hp gain from intercooler,exhaust and 6 more pounds of boost?

Yeah, I think he forgot to mention the 100 shot of NOS!

But for me, boost control to 12psi + intercooler transformed the car. Although, I've yet to get my 3" turboback... soon, very soon.

-mike

Buddy here had a 30 hp gain from a stock WRX exhaust to a custom job from tapp auto (cat-less 3"), just turbo back alone, 30 hp. Double the boost ie (15-16 psi max) any more and your blowing hot air, and you will see at least 50 hp. 15 psi will ofcourse need a FCD and an intercooler. Right there your looking at a good 80 hp. So i'm off by 10hp, throw in a cold air that should get you on the money

Mark,

Wow, man, that's amazing. Sounds like my 3" setup is going to have to come a lot sooner than I thought!

Correct mr of im wrong but they nobody makes a downpipe for my car, if they do who? and if not what whould I have to do to get one custom?

You are incorrect. Plenty of people make a downpipe, it's just they market it for the WRX instead of the legacy.

Again, this information is readily available through searching.

Custom exhausts can be done at any exhaust shop worth their weight.

Again, search.

So what your saying is I can use the WRX aftermarket downpipe for my 92 turbo?

yup, any WRX dowpipe will bolt right up. Mind you, your gonna need a system after that to tie it into.

Mark,

cool any sugggestions on pipe size i've heard the bigger the pipe (to an extent) the more HP is that so?

Not to hikack this post or anything, but do any of the WRX downpipes have the O2 sensor bung near the flange, I'm assuming no. So how could one get around this problem?

No problem in hijacking, its not like all this information couldn't be found through google anyway!

http://www.exhaustdepot.net/wrxedphasii3.html
http://www.300zxstore.com/phasiidowwrx.html
http://www.vividracing.com/prod_exdownpipe.php

as you can see, most of these have the o2 bung a little further down the way. If you want to elongate your wiring, you can do it that way, or weld yourself in a new bung. Otherwise, you can get a custom DP made.

Suggestions on pipe diameter:
http://www.majer-tech.com.pl/Exaust_Theory.htm
http://legacycentral.org/library/exhaust.htm
http://legacycentral.org/centric/t_members.htm (see what they've got as suggestions)

JasonGrahn wrote:No problem in hijacking, its not like all this information couldn't be found through google anyway!

Sorry... Thanks for the links

since we're talking exhaust i have a question.my local shop said they can do any custom exhaust i want within reason,but they do not mandrel bend the pipes.is this that big of a deal?you are only as free flowing as your smallest point and i would hate to pay for a 2.75 and get a 2.25 because of poorly bent pipes.any thoughts?

you can buy mandrel bends from Road Race Engineering, piece them together and take them to your local shop to weld them up.

http://www.roadraceengineering.com/eclindex.htm

so it is a big deal and i should go mandrel,or is that just an option for mandrel bent and its not that big of a deal?thanx

There's tons of opinions out there, but since I'm going to keep the car forEVER I want mandrel bent piping. Crush bending pipes makes the diameter smaller where the bend is. Mandrel bending is much more expensive though. Jason's right though, the best and least expensive way to do it would be to purchase the individual bends you need and have them welded up for you.

-Brian

crimp bend (what most local shops use) = fast to make, low quality, "ribs" in the bend cause turbulent airflow, bad for power.

Press bend (better shops use this) = slower to make, no ribs, better then crimp bending

Madrel (the best shops use it) = more expensive then both, slower to make, same diameter through the bend and straights, the best way to make your exhaust.

Madrel is what you'll do if you care for your car.

thanks for the info.i'll have to keep looking for a shop that will do mandrel bends or see if the other shop will weld pieces

Mandrel bends are really nice to cut and weld because you can cut them at any point, and the cross section will mate with straight pipe or another cut piece, as long as the cut is perpendicular to the curve. This means you just need to buy a few U-bends and some straight pipe.

Some people are of the belief that instead of getting (for example) a 2.5" mandrel-bent exhaust, you could just get a 3.5" crush-bent exhaust for much cheaper with similar results. I don't know if that's quite true since the lack of smooth flow might still be a problem (I'm not a fluids engineer).

Well i was talking to an exhaust guy today and he said to put a mandrel bent exhaust on our cars is like pissing away money.he said its mainly for cars with huge power,500hp+,and N/A's.he said it was a common mistake for turbo owners to severly overdo thier exhaust.he said something about na's needing large flow for more power but that a turbo's turbine is pushing out the exhaust so its not good to go big.he said he's done a lot of 3" exhaust on turbos that came in with like a 2" and they lost power.he aslo said that big coffee can mufflers are not good for our cars.he did say that we need a large downpipe,so he suggested a 3" dp to 2.5" back.he says that 2.5 is as big as i should go.i know a lot of you are probably going to disagree and may be right,the only thing that makes me wonder is he is actually trying to talk me out of giving him lots of money.why would he do that unless he truly believes what he is saying?let me know what u r thinking

It's hard to say...

Car stuff is fraught with misguided or incorrect logic. There are a lot of people who were taught stuff that is false or no longer true by others that they considered experts. And, most automotive issues are gray-area tradeoffs rather than clear-cut decisions. Lots of things that are true for one car are untrue for another. Add to that the fact that a lot of the technical information you get is from people trying to sell you one thing or another, and you end up with a mess.

It doesn't sound like this guy is saying mandrel bends don't work, but rather that he's saying you don't need the extra improvement in flow that they would give you.

The old wisdom used to be that you didn't need to worry too much about your intake or exhaust with a turbo. The idea was that the turbocharger could make up for any restrictions or limitations you had elsewhere. This is obviously flawed, as there's more to power than boost. If you can make more power without more boost your engine will last longer and run more efficiently. We've all seen turbocharged cars benefit greatly from free-flow intakes and exhausts.

You have to take anything anybody tells you with a grain of salt. I know mechanics who still believe they need to adjust the idle by turning the throttle stop screw when they do tuneups on late model cars. I know people who would insist that any "performance" spark plugs, wires, or coils are just for show. There exists a large faction of the automotive enthusiast community which still believes fuel injection is a silly idea, and that solid rear axles are the best. Some of these things used to be true or at least generally accepted.

My opinion is that a 2.5" or 3" mandrel-bent exhaust would be great. If you're not going with mandrel bends, 2.5" is too small to be much of an upgrade.