Exhaust help

Thanks for helping me out to buy tires, I solved that problem. Im not really looking for an exhaust, im just curious about some things since i am not very knowledgable with exhausts and it doesnt hurt to learn more.

I wanted to know what the lightest metal an exhaust can be made out of and does the material have any affect on gains?

Also Would having no muffler affect anything besides the noise?

Obviously these questions are more for anyone with F/I experience so share some knowledge

i doubt having a exhaust made out of light weight material will affect it's performance since the air flow will encounter the same resistance...it's the type of exhaust that makes a difference...the only thing you'd gain with a lightweight exhaust is weight reduction

i doubt having a exhaust made out of light weight material will affect it's performance since the air flow will encounter the same resistance...it's the type of exhaust that makes a difference...the only thing you'd gain with a lightweight exhaust is weight reduction


well that i already knew, how about the muffler part? does it affect performance to go without a muffler?

A muffler is just that... a muffler... it muffles sound so you don't hear the resonance of the engine's output. I've always heard that on FI cars no exhaust at all is best.

The lightest material would be titanium. But like Blu said it would only really serve for weight reduction. I only have seen one person go the titanium route. That was Emil from Slovenia with his low 13 second 4g civic. He had an exhaust custom made by DeVito that was titanium with mandrel bends with a removable muffler section for track days. Stainless steel would be be high quality and probably outlast the car. Alumnized piping works well and can be found at most muffler shops if you decide to go the custom route.

cools, i know for my car if i was to do an exhaust it would be a turbo back exhaust and i would probably get rid of the cat, besides the whole it's bad for the environment thing is there a difference in power between no cat and a hi-flow cat? Or is the difference very minimal that it wouldnt matter either way?

No cats or mufflers = huge loss of backpressure. I wouldn't be surprised if you experienced a loss in power by doing something like that. Like the other guy mentioned, Titanium would be the lightest setup, but it would be a hell of a lot more expensive than a normal metal/stainless steel exhaust. The weight savings would be minimal too. You'd get more weight reduction out of removing your spare tire and jack than you would a lightweight exhaust.

My $.002. :)

why not instead of all the exhaust being done, why not just an exhaust cut out? the least amount of backpressure, and its like running no muffler at all. you can place it before the cat converter as well. they have ones that come with electric openers(waste of cash since it'll be ruined by exhaust fumes), ones that come with like a pull-push switch to open and close it, or the manually opened one, with ususally 3 bolts, 3 washers, a gasket, and a piece of metal to keep the cutout from leaking.

you could always run a test pipe if you'd like to, until the emissions day. thats what most people i know do. but its your call.

Is this for the Rotary or the 1.8T? Cause I'd be worried that if you take away back pressure from the Renesis, it'd have almost no torque at all, they aren't torque machines as it is... might actually slow the car down.

if anything, i'd say its the jetta, as he is speaking about if you had F/I. but yet again, he might be planning something for the renesis. who knows. i remember him saying he wanted to to something to that engine, but im not too sure if he wants that released. can't remember that far back.

Check around for different exhaust made for your car and look up the specs made for them including wait. I'm still trying to get my carbon fiber exhaust...........................for my bike.

If you are talking about a car with a turbo, the turbo probably already provides more than adequate backpressure. So you don't have to worry about going too wide. On NA cars, that is a concern, with turbos...not so much. That is why you hear people say hte best exhuast on a turbo car is none at all. What you want is the freest flowing exhaust you can get your hands on. Cats, resonators, etc all are restrictions in some way or another...they are disrupting flow and this robs you of power. They keep the car quieter adn the cats are good for hte environment, but they steal some horsepower. If you have emissions I suggest swapping in a testpipe instead. A highflow cat is still going to be a restriction, even though it is less of one than a stock cat.

If you aren't concerned with noise and the cops wont be either, I'd say go for a full 3" mandrel bent single shot exhaust. Custom is cheap. But check out different exhausts for your car and see what sizes they are offered in. They will probably be a bit smaller. Also, ask people who own your car, where the biggest restrictions in your exhaust is. Each car has it's own spots that need the most improvement. For instance, my stock catback is fine, but my stock downpipe and cats blow...so they were my first focus.

Just keep in mind, the more you remove and hte more you widen it, hte louder its gonna get. So if a really loud exhaust is gonna bother you, your family, neighbors, or hte local police, a cutout maybe the route you wanna go. Power when you want it, back to normal when you want to be low-pro.

Also, as far as material, I'd just use stainless steel. It's cheap and doesn't weigh that much. Weight really only becomes an issue when people make dual exhausts and such for looks and double the weight of their exhaust...negating any gains they just got in power. I think htere are always easier ways to save weight, than paying 3x as much to save 15lbs in piping. just my .02

thanks guys, i am talking about the jetta cause the stock exhaust for the rx-8 is pretty much maxed out and the most anyone has gotten for gains on the 8 is about 3hp.

just by looking at the exhaust on the jetta you can see how restrictive it is, its probably a 1 1/2" pipe all the way to the muffler and the muffler tips look like two floppy guy parts. The stock exhaust itself is very heavy especially the muffler and people have saved at least 20 pounds by going stainless steel. Also there is no emmissions testing in florida, that was stopped years and years ago. And it would have to be a turbo back exhaust or else it is pretty much pointless to do an exhaust. My turbo runs off the exhaust and most people who have done a turbo back have freed up alot of torque becuase the turbo is able to spool up much quicker and it also allows the turbo to boost usually a pound or two more without any problems, im talking about close to 20-30wtq is what some people have gotten with the stock turbo, horsepower not so much though.

Also what is a cutout exhaust, sorry im not good with termanology for that section of the car cause ive never done an exhaust before. The only car ive had with an exhaust was the celica, but it was put on before i got it.

And like I said before, this is not something im doing right now, nor will it be anytime soon, i just want to learn as much as i can so when I get ready to actually do this I know.

hey here is another question, what about side exhausts? is there any actual performance difference between that and a normal one?

i think it's more of a "show" thing but it can be less restrictive depending on how short the run is or if it is just a straight run...like this
http://temp.corvetteforum.net/c3/themoneypit/side_exhaust.jpg

hey here is another question, what about side exhausts? is there any actual performance difference between that and a normal one?

Performance difference is doubtful. It will sound lounder though because of the pipes coming out closer to the cabin. That and the tips would sit a lot lower than a rear exit setup, you'd probably end up dragging them on speedbumps/getting the car on lifts/etc. Roman has that problem with his Mustang.

i would think a side exhaust would be alot less restrictive considering there is less travelling to be done.

Yes it would be a tad less restrictive. It will also be quite loud...ALL the time. If you run a turboback exhaust straight out the side, you will get every cops' attention, and you will scrape it on every speed bump. Some jackass at my old job had an srt4 with side exhaust, and it was always great seeing him bottom out just trying to pull into our washbays.

Yes it would be a tad less restrictive. It will also be quite loud...ALL the time. If you run a turboback exhaust straight out the side, you will get every cops' attention, and you will scrape it on every speed bump. Some jackass at my old job had an srt4 with side exhaust, and it was always great seeing him bottom out just trying to pull into our washbays.

lol, i know it would be loud, im just curious about it all. the thing i like about the side exhaust is that on the 1.8t you get flames when you shift at 4k or higher :grinyes:

There are some simple things to looks at when picking an exhaust for a turbo-charged car.

1. Bigger is better. Get at least a 3" mandrel bent system. Matierial isn't improtant unless you want bragging rights.

2. You do NOT need backpressure. Especially when the turbo itself is a huge restriction. Once the exhaust has left the manifold it has all the inertia it needs. Exhaaust simply needs velocity. It is your job give it the least restrictive path out.

So a side exit would be more powerful. It is quite simple, less bends and less changes in direction means more power.

There are some simple things to looks at when picking an exhaust for a turbo-charged car.

1. Bigger is better. Get at least a 3" mandrel bent system. Matierial isn't improtant unless you want bragging rights.

2. You do NOT need backpressure. Especially when the turbo itself is a huge restriction. Once the exhaust has left the manifold it has all the inertia it needs. Exhaaust simply needs velocity. It is your job give it the least restrictive path out.

So a side exit would be more powerful. It is quite simple, less bends and less changes in direction means more power.

no offense to you other guys, but i probably hold his opinion above alot of the resposes, though they were good and informative, reason is cause his exhaust system for the baron was just as restrictive as the jetta is and im sure he got alot of power off of it when he upgraded. so thanks and please keep the info coming.

Yeah, enough that the clutch slips. I wish I had done a baseline dyno before and do another run after to see what I gained. Most TD guys have shown between 30-40HP was freed up from dumping the restrictive exhaust.

I wish I could get rid of the cat.

most 1.8t guys free up boost and get about 15whp and usually around 30wtq, but that is with keeping a cat on the car, if i were to do an exhaust i would dump the cat and have one of those small mufflers at the end to keep sound a bit lower.

Yeah, the turbo will do a bit to help muffle as well. It would be nice if I could dump my cat, damn emissions. :(

Another thing I forgot to mention is the turbo is MUCH more responsive.

You want the least amount of restriction? Don't do side exhaust even, just get dumps.

Have a straight 3" pipe come off the turbo, no cats, no muffler, straight out to where the cabin ends, with a little turndown to angle the exhaust out.

Talk about loud.

if u take out the muffler u kill gas mileage and low end torque. removing just the cats so long as u still have a muffler doesnt do to much maybea power gain of a few horsepower not really worth taking it off.

if u take out the muffler u kill gas mileage and low end torque. removing just the cats so long as u still have a muffler doesnt do to much maybea power gain of a few horsepower not really worth taking it off.

:sly:

Not sure how you are getting a link between gas mileage and a muffler, so I'll just skip that one. As far as the lowend torque, it's not so much the muffler, it's the restriction which causes some backpressure. Generally the muffler isn't considered as much as the diameter of the piping, but regardless, this doesn't apply to turbo cars, only NA, as mentioned previously a couple of times.

:sly:

Not sure how you are getting a link between gas mileage and a muffler, so I'll just skip that one. As far as the lowend torque, it's not so much the muffler, it's the restriction which causes some backpressure. Generally the muffler isn't considered as much as the diameter of the piping, but regardless, this doesn't apply to turbo cars, only NA, as mentioned previously a couple of times.


And as for the gas milage i wouldnt care, not like it would urt it too much, When I got the car I was getting 350 miles to the tanks, now that I've increased the boost, added the CAI and increased the fuel I get 400 to the tank, which confuses the hell out of me, so i wouldnt mind if the average went back down to 350 on my car. But yeah from what i was told by alot of people, it doesnt hurt the low end torque on a turbo car.

Here is another question for you guys, does the piping have to be perfectly smooth like intake systems? because i know intake systems need to be smooth to get the best delivery into the engine, but what about exhausts? Or it doesnt matter, it just needs to vent out? Hope thats not a stupid question cause like I said i dont know.

Yes you want smooth. Leaks, or uneven piping, or anything else that causes turbulence screws up the flow...creating bottlenecks or restrictions.

As far as you getting higher gas mileage, that probably came with the accompanying tune that you should have gotten when you installed larger injectors. Most cars come pretty rich from the factory, to be safe from knock. When you add larger injectors, generally you add some sort of air/fuel controller or swap/alter the ECU to account for the extra fuel. With these devices you can lean out the mixture for more power (to an extent of course...too lean = kaboom) But when leaned out a bit, you will see increased gas mileage.

A muffler is just that... a muffler... it muffles sound so you don't hear the resonance of the engine's output. I've always heard that on FI cars no exhaust at all is best.

The lightest material would be titanium. But like Blu said it would only really serve for weight reduction. I only have seen one person go the titanium route. That was Emil from Slovenia with his low 13 second 4g civic. He had an exhaust custom made by DeVito that was titanium with mandrel bends with a removable muffler section for track days. Stainless steel would be be high quality and probably outlast the car. Alumnized piping works well and can be found at most muffler shops if you decide to go the custom route.

you only saw 1 person with a titanium exhaust? you dont get out much. i already have my titanium exhaust picked out, and its super sick. just waiting on money to buy it.
chuki_breath has the same one on his car.
http://www.automotiveforums.com/vbulletin/showthread.php?t=538903
cat back, no welds on the entire exhaust, all one piece, 10 lbs. compared to usually 25 or more for a stainless system. every pound counts, especially when the price tag is not a whole lot more. but all this is moot, because i dont know anyone who makes a cheap Ti exhaust for a jetta.

Yes you want smooth. Leaks, or uneven piping, or anything else that causes turbulence screws up the flow...creating bottlenecks or restrictions.

As far as you getting higher gas mileage, that probably came with the accompanying tune that you should have gotten when you installed larger injectors. Most cars come pretty rich from the factory, to be safe from knock. When you add larger injectors, generally you add some sort of air/fuel controller or swap/alter the ECU to account for the extra fuel. With these devices you can lean out the mixture for more power (to an extent of course...too lean = kaboom) But when leaned out a bit, you will see increased gas mileage.


thanks for the info but i dont have larger injectors, i upgraded the FPR from the stock 3 bar to a 4 bar to compensate for the increase in boost and from the a/f's that I got when I got dynoed I am running very rich as if my a/f's were stock.

:sly:

Not sure how you are getting a link between gas mileage and a muffler, so I'll just skip that one. As far as the lowend torque, it's not so much the muffler, it's the restriction which causes some backpressure. Generally the muffler isn't considered as much as the diameter of the piping, but regardless, this doesn't apply to turbo cars, only NA, as mentioned previously a couple of times.

From personal experience Ive ripped a few mufflers off while playing out in the woods. On a na 4 banger you lose enough tourque that your almost always on the gas just to keep up the the speed limit therefore your really wasting alot of gas. It didnt have much affect on my v8 though just pissed off the hole town because it was at 3am and Im cruising home with an stick shift 302 thats basically got open headers on it.

well i take all that back.
turns out that exhaust is discontinued and only 4 exist in the u.s.
so yeah, just get SS.
thats too bad, i had one on order but didnt have enough money for both that exhaust and my turbo/manifold. i chose the manifold. fuck.

one more question, if I ran without any exhaust what would happen? Besides my ears bleeding, would I cause flames to come from the turbo? Would I have too much boost creep? Anyone have any experience with this just for fun?

When I first got my 944 n/a the exhaust fell off from the cat back. The header was stainless from the factory so it was solid. I didn't see flames but it did sound like a jet engine and probably woke up everybody in that part of the county coming home at 1am... haha...

Lots of people run open downpipes on their turbo cars if they just don't want an exhaust or have a race only vehicle. All you need to do is remove the exhaust and put some custom bent pipe however long you want with a flange on the end bolted to your turbo. I've personally haven't heard of anyone just running the turbo and it doesn't seem like too good of an idea either...

reason why i was asking is cause someone mentioned being able to run off the turbo. Thanks for the info. If anyone has any info about running on just the turbo let me know, it would be very interesting to find out.

i know my friend runs a downpipe and thats it on his 1g dsm. other than it being loud as hell under throttle, it works fine.

Open downpipe is loud as hell...and I have shot flames with it. Open turbo...way too loud for the street. Your ears will bleed and every cop in 30 miles will be pulling you over. Could you...yes. Would you...no.

Open downpipe is loud as hell...and I have shot flames with it. Open turbo...way too loud for the street. Your ears will bleed and every cop in 30 miles will be pulling you over. Could you...yes. Would you...no.


thats what i wanted to know, thanks