I have an 07 Tc and im waiting for the 07 zpi kits to come out so i can get one, but my question is that i am doing a dual exhaust setup on my tc and i have the turbo canisters and i already have my bumper cut i don't know if i should go with a 3" pipe or 2.5" pipe? Any suggestions?

A single 2.5" pipe is more than enough. So going dual, you shouldnt go any larger. The dual exhaust is just getting you looks anyway, so dont go huge on the piping.

A search would tell you that the pundits say 2.5" is plenty. Go bigger, and you lose exhaust temp & velocity.

...and that's for a single exhaust. Strictly speaking, a 2.5in exhaust has a cross-sectional area of about 4.91in^2. So even 2" pipe after the split would be effective (having a cross-section of about 6.3in^2).

I'd say 3in and 2.5 after the split if you go dual. I would put 2.5in in an N/A of course it wasn't dual and yes I have seen it work I/H/2.5 Exhaust and feels great so there's my opinion. :D

Turbos work better with less or no backpressure.

I did a dyno test on my N/A 240sx before..

2.4 liter KA24DE

A 3" headerback exhaust showed a gain of at least 15whp

With stock exhaust it only pulled 157whp

With 3" exhaust it pulled 173whp

The mods were:
ASP crank pulley
OBX header
Custom intake
Fully advanced timing

So generally speaking, am i better off doing a straight 2.5" cat-back or 3" cat-back or 3" from cat to axel and then 2.5" from axel to mufflers?

The mufflers i bought have a 3" inlet so i thought that i should go with 3" pipe. I was told that turbo cars work best with bigger exhaust pipes since it helps the car somewhat breath better. I know for now its going to run crappy since my car is N/A but i plan on putting in a turbo so i really wasn't worried about that though, but then again it depends on how crappy the car will run.

TC's have the highest stock displacement for a 4 cylinder motor, so a 3" exhaust would actually benefit the car. Some people just can't stand the noise because the bigger the piping, the louder your car gets! It'll sound like a cross between a 4 banger and a muscle car. But bottom line, if you're gonna go turbo you might as well go 3"

your best bet is...after your turbo is installed, to get a 2.5"downpipe and 2.5" piping the whole way UNLESS you are pushing close to or over 300whp, then you can go 3" on both. You are not gonna have that much back pressure unless you're pushing a larger amount of hp

That's exactly what i want to go for once i get the turbo. I'm hoping for at least 300whp or very near to that. I plan on keeping my cat and getting rid of the resonator to sort of help tone the noise down a bit. Do you think that'll help? I was thinking of a high flow cat for now and then going cat-less once i get the turbo, but im trying to avoid getting CELs because this and my R32 will be my everyday car (mainly the Tc though).

TC's have the highest stock displacement for a 4 cylinder motor, so a 3" exhaust would actually benefit the car."

And you base this on... ?

Based upon most setups, and the word of the better tuners that have put time into the tC, 2.5" is all you will really see any benefit from. 3" on this sized motor is pretty much overkill unless you are doing huge numbers for the car.

I agree with 2.5" all the way.. unless you will be and are making over 315whp or up then you would want 3"...

BTW any idea how much hp a stock block can hold before having to do internals?

BTW any idea how much hp a stock block can hold before having to do internals?

I dont think anybody really knows exactly.. it has been debated many times... A few people were pushing 10psi and blew there engines... I would guess if your gonna push between 275 whp -300whp on a DD you would really want to look into beefing up the internals for longevity reasons.. better safe then sorry.

TC's have the highest stock displacement for a 4 cylinder motor, so a 3" exhaust would actually benefit the car.

I'm with engifineer on this one...wtf are you talkin about :blah: ....thats like sayin the mustang has the biggest v6 of any v6 so it must need huge exhaust...

as far as stock displacement goes, ever heard of a 2.5 litre...*ahem* subaru impreza hmmmm or bmw 325... :come:


It'll sound like a cross between a 4 banger and a muscle car.
:tap:
no it will sound like doo-doo. please dont ever compare the sound of a vette, a Mustang GT, a Viper, any V8 from the 60's, to a 4 cylinder with duals. I'm officially offended. :no:

sorry dont wanna be the bad guy...i might have been a little harsh. sorry

so you guys recommend that i go with 2.5" duals instead of the 3" duals on a turbo set up?

I think 2.5 will be plenty. I am running this set up on my NA and the "duals cause loss of back pressure" talk is BS. I can post my track times to prove it. :lalala:

Since you're going with dual exhaust...2.5" will be your best option. Dual 3" exhaust would probably actually rob you of some hp. If you're over 300whp, then a single 3" would do good, but with a dual setup...2.5" all the way!!

Thanks

the nissan altima has a 2.5liter 4 banger...

Yep, the 2.4 hasnt been the largest displacement 4 banger for a while.. and that doesnt mean it needs 3" exhaust. Hell, I know of some v8s that will waste most of the boosted 4 bangers on here that are running 3" exhaust.

As for the reccomendations, I dont reccomend duals at all for performance. You probably wont lose anything, but you arent going to gain anything you cant gain with a well designed single exhaust. If you are just looking for the bling factor, then go ahead.

On an NA setup, the scavenging is effected more by too large of an exhaust, so it can hurt you there. With a turbo in the line, you are a little better off in this area due to the resistance it produces.

Too large of a pipe can also cause another issue. The larger the pipe, the slower the flow. The slowe the flow the more the gasses cool within the system. The more they cool, the denser they become.. and the harder they are to push. So in a small way, too big is worse in some cases. A huge exhaust is in no way the same as an open header; some have the incorrect assumption that it is. The gasses are still in the system until they reach the end of the pipe, so design must take this into account.

TC's have the highest stock displacement for a 4 cylinder motor, so a 3" exhaust would actually benefit the car."

And you base this on... ?

Based upon most setups, and the word of the better tuners that have put time into the tC, 2.5" is all you will really see any benefit from. 3" on this sized motor is pretty much overkill unless you are doing huge numbers for the car.

Well, if you read my post above, I based it on an N/A motor with the same displacement and relatively identical horsepower rating. Look up the specs of a Nissan KA24DE motor on google. A lot of people say 3" is too big for an inline 4 N/A motor but how many of them have actually dyno tested that theory???

If I have to I can post my dyno sheets just to prove my point.

^^ I saw that you compared stock exhaust to a header-back custom 3" setup. Were the bends the same, was the cat installed on the stock pipe, what cat was installed on the 3" portion and how long did you run the car on the combination before running the dyno run? Was the second dyno on the same day, in same conditions at the same air and engine temp?

I am not trying to be rude or question your knowledge, but most, if not all, dyno proven results I have seen have a ton of holes in them as far as a scientific comparison. A million variables and no controls usually, so I have a lot of questions when it comes to them, especially when custom exhausts are replacing stock exhausts and we are only discussing the effects of sizing.

And I was aiming my other comments at your assumption that because it is a large displacement 4 banger it can benefit from a 3" exhaust. Compression, stock exhaust setup, tuning, setup, etc all play roles in this, so it cant just be based off of displacement.

I'm with engifineer on this one...wtf are you talkin about :blah: ....thats like sayin the mustang has the biggest v6 of any v6 so it must need huge exhaust...

as far as stock displacement goes, ever heard of a 2.5 litre...*ahem* subaru impreza hmmmm or bmw 325... :come:

I admit I should've done more research before running my mouth on here but let me correct a few things for you, mr expert.

Scion TC = 2.4L I-4

Bmw 325 = 2.5L I-6
Subaru Impreza = 2.5L H-4

Those cars aren't even close except for the new Nissan Altimas equipped with QR25DE 2.5L (2488cc) I-4 motors that someone else had brought up in this thread.

Please allow me to rephrase myself. The Scion TC has a 2.4L inline 4 motor which is only .1 liter away from being a 6 cylinder motor. It still doesn't take away the fact that 2.4 liters is about as high as it can get for a stock displacement inline 4 engine compared to the Honda B series motors, Lancer Evo and Nissan SR20s

So there, does that make you feel better now?


:tap:
no it will sound like doo-doo. please dont ever compare the sound of a vette, a Mustang GT, a Viper, any V8 from the 60's, to a 4 cylinder with duals. I'm officially offended. :no:

Nowhere did I mention any of those cars but I didn't know Corvettes, Mustangs (a GT at that, :rofl: ) and Vipers were the only cars considered as muscle. Well, I'm sorry for offending your "getonmylevel" expertise but let me ask you something, have you ever had or heard a straight 3" exhaust on a 2.4 inline 4 motor? Yes? No??? So how would you know how they sound like? I hope you didn't base your statement on how Hondas sound like with aftermarket rice muffler and stock exhaust piping...

Bottom line, the difference between a 2.5" and 3" exhaust is not that big of a deal. I believe it's a matter of preference and I personally prefer to have a 3" exhaust because I believe it performs better in certain applications.

I rest my case :bow:

I'd say 3in and 2.5 after the split if you go dual. I would put 2.5in in an N/A of course it wasn't dual and yes I have seen it work I/H/2.5 Exhaust and feels great so there's my opinion. :D

Are u talking about mine? :lol:

^^ I saw that you compared stock exhaust to a header-back custom 3" setup. Were the bends the same, was the cat installed on the stock pipe, what cat was installed on the 3" portion and how long did you run the car on the combination before running the dyno run? Was the second dyno on the same day, in same conditions at the same air and engine temp?

I am not trying to be rude or question your knowledge, but most, if not all, dyno proven results I have seen have a ton of holes in them as far as a scientific comparison. A million variables and no controls usually, so I have a lot of questions when it comes to them, especially when custom exhausts are replacing stock exhausts and we are only discussing the effects of sizing.

And I was aiming my other comments at your assumption that because it is a large displacement 4 banger it can benefit from a 3" exhaust. Compression, stock exhaust setup, tuning, setup, etc all play roles in this, so it cant just be based off of displacement.

To answer your questions, the dyno was done on a 2 day weekend dyno day at a shop called Racetune in Hayward. The 1st dyno was with the stock exhaust on day 1 and 3" exhaust from the header-back on day 2. I doubt a hi-flow cat would make any difference with power compared to a test pipe but the bends on the 3" exhaust is obviously not the same as the stock exhaust if you're talking inch per inch.

As far as condition goes, both dynos were done around 4-6pm inside the shop with a fan blower facing the motor. I'm sure there are a lot of factors that could yield horsepower gain but with 15whp increase, I think it's pretty obvious that the 3" piping made most of the difference.

just got with 2.5inch piping from the turbo back, and run it into a single exhaust.. no need for two mufflers.

happy bday bronxblaza

Dyno sheets!

DAY 1 DYNO
Mods:
ASP pulley, OBX header, Fidanza flywheel,
air filter, z32 fuel filter, Magnaflow hi flow cat,
stock exhaust, advanced timing, 150k miles

http://members.aol.com/s132fortysx/dyno/dynosheet.jpg


DAY 2 DYNO
Changes:
91 octane, ebay intake pipe,
advanced timing and new spark plugs

http://members.aol.com/s132fortysx/dyno2/dyno.jpg


http://members.aol.com/s132fortysx/dyno/1.jpg
http://members.aol.com/s132fortysx/dyno2/3.jpg

I admit I should've done more research before running my mouth on here but let me correct a few things for you, mr expert.

Scion TC = 2.4L I-4

Bmw 325 = 2.5L I-6 <---yes i should have researched that my bad...but when did we say boxer 4 or inline 4 or whatever...?



:tap:
no it will sound like doo-doo. please dont ever compare the sound of a vette, a Mustang GT, a Viper, any V8 from the 60's, to a 4 cylinder with duals. I'm officially offended. :no:

Nowhere did I mention any of those cars but I didn't know Corvettes, Mustangs (a GT at that, :rofl: ) and Vipers were the only cars considered as muscle.
Well let me reply to this so you understand as muscle goes i was goin for a broad spectrum...
Well, I'm sorry for offending your "getonmylevel" expertise but let me ask you something, have you ever had or heard a straight 3" exhaust on a 2.4 inline 4 motor?

!!!!!I hope you didn't base your statement on how Hondas sound like with aftermarket rice muffler and stock exhaust piping...!!!!!!

Actually yes i did....because only a forced induction four sounds any good with that size piping...otherwise yes you do sound like the geek down the street with the 20s on his accord and green neons and NOS stickers all over his windshield

Bottom line, the difference between a 2.5" and 3" exhaust is not that big of a deal. I believe it's a matter of preference and I personally prefer to have a 3" exhaust because I believe it performs better in certain applications.

I rest my case :bow:




By the way...My name is tC Get On My Level because i will not, cannot lower myself to drive rice. Because in case you didn't know before my tC i drove an SR powered 240 not the truck powered crap your postin up. So really before you get all butthurt over my post that i apologized for afterwards ---that is--- before you made a big stink, Just know that I am above you already in the game. I never attack people on the internet but you are truly pathetic. And when some newb like yourself feels the urge to keep on and on about some stupid $#*! people who have been here like myself will always come at you.

Just wait three days when i post up my new wheels homie


So while i may not be Mr. Expert you can call me Mr. I wishicouldbelikeyou

http://img176.imageshack.us/img176/8045/picture014yv0.jpg

http://img148.imageshack.us/img148/4628/picture016zo6.jpg

http://img148.imageshack.us/img148/7687/picture018ue8.jpg

http://img139.imageshack.us/img139/1954/picture022tf7.jpg

http://img148.imageshack.us/img148/7624/picture021np2.jpg


Sound Clip: http://www.youtube.com/watch?v=3gqMx2_5BVI

please let me know what you guys think

I'm not a Fan of that kind of muffler, but the setup looks good.

how did you get the tips to bend on the mufflers? looks pretty good

That looks really freakin good! My suggestion: Paint the piping thats visible black. Not the tips or mufflers.

That looks really freakin good! My suggestion: Paint the piping thats visible black. Not the tips or mufflers.

What should i paint it with? Spray paint? If so won't it get all over the chassis? Because this is a full cat-back

Some high temp engine paint or something. Not the whole piping just the parts you can see in the pics. Up until that point or you can do the whole piping if you want. Im sure you could put something behind the pipe as to not get paint on the car. Nice exhaust though! I really really like it.

Some high temp engine paint or something. Not the whole piping just the parts you can see in the pics. Up until that point or you can do the whole piping if you want. Im sure you could put something behind the pipe as to not get paint on the car. Nice exhaust though! I really really like it.

Thanks I really appreciate it. I just love the way it sounds.