what is the size of oem exhaust pipe?
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what is the size of oem exhaust pipe?
just under 1.75 i beleive...
1.75 OD. I would know, I took my muffler off and got pipe bent.
Yea it's 1.75"
The biggest you could go before you start having problems is 2", so if you get custom piping, try not to get much bigger than that. And DON NOT let anyone convince you otherwise.
ya unless u go with forced induction u will see some losses after 2" but some people think otherwise...
Umm I'd like to see numbers backing that up. You guys are probably right, but without any dyno sheets, who knows.
All I know is the stock system has a lot of bends that would benefit a larger diameter size. By the looks of it, the pipe from the cat to the stainless flex is 2 inches and from then on, it's 1.75... That would mean that the cat is a 2 inch, and that all the bends from the start of the exhaust system are restrictive. From then on 1.75 was "good" enough.
The problem I see with the 1.75 inch pipe are the two 90 degree bends near the rear axle. 90 degree bends are restrictive on any pipe size, therefore going bigger usually helps.
To make a better assesment, I should be buying a pressure gauge this summer and will test the stock system before and after the cat, with and without the muffler.
def. update us when u do thisQuote:
Originally Posted by ontarian_frog
I will no worries. Been reading Autospeed.com a lot lately and they have great tips on DIY mods on the cheap. You guys can also browse the archives with is great.
It's an online magazine. Best thing about it it's free.
You will lose some of your torque if you got w/ a 2" all the way back but gain a little hp.
Any bigger than that and there wont be enough back pressure.
aaahhh another "which size exhaust pipe is better debate?"
this has been argued so many times.......ugh :roll:
Umm... Horsepower is a measure of torque * rpm / 5252. SO if you gain hp, you automatically gain torque.Quote:
Originally Posted by sappy96
Uhm, not necessarily.
So you can have less tq at your current peak RPM but at a higher rpm it would be the same or slightly less. Sooo you can have less tq and more hp.Quote:
Horsepower = Torque * RPM/ 5252
Look at honda engines, no tq but all kinds of hp and the same displacement motor from someone else could have more tq but less hp.
Its all about where you make your power.
So
Car Z
has 100 lb ft of tq at 6000 rpm =60000/5252=114.242 hp
Car Y
has 95 lb ft of tq at 9000 rpm = 855000/5252=162.795hp
See, less tq, more hp.
If you take the same engine and make more horsepower with modifications, you have more torque somewhere you previously didn't.
Sure, but not a higher peak torque value necessarily. If it drops your old peak torque down 5 foot lbs then increases 3 foot lbs high in the rpms you have more torque somewhere, just not where you want it or need it.Quote:
Originally Posted by ontarian_frog
Not to mention that you will probably end up hurting hp and tq if you go too big of a diameter.
There is no reason for a 2.5" pipe for an aveo unless you are using boost.
hit the nail on the head... you can have 500 peak hp... but if it's for 200 rpms... it doesn't do you much good.
No matter what racing you're doing, you always looking to accelerate faster. A long linear high ft-lb torque band is what you should aiming for.
Take drag racing into account... the majority of your time is lost during shifts.
If you have a car with a short range where you produce a high amount of HP, you have to shift more often to keep it within that range (talking professionally here, you'll swap out the gears to compliment your engine, or at least the final drive in semi-pro).
Then lets say you have a car that produces less peak HP(gotta keep it in the ballpark of the other car), but delivers the power in a more linear way, and for a longer duration. That car can use a longer gearing, which means fewer shifts, and a higher (mechanical) top speed.
The latter car will have a faster 0-60 and 0-100... while the first may have a faster 60-100. Though, overall the second car should win.
Of course there's a lot of if-ands-or-buts in this scenario, though for all intensive purposes the linear, long, and consistent torque curve is what you should be looking for.
In drag racing you can deal with a power spike, although think about track/rally... you don't want to jump up 20 hp out of nowhere mid corner. You can end up sideways (more than you want) and meet an immovable object. If you can't finish the race/stage, it doesn't matter how much power you have.
Back to piping. I agree with anyone saying there is a size limit, never said there wasn't. I just don't like it when people say things without back up. How the hell does anyone here have an opinion on which size to go for? Who can truly say you'll loose torque or horsepower if you go with this or that?
Ahh yes... the butt dyno. The best way, without a dyno run to know for sure if your car runs higher numbers than before, is with a quarter mile finish speed average of before and after.
http://autospeed.com/A_108704/cms/article.html
there's nothing wrong with the butt dyno... but access to a dyno is much more accurate... :roll:
Lets see, my GTO has dual 2.5 exhaust for a 400hp+hp car.
The aveo is about 1/4 of that w/ even less than 1/4 displacement. Sooo 2.5 is way to big.
This is actual math equations I am sure to figure out the optimum size of exhaust tubing.
Unfortunently it has more to do with displacement then with horsepowerQuote:
Originally Posted by sappy96
go with 2" exhaust...no one on here has an aveo with enough modifications to warrant anything bigger...i believe brian was the only one who ever went for a 2.25 exhaust to 2" and felt a better pull for the two inch
Not really.Quote:
Originally Posted by y2daniel1981
A turbo 4 cyl car can use a 3" exhaust.
2" 2" 2" 2" 2" 2" 2" 2" 2" 2" 2" 2" 2" 2" 2" 2" 2" 2" 2" 2" 2" 2" 2" 2" denis you have seen my car ive got a 2 inch dont go bigger
Some even have a 4". But he is talking about N/A engines. The turbo provides all the backpressure needed. Hell, I have seen people go with a 4" downpipe straight to the ground. It helps spool the turbo.Quote:
Originally Posted by sappy96
Ok a s/c.
The point I am making is that if you make more hp you need to flow more air and to flow more air you will make more hp until a certain point where the exhaust no longer is conducive to scavenging. Same thing w/ an intake. There is a tube for a reason. Open TB sucks for intake velocity.
Im running a 2.5" exhaust after the downpipe with a stock nissan resonator and a edelbrock sdt chambered muffler.