LinkBack URL
About LinkBacks
2008 Chevrolet AveoWould it be worth Porting out the stock manifold?
Would it be worth Porting out the stock manifold?
Not unless you do it yourself, already have all the tools, and alot of free time. In other words, I wouldnt pay for it to get done.
Originally Posted by aveodude
thats all true. plus, if you haven't looks at it yet(i haven't) is it even cast that you could port it? the "other" economical car i bought had a stamped steel manifold. not porting sheet metal. plus if you do it yourself failure is more likely. cause when do you know if it is too thin for the heat?
i have an AEM CAI in my car so far, that's the only engine mod so far. I think i'm going to go with a magnaflow high flow cat, 2.25 inch piping to a flowmaster 40 or 60 muffler... i'm going to remove all the resonators and everything else, but keep the stock manifold....sound like a plan?
that might be too big. loss of back pressure will cause loss of power in lower rpm range.. and delay throttle response.
Might be a little loud, but you can always add a resonator or another muffler if you don't like the sound.
that might be too big. loss of back pressure will cause loss of power in lower rpm range.. and delay throttle response.
As for back pressure, that helps burn more fuel and thus cleaner emissions, however you do not need back pressure for power. What you want is exhaust velocity. Please research the difference and not post "loss of back pressure will cause loss of power in lower rpm range" as it is wrong will discredit the rest of what you say.
Exhaust velocity is the term of the speed of the exhaust flow and scavenging ability of the exhaust and typically goes up in higher rpm ranges. But with a lower velocity at idle, the back pressure is important to keep the engine running smoothly. if you are going to set your idle to 2500 rpm then yeah only worry about velocity. if you want to idle at 700 rpm(what ever is stock) then you also need to maintain back pressure if you want the car to produce power before the car hits 2500 rpm from a stop. its been proven on a dyno that once you go past a certain size where the back pressure is lost, not only does the engine not produce the same power until the rpms are past a point, but also that the car will start having trouble idling. and if you go past a reasonable exhaust velocity then it will produce less power across the entire power band.
2.25 is not too big of a choice for exhaust velocity so why mention that?, 2.5 with tuning could be done. but being that i doubt he has a turbo. a chip, a cam, itbs, standalone, or anything else that allows you to eliminate the need of back pressure that the oem fuel injection management accounts for at idle, he will need to maintain back pressure. A high flow cat, 2.25 pipe with only a 60 series muffler probably wont have enough restriction for a 1.6 liter engine to produce back pressure
is the performancec just going to completely suck below 3k rpm with the 2.25 piping? i thought 2inch or 2.25 were accepted 'norms' on this forum, at least from what i read from others about their exhaust setups.
the shop said the smallest they is go is 2.25, otherwise i would have done 2 inch i suppose.... would keeping one stock resonator in help out with backpressure? i figured by using the stock header that would also retain enough backpressure , the exhaust isn't being sent out as smoothly as it would be with a custom header. perhaps upping the idle by a few hundred could also help, is there an easy way to do that or does it involve hacking the cpu?
i might do some more serious engine mods after the exhaust work, like custom pistons, cams, etc, so 2.25 might come in handy. however, that might be some time down the road.
you can't say if it will suck or not, i dont know the numbers like the restriction or back pressure your stock exhaust has, and them how much each of your new components will produce. on a mildly modded car you can usually stand to loose almost 50% of the back pressure. with tuning sometimes more. but that varies with makes and models. if you were to go with a tunable muffler you could probably do straight pipe entire length and then tune the muffler to how you want or need the car to run. a resonator does add some back pressure but i wouldn't reuse stock you and you can get a decent resonator in the pipe diameter you are running for cheaper than labor to cut and fit the old one. but everything i have to say has been discredited because i addressed back pressure instead of velocity.
a very none technical way of seeing if you car will run without back pressure is to pull the exhaust apart and run the car. you will want to keep both 02 sensors in the system so to eliminate a lot of back pressure but not all would be disconnect the midpipe from the cat and run it. taking the cat off would eliminate almost all the back pressure. but to appease subachad, this will also change your exhaust velocity. in our shop we had a test exhausts that we could put on the car that had a tunable muffler and adjust to perform.
that's interesting just using only a tunable muffler, definately would simplify things, and simplicity is goodjust out of curiosity what do people when they have no cat and have to do their emissions inspection like we do every 2 years in maryland? bolt the stock exhaust system back on and then go do the emission test?
Posting Permissions
Reply With Quote