Im tring to learne a little bit about these engines, with a 2.0 SOHCeng. if you run it with open headers or over sized pipes/exhaust sys will it hurt the valves?

 

YES open header you do run the risk of burning valves... expecually stock exhaust manifolds... the longer the primaies the lesser the chance...

But you can use oversize exhast... ie 2.5' is good... 3' to big... well untill you get that sohc past 200hp just go with 2.5' and a free flowing muffler... And on a side note Neon's do not require much back pressure.

 

whats the shortest length exhaust needs to be?

 

On a NA car you would be fine with a dump right where the stock CAT would be... I wouldent go much shorter... You could but you would be running the risk of starting **** on fire... So I would just dump it right where the stock cat is... with a 90* bend facing the ground...

 

like transplant said, dump it right around where the cat is, most of the guys with serious drag neons are dumping it right there

the only reason for backpressure is to quiet it down, if you dont need it quiet then you dont need any backpressure, the exhaust length and diameter are what affects exhaust scavenging

 

ok so what is the point of the resinator or i seen on veroushious.com(if im correct)they had a short round cat .but with a long tail header the space is limited.can you install the cat after the last bend .then extend the down stream o2 after

 

ok some motors need backpressure so the motors do not suck the allready spent exhaust gasses back into the exhaust valves when it hits the end of the exhaust stroke... like hondas, smaller motors... we dont need that...

second off if you were to get a LTH you have options... like this one...
http://www.modernperformance.com/pro...d566b9172dd724
fits right on the end of the lth and fits in the tunnel perfect unlike the huge stock one... it wont be in its stock location but only off by about 5 inches...

 

backpressure actually holds up the exhaust from leaving the exhaust system, which makes it easier to suck spent gasses back in

in a 2 stroke, you have to have a certain amount of backpressure, because the intake gasses are entering the cylinder at the same time as the exhaust gasses are leaving, and having a small amount of exhaust trying to re-enter the port keeps any of the incoming air and fuel from leaving the cylinder before burning, allowing more fuel/air to be packed in

4 strokes dont have this problem, and therefore backpressure only serves 1 purpose, to quite it down, even tho muffler shops will give you all kinds of bs about whyyour cardoes need it, its just to sell mufflers

this is why hard core drag racers run open pipes, to eliminate as much backpressure as possible, any 4 stroke motor will run best with no muffler, and the correct length and diameter exhaust piping

 

why would having headers/exhaust manifold protect the valves form burnig, if it is the heat that doding it, wouldnt containing the exust gasses in a tube(header/manifold) cause the heat to be trapped in there?

??

 

if u go any shorter thanthe cat it will get the block, head and firewall really hotand i cracked the block, warped the head and melted the stuff off y fire all when everything on my exhaust system fell off rite after the stock manifold.