sonicii

I feel your pain.. backpressure is bad. But it's not the flow of exhaust that causes the scavening effect, it is the pulse of high pressure when the exhaust valve opens, followed by the pulse of low pressure when it closes. Idealy you want the low pressure pulse to meet at the collector when the exhaust valve of the next cylider opens, this helps 'pull' the exhaust out of the next cylinder. On a stock system, this happens reasonably low in the rev range, by opening up the exhaust system, the exhaust gasses move slower for a given RPM, therefore the scavenging effect occurs at higher revs.

In a nutshell -
the advantage of a smaller system is lower RPM torque, but excessive backpressure at higher RPM (backpressure is bad).
A larger system reduces the backpressure at high RPM (more power), but also reduces the torqure at lower RPM.

The only reason the engine runs like crap without any exhaust system is because it's cam is designed to suit the standard exhaust setup.

speedfreak4996

Isn't this the purpose of vtc? ve has 190ft lbs behind it.. more than vg if im not mistaken. vtc is supposed to bring this torque in earlier?

maximagician

ms.zilves..didnt you have the low power problem a while back?
i had it but am currently(for now) bypassing knock sensor with the resistor
what was wrong with yours?

94 max

funny thing is you can wrap your stock exhaust to increase exhaust speed due to heat staying in the pipe thus make the gases move faster thus increase efficiently thus increase horsepower

Alex_V

Also rusting it faster. Best thing is to get a performance exhaust and get it coated with a thermal barrier. Lots of company's do it now.

~Alex

mszilves

Yes, it was definitely worse in the summer with a heat soaked engine...

I found it to be my knock sensor, and I'm also doing the resistor bypass for the time being. Since I run only 91+ octane, I haven't had any problems. I've been putting off replacing it since it's a major PITA.

maximagician

and its exspensive. im wondering how my\our cars will run in the hot weather
since before i did the bypass it really only went low power in the summer heat
so you think heat messes up the old\worn knock sensors or creates more knocking? i have to remember the k.s. isnt a knock PREVENTER it only "hears'
knock and retards engine to "prevent"damage not totally eliminate it
i dont hear any obvious knock only lite tapping RARELY when hard accelerating (sounds similar to my vtcs)which i only hear a little when cold
im also using 92 octane has anyone ever had knock related damage on ve or vg engines...that they were sure about(not scammer mech. diagnosis)?
anyone think knock sensors are a luxury item to keep the motor quiet?

dking21

I talked to Dallas at Warspeed. He said that if you have a Sohc that the 2.5" y-pipe and cat are fine. But from that cat back he would not recommend going any bigger that 2.25".

goon9

iTrader: (13)

If you want to bottle neck your exhuast, have fun

CapedCadaver

iTrader: (8)

Duals on a 3rd Gen? Do you have pics of that? I've been wondering about how it would look having duals on a 3rd gen; it'd take some playing with the distance between them to get the right look (as well as possibly mounting them higher and cutting into the rear bumper like a 2000-2004 Mustang GT does)

Mizeree_X

iTrader: (9)

When I switched from a hi-flow cat back to stock, my low-end improved.

goon9

iTrader: (13)

http://forums.maxima.org/showthread.php?t=445808&page=2
http://forums.maxima.org/showthread....58751&t=438744
Note on the last link, I had a new pipe pipe bent from the cat to the muffler. I threw that together long ago just to drive it around. Still need to redo the rear end to make the tips look right.