driving with out exhaust

[Thothie]

I was told its bad for the engine to run it with out the exhaust. I am running with only the downpipe while Im getting my exhaust muffler replaced. Is this safe? Thanks.

[ricebike]

my muffler rusted out on me a while back... i just put on some jeneric flexible pipe & clamp on to the existing pipe to route it out the bumper<'til a fellow 240sx.org member sold his hks system to me~3 months later>

other than that, loud as hell, less backpressure/low end torque suffers just a bit.<whew, was gettin deaf & woulda break down to get a pacesetter; glad that didn't happen>

& u can route a temp to the sides.... so u won't be inhaling exhaust fumes while idling in city traffic or something.

another thing i've seen; a ground strap was under there that connected from the one of the cat bolt flange to the body of the car to reduce the chance of spark in the exhaust pipe in case the car's running rich in unburned gasses... never heard o that b4, but read it recently.

[Altiman94]

less backpressure is a good thing

[MikeMurphy]

less exhaust gas velocity makes torque suffer. Velocity is the name of the game.

[Thothie]

SO is it okay to drive around with only the dump pipe while I get the muffler changed? The drive is not that far and I do feel the power loss due to backpressure and the vibration and loudness. I can live with it while I get the exhaust changed. But will it damage the engine or anything else.

[ricebike]

nope, no other side effects... oh, just check the exhaust gaskets <manifold-to-head mainly> b4 addin on your cat-back system

[chmercer]

why would you feel a power loss from less restriction. and no it shouldnt damage your car.

[ricebike]

<shrugs> just a bit off the low end torque for some reason, not even that noticeable... i guess some NA engines like to have a little backpressure, i read somewhere, to "help" exhaust valves close easier??? i dunno

[Chingon]

not really....you shouldn't feel any loss w/o an exhaust.

the backpressure game is just rumors, haven't seen any proof of it. Back pressure in an exhaust system is always bad. The confusion comes from the fact that a system that is too large in diameter allows the hot exhaust gas to expand, cool, and the sound pressure waves to slow. This can result in a higher pressure pulse at the exhaust port when you need a low pressure pulse to allow the exhaust gas to flow out better.

in other words, gas velocity is what you are looking for. Like i've heard, "the best exhaust is no exhaust at all"

[Thothie]

Im driving it without the exhaust. Theres definitely a power loss. Also I can't let my tach go over 3500. Theres too much vibration and too loud.

Thats why I ask if this is actually harmfull for the engine. The exhaust should be in by Friday so two more days of driving from home to work.

[mikew04]

well while your driving it, it should not hurt (besides performance) at all. but i have heard stories about warped heads and cylinders due to cold air rushing in too fast. my friends probe had a clogged cat, then the insides of his cat finally blew through his exhaust, getting caught throughout. we pulled off his exhaust system, and he ran it for a few days before getting it welded back on. this was in 30 degree weather. a few days later his head gasket went, warped head. dont know if it was related tho... just an idea

[BB Turbo]

JW, how does it sound? I have wondered if it would sound like poo like all the wannabe honda drivers w/o exhaust in my area, but, even witha good exhaust, hondas still sound like poo, there are some exceptions of course. I know it must be very loud...just wondering though.

[IneedMoney]

if the exhaust pipe is too short and the car is hot and you turn off the car you CAN bend the valves thats i know of. so if you have it to the cat then you should be fine. and on the back psi that car will not get up and go as fast, the backpressure game is not just rumors!!

[chmercer]

my car was doing that when i had the exhaust disconnected but still on the hangars. It was making serious backpressure from the exhaust running into the pipe. but when i had my exhaust all the way off it would rev just fine. i would estimate removing the stock exhaust completly would give between 10 and 20 horsepower, and the butt dyno confirmed.