Please hurry!


what are some bad things about running your car with no exhaust? im telling someone its bad, but i dont know just what is bad about it (i know theres something)


Theoretically, you can end up with fumes in the cabin.


Without a exhaust manifold?


No exhaust?? No exhaust what? You mean removing part of the exhaust SYSTEM?? Which part?(s)


all of it


I have herd it could damage the exhaust valves, but I don’t know that to be fact.


Depending on what you really care about and how it’s mitigated you can actually get improved performance and fuel economy from removing the exhaust system. The problems that must be mitigated follow:

If the vehicle is fuel injected where would you mount the O2 sensor?

Without a catalytic converter you’re going to pollute more.

Exhaust gas is corrosive, if it’s not being piped away from the vehicle then whatever it blows on will corrode given enough time.

Without the back-pressure provided by the exhaust system the car may run lean causing a whole mess of problems including reduced torque and burned valves. You may need to mitigate this by making major carburetor adjustments or reprogramming the fuel injection system.

EGR won’t function properly (depending on how much is removed there may be no EGR) and that’s likely to lead to predetonation with also comes with a whole mess of other problems, including mechanical damage to the reciprocating parts (pistons, crankshaft, etc.)

It’s loud.

Exhaust gases in the cockpit are always bad. If they’re not being directed out from under the car there is a high probability they’ll accumulate in the cabin.

Oh, I forgot to mention it’s illegal! I assume the vehicle in question is an off road only race car or something similar. Even in that case I recommend at least running a straight pipe to get the exhaust away from the vehicle.


Exhaust in the cockpit means carbon monoxide poisoning. This can cause brain damage (especially in children) and even death if doses are high enough. Not worth the risk.


Running without an exhaust manifold is not a good idea. If you have open manifolds… usually there is enough pipe there to keep cold air out.

When you don’t run an exhaust manifold, you have the exhaust ports and valves exposed directly to the atmosphere. You run a serious risk of getting a rush of cold air back in to the exhaust port after the exhaust gas has been expelled, and the rush of cold (relatively) can fracture the exhaust valve. You may have heard of the term “sucking” a valve, well that’s it.