quick exhaust question

[hans999999]

if you dump out your exhaust like in this pic

will you still get a lot of fumes inside from air flowing up and into your k5? or is the out the back with a 45º the best setup to keep you from passing out?

 

[dyeager535]

Out the sides would still be better, you want the fumes to escape the vacuum created behind the truck. Air under the vehicle is turbulent, meaning it doesn't just slip underneath the truck, and since that air IS going to be eventually making it's way to the back of the truck...

Exiting from the sides puts the exhaust directly into the stream of air flowing along the sides of the truck. You'll never get rid of it entirely, but with a vehicle shaped like ours, you don't want exhaust coming out the back.

A 90* exit is probably better yet, but the difference in that from a 45* is probably minimal.

 

[hans999999]

thanks for the info i had a feeling

 

[BigCountryx]

Simple answer, YES. Mine is just like that except dumped down more.

 

[GruntHunter]

You guys that are modifying your exhaust, what are you doing to make the computer think it's NOT running cold sine the exhaust is going to be flowing with less back pressure and consequently cooler. The computer is going to try and make the TBI run richer and use more gas. I've heard about sensor heaters that 'trick' the temp sensor but have never saeen one. I wanted to go to dual exhaust until I get educated about the electronics involved.

BTW, I'm driving an '87 K5 with a 350 TBI

 

[PsychoticDeadGuy]

i have a 87 k5 too. right now i just have the stock exhaust manifolds and y-pipe. i will be adding a summit exhaust cutout right after each manifold. it does run a little richer but its not too bad. i have no top or tailgate so i only smell exhaust when i am stopped for a while. it wont be too bad if you have the top off but when i still had my top and tailgate on with the rear window down and my exhaust exited in the same place as in that pic the entire interior would fill with fumes.

 

[dyeager535]

Stock GM "acceptable" specs for backpressure are something like 4PSI at WOT, upgrading the O2 sensor because of change in backpressure is not really a concern.

The problem is if the O2 sensor is STAYING hot enough to work correctly. There is no tricking involved, if the O2 sensor gets too cold, it doesn't work right. Heated O2 sensors just make sure it's up to correct temp for operating, both to decrease open loop time at startup, and for all other conditions where the sensor might cool off, such as idling.

Typically you move to heated when you move the sensor further away from the engine, such as headers.