View Full Version : 94 cheyenne 2500 a.k.a. the brown cow
12-25-2011, 10:30 PM
hey guys, i was wondering if the rumors are true, that straight pipes on a 5.7 tbi motor with no cats will lose hp??? and i've also heard it can cause warped valves and cause some harm to a motor...my truck has 42,890 miles on it, so i really dont wanna mess anything up, but i want it loud as hell lol:cool:
12-26-2011, 01:05 AM
No, it won't reduce power output. The stock cam doesn't have a significant enough duration of overlap such that it'll have any significant effect.
12-26-2011, 01:12 AM
42,890 Miles on a 94???? Must........see.........PICS!!!!!!
OK back on track.....Its not going to warp your valves BUT if you have close/old neighbors, they may not like you or your truck on a cold startup in the mornings........
12-29-2011, 02:49 PM
i will post pics as soon as i figure out how to lol. the truck was purchased new by my grandfather and he hardly drove and he died in 06 so it just sat in the garage until my dad decided to give to me as a graduation present. pretty awesome lol its a super nice vehicle though
12-29-2011, 03:20 PM
i wouldn't touch a truck like that, loud exhaust is fun for a day, then its just annoying.
12-29-2011, 03:34 PM
valve burning occurs as a result of a very lean-burning engine, the myth of straight pipes cause burnt valves dates way back before you were born in days of old. Earlier cars with carburetion often could not adjust because of the way that backpressure caused air to flow backwards through the carburetor after the air already got loaded down with fuel, and caused the air to receive a second load of fuel. engines with performance exhaust no longer had that double-loading effect, and then tended to burn valves because of the resulting over-lean condition.
this is also partly where the back pressure is good myth came from too. to put it simple back pressure is just that, pressure that is pushing back about your engine, hindering the exhaust from clearing the combustion chamber. the key to a good performing exhaust system is exhaust gas VELOCITY. that is where the myth began, prime example is say take a 4 cyl engine, johnny ricer puts a 3" exhaust on his honda civic and noticed he lost power. he didnt lose power because he eliminated his back pressure, he lost power because he eliminated exhaust velocity. wider isnt always better….
12-31-2011, 10:22 AM
oh alright, thanks daisy dukes, i learned something today haha, and thanks guys for all your help
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