Corpserodeo666 Posted July 10, 2005 Report Share Posted July 10, 2005 I was wondering is it safe to run true dual exhaust with hi-flow cats or is it better to run no cats and mufflers. Because my buddies told me that if i run it the way it is now (no muffler) it will screw up my valves. Link to comment Share on other sites More sharing options...
zippy Posted July 10, 2005 Report Share Posted July 10, 2005 i'm not sure what the kick is on removing the cats or installing high flow units is. the stock cats flow really well considering and if you're still naturally asperated you aren't much challenging the flow of them. running with no muffler isn't going to hurt the valves. if you've ever looked through some of these newer straight through mufflers they are actually straight through. they flow pretty much the same as that of a straight pipe while just reducing the noise as it goes. you can run true duals on the truck if you'd like but i would recomend doing an x or h pipe to get rid of some of the resonance. let me tell ya, the secret to power on this truck isn't getting rid of the cats... Link to comment Share on other sites More sharing options...
misterp Posted July 10, 2005 Report Share Posted July 10, 2005 No disrespect but your friends are 'mis-educated'. You almost have to run the exhaust straight out of the head (no headers at all) to damage the exhaust valves. If you run the engine for any length of time straight out the factory exhaust manifold or ports then the engine could suck fresh air backwards over the exhaust valve/seat during the combustion overlap period (how much depends on cam grind), meaning you will be airing fresh oxygen over red-hot parts = burning metal, and severe valve seat erosion. But as long as you have a couple feet of exhaust pipe bolted to the port you are fine. Common practice in racing claimer cars is to run factory exhaust manifolds with the exhaust downtube cut off at the firewall (just enough to prevent poisoning the driver) then going like hell for hours without problems. We also ran zoomies (tractor puller headers) on cars without problem. Look at the exhaust on a Ferrari, or Pantera, or racing Vettes (including older sidepipes), they have no problems with burnt exhaust valves. Mr. P. Link to comment Share on other sites More sharing options...
Corpserodeo666 Posted July 10, 2005 Author Report Share Posted July 10, 2005 No disrespect but your friends are 'mis-educated'. You almost have to run the exhaust straight out of the head (no headers at all) to damage the exhaust valves. If you run the engine for any length of time straight out the factory exhaust manifold or ports then the engine could suck fresh air backwards over the exhaust valve/seat during the combustion overlap period (how much depends on cam grind), meaning you will be airing fresh oxygen over red-hot parts = burning metal, and severe valve seat erosion. But as long as you have a couple feet of exhaust pipe bolted to the port you are fine. Common practice in racing claimer cars is to run factory exhaust manifolds with the exhaust downtube cut off at the firewall (just enough to prevent poisoning the driver) then going like hell for hours without problems. We also ran zoomies (tractor puller headers) on cars without problem. Look at the exhaust on a Ferrari, or Pantera, or racing Vettes (including older sidepipes), they have no problems with burnt exhaust valves. Mr. P. <{POST_SNAPBACK}> Thanks for the input, but they where thinking that if there is no back pressure then something will go wrong, but I doubted them from the very beginning. Thanks for your inputs gentlemen. Link to comment Share on other sites More sharing options...
CoolBlueSS Posted July 11, 2005 Report Share Posted July 11, 2005 I agree with the others. The stock cats flow pretty good, and the only thing you'll really gain with no muffler is a loud truck. Link to comment Share on other sites More sharing options...
standby Posted July 11, 2005 Report Share Posted July 11, 2005 I agree with the others. The stock cats flow pretty good, and the only thing you'll really gain with no muffler is a loud truck. <{POST_SNAPBACK}> ...and the attention of those fellows with the pretty blue lights on the roof! Link to comment Share on other sites More sharing options...
00z71sierra Posted July 12, 2005 Report Share Posted July 12, 2005 When I upgraded my exhaust to dual 3" I replaced the stock cats with 3" high flow cats and haven't had any problems. I do have a supercharger so I needed the larger exhaust. It's still loud too so I don't think cats quiet it down much. I need to look into getting the x pipe though; don't have that. Link to comment Share on other sites More sharing options...
wrager Posted July 12, 2005 Report Share Posted July 12, 2005 I removed the cats from my Camaro SS (99 ls1) and immediately regretted it. The before and after dyno runs showed an increase in peak HP but moved the torque curve up the range to a point where it just wasn't as fun to drive around town. It was also obnoxiously loud. I like loud but this was rediculous. Link to comment Share on other sites More sharing options...
CoolBlueSS Posted July 13, 2005 Report Share Posted July 13, 2005 I agree with the others. The stock cats flow pretty good, and the only thing you'll really gain with no muffler is a loud truck. <{POST_SNAPBACK}> ...and the attention of those fellows with the pretty blue lights on the roof! <{POST_SNAPBACK}> Exactly. Link to comment Share on other sites More sharing options...
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