gbart Posted January 21, 2005 Report Share Posted January 21, 2005 ok guys walk into the muffler shop today and ask a quote of 2 40 series flows with pipes and tips and the guys says 6 liter right i say yes he goes well your prob gonna lose a noticable amount of torque when you put them on he said that the free flowing air is too fast for the o2 sensors to identify or somethin to richin and stuff i dont know if this is all true cause most of the people i talk to on here have free flowing exhaust and all i hear from them is that its loud and sounds good most of the time so if you have this problem or know what im talkin about let me know cause im wantin to get them put on by end of next week if it will work so let me know thanks alot guys Gbart Link to comment Share on other sites More sharing options...
smithl3 Posted January 21, 2005 Report Share Posted January 21, 2005 Well, I can tell you what I experienced. I originally had two 40 series flowmasters put on my truck as my very first mod. I met up with rico750 (chris) in albany and we bombed around town, and with his truck and a tune, we were pretty damn tied. So by no means is it a loss, you will gain some mid and high for sure. The o2 thingy, I have no idea our resident techs can help with that. Go for it, especially if you are going to keep moding the truck it will only help more in the long run. Good luck Link to comment Share on other sites More sharing options...
WhiteSS Posted January 21, 2005 Report Share Posted January 21, 2005 I noticed hardly any loss on low end on top end it helped alot for mine I got an 11" magnflow dual in dual out Link to comment Share on other sites More sharing options...
orion :: SS Posted January 21, 2005 Report Share Posted January 21, 2005 1) Drive back to that exhaust shop. 2) Get out of truck, find the guy who told you that. 3) Kick him squarely in the nuts. 4) Drive off, and DO NOT give that shop a dime of your hard earned money. - - - - - - This is like the "backpressure makes torque" myth that floats around...all BS. You want an exhaust that helps create the HIGHEST possible velocity, but is not so small that it chokes off in the upper RPMs. So big enough for the flow that's needed, but not so big that the velocity suffers... High velocity aids in scavenging, which will increase the VE, which will make more power. So he is dead wrong. - Brian Link to comment Share on other sites More sharing options...
Coda Posted January 21, 2005 Report Share Posted January 21, 2005 orion :: SS Posted Today, 09:06 PM 1) Drive back to that exhaust shop. 2) Get out of truck, find the guy who told you that. 3) Kick him squarely in the nuts. 4) Drive off, and DO NOT give that shop a dime of your hard earned money. Link to comment Share on other sites More sharing options...
gbart Posted January 21, 2005 Author Report Share Posted January 21, 2005 alright good deal thanks fellas i appreciate it i wont be goin back there Link to comment Share on other sites More sharing options...
zippy Posted January 21, 2005 Report Share Posted January 21, 2005 i agree, stay as far away from that backyard "mechanic" type thinking. i wouldn't even go to a shop like that for an oil change... Link to comment Share on other sites More sharing options...
BigTex Posted January 21, 2005 Report Share Posted January 21, 2005 That guys grasping with his description of the O2 sensor. There is no issue with the O2 reading faster flowing exhaust. I totally agree with the less restrictive highest fastest flowing exhaust setup that will support your needs statement. The low backpressure myth has some merit though but not because "backpressure makes torque". Its about all the components of the intake, engine, exhaust acting as a system and being designed to work together. On a stock truck, the components work as GM designed them, which was not for maximum power. By upgrading components, you free up some power, but you throw off the balance of the "system". Specifically, the camshaft on these motors have a large bias towards the exhaust. This leaving the exhaust valve open longer is needed to get rid of burned gasses through the restrictive stock muffler. By really opening up your exhaust flow with quality aftermarket components, the engine is able to get rid of all of the exhaust much easier. With the stock camshaft, the valve is open more than it needs to be in the low rpms with a good exhaust. This lowers cylinder pressure and scavaging the intake charge doesn't happen as designed any longer, so low end torque suffers. BUT, once rpms get going the engine can make more power because its not fighting against the stock muffler. The stock setup smothers the engine in the mid-upper rpm range. Thats why you often lose some low end torque but gain upper rpm power with a better exhaust. Taking this further - can you have your cake and eat it too? Yes, most definitely. But its going to require a planed design modification to the whole intake, engine, exhaust system. Meaning you really need to lay out your goals, your budget, and how deep you want to go. A typcal system upgrade could consist of a good intake kit, ported throttle body, new camshaft, headers, catback and tuning. Those parts allow more fresh air in, the engine to processes it better and allow more exhaust out. The camshaft is the one ingredient that changes the actions of your engine, the other parts are helpers that assist the engine. With the right camshaft, you can have a high flowing exhaust and actually gain torque. Getting into proper camshaft specs for a specific vehicle with XYZ mods is far beyond this thread though. Link to comment Share on other sites More sharing options...
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