good idea?

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good idea? - 11/22/2007 1:47:48 PM    92 blazin   Posts: 21 Joined: 11/18/2007 Status: offline i was thinking about putting dual exaust on my 92 blazer.. but will it mess with the back pressure? or should i just get dualls exaust from the muffler, or will that still mess with the back pressure to? suggestions would help Post #: 1

RE: good idea? - 11/22/2007 3:00:03 PM    HeyYou   Posts: 146 Joined: 9/19/2007 Status: offline Your engine is basically an air pump. The more air you can move thru it, the better it will run (more power, better efficiency, etc.) Headers, and dual exhaust all the way back will give you a noticable improvement on the Butt-Dyno. The suggestion that you need a certain amount of backpressure, in order for things to work "right" is a Myth. (in reply to 92 blazin) Post #: 2

RE: good idea? - 11/22/2007 6:19:59 PM    swartlkk Posts: 15276 Joined: 5/1/2005 From: Waterloo, NY Status: online True dual exhaust on a v6 engine sounds pretty bad...  If what you want is more performance, you can get that by increasing the exhaust diameter and putting on high flow components (cat & muffler). While 'required backpressure' is a myth, there is such a thing as oversized exhausts which hinders performance as well.  _____________________________ Kyle- 04 Rainier My Restoration Projects Please Do Not PM for Tech Help (in reply to HeyYou) Post #: 3

RE: good idea? - 11/22/2007 8:30:35 PM    Idriveachevy Posts: 909 Joined: 10/9/2007 Status: offline Is backpressure really just a myth? _____________________________ 1997 4door 4x4 thrush glasspack 31" bfg mud terrains 2 in. shackle lift and TB crank Soon to come - 2 inch body lift. (in reply to swartlkk) Post #: 4

RE: good idea? - 11/23/2007 4:45:52 AM    Hanr3 Wheels & Tire Moderator Posts: 3523 Joined: 5/11/2005 Status: offline YES!!!!!!! Your engine does not need nor does it want backpressure. Backpressure is a restriction to air flow. Every restriction to air flow the engine must overcome to exhuast spent gases. That effort robs you of horsepower. More backpressure = more restriction = less horsepower. It is that simple. _____________________________ "Some people spend an entire lifetime wondering if they made a difference. The Marines don't have that problem." -President Ronald Reagan '87 S10-Blazer - SOLD '93 S10-Blazer 4x4x4 - Sons DD, engine swap is done. '00 S10-Blazer 4x4x4 - My (in reply to Idriveachevy) Post #: 5

RE: good idea? - 11/23/2007 4:51:25 AM    Hanr3 Wheels & Tire Moderator Posts: 3523 Joined: 5/11/2005 Status: offline Most people get backpressure confused with is scavenging. Scavenging is when the exhaust pulls the air from the engine. That allows the engine to breath better. In racing engines scavenging is used to pull in the next charge of air/fuel mixture. More you can stuff into the chamber before it explodes the more power you can generate. This is why an engine is reffered to as an air pump. Teh more air it can pump, the more power it makes. If you set your exhaust up correctly it can be used to draw in more air/fuel and create more power. Backpressure has the oppostie effect, it reduces the amount of fresh air/fuel you can draw into the chamber.  _____________________________ "Some people spend an entire lifetime wondering if they made a difference. The Marines don't have that problem." -President Ronald Reagan '87 S10-Blazer - SOLD '93 S10-Blazer 4x4x4 - Sons DD, engine swap is done. '00 S10-Blazer 4x4x4 - My (in reply to Hanr3) Post #: 6

RE: good idea? - 11/23/2007 5:19:30 AM    rriddle3 Posts: 1545 Joined: 12/22/2006 From: Fort Worth,Texas Status: offline True, Tim. 'Backpressure' is a term of convenience that I am guilty of using just for simplicity's sake, but 'scavaging' is the correct idea. As with most things, there is a point of diminishing returns and when an exhaust system is 'too large' and the flow of gasses becomes too much in volume and too slow in speed, performance can start to suffer. This is why, for the 4.3's design, going over 2.5" for the exhaust pipe is pretty much useless even if you have installed headers to optimize the initial flow of exhaust gas. Staying with the stock 2.25" is probably the route to take. I also agree with Kyle that dual exhaust lines on our trucks accomplish nothing and do not have a good sound. _____________________________ 2002 Blazer LS 4dr 2WD Auto Trans Hypertech PP III Programmed Flowmaster 50 Series Delta Flow Muffler, C6 Corvette Exhaust Tip TYC Elegante carbon fiber tail lights (in reply to Hanr3) Post #: 7

RE: good idea? - 12/4/2007 8:30:04 AM    sdm1234   Posts: 40 Joined: 12/28/2006 Status: offline you can, however, use a 2.5in dual exhaust setup with an x-pipe. that will help equalize opposing pressure and, in turn, increase exhaust scavenging. not only will it help HP and low-end TQ, it'll sound better with an x-pipe, as well. _____________________________ '91 Chevy S10 Blazer 4Dr 4X4 NEWEST '97 Pontiac Trans Am WS6 '04 Yamaha YZF R6 '78 Pontiac Trans Am WS6 cardomain.com/id/sdm12 (in reply to rriddle3) Post #: 8

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