Dcrasta Posted October 31, 2003 Report Share Posted October 31, 2003 Ok custom exhaust fans, this is one I was thinking about last night while dreaming about building the ultimate quest. Some guy on ebay is building headers in addition to Chad's and others with external wastegate dump tube. Im thinking aobut a header l ike that, with a tial or greddy wastegate per say, then from that dump tube route it aft of the cat. So when the wastegate is closed (like at idle) everything goes to the cat, but when the wastegate is open (full throttle per se) exhaust flow can go past the restriction to a y pipe so its muffled.. I bet it would sound wicked. I dont think it would be that difficult to build and would probably permit a mix of either 2.5 dp with a post cat section of 3 inch / 4 inch or a 3 inch dp with a post cat section that would permit more flow.. Is anyone doing an exhaust like this? I think the advantages of the added capacity for flow would help keep the boost creep problem from occuring and could if designed right give u the flow of a large pipe with the low boost velocity for off boost response. Someone chime in pros' cons? Thnaks (I would really like to hear what the MPI folks think about that idea..) Link to comment Share on other sites More sharing options...
Technology Posted October 31, 2003 Report Share Posted October 31, 2003 pretty good idea, i can think of cons: extra weight higher cost why not just dump into the regular pipe where it bends to go under the car? only pro's i can think of now is avoiding the cat restriction, but in reality, it's not that restrictive, is it? i do like the idea of a dump tube going far down the pipe, but maybe not that far. also, if you wanted super loud sound, just do external dump! hehe Link to comment Share on other sites More sharing options...
Yellow_quest Posted October 31, 2003 Report Share Posted October 31, 2003 You dont get boost creep with External Wastegates that dump....unless you route them back into the exhaust flow....you'll cause turbulance that will actually push your Exhaust back pressure up.....thats bad, just do like shelby told me and put a Lawnmower muffler on the dump tube.... ;D ;D ;D I say dump it clean and screw the reroute. Yellow_quest Link to comment Share on other sites More sharing options...
shift1313 Posted October 31, 2003 Report Share Posted October 31, 2003 are you saying once its open route all the exhaust around the cat? what diam are these wastegates? not very large and i dont think all the exhaust flows through them. im not raggin on your idea i just dont understand completely what your going for. remember your not flowing more your just routing it different. i think chads wastegate mount is on #4 right? maybe i missed something in your idea dc but i think it would be more beneficial to just have an external dump. Link to comment Share on other sites More sharing options...
Dcrasta Posted November 3, 2003 Author Report Share Posted November 3, 2003 Ok havent tried it but in my minds eye.. I see the wg dump going back into the exhaust after the CAT so that it bypasses the CAT (restriction) but is muffled by the rest of the exhaust and doesnt create an exhaust leak under the car. RX7s used to have a 'thermal' reactor, and so the dump tube for it was a 1 1/4 tube that ran the length of the exhaust . I was thinking something along that line but having the dump tube rejoin the exhaust after the CAT just to bypass the cat . Like I said, just a stupid Idea never tried figured I would ask opinions. Link to comment Share on other sites More sharing options...
shift1313 Posted November 3, 2003 Report Share Posted November 3, 2003 its not a stupid idea man. i would just do alot of research on it. i personally would rather run an exhaust dump seperate from the exhaust. Link to comment Share on other sites More sharing options...
Dcrasta Posted November 3, 2003 Author Report Share Posted November 3, 2003 Wouldnt it be mega loud and where would u run it to under the car out the side? Link to comment Share on other sites More sharing options...
TerasKas Posted November 4, 2003 Report Share Posted November 4, 2003 I am actually working on building an external dump for my T3 with an internal wastegate. I built a new flange that covers the wastegate and then welded a small piece of metal to the flange to cover the hole inside that goes back into the exhaust. I am in the process now of cutting a hole in the middle of the flange(about 2 in.) then welding a pipe out then down and probably out of the side of the car. This will allow the turbo to spool better after dump and hopefully make it sound crazy. This process could also be applied to the TD05-TD06 which I might build one for next. Yellow-quest, a lawnmower muffler huh, how does that sound?If it makes it louder then thats what I want. Cory Link to comment Share on other sites More sharing options...
shift1313 Posted November 4, 2003 Report Share Posted November 4, 2003 dc, id run it out the side of the body right behind the wheel well. Link to comment Share on other sites More sharing options...
Technology Posted November 4, 2003 Report Share Posted November 4, 2003 Like I said, just a stupid Idea never tried figured I would ask opinions. i have a teacher that says, " there's no stupid questions, only stupid people." so, as you would expect, i don;t ask him any questions, cause i can;t let him think he's better than me, and he seems like the type of person who would. i hate that guy. but i saw him get pulled over by the cops, LOL, sucker. anyway. got any other ideas that i can shoot down? j/k Link to comment Share on other sites More sharing options...
Joel Posted November 18, 2003 Report Share Posted November 18, 2003 Nothing wrong with merging after the cat, so long as you merge it at an angle with the exhaust flow. In a 3" exhaust, pressure increase by the time your after the cat would be minimal in the exhaust system itself, although you'll likely have flow loss in the dump tube from the wastegate. For "max power" I would dump to atmosphere. For quiet, you could do this. For emissions, you have to do it before the cat. Joel Link to comment Share on other sites More sharing options...
importwarrior Posted November 18, 2003 Report Share Posted November 18, 2003 DCrasta you could also use a muffler or baffle off of a motorcross bike. like a CR250 http://www.denniskirk.com/denniskirk/b2c/catalog_images/1/109/10901/300pix/e4qp96500.jpg Link to comment Share on other sites More sharing options...
Distorted.Clarity Posted November 18, 2003 Report Share Posted November 18, 2003 i have a good idea about wastgates *as what they are and sort of how they work* but can someone take the "not so positive" ideas in my head and tell me how they work, what they do, or any other info? Link to comment Share on other sites More sharing options...
shift1313 Posted November 18, 2003 Report Share Posted November 18, 2003 what we are talking about here is an external wastegate, in the exhaust header. at the desired boost the wastegate is opened and lets the exhaust have an alternate route as opposed to just going to the turbine. thus not creating more boost. stock 12a turbos and most stock turbos have internal wastegates built into the housing of the turbo. alot of , most , aftermarket turbos require an external wastegate. the disscustion here is where to route the exhaust that passes through the wastegate. stock it goes right into the downpipe after the turbine. with an external you have the option to run it out to atmoshpere or to plumb it back into the exhaust somewhere. DC is talking about returning it to the exhaust system just after the cat. did that help out? Link to comment Share on other sites More sharing options...
Distorted.Clarity Posted November 18, 2003 Report Share Posted November 18, 2003 sure does why would you want to have it tho wouldnt it be better to keep that pressure? Link to comment Share on other sites More sharing options...
heefner Posted November 18, 2003 Report Share Posted November 18, 2003 The wastgate limits the boost without it we would all be running 25-30 psi with the stock turbo. The wastegate lets us control it to a safe setting. Link to comment Share on other sites More sharing options...
Distorted.Clarity Posted November 18, 2003 Report Share Posted November 18, 2003 got ya Link to comment Share on other sites More sharing options...
shift1313 Posted November 18, 2003 Report Share Posted November 18, 2003 exactly, once the turbine gets to the rpm for our required boost, opening the wastegate lets us keep that boost so we dont have spikes or just an endless increasing boost supply. i do know a guy that turboed a 350 without a wastegate. he just used the gas pedal to limit the boost. dont think id go that route, i like dropping the pedal to the floor. Link to comment Share on other sites More sharing options...
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