Dumps for turbos?

[ftmyerssleeper]

What types of exhaust systems are most people running for the turbo setup? From what I see ,and I could be wrong, most have catbacks or true duals. With a turbo, wouldn't you want the least amount of back pressure? Wouldn't dumps off the headers be the solution?

[RedFrk13]

Re: Dumps for turbos?

You cant have true duels with a single turbo. You cant have open headers. I would say most are running a 3" exhaust.

[ftmyerssleeper]

Re: Dumps for turbos?

most pro street turbo'd cars run with open headers because they want the least amount of back pressure creating a vaccum for the ambiant air pressure entering the intake side of the turbo. This allows just enough pressure to turn the turbine wheel. Without the need of a wastegate. When your exhaust pressure is too much for just a wastegate, you'll need a cutout. Why isn't anyone else applying this. The only reason you can't run with open headers is it would be too loud. I have an electric dump currently, from which I can open and close from the inside of the car. I just don't know why everyone else hasn't done the same. The waste gate is on the opposite end of the system.

[Arctc Wolf]

Re: Dumps for turbos?

if you dump before the turbo, then u have less exhaust energy(heat, velocity, ect.) to spin the turbine, causing a drop in boost pressure. you want to put a cutout direcctly after the turbo(for max hp track passses/racing), run the wastegate into the open air(not legal but more hp), and have an exhaust that matches the outlet of the turbine housing(usually 3" or bigger). this will cause the least amount of backpressure in the system. cam selection, header design, turbine design, housing size, and head flow will all affect backpressure on the turbo.

[UDLOSE98]

Re: Dumps for turbos?

most pro street turbo'd cars run with open headers because they want the least amount of back pressure creating a vaccum for the ambiant air pressure entering the intake side of the turbo. This allows just enough pressure to turn the turbine wheel. Without the need of a wastegate. When your exhaust pressure is too much for just a wastegate, you'll need a cutout. Why isn't anyone else applying this. The only reason you can't run with open headers is it would be too loud. I have an electric dump currently, from which I can open and close from the inside of the car. I just don't know why everyone else hasn't done the same. The waste gate is on the opposite end of the system.

i forgot to ask what kind of car do you have, and what kind of psi are you seeing with this turbo?

[crysmatic]

Re: Dumps for turbos?

you can't run open headers on a turbo car...it defeats the purpose of having a turbo! but you do -need- a wastegate to prevent overboost.

you'll never have a vacuum in your engine...think pressure differential! going from a very bad exhaust to a very good one may be ~2 psig. imho keep the full exhaust, keep it quiet, and if you want and extra few hp, crank up the boost 1 psi. and the 3800 can make more than 'enough' (define 'enough') power through a 3" single exhaust.

food for thought...a 3800 makes 200 hp. with turbo it makes 400 hp. that means the turbo is making just as much, if not more, hp than the engine itself. that means turbo selection is more critical than the engine setup itself.

[Joshua]

Re: Dumps for turbos?

I'm running 2.5 with the Y pipe then a 2.5 all the way back. I have a highflow 2.5 cat with flowmaster exhaust, No problems with the turbo and i have pushed 9 psi. In fact before i had the boost controller hooked up to my Tial wastegate i was only getting 2.5 psi and the wastegate was seeing the .4 bar(5.8 psi) from the turbo. Just goes to show you how much is lost in an intercooler and piping about 3 psi. At anyrate the 2.5 works for me, heck when you look at the inside of the stock y pipe it's actually 2 in sleeve.

[camaroman1181]

Re: Dumps for turbos?

yeah, maybe i'm missing somethign too, but why would you allow exhaust to dump to the atmosphere when you could be using that waste energy to turn the turbo, thus creating more power?!?!? open headers and a turbo!?!?? that tends to defy everything ive ever heard about turbo set ups...

[UDLOSE98]

Re: Dumps for turbos?

I think he means BIG *** pro street motors, wastegates may not be enough to handle the job of managing boost, so instead there are these dumps. Which can handle a much highler volume of exhaust then could say.....oh i dont know a wastegate.

[camaroman1181]

Re: Dumps for turbos?

im still not getting it.. ... i mean, thats teh point of a turbo.. use exhaust gas to spin an impeller, thus creating the vaccuum on the intake side to force compressed air into the engine. with open headers, you arent routing gasses into the turbos!??
if the turbos are too large for the application, use smaller turbos, use some form of relief plate, if somehow, there isnt a wastegate big enough (which im very skeptical about too) . I mean, these are pro drag cars... not like they cant change a plate every run.. i mean they tune their engines for optimal performance... agian, maybe im missing something, but if you want max hp, for max performance, then why waste energy by dumping exhaust gases before teh turbo???

[UDLOSE98]

Re: Dumps for turbos?

you realize a wastegate dumps exhaust before it hits the turbo right?

[camaroman1181]

Re: Dumps for turbos?

yes..... it helps regulate the amount of boost your car is making by allowing excess pressure to be released before the turbo... but im just not seeing how effectively allowing that wastegate to be open at all times is desirable for a drag car, where i would think youd want every last bit of boost you can make...

[UDLOSE98]

Re: Dumps for turbos?

i dont think he means at all times, i think hes talking electric

[crysmatic]

Re: Dumps for turbos?

we understand the wastegate principle...it's a valve that releases pressure between the exhaust manifold and turbine housing. when the valve opens, the turbine loses energy and boost. it's used to control max boost.

i think you are saying: electric dump = wastegate. with high exhaust flow, you need a very large wastegate/dump. whatever you call it. it's not that there is no wastegate, or that the car is running open dump all the time. no matter what you call the wastegate, it is NOT running OPEN headers!

you can buy 1.75" wastegates that flow over 900 hp. if we're talking 3800s, or even LS2s, you probably won't need more than that. a 1.5" wastegate would still be adequate for most cars on this board.

getting back to the original question: i plan to run headers with 1.625" primaries, 2.25" collector, 2.5" up pipe, custom turbo, 3" downpipe, and full 3" exhaust with cat and muffler.

you could run a dump AFTER the turbo (on the downpipe), but again, it's not going to make a huge difference if you already have a good exhaust. and imho open exhaust sounds like a$$.

[Kidcamaro98]

Re: Dumps for turbos?

i run a full 2.5" downpipe, and full 2.5" magnaflow exhaust....i have no cat. on my car and i make good low end power, and top end power....but i will be adding an electric cutout for next season at the track because its a provne fact that a open exhaust after the turbo ADD's horsepower....the faster you move the exhaust through your system, the faster you will spool up and the more power you will make...