Turbo spool and downpipe size?

550roofer

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If i do muffler delete, keep the cat, will the turbo be spooling to fast if I add a SCT X3 with a medium level tune (80hp would be nice)

Will a bigger down pipe slow the turbo speed or let it run faster?


I thought the rpm of the turbo would be to high with a stock DownPipe since the increase in exhaust air has to flow faster through a small area. Where as if i increase the down pipe size, the air doesn't have to move as fast to allow the same volume of air out.



i want to keep the cat, but will it be too restrictive and cause high back preasure. I don't need a blown headgasket, warranty ran out already.


Getting gauges soon, so many out there, im thinking wideband. they seem like a very accurate gizmo
 

95_stroker

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You will spool faster with a larger downpipe. The SCT X3 wont make it spool "too fast".

What the bigger down pipe gets you is less restriction and freer flowing air which allows the turbo to spool up better, same theory in removing the cat and muffler.

A blown head gasket isnt caused by excessive back pressures from an exhaust system, its caused by excessive combustion pressures with in the engine.
 

550roofer

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thanks for clearing that up

I've heard a rumour that dual tail pipes are not neccasary. is there a need for some back preasure with a turbo set up? i was thinking id just do a mufffler delete and cat test pipe. do u think there would be a BIG difference with a turbo back exhaust. its gonna make some difference, but i'll be adding a modest amount of horsepower soon and wanna keep it quiet so i might put the cat back on. how much horsepower is the stock exhaust rated for, or where would i find info on stock ford specifications?
 

95_stroker

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The turbo is your backpressure for your engine, anything downstream of that is in the way. Now that doesnt mean its not necessary, ie; cat for environmental reasons or muffler for noise reasons. You can get +400 hp through a stock exhaust system.
 

DaveBen

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The turbo would be happiest if you left the exhaust pipe off. Zero back pressure. The neighbors would NOT like it.

Dave
 

CAREYBO

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If i do muffler delete, keep the cat, will the turbo be spooling to fast if I add a SCT X3 with a medium level tune (80hp would be nice)

Will a bigger down pipe slow the turbo speed or let it run faster?


I thought the rpm of the turbo would be to high with a stock DownPipe since the increase in exhaust air has to flow faster through a small area. Where as if i increase the down pipe size, the air doesn't have to move as fast to allow the same volume of air out.

DO NOT LISTEN TO HIM! THE TURBO WILL NOT SPOOL FASTER WITH A LARGER DOWNPIPE...
IT WILL SPOOL SLOWER AND ALSO LOWER EXHAUST GAS TEMPS!!!

A SMALLER DOWN PIPE WILL RAISE EXHAUST GAS TEMPS AND SPOOL UP FASTER AND YES THERE WILL BE MORE BACKPRESSURE..........


i want to keep the cat, but will it be too restrictive and cause high back preasure. I don't need a blown headgasket, warranty ran out already.


Getting gauges soon, so many out there, im thinking wideband. they seem like a very accurate gizmo
..........
 

550roofer

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i think i'll keep the muffler and take the cat off, this should keep it quiet and give me the power i need with the X3
 

BIG JOE

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What 95 stroker said, for sure.

Anything we do to relieve any exhaust back pressure improves efficiency. Bigger Pipe, No muffler, No cat, Free flow muffler.. whatever. Staying with the stock exhaust, with it's Crush bends, S curves.. with or without a muffler or cat ? Havent moved very far toward Efficiency.

But everything is relevant. In-Take air volume and it's efficiency is as important as exhaust flow efficiency.

Then.. Fuel mapping. More Fuel needs to be injected, at the right time.. into the turbo charged air....(The SCT X3 will do that fer sure)

The Turbo will take care of it's self.. in direct relation to Intake AND Exhaust efficiency. Doubt very much you would hurt it with, or without the parts of a stock exhaust. EGTs need to be watched though.

Just an Opinion.. But i think most would agree.. a valid one.

;) :)
 
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550roofer

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sounds like what i want is a straight pipe on a butterfly valve. i could keep the stock exhaust and then when i'm out of my small nieghbour hood i could open the valve on the straight pipes. noise is very important to keep quiet.

i seen this on an audi S4 but seems expensive
 
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