Screamer pipes: Do they INCREASE or DECREASE BHP?

[@francisgallagher7189]

My 2 cents - by adding the additional flow from the screamer back into the Downpipe you’ve probably raised the volume travelling through the exhaust to the optimum level - and with the exhaust length and diameter it’s probably naturally scavenging like v8 boys try to achieve with specific length headers

[@4kinderboy]

I believe since the exhaust is being forced it would be creating a bit of a vacuum to further pull gasses from the gate allowing it to clear more efficiently.

[@perkins807]

I'd like to see the boost pressure for each run Runing the screamer probably allows the waist gate to work more efficiently keeping the boost under better control

[@risingstar1309]

I’m interested in that too, is is over boosting (minorly of course) without the screamer? Or under boosting (minorly) with it? Intriguing.

[@greenlightinsurance]

Car is on Syvecs S7+ Standalone ECU which has switchable maps. Both Runs were done on the same map setting literally back to back

[@mikeruthen6236]

Cyvecs or not your boost pressure will flactuate that very slightly anyway. And efficient boost control will drop the boost

[@mikeruthen6236]

Very simple physics. Exhaust pipe after turbo backpressure is keeping the wastegates valve that minute extra thus raising your boost pressure that tiny bit that your boost controller doesn't regilate. You only need .05bar to make 15hp at that power level.

[@jackgtir1]

glad someone knows what there talking about lol

[@Korruptionen]

As a Volvo guy, I'm super jealous we didn't get this car in the states. That car sounds rad.

[@En98zoomer]

we got them here in australia but its called a ford focus xr5 turbo. awesome cars with ever better engines

[@marcbirchley2418]

Get one one made, take a US Focus, take a 5 pot Volvo and put them together... import some stuff from us Brits or Aussies... only your imagination is stopping you... and money but its possible...

[@Korruptionen]

@@marcbirchley2418 I have a V70R, so it scratches that itch for me. I've swapped it with a later drivetrain and manual 6 speed and a few other bolt ons to help it breath better.

[@jonoclark1520]

Was the boost identical between the 2 runs? Was it struggling to control boost because it couldn't dump the exhaust out the screamer to slow turbo speed? Or was it like a mega scavenging effect increasing exhaust velocity away from back of turbo? Did boost increase?

[@risingstar1309]

Very curious.

[@greenlightinsurance]

Car Runs Syvecs S7+ ECU with switchable maps. The car was in the same map setting and boost pressure un-changed. When driving on track the Screamer seems to bring boost in slightly lower down the RPM and builds quick. These runs is on medium boost setting. On High Boost with E85 the car runs a faire bit more power but we did not have any E85 to use at the time.

[@mikeruthen6236]

@@greenlightinsurance this is the evidence why you see lower HP on the dyno

[@jackgtir1]

your extra power came from back pressure in exhaust , basically a small amount of boost creep made your extra power

[@qpzmak]

This all depends how much boost you are pushing, if you are running lets say same turbo one running 10 pounds and the other 20 pounds the one with 20 pounds will loose less power with the recirculated wastegate since it will be letting less exhaust gas out then the the one puvhing 7 ppunds

[@Antonchigurh69344]

External gate and screamer pipe control boost much better than internal, I’ve never seen a drop in power , the gain is the boost control

[@CAIDMASTEROFPYRO]

I have a screamer pipe because, I needed the car to be done and didn't have the time or budget to get a recirc fabbed up, and now I don't want to do it cause then I have to pay for another tune

[@pizletwizzler198]

Not too shocking... screamer-pipes dump directly into the atmosphere (~14.6959psi at sea-level) which acts as a natural baffle or restriction valve pushing back on exhaust gasses; whereas a turbine exhaust will constantly drive exhaust-gasses "down the system" creating a nice little flow-vacuum to suck excess pressure from your wastegate and pull it down/away from the system. Yes, you have the same pressure meeting the exhaust during exit, but now you have X-# of cylinders and a turbine assisting the wastegate's function. It's not technically "exhaust scavenging" because wastegates operate independently of valve-pulse or mechanical timing...

[@thelazycat_]

Maybe you can increase that effect by adding a venturi design that creates additional lower pressure in the system

[@-1dg4f-3]

all to do with back pressure imo

[@snu666]

Needing back pressure is a myth.

[@mehrshadvr4]

Maybe you'll on higher boost applications

[@risingstar1309]

I’d actually imagine the screamer would lower power because it might not flow as much thru the wastegate

[@lukepaul2882]

Who cares they sound sick