Detroit 60 series RPM range

Dump valve, blow off valve, call it whatever you want. Once boost reaches a certain pressure it diverts any extra, unwanted boost, usually back into the intake, pre-turbo.


By moving air I meant the volume of exhaust gas it allows through it. A 1.58 A/R housing allows significantly more exhaust to flow through it than a 1.15 A/R housing but the 1.58 takes longer to spool up. The 1.15 spools up faster but can't let the volume through it that a 1.58 can which causes a high drive pressure ratio. The fix is to put a small housing with a wastegate. You get the spool up of the 1.15 and the ability to move the volume of exhaust that the 1.58 housing has.

They don't limit boost or power. They lower drive pressure to help maintain a 1:1 boost/drive pressure ratio.

 

You are absolutely incorrect. A wastegate controls boost pressure by the spring pressure in the wastegate. A blow off valves are not 100% neccessary as no big trucks have them, their function is to relieve pressure on the throttle shaft of gasoline engines.

 

My wastegate is fully open at 30lbs of boost. I'm able to make more than 70lbs of boost on top of that. When does it start controlling the pressure?

Wastegates don't control boost pressure; they control drive pressure.

 

I'd call that an overboost and is usually caused by a wastegate [hole] that is too small and therefore CAN' t control ie [bleedoff enough] of the boost . If you are running 100lbs of boost then you obviously don't care if you blow your engine it's balls to the wall. Why do you even have a wastegate, can't you just block it off. 'the hole not the puck'.

A blow off valve and a wastegate are two completely different concepts.

A wastegate WILL and does control boost if properly developed. They are not a one size fits all concept.
To me a wastegate includes the hole in the housing not just the actuator.

 

Again you are confusing a blow off valve with a wastegate.

 

I think everyone is confused a bit.

There are 2 types wastegates. Internal type that is inside the turbine housing on the drive pressure side .And external type that is down stream on the boost side.

Benjamin is correct to a point that the turbine wastegate limits drive pressure and that its main purpose is to stop over speed of the compressor . Does it limit boost ? Yes but not as much as a external wastegate. The external gates main purpose is to stop compressor surge or chuff when letting off the throttle fast between shifts. The computer controlled external wastegate now a days will also control boost pressures but this is more common on gassers.

Hope this help clear up the confusion

 

I'm not confusing the two, I'm saying that a blow off valve is what limits boost while a wastegate is what limits drive pressure.

My truck isn't overspooling...You just can't build an 1800hp Series 60 with 30lbs of boost. If you were paying attention you would understand why I have a wastegate. It's to get the quick spool of the 1.15 housing and the high flow of a larger housing. If I took the wastegate off, my drive pressure, which right now never exceeds a 1:1 ratio, would increase above my boost pressure with would limit how much boost I can make and lower overall horsepower.

 

So you are saying you are using the wastegate to control boost [although not in the traditional sense]. 1900 hp how long would that last in a highway truck?

It would seem that a wasegate controls drive pressure which limits boost by bleeding off exhaust energy

A pop off valve limits intake pressure [boost] by bleeding off excess back pressure.

 

How It Works: Wastegates Explained

Some good info to whoever is confused