Single or twin external wastegates?

[Howitzer]

Hi all,

My engine is currently set up to run with a seperate wastegate and inlet on each bank...



I will be chopping off the elbows on each inlet and linking them together with a Y piece and having the throttle body on the end as I have little space either side of the engine currently due to the chassis.

I want to run a single throttle body for simplicity but was wondering if it was also better to run a single external wastegate linked into both manifolds?

Dave

[Slinky]

Wastegate + Inlet = ??

Wastegate + Turbo/Exhaust = Understood..

Are we talking dump valve instead of wastegate?

[Howitzer]

The boost control originally on it was a far too complex set up, I want to simplify it as it's just a basic drag car.

The original system literally operated as 2 seperate engines on a common crank and I think that is a waste of time for what i'm trying to do.

It was mentioned a while back how it would be simpler to run a single linked wastegate, but this would involve more exhaust work, I can't really see an argument for and against either system at the minute so want to be sure i'm not missing anything.

Dave!

[liner33]

If you have two turbos i expect two wastegates would be best , same for blow off valves if you have two throttles then your will need two blow off valves, there is some discussion as to whether drag cars need blow off valves at all though

[Howitzer]

The main reason for not using a BOV is that I hate the noise and want the car to be as quiet as possible when on the road.

Am glad I wasn't going against the grain with keeping the wastegates.

Cheers.

Dave!

[liner33]

For the road I would certainly have a BOV , i've tried my car with and without and the noise is sharper with the bov ie more of a pop but turbo chatter on my car is still pretty loud , quietest option by far is a re-circ bov

[c7mct]

Single or dual, take your pick as long as the single is large enough to vent enough exhaust gasses it does not matter,a waste gate does not improve performance it purely controls. make sure where the wastegate is plumbed into the manifold it is the same for both banks (wastegates exhaust both flow and pressure). For greater control its advisable to branch off the manifold on the outside of a bend after the merge.

Edited by c7mct on Saturday 28th March 10:27

[Howitzer]

Thanks for the replies chaps.

They are positioned in the correct place so they will be staying.

Dave!

[BB-Q]

For a vehicle being used on the road as well you need bigger wastegates to keep control of the turbos.

With regard to dump valves or recirc valves- you need to have something. A turbo really doesn't like trying to stall from 100,000rpm. In some cases it can shatter the compressor wheel, which in turn will be ingested by your engine. As mentioned above, compressor bypass valves are the quietest. Bailey do them for about £80.

[liner33]

Had a long discussion on another forum about dump valves and the term "stall" some think the term wasnt appropriate as it infers that the turbine stops rather than that the airflow over the blades is disrupted and the airflow "stalls" , i personally have no doubt that the turbine is dramatically slowed by the build of pressure but this opinion isnt widely held in some circles

Either way it takes seconds for me to disable my BOV so i've tried both ways and I'm convinced the car is quicker using it than not.