atmospheric or recirculating?

[Rallye]

So whats the standard s2 wastegate, is that a posh name for atmospheric dv ?

wastegates and atmo/recirc DV's are a totoally different parts, which do different things

[Ski]

So why is it called a wastegate and not a dumpvalve? sorry to ask the obvious, i have about 50 years of engineering evolution to catch up on

[CR500Dom]

So why is it called a wastegate and not a dumpvalve? sorry to ask the obvious, i have about 50 years of engineering evolution to catch up on

Because it deals with Waste exhaust gasses and the majority of them open like a gate.

Dump valves dump excess pressure in the inlet tract, post compressor, either to atmosphere or intake upstream of compressor as Paul already explained.

HTH
Dom

[Ski]

I think i will stick with my wastegate untill a "mechanics for dummies" book is released

[meep]

I think i will stick with my wastegate untill a "mechanics for dummies" book is released

Ok a wastegate is after the engine so to speak. It decides how much exhaust gas will go through the exhaust side of teh turbine and how much that will pass besides it. When your boost is reaching desierd levels the wastegate opens and lets some exhaust gas by the turbine. This lets the turbo keep a constant level of boost. Without the wastegate your turbo would boost untill it cant push any more air for some reason. This would something in the line of 2 bar or more. This would in turn lead to your engine going to bits and the turbo would probably be abit less lively to.

A dump valve is something that is on the inlet side of the engine. When you close the throttle the air that is pushed in to the engine will go against a brick wall so to speak and has nowhere to go.
When the turbo cant push any more air into the very small compartment that is the inlet pipes it will stall. And it will be a violent stop to. This in turn is very bad fot the bearings and shafts that connect the exhaust and inlet parts of the turbo. A dump/pop off - valve is simply a valve that opens when the preassure in the inlet pipes reaches a certain value.
Because of this the turbo will be able to continue to spin and not do a total halt.
The difference between a recirculating valve and an atmospheric one is that while the recircualting will route the dumped air in the inlet pipes before the trbo again the atmospheric will just dump the air under the bonnet.
In that respect the recirculating one is better since it will spool the turbo abit.

Sorry for the bad english im from sweden so some words might be spellet badly.

Hope its abit clearer though.

Edit:

Ohh yea as for dummy books on engine there are a couple that are really good and prety easy to understand.

Forced Induction Performance Tuning: A Practical Guide to Supercharging and
ISBN: 1859606911

Maximum Boost: Designing, Testing, and Installing Turbocharger Systems
ISBN: 0837601606

Four-Stroke Performance Tuning
ISBN: 1859604358

MODERN ENGINE TUNING
ISBN: 1859608663

Turbochargers
ISBN: 0895861356

I would try and go to a book store and se if they have any of them and look through em abit to get the feelling for wich one suits you. Happy reading and dumping

[jg_bgt]

So Recirc = better spool up than Atmosphere and Atmosphere = Bigger Noise
??
but other than that little difference?
Jon

[Greg_S]

pretty much, they both do similar jobs. The idea of the recirc part is that the air is fed back into the turbo inlet to help keep it spinning. So when you have selected the next gear you have less lag

[Smith_S2]

just a quick question does a waste gate valve open on an ABY even when your not on the turbo and lifting off the throttle? Mine seems to dump all the time. I like the sounds of putting a cone filter on. Please send me info

[Smith_S2]

not waste gate valve, dump valve

[Jas11n]

If you mean the DV (dump valve, better described as the throttle bypass valve)
Then yes, it's open when not on boost.
Vacuum in the inlet manifold holds it open, jump on the go pedal and it snaps shut when the inlet see's boost rather than vacuum, shut the throttle and it opens again.
Drive off boost and it stays open.

Jas..

[Billman]

Anyone has Experience with these valves? Is this design better than the classic "Forge Style" single Piston?

http://cgi.ebay.de/Turbo-Blow-Off-Po...QQcmdZViewItem

[GT500]

Anyone has Experience with these valves? Is this design better than the classic "Forge Style" single Piston?

http://cgi.ebay.de/Turbo-Blow-Off-Po...QQcmdZViewItem

Thats a HKS copy, with the recirc adapters. Probobly a good thing. Got to be better than a Bosch plastic christmas cracker effort!

Try it, its a good price!

[Billman]

in this site you could hear many types of Blow off valves but the HKS SSQ has many different sounds from High pitch sound to low frequency shooting like.

I like this one:

http://www.935motorsports.com/media05/Evo8SSQV.wav

[Floppy]

Hmm hard to decide. I like all these sounds but less lag is also a god gift.

Wish we had bi-turbo 1 recirc and 1 atmos

[KaraK]

I recently swapped my atmos DV on the scooby (dont look at me - it had one when I bought it) for a stock re-circ one and as much as the noise appealed to the 10-yr old kid inside of me the reduction in lag when shifting is massive so I'm much happier with the re-circ.