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The mkiv Supra Owners Club

Removing Stock BOV altogether ??


j1mb0b1

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id rather not risk it, if toyota fitted them then i suppose it was for a purpose, they do sound nice and if i get the revs just right around 3 tho and let of slowly i get the single sound so im happy. Uk running 1.35.

 

Yup, noise suppression :eyebrows:

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I have not run a blow off valve, recirculating, or vented to atmosphere, on a high performance turbo engine for years. IMSA GTP turbo cars, Le Mans prototype turbo cars, F1 turbo cars, the new 450 bhp F2 Mazda engined turbo cars, the AER 4 cylinder 600 BHP 2 litre turbo engine, blah blah, (engines ancient and ultra modern), none of these run a blow off valve. They were instigated by Saab on the 99 Turbo engine, and made by Bosch, as a means of STOPPING turbo noise, which was deemed inappropriate for owners of cars who didn't know what a turbo engine may, or should, sound like, and inappropriate for a refined car without real sports car pretensions. Urban myth has given them magical qualities, mainly of reduced lag, and that running without one will kill the turbo. Turbo Dynamics, Turbo Technics, BBR and others all agree, not to mention that I feel it safe to say that if these myths had foundation F1, IMSA, Porsche and AER would have put a tuppeny bit, and lightweight valve on their engines!

 

I'm convinced :cool:

 

Another bit of useless tat coming out of the engine bay this weekend :innocent:

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Le Mans cars had to run for over 24 hours at race speeds, so anything that gave the turbos an easier time would be used, especially something small, light and simple. Anything that reduced lag would be used. They weren't, so I have to let the end user decide. It's hardly costly to renew, so if anyon'e uncomfortable just renew the stock one, although in all the years I have worked on the MKIV TT I have seen exactly *ONE* that was leaky or faulty.

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my understanding was always that BOVS were designed to relieve the intake system after the throttle plate closes not for sound depression. I couldnt justify removing it from the system entirely, i mean wheres the air thats in the pipes going to go except backwards out the way it came, through the turbos, causing the blades to slow down which in term causes lag as they have to spin back up again plus all that air going back out cant be good for the turbos at all surely?? :shrug:

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my understanding was always that BOVS were designed to relieve the intake system after the throttle plate closes not for sound depression. I couldnt justify removing it from the system entirely, i mean wheres the air thats in the pipes going to go except backwards out the way it came, through the turbos, causing the blades to slow down which in term causes lag as they have to spin back up again plus all that air going back out cant be good for the turbos at all surely?? :shrug:

 

Thats always been the assumption but i guess the lack of load in the engine means that there isn't enough back pressure for it to matter.

 

It would be an issue with high boost levels though, again just my opinion.

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I think he was referring to the vent to atmosphere ones lol.

 

I did indeed mean the vent to atmosphere ones.

 

Think the main thing with a BOV on something thats not putting out a vast amount of volume and pressure is that the impetus that is already spinning the turbo can compress the gasses just enough so that the "stall" on the turbine is negligable.

Also obviously the bigger the turbine the greater the effect back pressure will have due to the area of the turbine.

Would be interesting to know at what size there is a positive benefit from utilizing a BOV

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