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The mkiv Supra Owners Club

BPU to Single...Final Impressions;)


wkdtime

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Terrible quality and view (I gaffer taped the camera to a washing power box and gaffer taped that to the back seat :D ).

 

Still on 0.9 bar and overfueling as it's not had a pro map yet, but gives the right idea ;)

 

Sounds superb, I know what you mean about running rich, mine's running rich too, but that's down to the limits of the Map ECU and 880cc's, I'll go standalone soon:)

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Terrible quality and view (I gaffer taped the camera to a washing power box and gaffer taped that to the back seat :D ).

 

Still on 0.9 bar and overfueling as it's not had a pro map yet, but gives the right idea ;)

 

That sounds great:cool:

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Is that the wastegate then or the air coming back in ????

 

It's already been explained by wkdtime, some more info:

 

The waste gate only lets excess exhaust gases out once the target boost has been achieved. It has nothing to do with the chatter you get on most single conversions when the throttle is released.

 

The chatter is caused by pressure from the manifold, IC and pipework being forced back though the system once the throttle has been release (hence need for pressurised air removed). This air has to go somewhere and can only go back through the turbo compressor. This is where the BOV comes in, once it detects this pressure after lift off it should open the 'dump valve' and allow the pressure to be released. In a single turbo situation, this pressure or air mass is too great for your average BOV to compare with and hence causes the air pressure to push back through the turbo and cause it to stall (bad). This is what causes the tsh tsh tsh sound on singles - it's compressor stall.

 

There are several ways to solve this, to properly do so requires a very expensive BOV (HKS racing for example), the cheap way is to fit a slow reacting XS power BOV, of fit a couple of HKS SSQV's.

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After finally getting use to the clutch and the way to drive the car, im totally loving every moment driving the Supe, the power is alot more linear and a hell of a lot more predictable.

 

But it doesn't just stop there, it truly has transformed the car....Once again thank you Michel:)

 

Conclusion.....If BPU was WOW then the Single is WTF OMG WOW:D

 

See the link for a taster.....and oh...the Turbo whistle:)

 

 

http://www.youtube.com/watch?v=roaVZwKrR8M

 

 

 

Any problems with traction? Even though you say power delivery is much more linear than BPU, I would have thought a single would come on much more violently and with your 19" wheels cause major traction issues in lower gears?

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Any problems with traction? Even though you say power delivery is much more linear than BPU, I would have thought a single would come on much more violently and with your 19" wheels cause major traction issues in lower gears?

 

It's the opposite. The power delivery is actually far smoother than BPU so traction issues while spooling are smothed out. The problem is that it makes so much power once the rpm's ramp up that traction is near impossible. Seriously sticky tyres are needed. R888's are next my list of upgrades.

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My car used to make that fluttering noise every time I took my foot off the throttle. I used to really like it, ...until my turbo bearings broke.

I think I'd better check my BOV is working properly before I fit the new turbo. Come to think of it I don't remember hearing the BOV ever.

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My car used to make that fluttering noise every time I took my foot off the throttle. I used to really like it, ...until my turbo bearings broke.

I think I'd better check my BOV is working properly before I fit the new turbo. Come to think of it I don't remember hearing the BOV ever.

 

I for one can clearly hear the BOV making it's usual noises (it's audible on the vid). However the 'turbo stall' noise is there at any RPM, regardless of RPM or boost.

 

Interesting discussion tough, might rip these posts out to tech to discuss further :)

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my stock tt makes this noise when coming off very light throttle, its not in the same league as that, but it definitly does it. I've read that the SSQV doesn't open at very very low boost and so you get slight compressor stall.

 

In the big pod vid i did you can hear mine do it just before pod section, after the convoy part, when the fella with the silver supe overtakes everyone :D

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Right that's it I'm having a single and that's final. As for the sound arguement it's the flutter sound that gets me going over the Tshh from a normal valve. Is that the wastegate then or the air coming back in ????

 

As Darryl said:)

 

It's weird how it makes it at even low boost and low RPM's.

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My car used to make that fluttering noise every time I took my foot off the throttle. I used to really like it, ...until my turbo bearings broke.

I think I'd better check my BOV is working properly before I fit the new turbo. Come to think of it I don't remember hearing the BOV ever.

 

Same here, i sprayed mine with WD40 as thought it may have been stuck. Only hear it when i lift off slowly now ???

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I too have the HKS racing BOV and get a lot of compressor stall,the HKS racing bov is supposed to have a very stiff spring and as said by a few top american tuners to not open fully unless you are running 21psi or more.So will actually worse for compressor stall in theory unless you are running high boost.

 

Even with the HKS Racing BOV on mine I get the same sound.
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