Aftermarket BOV, performance or wank factor

[Cefiro_PWA]

Mate, it was a quick way of saying he (riceracing) has alot of knowledge for those not familiar with him, dont interpret my comment as a direct comparison or some form of competition....

Exactly, nice and quick.

Rice racing....... GOD of turbo and tuning.:werd:

[gtrGhosTDoGG11]

I believe the sound of no BOV ie the pigeons sounds tougher than any BOV, time to figure out to take out my BOV.

[Sydneykid]

Originally Posted by Cefiro_PWA

Mate, RICERACING ( peter ) has much more knowledge then anyone on these forums,and has a car that is 30 times faster and more upto date then Sydneykid will ever have..

nuff said.

Mate, it was a quick way of saying he (riceracing) has alot of knowledge for those not familiar with him, dont interpret my comment as a direct comparison or some form of competition....

Bummer, I was looking forward to a 20 lap race around Oran Park:cheers:

PS; I though I would clsoe with this quote from Peter

rotaries are renound for "ample" exhaust energy so maybe not the best example to see the responce gains of a BOV

[Roy]

Re the footage showing of the drag run? Is that what we are talking about here between gear changes...or are we talking about rolling up to a corner...oops a bit of oversteer so off the throttle...ok back under control and on the looud pedal only to find no boost? When changing gears in fractions of a second in an accelerwtion run, i think any difference is going to be so small it is negligible ?!?!?!

Yeah, well I have only gone up to a 3037S on my 33, approx 321rwkw (0.87exhaust ar on decompressed (8.5:1) rb25), so medium sized (close to a TD06, depending on spec) - I did notice a huge amount of throttle lag - thats why I diced the bov.  The D1 guy I am talking about uses a 2.2 stroked SR20 with T78, not really a small turbo as you suggested

Sorry Roy, but you lost me here, I find that sort of remark somewhat condescending - I tend to consider ALL ideas thoroughly and dont just accept the words of others as gospel.  I do say though, I give weight to the words of someone based on their experience - alot of weight, as I believe experience is so much more valuable than words and theory.

Sorry Steve, wasnt being condascending, sorry if it came accross that way. Just stating that its perhaps worthwhile to look at individual setups and if that accounts for ppls differenct experiences ...

And i dont know any drifters, but have seen pics/footage fo Jap cars, and a lot of the D1 cars have NOS bottles in their boots! The T78 2.2L you are thinking about, which workshop is it, is it running NOS?

When you say throttle lag, do you mean if you are pulling 5,500rpm in 3rd gear and you briefly get off and back on the throttle?

Anyway, im jumping out of this thread, they are always good for bouncing thoughts off one another, but perhaps its only going to go down hill from here:)

[Steve]

Re the footage showing of the drag run? Is that what we are talking about here between gear changes...or are we talking about rolling up to a corner...oops a bit of oversteer so off the throttle...ok back under control and on the looud pedal only to find no boost? When changing gears in fractions of a second in an accelerwtion run, i think any difference is going to be so small it is negligible ?!?!?!

Sorry Steve, wasnt being condascending, sorry if it came accross that way. Just stating that its perhaps worthwhile to look at individual setups and if that accounts for ppls differenct experiences ...

And i dont know any drifters, but have seen pics/footage fo Jap cars, and a lot of the D1 cars have NOS bottles in their boots! The T78 2.2L you are thinking about, which workshop is it, is it running NOS?  

When you say throttle lag, do you mean if you are pulling 5,500rpm in 3rd gear and you briefly get off and back on the throttle?  

Yes, that is what I am talking about, I agree completely with straight line rapid changing making very little difference.

No probs, the guy drove for Signal, AFAIK it didnt have nos.

Yes, that is exactly what I am talking about

Bottom line, its individual choice. If it works for your its all good. As I posted once before, I went from stock to aftermarket (on GTSt) and found an improvement - I swore by these things - until I took a step in the opposite direction.

PS, I though I would close with this quote (or two) from Peter (huge I know, but the guy writes so eloquently, I would love to meet this guy one day)

History on turbo race machines proves it.  

Every International Group C sports car to 1991 NO BOV  

Every F1 car from 1979 to 1988 NO BOV  

Every Indy car from 1970 to NOW NO BOV  

DJR Group A Sierra till its last races NO BOV  

...This is not an attack on anyone... its more a statement of facts as they relate to many examples from some of the most leading/respected race engine engineers of ALL TIME, from the greatest ever period of turbo charged race engines F1 from 1983 to 1987. BOV's are never mentioned as they were never required. Same in old publications like Turbochargers by Hugh McInnes, not one farking BOV mention in whole text ! They are a falicy of the highest order and people selling them are perpetuating lies by stating that they should be mandatory in high boost high HP applications. Complete and utter rubbish !!!!! ....

Hmmm local example  

1991 Bathurst race  

Caltex Sierra of Colin Bond equipped with BOV (see in car footage) comentators of the day describe it as shounding like doors on a bus opening, funny how they could not pick the traction control misfire on every corner as the car put it power down or when it went over humps on Conrod Straight, then amazingly came clean once the car straightened up ?  

Anyway car retires with turbo shaft failure !  

DJR cars running no BOV go on to finish race !  

There you go conclusive evidence that BOV's cause turbo failures in high boost race applications, these were very small shaft turbos, running very high boost and making in the region of 650bhp depending on which teams car.....

There is more evidence of BOV's causing performance loss and harm to turbos than giving any potential performance gains ! There are quite a few racers who refuse to use them cause they have the potential to cause overspeed of your turbo if they leak while you are under WOT full boost conditions.  

Many top level circuit racers site the same reasons for never using a BOV as its a potential source for failure that is hard to detect via the different systems on the car, hence they dont bother using them. Just like the "old" days when they never existed

[Beer Baron]

I did think about it long and hard, especially as it flew in the face of what I believed at the time to be true, but I had a problem (throttle lag) and was given a solution by a PRO DRIVER and EXPERIENCED JAP PERFORMANCE MECHANIC AND WORKSHOP OWNER.  What would you have done? ignored a well respected jap mechanic and pro driver with 15 years experience drivng and building performance cars?  Well I didnt, I listened, asked questions and tried to understand - I gave it a try, because I had NOTHING to loose - and I found he was not talking shit based on what others had said - he based his ideas on tried principals that work for him.  I have seen him solve problems on cars in minutes that others (here) had spend many hours on - respected, well know workshops - this guy KNOWS what he is talking about. Why would he suggest that I DOWNGRADE my setup?

may i ask who is this D1 driver/workshop owener? I am just interested that's all. would like to google up some info on the car set-up etc.

Thanks mate,

Richard

[Sydneykid]

I have read back through this thread and there is one point that I need to emphasise.

The "no BOV" supporters put forward the logic that by having a BOV you let all the pressure out of the inlet system. This means that pressure has to be rebuilt, hence "lag". The 'pro BOV" supporters point to the change in direction of the airflow, which has to be corrected, hence "lag". Both have an element of truth in them, that's the difficulty.

The real questions is which is better (ie; creates less lag)?

In a race environment (without giving out too many secrets) we tune the BOV so that it doesn't let all the pressure out of the inlet. Just enough so it doesn't stall the compressor.

An example, say I run 1.5 bar and 105,000 rpm shaft speed, I can tune the BOV so that on throttle off we maximise the compressor rpm (not less than 40,000 rpm) and still hold 0.5 bar boost in the inlet system (between the turbo and the throttle bodies). In practise this is not quite what we do, but it is conceptually sound.

So the question then becomes a choice between;

1. Full open BOV, zero boost and 80,000 rpm shaft speed

2. Controlled BOV, 0.5 bar boost and 40,000 rpm shaft speed

3. No BOV, 1.5+ bar boost and zero rpm shaft speed

Which gives the best performance? According to our data #2, but others may have different opinions. Not to be overlooked is the fact that we have the throttle bodies very close to the inlet valves. Perhaps in an application where there is a very large plenum between the throttle body/bodies and the inlet valves, it may well be a different answer.

[Steve]

Nice post Sydneykid, excellent food for thought! makes alot of sense.

Just on a previous post,

Lastly, on the engine dyno we can actually see the compressor blades turn backwards when we abruptly shut the throttle with no BOV. It is very easy to see using a timing light as a strobe.

What you are very possibly seeing is a harmonic frequency, which occurs because of the strobe light, just as wheel spokes sometimes seem like they are travelling backwards when cars accellerate and decellerate.

[Roy]

LOL...yeh its interesting to see that turbos from the turbo era didnt use them. But that was yesterday, just liek yesterday the car manufacturers didnt use them on std road vehicles:)

Id be more interested in seeing if todays WRC cars use them (perhaps a bad example as they use anti-lag), Indycars when on road courses, GT Race cars etc etc. These are race cars that use todays turbo technology.

But again many of these cars use anti-lag, i did have an article of the Millen Pike Peak Celica that run something like 2.2bar and it used a BOV?!?!?! I dont think this has a right answer:)

[xRHETTx]

What would happen if I plumbed my BOV into my exhaust turbine housing, and used a AFM to compensate for the air not flowing into the engine (stopping the rich spike)?

This way the compressor can freely spool when the throttle is closed, and the turbine can spool too. Wouldnt this be the best way to stop the turbo from slowing down between throttle loadings?

Would this be some type of crude anti-lag device, or just blow up? ;-)

[Steve]

another good article: http://autospeed.drive.com.au/cms/A_1457/article.html

Simon Gishus of Nizpro

the question is asked

"What are some areas where people often make errors modifying their turbo car?"

"The blow-off valve is designed as an emissions control device for OE manufacturers...The airflow meter is not all that smart and does not realise the air is going in the wrong direction; it therefore measures the air twice (once going into the engine and again going out in the wrong direction). The computer now tips in twice as much fuel as what's required, making it run rich - making it not pass emissions."

Also goes on to say that he has "...tested one on a manual gearbox performance car run at Winton Raceway. I think it was running 1 minute 40s back then, but it would lose 2 seconds a lap putting the gobble-gobble valve on. When you look at data acquisition, what you find is - as you change gear - the blow-off valve dumps all the pressure built up through the intercooler and pipes. It then goes back to zero manifold vacuum when you get back on the throttle, you have to build all that boost back up."

[psybic]

Is a turbo timer rice too??? it doesn't help performance, just helps keep your engine healthy.

What about air filters? they don't help performance, they just help it last longer, lets f#7k them off too.

How many big drag cars run no filters and no BOV's and no turbo timers? HEAPS!!!!! So lets all do that on our street cars, cause we all know that DRAG cars and F1 cars are AWESOME for cruising around with minimal time spent under the bonnet fixing stuff.

[Steve]

Beer Baron, his name is Bai, he was (until very recently) Signal Auto's D1 driver. He has his own workshop in Osaka.

[Steve]

Is a turbo timer rice too??? it doesn't help performance, just helps keep your engine healthy.

What about air filters? they don't help performance, they just help it last longer, lets f#7k them off too.

How many big drag cars run no filters and no BOV's and no turbo timers? HEAPS!!!!! So lets all do that on our street cars, cause we all know that DRAG cars and F1 cars are AWESOME for cruising around with minimal time spent under the bonnet fixing stuff.

What does turbo timers have to do with BOVs????

Do you really think your car, with its bov, will be able to maintain anywhere near the loads maintained by an indi car or an F1? think again.

If in the pinicle of racing where RELIABILITY and PERFROMANCE are paramount, with cars that make massive power - they choose not to fit one, but a street car, with alot less power, and no where near the levels of reliability has one - and thats relevant how? (try punting your car around an F1 track and see how long it lasts)

I really fail to see where you are coming from here.

[Sydneykid]

Nice post Sydneykid, excellent food for thought!  makes alot of sense.

Just on a previous post,

What you are very possibly seeing is a harmonic frequency, which occurs because of the strobe light, just as wheel spokes sometimes seem like they are travelling backwards when cars accellerate and decellerate.

Yep, I have allowed for that possibility, the same thing happens when you record it with a video camera. It is hard to show but you can now measure it for around $US350. Kernco make a Digital Laser Non-Contact Tachometer to measure up to 100,000 RPM. You place the reflective tape on the shaft to be measured, aim the laser at the shaft, and press the button for a reading. For turbo you could put the tape on one of the compressor blades and aim the laser into the inlet.

[Beer Baron]

Beer Baron, his name is Bai, he was (until very recently) Signal Auto's D1 driver.  He has his own workshop in Osaka.

yeah, i know (of) the guy. i believe i met him in Tokyo in january. he was also here for drift comp last year if i remember correctly seemed friendly enough, but i speak bugger all japanese and he seemed to speak bugger all english so not too much to talk about. i have always been particularly fond of the signal cars. very nice and very competetive

[psybic]

What does turbo timers have to do with BOVs????

Do you really think your car, with its bov, will be able to maintain anywhere near the loads maintained by an indi car or an F1?  think again.  

If in the pinicle of racing where RELIABILITY and PERFROMANCE are paramount, with cars that make massive power - they choose not to fit one, but a street car, with alot less power, and no where near the levels of reliability has one - and thats relevant how?  (try punting your car around an F1 track and see how long it lasts)

I really fail to see where you are coming from here.

Um thats EXACTLY my point dude.

My car is NOTHING LIKE AN F1!!!!

Thats why I'm saying people who were saying

"F1's don't run BOV's so theres your answer" are comparing something not worth comparing.

Turbo timers have nothing to do with BOV's nor do air filters.

My point there was:

Just because something is on your car to help it last longer and doesn't provide a performance gain, doesn't make it rice.

Man seriously, did you read my post at all?? Like in context of the discussion?

[Steve]

Yes, I did. Let me ask, did you read the rest of this thread, in its entirety?

did you check out the link to the discussion on the rotor forums?

if you did, I think you would find that the little I did quote isnt the be all and end all.

BUT, in context of reliability, yes, a indi car is needing reliability far, far more so than a street car.

And if you are trying to say a turbo timer increases reliability? well, I could suggest it is only a convenience, for those that dont want to cool their car down adequately before turnig off.

Argueably, they have a negative effect, as if you idle a car to cool it down, your water temps will go up, even though the oil temps go down MUCH better if you drive conservatively to allow things to cool down, rather than idling. Especially if you have been thrashing - like a cool down lap (sorry for the racing analgy, but race cars do require reliability as much as performance) If a turbo timer increased reliability, why dont they have them????

[Roy]

Beer Baron, his name is Bai, he was (until very recently) Signal Auto's D1 driver.  He has his own workshop in Osaka.

Is it the S13 or S15. I dont know what turbo the S13 is running, but i know the S15 is running a T78 so that could be it?!?!

And since its Signal and they arent likely to be letting the competition use something that will give them an advantage, i wouldnt half mind a friendly wager that the T78 S15 (white LMGT4 wheels) runs NOS, remembering the HKS / Apexi / Top Secret cars etc all use it?!?!?!?!

[Steve]

No that is in the S13 180sx - at least it was when I asked him about a year ago.

Bai's road car (an S15) I think is currently running a T518Z