Greddy Turbo - Should I Weld on External BOV?

[infinite012]

omg no. stop.

The compressor will spin to infinity rpm if you have no wastegate, melting your turbo.

The intake air will get jammed into the intake pipe if you have no BOV, blowing your intake pipe off the engine.

In both cases, you still get an F for this class.

[King Tut]

Originally Posted by shiro

Furthermore, understanding that the waste gate regulates boost (PSI) level, why do I get a fudder noise when I let off on the gas at a high RPM with no BOV installed? I'm guessing that is because the waste gate is dumping the extra gasses not needed to produce the boost. Hence, would it still dump with a BOV installed?

You get a fudder noise because you have no BOV or way for the compressed air in your piping to escape once you slam the throttle closed so it heads back to your turbo. The wastegate starts opening as soon as you hit your target PSI and then opens/closes as needed to maintain your desiered boost level and then as soon as you let off the throttle and boost drops, it slams closed. Think of the BOV and wastegate as being opposites. Wastegate opens and BOV closes when it sees boost. BOV opens and wastegate closes when it no longer sees boost.

[shiro]

Originally Posted by infinite012

omg no. stop.

The compressor will spin to infinity rpm if you have no wastegate, melting your turbo.

The intake air will get jammed into the intake pipe if you have no BOV, blowing your intake pipe off the engine.

In both cases, you still get an F for this class.

Lol, no F+?

[shiro]

Originally Posted by King Tut

You get a fudder noise because you have no BOV or way for the compressed air in your piping to escape once you slam the throttle closed so it heads back to your turbo. The wastegate starts opening as soon as you hit your target PSI and then opens/closes as needed to maintain your desiered boost level and then as soon as you let off the throttle and boost drops, it slams closed. Think of the BOV and wastegate as being opposites. Wastegate opens and BOV closes when it sees boost. BOV opens and wastegate closes when it no longer sees boost.

Right on; sounds like the push-pull method in martial arts. Love it!

[Cessblood]

A few FRSs and BRZs is running the greddy turbo kit without a BOV. Ken Gushi's Firestorm red FRS doesn't have a BOV, Greddy's raven black FRS track car doesn't have a BOV, Mackin's FRS doesn't have a BOV, and notorious BRZ's doesn't have a BOV. When I called the Greddy tech about the kit I asked them why are they not using a BOV, they said the kit doesn't really need it. I got a BOV anyway.

[shiro]

Originally Posted by Cessblood

A few FRSs and BRZs is running the greddy turbo kit without a BOV. Ken Gushi's Firestorm red FRS doesn't have a BOV, Greddy's raven black FRS track car doesn't have a BOV, Mackin's FRS doesn't have a BOV, and notorious BRZ's doesn't have a BOV. When I called the Greddy tech about the kit I asked them why are they not using a BOV, they said the kit doesn't really need it. I got a BOV anyway.

I think this thread might help those that want to get the Greddy Turbo Kit have a better understanding of it's design. Greddy USA said the same thing to me. I just really like the sound

[STV3]

Its always better to have a bov to reduce the stress on turbo. When the air bounces off the closed throttle body you have the air going back through the turbo trying to spin it the other way while the exhaust is still spinning forward.

[Element Tuning]

I'll give you guys the tech on BOVs. First off I bet the race team doesn't use the BOV because it doesn't work well. I've probably tuned with every BOV made and you would think its impossible for them to leak but some do and the best do not.

A BOV actually works off of pressure differential between the top chamber and the bottom of the valve (part connected to the charge pipe). This is why a BOV can vent at partial throttle and it's part of the reason why a drifter or racer my not like how the BOVs reacts to throttle inputs. If you bov has a light spring pressure differential is reached easily causing the bov to dump and therefore the driver must continue to dip into the throttle more and more to maintain speed. I can't stand that so I run a BOV that not only has a very stiff spring (requires high pressure differential) but also bas preload adjustmentt to fine tune it. This way when I apply 50% throttle boost increases and I get a steady rate of acceleration and my BOV only dumps when I slam the throttle shut.

Ok nerd button off

Thanks,
Phil Grabow

[shiro]

Originally Posted by Element Tuning

I'll give you guys the tech on BOVs. First off I bet the race team doesn't use the BOV because it doesn't work well. I've probably tuned with every BOV made and you would think its impossible for them to leak but some do and the best do not.

A BOV actually works off of pressure differential between the top chamber and the bottom of the valve (part connected to the charge pipe). This is why a BOV can vent at partial throttle and it's part of the reason why a drifter or racer my not like how the BOVs reacts to throttle inputs. If you bov has a light spring pressure differential is reached easily causing the bov to dump and therefore the driver must continue to dip into the throttle more and more to maintain speed. I can't stand that so I run a BOV that not only has a very stiff spring (requires high pressure differential) but also bas preload adjustmentt to fine tune it. This way when I apply 50% throttle boost increases and I get a steady rate of acceleration and my BOV only dumps when I slam the throttle shut.

Ok nerd button off

Thanks,
Phil Grabow

Lol, the stiffer the better...what she said :P

Thanks for the input!

[midnight23]

Videos please @shiro !

[shiro]

Sure, I'll see what I can do after work on uploading a video here / youtube

Originally Posted by midnight23

Videos please @shiro !

[shiro]

Took some time to get back to you all; it's been a really busy week. For right now I have my Dyno chart to post up. Let me know what you think. She feels like a rocket when the 1000cc IDs kick in at 5K RPM

[ft_sjo]

There's some awesome factoids in this thread (I recommend looking up what a factoid is).

I'll add some of my own..

- Lots of cars came from the factory without re-circulation valves
- They don't tend to do that these days due to the MAF base configurations
- Modern turbochargers like the GT range with delicate ball-bearing cores are spec'd to be used with a re-cir valve. The shafts are thinner than the old T-series, for example, and are prone to breaking without suitable measures in place.
- You do not necessarily need a wastegate to control boost. Lots of engines effectively run without wastegates when the engine and turbocharger are specified correctly.


Yours Unicorningly,
Unicorn.

[King Tut]

Originally Posted by shiro

Took some time to get back to you all; it's been a really busy week. For right now I have my Dyno chart to post up. Let me know what you think. She feels like a rocket when the 1000cc IDs kick in at 5K RPM

Attachment 52262

Very interesting. That small turbo didn't spool as quickly as I thought it would, but that 14 psi hit gave you a real nice torque peak, unfortunately it starts tailing off immediately and you drop to 10 psi by redline. Still I am very impressed with the kit and I bet it does feel amazing at 5000 RPM.