propane turbo build

[Landcruisin'60]

I wouldn't label everyone who has an atmospheric dump BOV as a ricer. The vast majority are. But with proper tuning there are performance benefits to an atmospheric dump.

Other than what you say about a using a BOV for boost control I think we're saying the same things in slightly different languages.

I did some quick research and came up with nothing in terms of a BOV for boost control. Please link some information so I may read about it. I'm very curious.

 

[rover67]

well got it done and hopefully tomorrow tune it in a little and run some exhaust and put a oil restrictor in and I will be ready to go wheeling this weekend and break something
YouTube - jodys turbo?

SWEET!!!!

 

[ntsqd]

I don't have any links. A BOV is a valve designed to blow open when the pressure exceeds it's setting. Works exactly the same as the over-pressure safety valve used on air compressors and it does the same job. Because of it's location it has the least system inertia and will react the quickest. A WG has the inertia of the two columns of compressed gases and the rotational inertia of the shaft and wheels to overcome before it's effect will be felt by the system.

I don't see a performance benefit in an atmospheric dump from a BOV. All that I'm seeing is that doing so will cause an over-rich condition during the time that the BOV is open and for a short period after it closes. What am I missing?

 

[Landcruisin'60]

I'm well aware how a BOV works, I'm also very informed in the world of stock and custom turbo applications. Never have I heard of such a set up where a BOV is used for boost control. Your lack of available proof leads me to believe no setup is commonly used. It really makes no sense. Ok, so the engine in my Subaru runs 22psi of boost, limited by a 38mm Tial EWG. If I were to use a BOV for boost control the turbo would be spinning at a much higher speed to generate the 22psi if a BOV were bleeding the boost off rather than the WG slowing the turbine speed to control boost. That extra speed is going to wear out my turbo faster. At $1000 for the turbo I'd rather not put any added stress on it and for what? Its still 22psi. I'm also curious what the effects of constantly recirculating pressurized air would have on the performance of the turbo.

An atmospheric BOV does cause a rich condition on a draw through MAF set up. But as I said in properly tuned vehicles (read: speed density, blow through MAF set up or no MAF at all) it can have a positive effect on performance. Basically when you recirc the air you're creating turbulence in the intake. Turbulence is bad for performance. Same reason people run atmospheric dumped EWGs.

I had an atmospheric dump BOV on my last Subaru. I noticed no performance losses. It only flashes rich for a fraction of a second as shown by my wideband.

 

[ntsqd]

Tell me why anyone would want a BOV for any application, because I'm mystified what it's use is if it does not limit boost.

As I seem to have to keep saying, the BOV is much faster reacting than a WG. It will respond to exceeding the desired boost limit much faster than the WG can. Ultimate boost control is the job of the WG. Immediate boost control is the job for the the BOV.

I've said this before, but it doesn't seem to be making a dent so I'll try one last time; with the BOV set slightly below the WG's limit the BOV will pop open when the throttle is slammed closed from a WOT or nearly so condition during a shift. That vents boost to somewhere other than up against the closed throttle plate, which keeps the compressed air column from acting as a brake against the compressor wheel and causing the shaft to slow down. Because this is a high speed transitory condition the WG will not respond fast enough to start limiting boost. This keeps the turbo shaft spinning near it's max speed or at least in it's map so that when the throttle is opened again the BOV will close and you'll have an already spooled up turbo making boost in the next gear.

Of course, my employment developing this turbo probably means that I don't know anything at all about turbos. I know that there is a lot about matching turbos to applications that I don't know, but how a turbo works and what it wants to do it's job, and even how to destroy them intentionally is something that I've been immersed in for the last 3-4 years.

Turbos don't wear out from excessive speed, they blow up from excessive speed. Turbo's wear from cold starts-ups, hot shut-downs, and from hours in service. IF the bearings & seals used are quality parts and of the correct specs then it should be many, many, many hours in service. A shorter turbo life span is the fault of the support system(s), not the turbo.

Turbulence, in the right place, is the best possible condition for engine performance and economy. Look up "tumble ports".

 

[Landcruisin'60]

Proof....I will say it once more. You are unable to provide proof. I can provide countless hours of reading for the proper use of a BOV. Which is to release the pressure between the turbo and throttle plate when the plate is closed. I have never heard of what you're talking about.

Please read this informative article.
BOV

Funny my WRX comes stock with TGVs: tumble generator valves. Oddly enough one of the most common things to do when seeking higher power levels is to delete them to cause a smoother flow through the intake.

 

[motoman426]

I think he is thinking of a boost controller plus a blow off valve usually the vroom
Vroom go fast cars run them both at the same time and that is where he is getting that a blow off valve only works when it senses vacuum the waste gate goes off pressure

 

[ntsqd]

.....Which is to release the pressure between the turbo and throttle plate when the plate is closed.

Your own quote is all the proof that I need to support my statements. If that isn't boost limiting then what is?

Coming from a professional engine development employment situation I do not read articles on the net as they are rarely scholarly and are usually full of errors, omissions, half-truths, and WAG's presented as fact. Even when they are authored by someone who should know better.

 

[Landcruisin'60]

That link explains that a BOV only opens to vent the compressed air trapped between the compressor and TB when the plate is closed. It makes no mention of using it to bleed off pressure to control boost. Opening to release the pressure when the throttle plate is closed IS NOT boost control and has no correlation to the WG or its function.


Motoman boost control whether it be an MBC (manual boost controller) or EBC (electric boost controller also called an electric boost solenoid) is run inline of the compressor housing to the WG, again it has no connection to a BOV or bypass valve.

 

[motoman426]

I know where a boost controller goes and I know what both are as far as waste gate and a blow off valve like I said the waste gate is what limits controls or whatever u want to call it. The blow off valve doe not do that because it doesn't open upon boosting situation it only opens at vacume. The blow off valve dumps the air in between the turbo and throttle plate so that it doesn't cause the turbo to suddenly stop.

 

[motoman426]

here are a couple pics from the weekend and so far I have seen 10lb of boost but it is kinda hard to pay attention to it when wheeling and trying to watch everything else but when it comes in it is very strong

 

[72rockcruiser]

Nice!

 

[motoman426]

yeah I hit so hard it opened the tank brackets and my propane fell out I guess I am going to have to ratchet strap them for a little extra security but other that that it was awesome

 

[72rockcruiser]

How big around are those propane tanks? I think I have some really big hose clamp-type things laying around somewhere that might work good. You can have them if they will work.

 

[motoman426]

I have actuall fork lift tank brackets but under that much hit they do not stand to well I think I am going to cut them out and make some differnt mounts to make sure they stay in place I know they will with a ractchet strap but I dont know what I will do. The tanks are probably about a foot across

 

[ntsqd]

That link explains that a BOV only opens to vent the compressed air trapped between the compressor and TB when the plate is closed. It makes no mention of using it to bleed off pressure to control boost. Opening to release the pressure when the throttle plate is closed IS NOT boost control and has no correlation to the WG or its function.

No, by your description that is how the BOV is tuned to function, not the only way it can be made to function. Take a good look at how they are made and how they operate. There is no reason that they can not be used to limit boost, they just aren't tuned to function that way.

There is no reason that the BOV can not be used to limit boost like it does when the throttle plate is closed. As I previously mentioned, a very highly calibrated and repeatable blow-off valve was used by several high end racing sanctioning bodies to limit the boost to the same amount for everyone. Those valves belonged to the sanctioning body and were bolted onto the top of the plenum above the throttle plates for each race. The sanctioning bodies did nothing with the WG to control maximum boost.


All of this is moot anyway, with a draw-trough system a BOV would be pointless or dangerous depending on placement.

 

[Tapage]

but in that scenario the BOV will open progresive ( limiting boost ) or suddenly as it should do in it " normal " function ..?

 

[dohcdelsol93]

all this arguing over BOV's....In any throttle body type system there should be a BOV. It reduces stress on the charge side of the turbo.

When your putting a load on the engine (racing/towing) and immediatly let off the gas to change gears or slow down all that air moving will hit the closed butter fly causing a chain reaction that puts stress on the turbo.

By using a BOV you reduce this stress because it allows the pressure in the charge pipe to drop to the pressure in the intake manifold (back side of the throttle body)

In most stock turbo vehicles the mass air flow sensor is before the throttle body. This is a pain in the ass. You must run a re-circulating BOV to keep the sensor from going crazy on you. For those lucky enough for a throttle body mounted MAFS you can keep the set up simple and clean and vent into the atmosphere.

IMHO the best place to put a bov is between the turbo and intercooler. The turbo will react quicker since it has less air to push and less of a distance to push it than it would if it were an atmosphere release BOV mounted on the charge pipe up near the TB.

a BOV certinaly does not work as a boost controller, a boost controller through your waste gate. All a BOV does is relase charged pressure on the charge side of your turbo to relieve stress on your turbo. Is it a must...no...but for long term reliablity i think it's a great option.

As for an EGT gauge, it's useful if you can figure out which cylinder burns the hottest and mount it there otherwise it's going to give you skewed results and your no better than a ricer with and EGT gauge or a narrow band O2 sensor on a stock engine with an intake and exhaust.

I recomend a wide ban 02 sensor. Mount it, tune by it and keep your car safe with it. A lot of professional tuners don't even use an EGT gauge to tune but they all use a wideban 02.

 

[Mace]

all this arguing over BOV's....In any throttle body type system there should be a BOV. It reduces stress on the charge side of the turbo.

When your putting a load on the engine (racing/towing) and immediatly let off the gas to change gears or slow down all that air moving will hit the closed butter fly causing a chain reaction that puts stress on the turbo.

By using a BOV you reduce this stress because it allows the pressure in the charge pipe to drop to the pressure in the intake manifold (back side of the throttle body)

In most stock turbo vehicles the mass air flow sensor is before the throttle body. This is a pain in the ass. You must run a re-circulating BOV to keep the sensor from going crazy on you. For those lucky enough for a throttle body mounted MAFS you can keep the set up simple and clean and vent into the atmosphere.

IMHO the best place to put a bov is between the turbo and intercooler. The turbo will react quicker since it has less air to push and less of a distance to push it than it would if it were an atmosphere release BOV mounted on the charge pipe up near the TB.

a BOV certinaly does not work as a boost controller, a boost controller through your waste gate. All a BOV does is relase charged pressure on the charge side of your turbo to relieve stress on your turbo. Is it a must...no...but for long term reliablity i think it's a great option.

As for an EGT gauge, it's useful if you can figure out which cylinder burns the hottest and mount it there otherwise it's going to give you skewed results and your no better than a ricer with and EGT gauge or a narrow band O2 sensor on a stock engine with an intake and exhaust.

I recomend a wide ban 02 sensor. Mount it, tune by it and keep your car safe with it. A lot of professional tuners don't even use an EGT gauge to tune but they all use a wideban 02.

A draw through system uses a TB. Are you saying that a draw through needs a BOV?

 

[dohcdelsol93]

A draw through system uses a TB. Are you saying that a draw through needs a BOV?

a draw type system would i think (in theory) put less stress on a turbo when going from full boost/WOT to little/no throttle than a blow through system. A bov would have to be re-circulating in this set up as the released gasses/air could become a really cool flame thrower. the bov is not a "need" item in any turbo set up but i do think it's a good way to help prolong the life of the turbo.