Ok I have a question, a turbo works off the exhaust gases, correct me if Im wrong.

Therefore some time is required from proper spool for the turbine to reach max speed. A blow off valve is than initiated once the turbine has sped up enough and the gas pedal is slightly released.

My new question is say you have an air force that is constant, there is no spool up, you just have max turbine speed from the time you start the car to the time you shut it off, how would the blow off valve react, would it constantly be letting off air, or would it work the same as if the air force was spooling up and the gas pedal was being let off? What im trying to get at is once you hit the bov the turbo slows down and has to spool up again, but what if there was a constant force, and nothing had to spool up, would it just be blowing off a hell of alot more air, would the bov brake???

I'm not exactly sure of how a blow off valve physically works, is it pressurized by vacuum and than once vacuum is lost by letting off of the gas pedal does it than blow off the forced air?

thanks for any help, and no dont get any ideas im not trying to make a fake blow off valve or anything, i have a very big imagination =D

 

A blow off valve works when there is boost pressure built up and the throttle plate is closed. If you didn't have a blow off valve or recirculation valve, pressure would spike because the compressor in the turbo is still turning and moving air. This is bad for the compressor so when the pressure goes above the limit for the valve, it opens and vents the pressure.

If you had a constant pressure source which didn't change with engine rpm, I would assume you would need something like a wastegate to control how much pressure is in the intake by partially opening and venting out some of the air.

I'm no FI expert by any means but that is how I understand it.

 

if u had a turbo that was constantly spooled u would have to vent all that air somehow when the throttle was closed

now if u had a means to keep the turbo spooled up regaurdless of engine load and rpm. using a bov or wastegate to vent the excess air would prolly make the turbo rpms goto the moon. possibly redlining the turbo

dont forget a turbo rpms increase with motor rpms to keep up witht he airflow and boostlevel demand

at 3000 rpms and 7 psi that turbo may be spinning at 60k rpms

and at 6000 rpms 7 psi that turbo could be spinning about 120k rpms

etc

 

Here lets say there was a fan capable of withstanding 120,000 rpms and it was centrifugal and about 3 inches in diameter and it was placed into the exhaust, a 3 inch exhaust. The fan, provided its metal and not plastic, would begin to spin as exhaust is created. Now lets say we mount a blow off valve directly after the fan on the exhaust and hook it up to a vacuum source, as the fan builds up upon the rpms and begins spinning at a significantly high rpm creating a force upon the muffler, would the blow off valve release the "forced exhaust air" out thus releaving pressure built up between the fan and the muffler? Is this example feasible, or would the blow off valve simply not blow anything off because its being hooked up to a vacuum source which isn't being pressurized?

 

a bov is basically a vacum operated valve

well take a digraphs type

u have the outer case
inside the case is a spring ontop of the diaphragm

above the diaphragm is a vacum port
below the diaphragm would be the pressure side. i.e boost

now if u do not hook a vacum source to the port ontop of the diaphragm and just left it open air

the valve would not open till preasure exceds the the force of the spring holding the diaphragm closed.
once u got say 1psi over this point it would start to bleed off the extra pressure opening more with the increase in boost

now with that top port hooked to the intake manifold when the throttle is open vacum drops above the diaphragm leaving the valve closed(although it wont even open at a dead idle the vacum in effect makes the spring force easier for the boost to over come)

now when u jump on the throttle and boost builds and then u let off u have all the presure pre throttle blade and pushing against the bottom of the diaphragm. at the same time vacum inside the manifold has just went up and the vacum pulls against the diaphragm allowing the presure to escape


hopefully i worded this so u can understand it lol but thats basically how a blow off valve works

there are other tpyes of bov's but they all work on the same concept some have a pistion and spring, and theres a few other styles


now a wastegate on the other hand is basically the same thing

spring- diaphragm and generally a stainless valve

as boost increases thers is a line atatched to a port below the diaphragm when the presure reaches a setpoint it pushes the diaphragm up opening up the valve

 

would the blow off valve work if it was hooked up to a source that is not compressed? im just curious, say if i put a blow off valve on the tube of my leaf blower and hooked it up to a vacuum source would it blow off the air created from the leaf blower? or no because the air is flowing straight out of the tube regardless

 

if there is presure inside the tube, or u mounted it in a way that the airflow would naturally flow threw the bov.

but most blow off valves need a certian amount of preasure below the valve to atleast open 1-2psi u might be able to find an adjustable one that will open with just vacum aplied to it though

 

ok, im just making up engineering sketches at the moment, but i think i may have found a cheap power adder lol, and im not talking electric "2-3" psi turbos im talking serious horsepower, manual performances no electric crap

 

I hear ya, been working on the perpertual motion machine lately. I almost have it done.

Learn the laws of Physics. What you are describing requires energy. The source of energy is gasoline which makes the exhaust for the turbo to spin. It makes the crank spin which is what makes the blower spin. It makes the wheels move........it makes everything in the car operate.

The only way you can make a "new" power adder that is more efficient is to use nuclear power. Sorry, but you are wasting your time on "engineering sketches". Not trying to bash your idea........just trying to save you some wasted time.

EDIT: The most efficient power adder you are going to find for a vehicle is running a 500cc 2-stroke engine in your trunk spinning a blower for the car engine. The power to weight ratio is better than crank HP lose.

 

hey now lol ppl say **** cant be done all the time lol

electric turbos come to mind lmao hey there are some out there that do work

the best and ive seen it first hand was a turbop converted into a supercharger not all that big of a deal but this guy had it hooked off a electronic circut that would engage the drive clutch only at wot, talk about trick was belt driven off the engine which turned a gear drive to step up the speed and had a clutch in there somewere to disengage the drive when not needed
sad thing is it got wasted on a honda civic for his boss'es kids car deff woulda found somethign much cooler to put that on

then again the same guy who built this thing has built a automatic 3 speed transmission for his kids go cart,

and an electronic remote control automatic fireworks launching system(im not talking something that automatical lights baby fireworks that u would buy at ur typical fireworks stand, i mean this thing held the motar like 30 of them and roated around 8 tubes. it would light the fuse and drop each ball into its own tube) and all sorts of cool ****

point is u never know what one person could think of and it just actually may work.

 

my idea is basically have an exhaust pipe running to a muffler. along that pipe have another pipe welded and have it run straight into the motor via carb/fi. right where the pipes meet i want to have a bar run thru the exhaust and have dual fans mounted, one in each pipe. as the exhaust flows thru one pipe the fan begins to spin, thus beginning to spin the fan in the air intake pipe. this is sort of like a turbocharger without the need of an actual turbo. check out the pic for a basic idea

 

why r u doin this? as in whats the reason behind it? i know to make more power but why do that? a remote mounted turbo would be a lot easier to do if you are set on have a power adder under the car.

 

im trying to make my own, be creative, be unique, it might sound stupid but if it works it would save about $4000, cuz it would only cost about $300 to build, piping, blow off vavle, couplers, and the bar/fans setup

 

uhhh...what you drew is a turbocharger setup with out the turbo, except replacing the turbo with cheap fans. fan blades aren't efficient enough to build boost.

 

thank you for your input, you might think its not going to create good boost but so far a mock up test i have is certainly working

 

I am all for being unique and creative, but you are simply building a very inefficient turbo system so it isn't that creative. Definitely unique though. Since all you are saving on in terms of money is the turbo itself then all you save is about $200 for a perfectly good used turbo for an engine size you have in your signature.

It amazes me that your custom setup will only cost $300 and somehow using your math the turbo itself would cost (4000-300) = $3700.

Excluding piping, BOV, couplers, etc.................my last turbo setup cost $200 for two rebuilt turbos. Anyway, I am all for new ideas but no one does this because for one it is inefficient and two it is highly unreliable. Ever heard of Iconel? Where are you going to find a fan that will handle the heat? You won't. Where will you find a fan with the proper blades, diameter, and pitch? You won't.

 

I wasn't trying to rain on his parade, just trying to be realistic.
Yes, the turbo converted to supercharger can be done. But why? Turbos can't withstand any radial or axial loading on the bearings. It will end up needing thrust bearings way sooner and/or journal bearings. Just to get the balance right on the drive for a radial speed of 120K RPM is crazy. It would have been smarter to do like 83CrossfireTA did and get an SC out of the junkyard for $100 and make an adapter plate. Honestly, only having the turbo work at WOT on a low HP Honda is a waste. I would rather have it spool at 1000 RPM on that Honda to give it some usable power.

The three speed auto on the go kart and firework setup is neat.

I understand where the poster is coming from. I like building my own stuff. Lots of parts hanging around that get pieced together because I am cheap and like making things. Building a turbo setup that actually is reliable enough to be on the road and actually make HP is not going to happen with the method he is proposing. If he really wants HP and likes building stuff.........get a $100 used T4 unit and cobble some pipe together. I paid $90 shipped for my last ebay T4 that is good for about 400-425HP. Turbos are cheap and make sense.

Sorry for sounding so negative about his idea. It is just that he drew a picture of a "new" idea which is an exact picture of a remote turbo setup. Instead of using the turbo he is going to use two fans that are not connected. It just doesn't make any sense to do that. Just put a turbo there with two connected fans.

 

in the drawing, they are connected. That's a main problem. to build boost, a turbo impeller wheel spins anywhere between 20,000 and 100,000 RPM. an inefficient 5 or 6 blade fan mounted in the exhaust path won't reach those speeds, and if it somehow did, any standard fan would come flying apart. that's why turbo impeller and compressor wheels are made as a solid piece, precision balanced, and assembled with close tolerances, unlike this setup. Go with the junkyard remote turbo.

 

well your mock up may spin a fan blade but it probably isnt making "boost" not trying to sound mean but i think you may be a little ahead of yourself.

 

Why does everyone have to be so negative? like really im just using my imagination and experimenting with useless crap. What you can take is a 90mm computer fan and place it in the exhaust, but make sure it is aluminum because the melting point for that is 1200 degrees which unless your timing is rediculous wont hit where I plan on placing the fans

 

completely off topic question here, besides for fabricating one myself, anyone know where I can purchase just a single turbo manifold for a small block chevy, one that feeds upwards and sits the turbo right above the manifold itself?

 

Everyone is just being real. There is nothing wrong with experimenting but a lot of us have experimented enough to know that this will not work. Just think of it as us having more experience imagining and experimenting.

Hilarious. I am *sure* the bearings are designed for repeated exhaust temperatures. Think about why turbos have oil cooled and sometimes water cooled center sections.

 

Actually it is ON topic. It shows you are starting to get real about doing a turbo setup.

Contact BBSDESIGNS here at this forum. There are current threads not even weeks old than this thread that you would have seen if you looked at any of the other recent posts. A simple search would also bring it up. You could also do a search on ebay using "single turbo chevy" and get 10s of hits for chevy single turbos which look like a copy of BBSDESIGN single header for $243 shipped.

One other thing, the more you research stuff......the more you will find it has already been done........and the less you will imagine and experiment. The not knowing makes one think that they are the first to come up with an idea. The less one knows will make one feel more imaginative...........BTDT.

 

im talking literally a single manifold not two manifolds that feed into one turbo, just a single manifold preferably one that mounts on the drivers side and sits the turbo right above the valve cover

 

Take a set of dual turbo manifolds and only use one of them. Yes, it's been done.

 

im aware its been done and im aware its possible but i was hoping that there was a manufacturer or something of that sort that made single manifolds

 

Just block the cross over pipe.

You are joking about the single exhaust turbo, right? Check out SAAB. They tried it in production.

 

I believe that the Gale Banks kit that was on my car when I bought it many moons ago was a single turbo on one manifold, but I don't recall.

 

you say saab, now are you referring to the saab automobile? or is this a manufacturer of these manifolds, just curious

 

SAAB the manufacturer. Yes, they make automobiles. They did the single on a truck. A search here at TGO will bring up that information.

 

There is a reason name brand turbos cost more than a home made turbo. First off, reserch and develpment. They have tested and tested so many differant designs/ideas, we couldnt even imagine. Then the cost of making the parts. All the parts are exclusivly made for the operating temps and characteristics of a turbos operation. We arent putting your idea down, its just unrealistic to make a turbo out of parts that are not designed to be used as a turbo.