Zero PSI turbo

[Bluevitz-rs]

Anyone ever though of setting up a 0 psi turbo like the ones used on aircraft. It would give the car a massive boost of torque without the problems that arise from going into boost and tuning. A small fast spooling unit could be used that would be up to speed by 1200-1500RPM.

[cdydjded]

That is not possible. You cannot run less boost than the W/G allows. Unless you use a pop off valve that bleeds boost. Good luck finding one that can go that low....

[Bluevitz-rs]

Your waste gate will allow you to run whatever boost level you want provided you use the appropriate spring inside. Or run an external one with electronic controls.

As I said, airplanes use it to compensate for altitude, so don't say it can't be done.

[xixarchangelxix]

We're not flying our cars at 30000 feet in a thin atmosphere. As you said, they use it to compensate. They are meant to keep intake pressure regulated so that it is equal to sea level. They are "0 psi" because at altitude, the pressure that might be 10 psi (for example) at ground level becomes 0 psi at altitude. So unless you plan on strapping on wings to your yaris, it can't be done in the manner you're speaking of. Can you run a turbo at 0 psi at ground level? Yes. Will it do anything? No.

[Bluevitz-rs]

Ok, then tell me why my car had a massive boost in torque from 1500rpm at 0 psi when I had the turbo on my car?

[xixarchangelxix]

Massive boost? Can we see a dyno chart? And no, a picture of your butt won't suffice.

[cdydjded]

Originally Posted by Bluevitz-rs

Your waste gate will allow you to run whatever boost level you want provided you use the appropriate spring inside. Or run an external one with electronic controls.

As I said, airplanes use it to compensate for altitude, so don't say it can't be done.

Sorry but no. No matter what spring you have in you waste (4lb,6lb,8lb ect) you cannot run lower that that #. I have no idea about how planes do it @ 33000 ft. In a car it cant be done with the wastegate. Based on you OP I dont think you have a good grasp on how a W/G works. Which is fine. I had a hard time understanding also how it worked @ first. The only way is to bleed boost through a pop off valve. And even then the one Greddy makes lowest setting is 11psi.

[Scubaru Steve]

you can, get the spring out of an aircraft. i know the added torque your talking about. it only give you low end and would probably rob power in the higher rpm range.

[cdydjded]

Originally Posted by Scubaru Steve

you can, get the spring out of an aircraft. i know the added torque your talking about. it only give you low end and would probably rob power in the higher rpm range.

Really? Which one:
spring.jpg

[cdydjded]

Blue: Just to let you know on a N/A motor as RPM goes up, vacuum goes down. So for all we know our car @ WOT has 0 vacuum (same as 0 psi). I cant do this test cause Im boosted. If you are not boosted, connect a gauge to you car & do the test.....

[Parmas]

Blue: You need to consider many things about this theory but I think I understand what you want to point out.

Let's say you are N/A and have a short intake pipe venting from the front and have constant high wind speed blowing directly into this pipe... then in my opinion that way you will see a good amount of engine reponse at all rpm loads.

But if you want a turbo at 0 psi to make the same effect you need to install the turbo discharge pipe short and straight into the throttle body.
Keep in mind turbos have a negative effect to exhaust flow since they are restrictive due to the small exhaust outlet into the turbine and that is enough to cost you some power loss due to back pressure.

Also to do this 0psi turbo setup you need to do a custom turbo setup that costs much so who with all that money spent will keep this damn thing at 0psi!

[Bluevitz-rs]

HAHAHAHA, ok

I'll do my best on explaining how a waste-gate vavle operates.

You normally have three different air forces at work inside the valve itself. Atmospheric, vacuum and a positive pressure. On the side with the rod, you have atmospheric pressure. (aprox 14.7 psi a) On the other side you have vacuum at idle 0 psi a (ideally) and normally, boosted pressure, so anything above 14.7 psi a. I'll use 4 psi g as our target boost pressure.

Also on the rod side you have a spring (6 psi) to hold the valve closed adding to the pressure of the atmosphere, adding up to 20.7 psi a. When the car is running, you have exhaust gas pressure building up on the other side of the vavle wanting to push it open, your "back pressure". Lets say that the pressure difference is only 2 psi g across the internal waste-gate valve. When you deduct that pressure from the total pressure on the valve, you're back down to 18.7 psi a or 4 psi g, <--your set wastegate pressure.

20.7 psi a - 2 psi g = 18.7 psi a

18.7 - 14.7 = 4

If you have a restrictive exhaust system beyond the turbo, it will affect the pressure drop across the turbo increasing your waste-gate set point. The freer flowing the rest of your system is, the lower the boosted pressure will be do to the greater pressure difference. The more pressure wanting to push the valve open, the sooner it will open.



So to make an atmospheric waste-gate work, you only need to use a spring stiff enough to overcome the pressure difference across the turbo and use vacuum pressure to keep the valve shut. As vacuum pressure approaches atmospheric pressure the valve looses to the pressure difference across the turbo and the valve is pushed open.

Now if you used an electronic vacuum valve you could control valve exactly when and how quickly it opens. Just like if you were boosted.

I'm pretty sure I have a grasp of how a simple spring loaded pressure valve works.

I can post up some thermodynamics problems from school if you want something complicated.

[Bluevitz-rs]

Originally Posted by Parmas

Blue: You need to consider many things about this theory but I think I understand what you want to point out.

Let's say you are N/A and have a short intake pipe venting from the front and have constant high wind speed blowing directly into this pipe... then in my opinion that way you will see a good amount of engine reponse at all rpm loads.

But if you want a turbo at 0 psi to make the same effect you need to install the turbo discharge pipe short and straight into the throttle body.
Keep in mind turbos have a negative effect to exhaust flow since they are restrictive due to the small exhaust outlet into the turbine and that is enough to cost you some power loss due to back pressure.

Also to do this 0psi turbo setup you need to do a custom turbo setup that costs much so who with all that money spent will keep this damn thing at 0psi!

You'd simply need to modify the spring in your waste gate and use an electronic boost controller. That way you could run it with boost or without, kind of like a supercharger with an electronic clutch.

[Bluevitz-rs]

Originally Posted by cdydjded

Blue: Just to let you know on a N/A motor as RPM goes up, vacuum goes down. So for all we know our car @ WOT has 0 vacuum (same as 0 psi). I cant do this test cause Im boosted. If you are not boosted, connect a gauge to you car & do the test.....

Have you ever taken a class in auto mechanics?

[cali yaris]

Let's see some real life examples of turbocharged CARS running 0 boost. If the theory is sound, someone has tried it and posted data.

I'd like to see that "massive boost of torque" demonstrated, since you are claiming that as fact in post #1.

I really am curious about it; never heard of it being done.

[Bluevitz-rs]

My ass told me so when my boost gauge read 0 and I was only at 2000 rpm. As soon as I took the turbo off, I didn't have nearly the same pull at 2000 rpm.

The whole point of it is to make a high flat torque curve from low rpms for efficiency.

Edit: Ok, the point I'm trying to make is that an N/A engine is only sucking in as much air as it can due to volumetric efficiencies. As RPMs go up air inside the air inside the intake track speeds up compounding the effect and power is increased. With the turbo, you have a constant rate of air being pushed by the turbo eliminating the need for high RPMs to achieve the desired torque.

Holy crap, sorry for thinking outside the box.

[cdydjded]

Originally Posted by Bluevitz-rs

Have you ever taken a class in auto mechanics?

No Im self taught. I rely on Practice vs Theory. In other words Im street smart not book smart.

[Bluevitz-rs]

Originally Posted by cdydjded

No Im self taught. I rely on Practice vs Theory. In other words Im street smart not book smart.

well, i've got both behind me. I've worked at Toyota Canada, and taken it in school.