A positive-boost turbo system???

[Dirgle]

Before the throttle plate is called ported vaccum. But you dont have any until the plate is opened. Or very little anyway. If you have a throttle body with a plate, you have vaccum. Or more accurately, lower pressure.

hmm..Good point, it would be impossible to maintain a state of positive pressure anywhere in the intake, on a system where you have a throttle plate.

It's possible to elimanate the need for a throttle plate if you use direct fuel injection, but I'm sure Nissan didn't go this route.

http://www3.bc.sympatico.ca/Volvo_Books/engine6.html

 

[figgie]

The biggest problem with VNT is getting it to run on gas. Diesel runs much cooler. Gas will trash a VNT in short order.


They could be using oil pressure to keep the turbo spooled. That's been done before.

I'd like to see working VNT on gas. It makes the newer garret GT turbos look like a fucking joke.

I wonder if the Air Force would be willing to disclose the alloy used on the exhaust vanes of the GE-F101 engine that is used on the B-1 30,000 lbs thrust on afterburners and those EGT are 2000+ degrees at the exit point

 

[jdub]

I wonder if the Air Force would be willing to disclose the alloy used on the exhaust vanes of the GE-F101 engine that is used on the B-1 30,000 lbs thrust on afterburners and those EGT are 2000+ degrees at the exit point

The turbine blades on the General Electric F110-GE-100 turbofan (basically the same engine) uses a blade where the grain of the metal is aligned...very, very strong. The Pratt & Whitney F100-PW-220 had a nasty habit of throwing a turbine blade on occasion...not good on a single engine airplane!

 

[figgie]

The turbine blades on the General Electric F110-GE-100 turbofan (basically the same engine) uses a blade where the grain of the metal is aligned...very, very strong. The Pratt & Whitney F100-PW-220 had a nasty habit of throwing a turbine blade on occasion...not good on a single engine airplane!

no not talking about the turbine blades. that is a different alloy all together And the B-1b uses the F101-GE-102 I am talking about the electronically controlled thrust vanes on the exhaust side of the engines.

 

[jdub]

no not talking about the turbine blades. that is a different alloy all together And the B-1b uses the F101-GE-102 I am talking about the electronically controlled thrust vanes on the exhaust side of the engines.

We're actually talking about the same thing...the hot side of the engine. The F110 and F101 share the same core...both have 2 low pressure and 1 high pressure turbine. The biggest difference is the F110 has 3 fan and 9 compressor stages, the F101 has 2 fan and 9 compressor stages.

If ya want to see something really cool on the hi-tech side of jet engines...take a look at the F119 and F135 motors

BTW...the hot side low/high pressure turbine blades are fixed...here's a couple of pics:

 

[figgie]

We're actually talking about the same thing...the hot side of the engine. The F110 and F101 share the same core...both have 2 low pressure and 1 high pressure turbine. The biggest difference is the F110 has 3 fan and 9 compressor stages, the F101 has 2 fan and 9 compressor stages.

If ya want to see something really cool on the hi-tech side of jet engines...take a look at the F119 and F135 motors

BTW...the hot side low/high pressure turbine blades are fixed...here's a couple of pics:

lol
i know the turbiine blades.

here let me show you what the exhaust vanes are


See the red circles. Those vanes close and open depending on the where the throttle position is at

 

[jdub]

lol
i know the turbiine blades.

here let me show you what the exhaust vanes are


See the red circles. Those vanes close and open depending on the where the throttle position is at

Ohhh...I see. Aren't those the spray bars on the afterburner? I know on the F110 the AB is variable through 5 stages based on throttle position to the AB fuel control.

 

[figgie]

Ohhh...I see. Aren't those the spray bars on the afterburner? I know on the F110 the AB is variable through 5 stages based on throttle position to the AB fuel control.

nope

those are the variable vanes. They are the smallest at mid power to aid in cruising speed and open all the way at full throttle to let the 30,000 lbs of thrust do it's thing All turbo fans with afterburners have them.

 

[Clip]

Gas will trash a VNT in short order.

what about the use of an exhaust cooler, similar to an intercooler? maybe run a top mounted one and use a hood scoop to pull the air over it. i was poking around under the hood of my uncle's freightliner coronado and saw that he had an exhaust gas cooler from garrett.

hell, i dont know enough to be posting on this topic. would an exhaust cooler lower the temp to a reasonable level? what's the average exhaust gas temp? would it be possible to run that much piping? im sure it'd affect the flow. if the manifold itself was cooled by a constant fog of nitrogen, dont think that'd work because the gas is probably too hot to be affected. might also put too much stress on the manifold.

can anyone set me straight?

 

[SnowMongoose]

VNT on one of those remote mount turbos?
<no clue how much EGTs drop over the course of the exhaust>

cool thread, I like that my new-to-automotive-stuff ass can finally follow topics like this to some extent.

 

[figgie]

what about the use of an exhaust cooler, similar to an intercooler?

nope

what you want is heat and the most of it possible. If the gases are allowed to cool any then you have lost alot of energy to spin the turbo. Heat has to stay in the exhaust.

 

[Adjuster]

Actually, the guys at STS are blowing alot of the old "rules" out of the water lately. They have found that the cooling effect of the exhaust pipes on the hot gas from the motor must be condensing the mixture somewhat, and it offsets the lost heat since the turbo's mounted in the rear of the car seem to be making boost almost as quickly as ones bolted right to the engine.

For a VATN setup, this cooler exhaust gas would be perfect, and with the advantages of the VATN arrangement, even faster spoolup would be possible on a larger turbo capable of higher flow rates, even on smaller displacement engines.

So, here is the perfect VATN setup.
3.5L I6 with VVTI or whatever. (Heck, use the BMW Vanos, and have no throttle body even.)
Audi's FSI direct fuel injection, so no detonation issues, and very precise fuel delivery. COP from Audi too since that ignition works very well.
Design the bore and stroke so you can turn 12k stock. (Larger bore, shorter stroke.)
Put this into a AWD platform.
Hook up a larger VATN based turbo where the muffler would normally be, and design a flat extruded tube intercooler that forms part of the floor pan to cool the compressed air being sent up to the motor along the way.

Air cleaner goes in the rear quarter panel. No need for further FMIC as the long route from the rear of the vehicle to the front would cool the intake charge plenty. (I'm thinking extruded alloy "pipe" with multiple channels, and fins built into the extrusion. Think amp cooling fins, but make this about a foot wide, and 10 feet long with a 3/4" ID height. Should not be too difficult to figure out how wide to make it to flow say 800cfm easy.... Ok, that might be overkill, but you get the idea.)

Any takers there BWW/Audi? (Give me a FSI V10 A8s with VATN turbo's in the tail and I'd morgage the house to drive one.

 

[figgie]

Adjuster

I am aware of STS

and am also very well aware of thermodynamic principles.

5.7 Liters of air each revolution MUST go somewhere But trust me on this that if the turbos where shoe horned in the engine compartment they would spool much faster as there is more volume of it (heat expands gases, etc) Physics 101 with some thermodynamics. Does the STS system work. Of course. And since the vettes/camaro/firebirds have zero room for a turbo, that is the only place for them to get a turbo

 

[miekedmr]

Any takers there BWW/Audi? (Give me a FSI V10 A8s with VATN turbo's in the tail and I'd morgage the house to drive one.

Hmm, TT insta-boost V10??
Lets see, the new M5 V10 makes 500hp. Lets strap a couple of these VATN turbos on there and that would be an easy 750hp.

This hypothetical car would be a good candidate to introduce forward-facing jet engine assisted braking, too. :icon_mrgr

 

[Dirgle]

I wonder if the Air Force would be willing to disclose the alloy used on the exhaust vanes of the GE-F101 engine that is used on the B-1, 30,000 lbs thrust on afterburners and those EGT are 2000+ degrees at the exit point

That would be Ti-35V-15Cr (Tiadyne 3515) a.k.a. alloy C, also used on the F-22 Raptors thrust vector nozzles.

Snowmongoose: Remote mounting the turbo would defiantly take care of the EGT problem, but I would have to go with Figgie on the idea that you will loose a good deal of exhaust gas energy over the distance. Plus those big V8 have the low down torque to pick up the extra weight of all the extra piping and components. And they are almost pumping twice as much air, without the aid of exhaust energy, as us at any given RPM

Just to give people an idea of what were talking about, here are some pictures of a VNT (Variable Nozzle Turbine) Turbo.

And this is the Porsches VTG (Variable Turbine Geometry)turbo &#8211; aka VGT turbo

Adjuster: That set up is very good, and probably very close to what Nissan is going to use.

Let&#8217;s talk about the benefits of Spark-Ignition Direct Injection for a moment.

Because of the ability to atomize and control the fuel better within the combustion chamber, it can cool the intake charge as well as create a stochimetric bubble with a lean mixture surrounding it and still control pre-ignition. Direct injection has the ability to operate at a very homogeneous mixture (lean: even to the point of 20:1) this can make for very good fuel consumption.

This is great news for economy cars, but what can it do for performance cars? Well it can allow for the use of higher compression pistons in boosted applications while maintaining control over pre-ignition. Proof of this is in the new Mazda CX7.

http://www.mazda.co.uk/AboutMazda/MazdaNews/LatestHeadlines/Articles/news 04-01-2006

It utilizes, spark ignition direct injection, on a 2.3 liter 4 cylinder motor with 9.5:1 compression. It&#8217;s peak torque of 258 ft/lbs is at 2500 RPM.

It&#8217;s a scary thought but this little 2.3 liter 4 banger produces more torque and at a lower RPM than our mighty 3.0 liter I6 7M.

The high compression pistons gives the motor a lot of off boost power, and at the same time allows the turbo to spool ultra quick, imagine what it could do with a VNT turbo.

So as we can see Direct injection as some very good benefits to offer the high performance market.

Now on to my original question. After doing some research this is what I think the motor will be like in the new GT-R.

Some say that they will use the 3.5L V6 from the VQ family. But industry experts say it more than likely will be a 3.7-4.0 liter V6 VQ motor. OK fine, I&#8217;ll take a 3.7 for my example.

3.7L V6 w/ Continuously Variable Valve Timing Control System (CVTCS)
9.5:1 or more Compression Ratio
COP ignition
Direct Injection Spark-Ignition
Intercooled Twin Garret Turbos with VNT technology
6-speed manual or CVT auto.
AWD( obviously, it&#8217;s a GT-R)

So what do you guys think, would this produce a motor with zero lag, and the ability to maintain almost continually a state of positive manifold pressure, without it dropping in to the negative range except when the throttle is shut?

All of this technology exists but it just needs to be brought together

 

[americanjebus]

wow, went over my head in direct injection,

when i saw this zero lag i figured they found a twin turbo set up with a smaller turbo that would be able to spool off of lower engine speeds. if it was an auto there could be something like a higher pressure tq that would increase the load on the engine slightly and the rpms slightly to where the smaller turbo would be able to produce the constant positive boost. Bassicaly an ecu controlled power breaking feature.
primitive but simpler/cheeper

 

[IHI-RHC7]

Wow, I like that setup. If it's running direct injection then, what's the point of a throttle plate? That would be zero vaccum right there.

 

[silvergsx623]

this is very interesting. i have never seen anything about positive boost turbo systems and the VTG type turbos.
i have alot to read up on

 

[Dirgle]

Americanjebus: Don&#8217;t worry to much, direct injection on gasoline motors is fairly new. I thought it was still in its experimental stages until recently. But with Mazda, Mitsubishi, Nissan, Toyota, offering Spark-Ignition Direct Injection motors and GM getting in on the action this year with their turbocharged 2.0 liter Ecotec motor. We are going to start hearing a lot more about them.

IHI-RCH7: I&#8217;m still uncertain as to how a direct injection system would react to not having a throttle plate in turbocharged applications. On a naturally aspirated motor you can easily control engine speed through fuel control. This eliminates the need for a throttle body as well as a restriction in the intake track. The reason I think they keep them on modern cars is to create the vacuum in the intake manifold, needed to operate things like power brakes. Of course this is easy to get around, as they have done it on hybrid cars where the motor can actually turn off while the car is moving.

But on a turbocharged motor I think the throttle plate is still needed to stop the air flow when you let off the accelerator pedal. If you didn&#8217;t have a throttle plate and you let off the accelerator it would lessen the fuel being injected but for a fraction of a second the turbo would still be pumping large quantities of air in to the cylinders. This would result in a lean condition for a short time, long enough though to have detonation across several cylinders.

Maybe I&#8217;m wrong and there won&#8217;t be detonation when there is no load on the motor. If someone could enlighten me on that point, please do.

But what about at partial throttle going up hill. The vanes on the VNT turbo will have to control air flow and not necessarily boost (although it will have to control the air flow via boost, if that makes since.) Because under load the turbo will try to spin up really high, forcing more air into the cylinder, but you&#8217;re trying to maintain a certain speed so you have the accelerator only partially down and the ECU is only injecting the necessary fuel to maintain that speed. Therefore the VNT turbocharger vanes will have to keep the turbos airflow down to a point where it doesn&#8217;t go to lean. I&#8217;m even sure if this is possible.

If anybody has any ideas on the theory please go ahead and input.

However if it is possible then you would be able to remove two things from the intake system. The throttle body and the BOV. This would considerably clean up the intake track, and remove restrictions as well as improve spool time. Both pluses, so it would be very nice if it were possible.

silvergsx623: I hadn&#8217;t heard anything about positive boost turbo systems before I read that article on the GT-R. And were still working on if it&#8217;s even possible.

 

[Nick M]

When Toyota was working on direct injection, I remeber the report of the increase in power and mileage. The 25% efficency of a 4 stroke gas engine went up considerably.