Compressor diesel? more power from diesel

[Benjamin]

My thinking is that any engine uses about 1/3 of the energy it makes to power the car, 1/3 is wasted in aerodynamics and the other 1/3 is lost in exhaust heat. Why not use the 1/3 of the exhaust heat to power a fan *turbo* and use a little of that wasted heat...your making it anyway.

Offcorse, i like turbos more than any other perfomance product.
but for high perfomance outputs on our diesels there are some problems.

on TDI engine's you have the limited feul, 12mm cant rev to high becouse it can break the plunger wich can give a total engine failure.

but on our IDI we dont have problems with plungers so we can feul on, maybe even with 14mm heads.

A stock T2 or T3 is a cool turbo, but what if you want more?
the cheapest way i think is going for a VNT turbo and on a 1.9 the VNT25 is the biggest you can get spooled up, if you want any bigger you are idmediatly on a VNT30 or VNT32.
There are also ballbearing turbos, wich are more expensive, and as far as i know, you can get almost the same spool up with the same output as the VNT25 does.

bigger turbos dont spool quick enough or you need to shift above 5500a6000rpm, this bring some problems, for the internals, but maybe also for the feuling!

In that way i am looking forward for bigger powers.
i believe 250hp is possible with a vnt25. but what about 300 or +400hp?
With wich forced induction can you make this happen.
Gasoline can, and diesels cant, why, i dont think the problem is the burning proces or the injection time is to long, i think we just need a better forced induction

Greetz, Benjamin

[sootyperry]

I think we will run out of internal engine part strength before we run out of options for forced induction. The crank, rods, pistons, block and cylinder head would all have to be strengthened to get 250hp out of a precup 1.6- 1.9L diesel. head lift would be a serious problem with extremely high boost pressures. Looking at the aircompressor trailer made me think of a funny scenario. The us airforce used to use a horizontally opposed two cylinder fourstroke engine running a roots type supercharger to start jetengines with compressed air. Why not use a small motorcycle engine running a supercharger mounted in the back of a caddy to feed the engine and avoid parasitic losses from the supercharger? granted it would add weight and complexity and it would burn gasoline or better yet methanol and you could inject the methanol into the diesel as well. that way you would have boost on demand. Electric start ont he supercharger engine and a twist grip on the shifter or a servo to control the throttle controlled by a potentiometer on the go pedal. ha. Oooh I know you could build a very light chromoly tube chasis say 1000lbs and then you wouldn't have to do much to the motor, power to weight. supercharger and turbo

[Darkness_is_spreading]

Owwww my brain hurts from reading that......   I believe an easier way would be called Nitrous or compound turbo.....    Or VNT if  you want beautiful  response from your turbo

guys, i have a small idea,

i think the main problem with making big power is not feuling, but getting that big turbo spooled up...

Interesting subject B

My own crazy idea is that the design of combustion engines including diesel IC needs to be revisited from the ground up. When we look at performance we do not differentiate between "continuous duty" and "discontinuous on demand type of duty" the way most machinery is normally rated in the industrial sector.

On cars I see a need for cruising and a need for passing (or impressing). The latter is rarely ful time and the engine does not need to be designed for it.

In other words we should make engines capable of storing energy and this I think can be done either in the form of DC electricity fed supercharger, or by storing high pressure air to be injected in a diesel intake without turbo or supercharger.

This is what I am looking at. An air compressor with a magnetic clutch ran by the alternator belt, a high pressure air tank, a throttle link type of control,  some sort of a cooler and a hose to the intake manif.

Here is my supercharger...please don't  laugh.

Haybayian

[burnt_servo]

My thinking is that any engine uses about 1/3 of the energy it makes to power the car, 1/3 is wasted in aerodynamics and the other 1/3 is lost in exhaust heat. Why not use the 1/3 of the exhaust heat to power a fan *turbo* and use a little of that wasted heat...your making it anyway.

Offcorse, i like turbos more than any other perfomance product.
but for high perfomance outputs on our diesels there are some problems.

on TDI engine's you have the limited feul, 12mm cant rev to high becouse it can break the plunger wich can give a total engine failure.

but on our IDI we dont have problems with plungers so we can feul on, maybe even with 14mm heads.

A stock T2 or T3 is a cool turbo, but what if you want more?
the cheapest way i think is going for a VNT turbo and on a 1.9 the VNT25 is the biggest you can get spooled up, if you want any bigger you are idmediatly on a VNT30 or VNT32.
There are also ballbearing turbos, wich are more expensive, and as far as i know, you can get almost the same spool up with the same output as the VNT25 does.

bigger turbos dont spool quick enough or you need to shift above 5500a6000rpm, this bring some problems, for the internals, but maybe also for the feuling!

In that way i am looking forward for bigger powers.
i believe 250hp is possible with a vnt25. but what about 300 or +400hp?
With wich forced induction can you make this happen.
Gasoline can, and diesels cant, why, i dont think the problem is the burning proces or the injection time is to long, i think we just need a better forced induction

Greetz, Benjamin

research compound turbo's  .....  very , very fast spool up , and more than enough boost presure to blow the very best combintaions of headgaskets , o rings/ fire rings , and huge head bolts/ studs .

[Turbinepowered]

In that way i am looking forward for bigger powers.
i believe 250hp is possible with a vnt25. but what about 300 or +400hp?
With wich forced induction can you make this happen.
Gasoline can, and diesels cant, why, i dont think the problem is the burning proces or the injection time is to long, i think we just need a better forced induction

More intelligent minds than my own have said repeatedly that the performance barrier in diesels is their rev limit, and the rev limit is a directly affected by diesel's combustion speed and injection duration.

Typically even highly fueled diesels operate in an incredibly lean situation; when you see black smoke coming out of the back of a diesel, it's more often a result of too-long of an injection duration or very poor atomisation of the injected fuel: either way, you don't have enough time to vaporise and burn all the fuel charge before the exhaust stroke.

Gasoline engines produce massive horsepower through their ability to rev very, very fast. The homogeneous nature of the fuel/air charge and gasoline's very rapid combustion rate combine to allow them to burn their fuel in a very, very short period of time, which can be aided by adding additional spark plugs to the chamber to provide additional ignition points.

Diesel, with stratified in-chamber injection, must both inject the full fuel load and fully combust it in a duration only slightly longer (At higher RPM) than the full combustion event of a gasoline engine. The air-fuel mixture immediately surrounding the injected spray of fuel is over-rich, which limits combustion speed. Turbulence in the cylinder works to increase combustion speed by rapidly spreading the burning fuel around and combining it with fresh air, reducing or removing this over-rich condition.

This, by the way, is the reason given to me why an IDI diesel will rev a bit faster than a DI diesel; the prechamber port's restriction promote more turbulence inside the "Swirl" chamber in the head, so the burn is faster.

[haybayian]

quote
More intelligent minds than my own have said repeatedly that the performance barrier in diesels is their rev limit, and the rev limit is a directly affected by diesel's combustion speed and injection duration. (quote)

Thank you for these points. This sums up my current (limited) understanding of how diesels work. As I was reading last night about two V12  diesel engines the K10 Audi and Peugeot 908 Le Mans I found that for instance the K10's engine is designed to rev at up to 8000 rpms but that the engine's power band for both torque and HP is between 3000-5000 rpms and the the rev's limiter has been set accordingly.  The type of  fuel combustion/oxydation that is taking place in a diesel engine is slow, problematic and yields a slower rpm power band. This suggest that pursuing higher rpms may not be the way to better performance unless spectacular new ways are found to improve diesel combustion. I understand that multiple staged injection is now the state of the art. But I also understand that the most promising area is in the actual "fuel" being burned.  I am thinking of mixed combustion involving for instance ethanol, water and God knows what else. The point I am making is that the way to diesel performance is probably not just  in mechanical changes but rather in the chemistry and electronics.

Haybayian

[mattbondy]

HCCI seems to be the way things will go in the internal combustion field.

[KTZed]

HCCI seems to be the way things will go in the internal combustion field.

Indeed...look up Benz's Dies-Otto...pretty neat!

[theman53]

I don't know too much about the diesel combustion, but all I do know is that in my 1984 Rabbit the electrical system is a nightmare. I could add a turbo to it easier than I could an electric supercharger, but that is just me. My car is a piece of ---- and I wouldn't want to add anymore tax to the wiring in that car. I am glad you are thinking outside of the box though. I hope it works for you eventually. Who knows maybe my next project in 10 years I'll be using something exactly like what you have here....but no way will I be with this car.

[Turbinepowered]

HCCI seems to be the way things will go in the internal combustion field.

If they can figure out how to get it to work under a wide variety of load conditions. HCCI is turning out to be very, very difficult to control, requiring the addition of a lot of complexity.


On the topic of electric superchargers, has anyone figured out the size of the 3-5hp electric motor those things are going to need powering them to generate appreciable boost? It'll be like stuffing a Briggs and Stratton under the hood! The B&S might even be smaller!

Edit:

Also, some numbers.

A typical supercharger takes that 3-5hp to generate their boost, right? Seems to be about right from what I know of superchargers, their boost isn't "free" like a turbocharger's is, they have to draw power off the crank to accomplish the same task.

3-5hp is 2235-3725watts. We'll go easy here, and go with the lower 3hp figure, so 2235w to power this supercharger electrically. Staying with 12v to avoid the need for a transformer (efficiency loss, more space), this comes out to 186.25 amps, give or take a small bit. Time for an alternator upgrade, for one!

We'll say you run this thing off a battery rather than straight off the alternator. A 550 amp-hour battery, if you wanted to totally discharge it, would provide power to run this monstrosity for almost three hours. Not bad, but this is only a 3hp supercharger, your boosting potential is going to be limited.

You've exhausted your battery, now you get to recharge it from your engine. Assuming 90% efficiency for the alternator (Mechanical->Electrical conversion) and the same for the battery (Electrical->Chemical, Chemical->Electrical), you end up with this:

2235w/.9=Power stored in the battery=2483.33w Chemical

2483.33w/.9=Power demanded from the alternator=2759.259w

2759.259w/.9=Power drawn from the engine=3065.844w

Means your supercharger's total system efficiency would be 2235/3065.844, or 72.9% efficient. This is not counting the efficiency of the supercharger itself, just the drive and recharge system that supports it. This is also best-case scenario, as I am given to understand battery efficiency is more around ~80% and alternators ~85%, rather than the ninety I gave them each.

A good turbocharger can easily net that exact same efficiency, including the efficiency of the compressor and turbine setup.

[OM617]

A VNT works darn well for me. It moved my torque peak from 3200rom to 2000rpm.

[Benjamin]

A VNT works darn well for me. It moved my torque peak from 3200rom to 2000rpm.

i have a bigger turbo on a smaller displacement, but i think this is almost the limit. as said before, how to get high powers like +200/liter from a diesel.

I did some research, URL  the electric compressor from thomas knight do have 3engines from 5hp. (to drive the roots)

In 1996 Knight looked into a 90-hp DC motor, but it was bigger than a car engine and weighed 1000 pounds. He decided to lower the engine size to a reasonable amount. Even a 2.0-liter engine making 15 psi at 8000 rpm required a 30-hp DC motor. Knight looked into smaller motors, which were still too big and heavy.

centrifugal:

"In 1998," says Knight, "I remembered the model boat multiple motors, and realized I may have a solution. Two or more motors; three or four. Why not?" So he applied for patents and researched motors. The 4kw brushless model plane motors were $1,000 each, and each supercharger unit cost $4,500 to make. He made one with three model motors drawing 3,500 watts each at 60 volts. This one used a centrifugal supercharger with gears, then belts, etc. Gears were parasitic, and belts were destroyed in a short time.

you can also read other items but no any application takes a low-power engine.

turbo is not free power

Turbos are not free power, as some will claim. A turbo is a turbine-driven supercharger and to drive something requires horsepower. The turbine needs velocity, volume, heat and pressure to operate. The first three won't make any boost. It's pressure that makes boost. The first three help with greater efficiency. The pressure in a turbo is measured by the difference in intake manifold pressure and exhaust manifold pressure. This is referred to as the exhaust-to-intake pressure ratio. Most turbos operate at a 2:1-to-3:1 ratio, meaning that if 10 psi is in the intake manifold, the exhaust manifold will see 20 to 30 psi. (The GN operated on a 2.5:1 ratio and the 300ZXTT had a 2.7:1 ratio). Some racecars make PR better than 1:1, but they're still making backpressure. Backpressure is a restriction, and a restriction is not free power.

A turbocharged JET with the shaft connected to a compressor would be an idea. Alltough, its also not realy so practical. But forget electric drived compressor at all.

Greetz, Benjamin

[QuickTD]

A typical supercharger takes that 3-5hp to generate their boost, right?  

Wrong. A typical supercharger takes 18-22hp to produce 450cfm @ 8psi boost or 80-100hp to develop 780cfm and 15psi boost, have a look at the previous page. A lot of people underestimate the power necessary to pump the volume of air required by an engine. I like the triple starter motor setup pictured, nice bit of machinery, if a bit silly.

[jimfoo]

I can see it now, all those Merc guys digging frantically through their trashcans to find the VW nozzles they took out.  :lol:    :lol:

[Turbinepowered]

A typical supercharger takes that 3-5hp to generate their boost, right?  

Wrong. A typical supercharger takes 18-22hp to produce 450cfm @ 8psi boost or 80-100hp to develop 780cfm and 15psi boost, have a look at the previous page. A lot of people underestimate the power necessary to pump the volume of air required by an engine. I like the triple starter motor setup pictured, nice bit of machinery, if a bit silly.

So I was really erring on the low side. I was trying to take into account lower volumes for lower displacement engines, and I guess I overcompensated a touch.

Still, 18-22hp required just makes the overall efficiency, size and now cooling problems that much worse.