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Discussion Starter #1
Congratulations Julian Edgar.



http://autospeed.drive.com.au/cms/A_2567/article.html



Julian Edgar has written more than 600 magazine articles on car modification. He has contributed to Street Machine, Fast Fours & Rotaries, Sport Compact Car, Turbo and Hi Tech Performance, Fast Car and many other magazines around the world. He was the founding editor of Zoom, and currently edits the Web magazine AutoSpeed.

Autospeed owns btw. Very A-typical compaired to most.
 

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Strangely enough I agree with hyperion. Seems like a waste of time and energy.
And a few months ago I posted information about a company that was looking to make a turbo kit for the Prius. They had apparently developed it, but were looking to gauge the market demand before putting it into production. So, Julian Edgar isn't the first to tweak a Prius.

And Toysrme, that was a rather fawning intro, don't you think?

Spike
 

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Tim the Toolman would have pulled the Synergy Unit out and crammed a Hemi in there along with the supercharger. Put some slicks on it too.
Seriously though, if you want to make a hotrod, start with a Chevy or something. That's not what a Prius is for.
 

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Hey guys,
Give Julian a break. He's doing these experiments to find out more about these strange new hybrids. As such they are definitely not a waste of time. He modifies lots of cars in order to write articles for his magazine. His Prius is just the latest "victim". He's learned a lot about what can be done to trick the computers into accepting an engine that performs differently than they expect. And he's discovered some hard limits along the way.

He's lucky to have the time and resources to do this. It's not really that important that this particular modification won't be replicated in lots of other Prius.

Anyway, after supercharging his Prius, he decided he didn't like the additional noise, so he ripped that out and is currently adding a turbo to it.

Along the way he seems to be discovering something very interesting. The turbo doesn't improve output at the wheels over a Prius with well charged batteries, but it does tend to keep the batteries well charged. His preliminary fuel economy tests appear to indicate an improvement! So his experiments may indicate that running the engine at higher output for shorter times and relying on the battery in between (pulse driving) really does improve efficiency despite the inherent loss in battery storage.
But these are preliminary results and may not hold long term. Since he increased the fuel pump pressure, the display readout of MPG is no longer accurate, so he has to go by tank fillup (at least his model doesn't have the bladder in the tank).
 

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From what I have read about the design of this engine, Prius engineers have determined the maximum hp that is usefull in this hybrid and limited the rpm so this figure isn't exceeded and fuel wasted. So super or turbo charging would be a complete waste of time and money. John 1701 could probably explain this much better.
I believe this gentleman could do more good by designing a simple tach installation so that we would all know exactly what this engine is realistically turning and just what his aims are. The only way I see for someone to get more HP or performance out of a 1.5 L engine is with increased RPM and I don't think any of us want to see that. Increase the HP and increase the fuel consumption. Especially with a "blower"
 

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So just so we've all got it clear: none of you know the power or economy results from the supercharged Prius, but in the opinion of some, it's definitely a waste of time and a stupid thing to do.

Yep, sounds a logical perspective to take....
 

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:)
 

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Realistically, for better economy, a light turbo Prius would be the best option. You'd get a very nice performance boost without much of an economy hit (if any).

Superchargers do hit the fuel economy primarily because they're belt driven. A turbocharger is powered by the exhaust from an engine, so it really works on the 'wasted' output.. kinda like regenerative braking, except the energy is used immediately rather than stored.
 

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"...not the traditional idea of "supercharge" which usually means faster, bigger, louder, noisier, dirtier."

I can't help it if you have odd ideas about what supercharging consists of. In fact, a forced aspirated Prius can be quieter than standard - the engine revs less to produce a given power output. And certainly a supercharged Prius can be more economical than standard at low speeds.

"Realistically, for better economy, a light turbo Prius would be the best option. You'd get a very nice performance boost without much of an economy hit (if any)."

And yes, I now drive a turbo Prius.
 

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Discussion Starter #11
Not to mention the fact that a turbo will cut the noise in an exhaust by a ton.
Emessions??? Emessions can be improved if you're actually interested in doing so with a turbo.

Julian we've talked in e-mail before via Autospeed.
I see why yall cut out the old AS forums, and don't like frequenting them.
Seems like they're trying to castrate you for improving on the car. That's no cool.


Spike, I don't own a Prius. I own a turbocharged ES 300. (One of two I know about) I joined to post simply because a turbo Prius is cool, and that I figured it was a high probability it would slip through the cracks. Tho I have no personal use for a Prius (No offense meant), I would love to see every vehicle on the road with such technology.
 

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Julian Edgar said:
"...not the traditional idea of "supercharge" which usually means faster, bigger, louder, noisier, dirtier."

I can't help it if you have odd ideas about what supercharging consists of. In fact, a forced aspirated Prius can be quieter than standard - the engine revs less to produce a given power output. And certainly a supercharged Prius can be more economical than standard at low speeds.

"Realistically, for better economy, a light turbo Prius would be the best option. You'd get a very nice performance boost without much of an economy hit (if any)."

And yes, I now drive a turbo Prius.
Julian, I am not an auto buff in any sense of the word. Perhaps I use the word "supercharge" improperly to someone knowledgable such as yourself.
 

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Julian Edgar said:
And yes, I now drive a turbo Prius.
Street legal at all?
I'm keen ... I'll take one ... I think a turbo is the next logical step for the Prius and I wouldn't be surprised to see Toyota deliver. Some of their hyper-economy vehicles in the Japanese market are sub-litre with various forced-induction configurations.
 

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Turbo Prius

A tuner called Blitz has also come up with a low-pressure (6psi max) turbo for the Prius. They are claiming about 123 hp and 144 foot pounds of torque at the wheels. Of course no mention of what happens to fuel economy (or to engine longevity).
 

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Hi All,

Its unclear to me if Turbo-Charging a Prius is only an exercise in power enhancment. What does Turbo-Supercharging do? - it increases the fuel-air charge density utilizing waste energy in the exhaust stream. The emisions control feed-back loop should increase the fuel to match the increase air density, just as it reduces fuel to match low air density in the mountains. This is one of the side benefits of emisions controls, altitude adaptability.

Now denser air and more fuel to match the number of oxygen molecules in that air results in more energy made per revolution, or in other words more torque. This also generates allot more heat of combustion, which in the same volume gets hotter. Being hotter, the Tin/Tout ratio might be made larger and thermal enegy conversion more efficient. It can go either way.

Turbo-chargers were originally developed to allow aircraft to be able to have lighter sleeker engines (and less aerodynamic drag). One of the two reasons (the other being laminar flow wings) the P-51 fighter plane from WWII had such great range was its sleek turbo-charged engine. There is a double wamy in this story as well. The turbo charged engine increased the aircraft ceiling and the air being thinner up higher required the plane to have to fly faster to stay in the air and this was easily possible as thinner air has less drag. Both higher speed and longer range were the desired for the long-range aircraft. The P-51 also had a prop-pitch control. The ultimate outcome of this might one day be turbo-recuporated (apply exhaust heat energy recovery to turbine engines) passenger air-liners.

If the Prius control system is smart enough to know that the engine has more torque, and then adjusts the drag from the MG1 appropriately so that it generates more electricity for MG2, the Priius should accelerate quicker.

The question of will it improve fuel economy is harder to figure out. Turbo-charged engines can be designed to have better efficiency. This is why most over-the-road trucks are turbo-diesels (besides the mountain crossing advantages). The Prius control might not close loop on engine torque however. But just have hard-coded the expected torque for a give RPM and intake air temp. If a torque loop was closed, then the control would turn the CVT ratio up and the ICE would run slower and should have less pumping losses. This might work against deriving heat energy from the exhaust however, in that the turbo might not be aerodynically efficient at the lower exhaust velocity. The true fuel economy improvement has to come from recovering waste energy in the exhaust. A special turbo might be needed that spools up to high speeds at even lower exhaust flows than a standard turbo for a 1.5 liter engine to get improved fuel economy.


If a lighter weight tubo-charged engine replaced a heavier atmospherically asperated engine, that would definately save gas. The chasis could be made lighter, and the whole vehicle would be much lighter.

The other issue is that the Atkinson compression cycle is going to be pushing against the pressure that the turbo generates. This seems to indicate the Atkinson partial power advantage would be reduced. Unless there happens to be an intaking cylinder for every cylinder pumping air out the intake during a compression cycle and a large plenum between the cylinders.


I think one way that may be more certain to get more power or economy out of the Prius from an engine modification would be a turbo-alternator. The turbo-alternator has the turbine like the turbo-charger, but rather than spooling up a supercharging air compressor, its spools up yet another Brushless Motor/generator to generate electricy from waste heat energy. With an electronic power converter, the voltage and current from the wildly varying alternator output could be matched into the battery pack. That would make the Prius a series-parallel-series (!) hybrid electric vehicle. I beleive I have heard that large diesel powered electricty generators have tubo-alterntors after the turbo-charger. These plants can get about 50 % energy conversion efficiencies.


Here is a final parting thought on this Just like the Prius has the warp-stealth mode, turbo-alternator Prius could have a warp suck mode. And actually use the turbo as an air pump (runing the generator as a motor) to exhaust cylinders to negative pressure. Which when the exhaust valve closes and the intake opens, could aid in supercharging the intake by ram-tuned induction. Puegot brothers look out!
 

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An04Prius said:
Julian, I am not an auto buff in any sense of the word. Perhaps I use the word "supercharge" improperly to someone knowledgable such as yourself.
You don't need any special knowledge to know what "supercharge" means. And if you still didn't know what it meant, there's always the dictionary. I don't know about you, but I tend to look things up when I don't know their meaning, rather than guess and assign my own meaning (which nobody else would share).

Supercharging just means forced induction. If the supercharger is driven via exhaust gases, it's called a turbocharger. The most common type of (non-turbo) supercharger is driven off the engine crankshaft with a belt. I've also heard of Roots-type blowers that could be driven for short periods with electric motors (I'm not talking about that little fan that fits inside your cold-air induction intake).

Mating a supercharger with a Miller-cycle engine makes a lot of sense in a non-hybrid application. You get the increased efficiency via reduced pumping losses of the Miller-cycle, and the supercharger makes up for the lack of low-end power of the Miller cycle engine. As I understand it, the efficiency hit of the supercharger is smaller than the efficiency gain of the Miller-cycle, so you get a small net increase in efficiency over a normally aspirated engine. The old Mazda Millenia S here in the US had a supercharged Miller cycle engine. I don't know why more cars aren't sold with supercharged Miller cycle engines, perhaps the additional cost and complexity weren't worth the small gain in efficiency.
 

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hyperion said:
From what I have read about the design of this engine, Prius engineers have determined the maximum hp that is usefull in this hybrid and limited the rpm so this figure isn't exceeded and fuel wasted. So super or turbo charging would be a complete waste of time and money. John 1701 could probably explain this much better.
Ok, you owe me a new Dell 2001FP 20" LCD monitor. I blew soda all over my monitor when I read that last sentence.
 
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