On demand computer controlled Supercharger

No expertise here, but I like the idea. Then you could make the ICE a little smaller and depend on the supercharger for the times you need a little boost.

 

Here's the downsides that I can think of for supercharging. You decide. Feel free to post any that I overlooked and to think outside the box to overcome these issues.

1) Increased temperature of intake air (AIC) caused by the compression. Higher temp = less density. This is usually overcome by an intercooler which adds weight and air restrictions. These have to be overcome with even more air compression and therefore more fuel to maintain the optimal fuel to air ratio at stoichiometric 14.7.

2) Additional blow by gasses caused by the increased cylinder pressure. This causes engine wear due to the degredation of the oil and will result in more emissions that can't be comsumed by the EGR system.

3) Power/Availability. A supercharger has to be powered somehow (for Prius it woul have to be electric) and none exist today (that I know of) that can be "turned off" and still allow unresrticted air to the combustion chamber. So, it would always have to be on (at a low level) so as not to starve the engine for air when it kicks on. This would mean additional drain on the battery to keep the compressor spinning. With a big enough fly wheel, this may not be too much of an issue.

4) Space. Looked under the hood lately? Not much room there for additional equipment. Intercoolers are pretty good size, and an electric compressor? Well, I have no idea how big that would be.

5) Last is COST. Add 4 thousand to the cost of the Prius...

After driving a supercharged Mustang, I can say that it was a hell of a lot of fun. That's not what the Prius is about though. Quite honestly, I think the Prius does ok for power. If you start looking at ways of increasing it, you have to compromise on economy, emissions, etc. Why? If you want performance, get a different car!

 

On-demand describes what a turbocharger can do without restricting airflow.

 

Don't get me wrong Dr. E. I'm totally into perfomance and I think your idea is to get as much power out of a small plant as is possible. That's a good idea! No, that's a GREAT idea. I'm willing to bet that the Toyota engineers have discussed ways such as supercharging to increase HP without sacrificing economy and emissions. They WILL figure it out and that's why I added the think outside the box comment. I'm old school hot rodder mentality. "Throw money at it to obtain as much power as you can and don't worry about how much gas you're gonna burn in a 1/4 mile."

 

what i was told...

the prius has a high compression of 13:1. adding any kind of boost would raise this compression. raising much higher than 13:1 isn't a very good idea. you could though replace the pistons with lower compression ones, then add a supercharger, but that would defeat the purpose.

i know of the turbocharged prius, yes it can be done. but if you look at what they did, they changed the engine out for an echo engine if i remember correctly. the echo's don't have such high compression. you would also have to edit the computer code to deal with the changes the boost would make.

now a low power no2 system... that should work, and you would only end up using it when you hit the button. and it would be cheaper too, well, depending on how much no2 you use.

i'm not a mechanic. this is what one told me. he may even be wrong.

 

Expansion ratio is 13:1. Compression ratio is actually 9.5:1. I had trouble understanding "expansion ratio" until I read up on the Atkins cycle engine.

 

<div class='quotetop'>QUOTE(unruhly @ May 25 2006, 01:16 PM) [snapback]261030[/snapback]</div>

You still have to lower compression ratio with a forced induction engine to prevent detonation. It's also going to require premium fuel. Look at the Subaru Impreza, same 2.5l flat-4 available normally aspirated and with two different levels of boost:

2.5i - Normally Aspirated
10.5:1 compression ratio
Runs on regular 87 octane fuel
29mpg highway

WRX - 11.6psi boost
8.4:1 compression ratio
Requires premium 91 octane fuel
26mpg highway

WRX STi - 14.5psi boost
8.2:1 compression ratio
Requires premium 91 octane fuel
24mpg highway

So whenever you're not using the turbo (which is most of the time), you're paying the penalty of having to use premium fuel, and a lower compression ratio (less efficient). That doesn't make a lot of sense for a car whose primary attibute is fuel efficiency.

The main problem seems to be in avoiding detonation. If there were a way to make large changes in compression ratio (like 10.5:1 for NA mode and 7.0:1 for forced induction mode), or cool the intake charge a huge amount (more than you can with any air-air intercooler), then you might be able to have forced induction without paying the fuel consumption penalty during normal operation.

 

<div class='quotetop'>QUOTE(kDB @ May 25 2006, 12:49 PM) [snapback]261012[/snapback]</div>

The Echo engine was used because it was the same size as the Prius ICE and was it not also a Otto cycle enginge as well?

 

Well im no expert (but I did stay at a Holladay Inn ). I had a 2004 Mini Cooper s (s= super charged) it was designed to give optimal performance @ around 4300- 6150rpms. With average driving I could get about 25- 30 mpg combined now that’s with the manual close ratio transition. To get the advantage of the super charger my mpg would drop to about 18- 20mpg. You do get 168 hp out of a 1.6 liter 4 cylinder ice. I would imagine that a prius would suffer a large hit to its mpg as well .

On the other hand you might be able to get an electronically controlled blower. The air intake could stay open for normal driving, when you need power it increases compression by spinning up with a high rpm electric motor. (Then you go fast really fast followed by a big big drop in mpg )(we have fun at mother natures expense :angry: . Oh and our wallet shrinks.)

I don’t think that would work though. Then again there’s always a way to do new things, and to do old things better. Look at the design of the Prius ice if I am not mistaken it is based on a 1903 (or somtime around there) design (made better obviously).

 

I may be showing my ignorance, but here goes. Theoretically, if you compress the mixture up to 9.5 times and then allow the exhaust gases to expand 13 times the original volume of the intake, you would lose power. However, there will be increased efficiency by allowing a longer power stroke. The easier way to do this with an Otto cycle engine seems to be shortening the intake time by adjusting the valve timing. Does variable valve timing allow this scenario?

 

This is a 10 year old thread. Many of these folks, including the OP who bought a Tesla years ago, have moved on.

 

You have resurrected a thread over a decade old.

A motor about 3 times the size of the A/C compressor (it is 201 V DC, just as the super charger would be) would power a Supercharger just fine. You could 'throttle' power by detecting 'ping' as the Prius does already.

More air means more fuel means lower MPG*. (Unless you use a smaller engine) Even with the supercharger motor off, increased plumbing complexity will lower MPG, an ideal might be to run it just enough to not restrict air flow.

Case Study - Electric Supercharger (eSupercharger) for Range Extender Engine | Aeristech
This looks to be 1/2 size of MG/1 to power the turbine. This example is 48 volts

* except diesels where the air to fuel ratio is not a constant

 

Did I do something wrong?

 

It is considered bad form to resurrect the dead, yes. Proper form is to start a new thread if it has been dead for 6 months. (Some topics, like snow tires will only be relevant at a certain time of year, so my be OK to resurrect)
1) You will find the folks have moved on to other lifestyles in a decade.
2) They are unlikely to recall why they held the opinion they did. If no one recalls the thread, why not start a new one?
3) some screens (phones) are less able to scroll back and forth to find what you are replying to.

 

Yet I find it worthwhile to post this...
(48V electronic supercharger to help out before the regular turbocharger spools up (if I understand correctly), to be placed in cars from 2018 onwards)

So the OP was on to something... (as was my friend in 1987 when he switched a fan ON on his CB50 4 stroke 50cc Honda moped that did 52km/h without the fan and about 55km/h WITH the fan. Makes no sense as the fan could not supply as much air as the engine needed, but it simply went faster WITH the fan compared to the fan being OFF or even the fan being removed. Maybe it got the air to swirl more efficiently like on the infomercials...)