Contour Enthusiasts Group Archives Forums Modifications Forced Induction intercooler vs. more boost

Paul,

You calculated that you need 0.15m^3 of air at 5psi every second. Lets assume you have an intake system that actually has two 0.15m^3 tanks with a valve that seals either one tank or the other from the intake, and that the system switches between them every second. So the first second, your compressor fills tank A to 5psi, then the compressor switches to tank B and fills that to 5psi. While the compressor was filling tank B, the engine took the air out of the tank A, then while the compressor is filling tank A, the engine takes the air out of tank B, which was just filled to 5psi. The cycle constantly repeats like this, as long as the engine is running. Sounds like a great system. Except that the engine will only be fed air at 5psi from tank A the instant that the valve on tank A opens. After the valve opens, the pressure gradually decreases as the air leaves the tank. So you may have 5psi of boost at the start of each second, at the 0.5 second mark you'll be at 2.5psi of boost, at the end of each second you are NA.

This is why, as Rara stated, your calculations for power are much lower than they should be. You were calculating how much power is required to pressurise 0.15m^3 of air to 5psi every second, not how much power is required to keep a flow of air of 0.15m^3/sec at 5psi.

Hopefully this makes sense,
Bob

I have done some work on automotive power electronics. Cant say much, but if you are serious, look into power conversion. You will achieve much higher efficiency at higher voltages. Most automotive power engineers agree high power systems cannot be run on less than a 42v core. FYI the next gen Toyota hybrid will be running a 42v battery to a sealed voltage converter to a 300-500v core ISA.

Now I would love to see it when its done, but every application of e-turbos I've seen is supplimental. Turbos alone are very very efficent, however they tend to have lag. E-turbos have no lag, but use lots of power. Once combined the system works very well, the e gets the engine to speed and starts the turbo, which then takes over. Some systems are even so advanced that the e-turbo can extract power and prevent over-boost without a bov.

Paul, you are still missing the point between continously compressing a given amount of air, and compressing a continuous flow. It sounds like its the same thing, but the difference is huge. If you don't believe me, try it.

I have a fairly decent grasp on the laws of physics, and
all I can see from all these posts is that Rara has a
pretty good grasp too. You maybe need to study this stuff
better before you waste alot of money on your prototypes.

First of all, a starter motor doesn't come anywhere near
even close to 10 hp. The only reason it can turn an engine
over is because it is gear reducted (ie. big flywheel vs.
tiny starter gear). If you were to gear it the other way
to try and turn a compressor impeller the speed necessary
to feed an engine running at 5000rpms with 4psi say, I
don't even think the starter would barely turn over (the
vacuum from the engine's intake across the impeller would
probably help the starter turn a little). I don't even think
you could get .001 psi at 5000rpm with a typical starter motor
off a car. A guy I know has slow-acting hydralics on his
Impala (not even fast acting mind you), and he requires 6
Optima batteries in the trunk to run just 2 motors and they
don't last very long at all. You are going to find that
electricity is not very efficient for trying to run
compressors. Do you know how hard it is to even turn a
compressor by hand? I have a customer that we put a Paxton
supercharger kit on his truck a while back, and when you
take the belt off it and try to turn the pulley with your
hand, it is VERY hard to turn. You cannot even make it
spin by it self (you'd have to mount a huge flywheel to it to
make it do that). You are going to find that you are
trying to accomplish the unsolvable task doing this on a
backyard budget. Believe that Ford, Chevy, Chrysler,
Kenworth, Peterbuilt, John Deere, Case, Caterpillar, and
others have experimented with this idea for years, and
who knows,
maybe in 10-20 years they will be able to make this
workable, but don't hold your breathe. I'm not trying to
discourage you, I'm only trying to save you $$$. You don't
think people have tried this crap for years? People have
tried every way to convert the engine's byproduct energy or
other engine energy into power and so far, turbo and
blower is the best that's out.

Here, read this: http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2426797798&category=33742

and this: http://www.bamaclassifieds.com/ebay/warning.htm

And check this out: eBay search page

and

http://www.electricsupercharger.com (haha)

Those are all the current scams out because this topic of
electric superchargers is such an easily convincible
subject, because at first quick thought it
sounds 'feasible' but if it REALLY was then don't you
suppose the professional racers (with millions of dollars in
sponser money mind you) and the automakers would be in on this too? Trust
me, this is not just some well kept secret. There's just
too much efficiency loss, and high-powered electric motors
are really HEAVY. Why not just use a pulley/belt and a
shaft (ie. Vortec) to get the power directly and avoid all the heat losses from
electron movement (not to mention the weight from motors and batteries)
, or use the 'free' exhaust gases (heat energy) that the
motor just throws away anyways and convert that to usable
energy (ie. conventional methods)??
By the way, I had your same idea when I was like 18-19 years
old and it DOES sure sound like a good idea on paper, but it just can't
work with today's technology. Wouldn't you just rather work
extra hard for a summer and then just buy the complete turbo
kit? Sounds much easier to me than trying to defy the laws of physics