BIG JIM 54

I see my topic went a little astray...

But that's OK. Still guys, a squirrel cage fan and a whimpy 700 watt motor isn't going to do anything to an air-gulping Chevy SB. Maybe a Ford Ranger 6 cyl. But at least I sparked a topic that will be the wave of the future, IMO.

My prediction, EVERY accessory (except the alternator of course) will be electric in the near future. Water pump, oil pump, A/C, power steering and yes, REAL forced-induction. Batteries will be bigger and alternators will be capable of putting out 200A plus.

I had a vision, haha.

BIG JIM

Z-PDX

Hang in there Jim.

If the industry magazines prove correct, 48volts is in your automotive future.

-Z

xs650

It's difficult to see how it would end up less expensive than as a belt driven Roots blower. The blower will cost about the same no matter how it's driven. The questions is, does a batch of starter moters, gears and custom built gear box cost less than a conventional belt drive from the crankshaft. Plus whatever beefing up you need to do to the electrical, system. It looks like a solution in search of a problem. If all you want is an ocassional **** of power, a blue bottle makes more sense.

And it will take about twice the capacity of the one shown on the VW forum to feed a 5.7l Corvette engine. 6 starter motors and an extension cord to the power company? :jester


[Modified by xs650, 9:30 AM 11/25/2003]

George West

xs650,

"It looks like a solution in search of a problem." :D

You are exactly right. Two are used, in the front and trunk. Combined with rubber skirts, they create a low pressure area under the car. The car would be glued to the road. You could drive on the roof of the Lincoln Tunnel. 2G turns could be achieved.

Or a back-up air bag emergency inflation system.

Portable smoke clearing system? Trunk mounted air cannons?

George

mrvette

Remember, I said the target was 20-25,000 impeller RPM but that I could go a lot more. I believe 50,000 RPM is possible which even if 20-25,000 wouldn't make significant boost, 50K would. And who says I have to stop at 24 volts. I'm sure I could get away with 36 or even 48 volts going to this motor for short periods. That's the beauty of electric power. 48 volts will double the motor's power output to 7.6 HP. I'd bet my reputation on that being enough power to turn that compressor at any speed I need to make the boost I want.

Uhh. right there the doubling of the input voltage, assuming the currents are adequate and they will NOT be with a bike battery...maybe two deep cycle marine diesel batteries...maybe....BUT in fact, doubling the input voltage to any DC brush motor will yield FOUR times the power from the motor, untill it blows up from overheating that is....or the brushes burn....

GENE

TreyZ28

cetrain cars want peak power. Close gearing = short, peaked powerband.
supras are great cars- just poopiety drivers :)

BIG JIM 54

I like that joke about the Toyoto Supra's and it's pretty much true as well.

An acquaintance of mine boosted his new Supra's (you know, the one that looks like the "Brain Bug" from Starship Troopers from the rear but with the wing a 16 year-old would put on the car) output to about 450 HP.
He went to the drags expecting times commensurate with his new HP. Came away with his tail between his legs. The thing either bogged badly off the line or the tires went up in smoke. 13 second time slips. And this is no joke.

Anyway, about increased voltages and electric motor output someone said, I'm not sure they are right about 4 times the power with double voltage input. I work with r/c car electric motors and a Competition Electronics TurboDyno 45 all day and I don't see it. But if it was 4 times, my job of making 5-6 pounds of boost in a Chevy 350 @5000 RPM will be so much easier.

Why do it? Any squid can screw on a bottle.
But doing something that the experts say can't be done is the challenge. I never plan to go into the biz of sell such an item. It's just for fun. There's a certain amount of satisfaction in having serious, dependable (and non-exhaustable, unlike squeeze) HP on the street and doing it in a way no one else has been able to do. The ultimate unique vehicle-one of a kind. And isn't that what customizing is all about?

JoBy

U = R * I => I = U / R

P = U * I = U * U / R

Example:

R = 10 ohms, U = 10 Volts
P = 10 * 10 / 10 = 100 / 10 = 10 Watt

R = 10 ohms, U = 20 Volts
P = 20 * 20 / 10 = 400 / 10 = 40 Watt

Dan Parker '96

Big Jim, I just don't see a 3.8hp or even a 10hp electric motor being able to deliver the "oomph" necessary for the boost.

Just some rough calculations off my head...

Internal combustion engines are approximately 30% efficient at best (this is highly conservative).
This means a 300fwhp engine has a 100% potential of 1000hp. Since it is only 30% efficient that means it loses 700hp through heat.

So.. let's say that the radiator (plus radiant heat) removes 90% of that heat engergy. That equals 630hp. This is quite optimistic (and probably very unrealistic). So now we're left with 70hp flowing through the exhaust.

If it takes just 10% of that energy to spin a turbocharger to the speeds necessary to produce a useable amount of boost then we're talking 7hp.

Now.. the figures I've used are wildly optimistic in your favor. Unrealistically so. That is why I believe your project will not produce the results you desire.

smacko

'BJ' I see you DIDN'T get out of corvettes after all??

Using a 50POUND motor to blow your car...Wouldn't that take away some of the benefits?

Anyway, GOOD LUCK!
I still recall as a kid, the thought of putting a 12v vacuum cleaner in reverse and forcing induction, so long live dreams, especially when they become reality! :seeya

TreyZ28

thats not exactly true-
things to remember:
about 1/3 is used to make power (like you said)
1/3 is used in heat that is wasted
1/3 is wasted in sound i believe (i have to double check but i know there were 3 parts)

this is back in the 70s so its probobly at 40% or so now.

but keep in mind that of that 30% used in heat, thats exhuast, coolant, lost in block/heads, heating oil, ect.

A lot of it has to do with the pure momentium of the air and such, the efficency of the radiator has almost nothing to do with EGT or airflow on the exhuast side. The air, under pressure is being sucked out by vacuum and pushed out by incoming air due to overlap on the cam. When its forced in, its leaving faster too and theres more air and that whole 9 yards. Thats why displacement = less lag. more air!

The importance of a good exhuast system. preferably a tuned one is HIGHLY under rated. Just some reading i've been doing in my spare time, but even from the minimal amount I absorbed- I can see its importance.

Everytime an exhuast valve opens, it creates a pulse, a wave of air. tuning these pulses to interact propperly and "pull" each other out is extremely important. If not, you can actually get exhuast flowing BACK into the exhuast port!

Using these pulls and pushes, you can actually "naturally" supercharge you vehicle. thats right- achieve over 100% volumetric efficeny by propperly tuning the pulses. This is why its particularly important to look at intake and exhuasts as pulses and not constant waves. they interact with each other. they can help or interfere with one another. I wish i just knew HOW to do the above, not just kinda sorta understand it :(

I'm not really confident in the above, just what seems logical. Id really like one of the big dogs to throw their 2 cents around for a bit. maybe i'm missing something with the radiator thing? If no one responds, i'll go get my book from work with the energy breakdown.


[Modified by TreyZ28, 10:28 AM 11/26/2003]

scorp508

You'd be surprised how inefficient even a turbocharged car really is. Those 3 parts are way generalized and I think off. The amount of energy wasted in heat by all internal combustion engines is rediculously high. If we could harness all of that heat we'd be rocketing around like there was no tomorrow.

TreyZ28

67% of engery wasted isn't good enough for you :lolg:

you think thats bad? try driving a smaller displacement motor. I'm not quiet sure how big displacement engines got branded as inefficient?use more gas overall? sure, but last time i checked, effiency was output/input.

now, imput is obviously gasoline. output is the desired result- power.

hp/(1/mpg) or hp*mpg is much higher for a V8 than a 4 banger.

think about it. even the F-car (vettes are to exotic for this ricer showdown)

325 * 26 (average between A4 and M6) is definatly better than the all mighty S2000's 220 * 32


8450 LS1 > 7140 S2000

even the old and dated Lt1's 25mpg and 285hp= 7125, about the same

the number concidered are just highway numbers, but you get the idea. and we compared the top of the class to an average V8. We start throwing arround some more "technical" cars like 405hp 30mpg Z06's, 345hp/29mpg C5's and give the LS1 fbody 320RWHP and its even more dominant. or even compare manual to manual (not an average of manul/auto to full manual)
Maybe even use their average cars like 110-160hp civics.

and saying the .50 6th gear is why doesn't count either. V8's can run along at 1800rpms without any problems. 4 bangers NEED to be reving at 3-4000 to have any prayer of doing anything remotely productive in their cruising gear.

by using hp/L- a carbed 350 making 300hp and getting 10mpg is as efficent as an LT1 vette :racking in 27mpgconfused:

whats the point of a smaller motor if its going to make less power and use more gas (unless its the physical size which is a restraint- not typical in new car design)

if you want to use less gas overall- by all means get a smaller car. If you to use that efficent line with me, i might have something to say.; and since most ricers mod- lets do it after full bolt ons. after full bolt ons, most v8s gain a good 60-80hp (depending on vehicle- intake, exhuast, rockers, TB, headers, tuning) and done lose any gas milage. Ricers will be amazed to gain ten hp (dyno, not magazine rated)

id love to see gas consumption vs power output of the cars with no external forces such as aero, weight ect. maybe i'll eat my words? :boxing

:lurk:


[Modified by TreyZ28, 10:50 AM 11/26/2003]


[Modified by TreyZ28, 10:53 AM 11/26/2003]

George West

It takes quite a lot of HP to make useful boost.
According to the Knight blower people:

"George, It will be about a year till I release a supercharger capable of flowing enough air for a 350 SBC. That engine at 7 psi flowing 600 CFM would need 45hp to power the ESC."

But the gains would be large, of course. Normally aspirated engine pressure might reach 14.5psia (0psig), the blower would bring it to 22psia. If there was 300HP in normally aspirated trim, the electric blower would bring you to 455HP gross - 410HP if the electric power is generated "on-the-fly" - intermittent operation can minimize electric power generation losses. So 440HP could be had, about 25% of the time. A 200 amp alternator could charge 2 batteries continuously.

So it can be done. Next question is why? It is not cheap, it is not small, and it cannot boost efficiency the way an exhaust driven turbo can.

George

Darcane

The great thing about statistics is that you can manipulate them to look like they support your case.

The problem with your examples is that you are comparing peak horsepower to the highest average fuel economy. If you spent an entire tank of gas making 300hp, I'd guess you'd be in the 1-2mpg range. At 25mpg, our Vettes are probably only making about 40hp.

TreyZ28

sorry, i didn't have the stats available so i used the only stats i knew.
GM didn't publish their WOT gas milage on the Z06 this year :rolleyes:

would you care to show me other stats? i'm ALWAYS up for learning something new.

Darcane

We're kinda hijacking the thread here...

Anyways, I didn't say I had those stats, or that they would be easy to get. I just made some educated guesses to get close. However, that doesn't make your assumptions any more valid.

A very good measure of efficiency is similar to what you are trying to calculate. It's called Brake Specific Fuel Consumption (BSFC) which is the lbs/hr of fuel used per hp. Unfortunately, this is another stat that you won't find published anywhere AFAIK.

While the most efficient engine I've heard of is also the largest engine I've heard of (I'm sure you've all seen the pics of the huge Inline-12 diesel engine for ships made by Sulzer) that doesn't mean that our larger V8's have higher BSFC than the smaller Hondas. I would guess the Honda is more efficient, but I don't have any solid info to base it off of.

85 Dave

The rule of thumb is that 1/3 of total heat goes to the crankshaft, 1/3 goes out the radiator, and 1/3 goes out the tail pipe.

A turbocharger uses a turbine to use some of the heat energy from the exhaust gases to spin the compressor. The turbine allows the hot exhaust gases to expand and cool, which converts the waste heat to work (by spinning the turbine).

So extracting 45 hp from wasted exhaust heat is entirely possible. Good luck, Jim, with your project. Be sure to post your results.

mrvette

I just look at the rated HP and the CI capacity of the engine, and that seems to say more to me than anything else....and it's a damn RARE engine that does 1 hp/cu inch...damn rare....from the factory that is.....
now in the last couple of years that situation has been changed somewhat, but largely it's still true....
like our 405 hp C5, and the ~300 hp caddy.....are some noteable exceptions...there are others in the last few years...funny how for all the DOHC and such in all kinds of engines the multi valves, all the airflow tricks...getting just 25% more HP than CI numbers is where it's at...

GENE

TreyZ28

well my point was- valid or not, i am doing some research- is the following

why is effiency measured in hp/L?

Effiency is output/input-
X amount of Gasoline has A amount of potential.

gasoline in / hp out = effiency

I miss why the size of the motor is relivant unless we are talking hp/lb of the motor.