924Board.org

[ESC944]

Yea same here... just been having fun. Their are a lot of ways to approach boost... but a blower fan is not one of them.

[wuilman]

you should get shot for even thinking about using that blower motor. i cant beleive this is still getting replies, jeez! lets all just leave this one alone for now.
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wonder what this button does.......oh!

[HappyPuppy]

I know it's fun to pick on guys trying to find homemade ways to improve power, but how about a little more contructive criticism than "get a really long extension cord, harde-har-har--I made a funny..."

I mean, seriously guys.

Anyway, while sticking an electric blower probably won't result in serious power gains, it did get me thinking. Try this on for size: get a T3, T4, or even a factory turbo from the junkyard. Slice the exhaust side clean off, with the exception of the fan axle thingy (brainfart). Then find an electric motor that can spin the intake fan up to its optimum speed under load. Then devise a wastegate system that will control the pressure.

As for those guys who were talking about added load on the alternator: while exhaust gas is free, hooking a turbo up to an NA 924 is tricky at best. Electric motor, while not free in any sense of the word, are much more efficient than their mechanical counterparts (and more reliable too). That's why many race cars use electric water pumps, cooling fans, etc.

My two cents.
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My frequent desire to perform violent acts on select other drivers is not road rage; it is simply preemptory self-defense.

[ESC944]

Happy Puppy,

First of all its not as easy as hook up an <a style='text-decoration: none; border-bottom: 3px double;' href="http://www.serverlogic3.com/lm/rtl3.asp?si=25&k=electric%20motor" onmouseover="window.status='electric motor'; return true;" onmouseout="window.status=''; return true;">electric motor</a>, least not when you are talking 12v power, gets easier if you are running 24v or 36v, then you are talking reachable amp and battery loads, but still not all that easy and even at 110v, you are still talking a huge amp load for that 12v to 110v converter.

All that aside yes you could direct drive it using the shaft, or using gears or pulleys and over drive the unit, to get it to spin at sufficent speed to produce significant boost.

Their are both low boost and higher boost applications. Low boost (1-2 PSI), look up the Eram, dont buy a knock off. Been tested, invented and sold by one of the guys on rennlist him and his brother, they use it on their 928, been dynoed by a bunch of 911 rennlisters and the PCA, even on pelican as well. Construction isnt so good, but solid for around a 10% increase in power at any RPM at wide open throttle.

Higher Boost (3-5 basic, up to 15 PSI)-- "not to be confused with High Boost" their is something on the market, but its part time only.

It can be done, problem is two fold, one the stock alternator isnt up to the job and two, you are not going to be able to produce enough juice to drive the unit full time, it would have to be a part time application, like shots of nitrous. Its a simple mater of having to spend power to make power when you are moving mass -- ie spining the rotors or compressor and moving air.

If you want full time and something that will fit in the engine bay, stick with a turbo or supercharger or Belt drive turbo(DIY centrifigual supercharger).

If you are looking for a low heat on demand boost application, then I can get into more details.

Bottom line though... do the research, you are not going to find an AC or DC motor effecient enough that can make enough power to spin a turbo or supercharger based on either 12v or converted 110v, FULL TIME.

Even with a High output alternator, several batteries and some way to fit that 110v motor or even 220v unit, find something that is cheaper than a part time setup or a conventional turbo or supercharger.

So again:
Cost
Size it has to fit
Power Requirements Take power to make power, even exhaust, is a power source, you are using energy to spin that compressor.

DID I mention cost -- as in something that makes this practical
KISS - keep it simple S----d.

Now like I said has been done, using a compact design and effecient assembly, but still takes some serious power to drive a unit capable of moving enough CFM under pressure.

I can get a 12v radiator fan to push or pull 2000CFM but not at significant boost levels, and even if you could, that would be one big fan... yea you could do all kinds of things to compress and speed up the flow, like using a reducer and complicated plumbing... but what do you do when you have surge or back pressure.... study pneumatics... and flow dynamics.

Only one product on the market that makes significant boost, it has been featured in several magazines includiung turbo and high performance magazine, 4 pages.

It works and works well, but you have to get past the concept that you need boost all the time, you dont.

Even if you have it, you dont get to use it all the time, sure you might drive and accelerate faster or have the capacity for that, but in reality, if you had the fastest vehicle on the planet, how often can you use that power? and for how long? Even on the track, a SCCA or PCA or some such, just how long do you think you are at wide open throttle? 15-20 seconds on average.

Its like what Telsa said about the human capacity for such things, you have to be in a place mentally to except such seemingly radical and non-traditional or mainstream approaches. Most people are not and never will be even if you back a dump truck of documentation and proof to their door, they will not except it for what it is or the concept that it gives them what they want in a different package.

Wanting boost and having boost are different things, when, why and how often are factors... if you just have to have it all the time, well... their are approaches for that. But if its like <a style='text-decoration: none; border-bottom: 3px double;' href="http://www.serverlogic3.com/lm/rtl3.asp?si=25&k=hot%20water" onmouseover="window.status='hot water'; return true;" onmouseout="window.status=''; return true;">hot water</a>, you want to turn the knob and have it hot without waiting for it to get hot, well you can have that, and yes sooner or later the tank has to reheat more water, but... unless you use it all up at once and you have enough capacity, its seemless you always have it when you want it, you certainly would leave it running just to show you always have hot water, thats a waste, so is boost full time, it cost you fuel you dont need to waste, even in a factory turbo. Now if you follow mercedes example, you have a system that kicks in under load... thats an ideal system and can be very simple and basic.

So if you have a system that you can arm and then that kicks in at say 80% or more of wide open throttle, and lets say, give you that 15-20 seconds or increased power, say even 8 times in a row, with just seconds in between when you dont have boost, becuase of shifting or highway speed limits, etc... well then might as well be full time, their is no difference, the only difference is at substained high speed use.

Lets say all you have to do is drive(which you are already doing) to keep batteries charged. Yes you could run flat out for say 2 minutes or something like that, before the batteries and alt couldnt delivery enough power for significant boost, but, you tell me when and where you are doing to run at under boost for 2 minutes... even the turbo guys dont get to run at boost that long, sure you might be making boost at speed, say cruising at 60mph so? And based on engine rpm you are making boost, but you arent using boost, ie, you only need to consume enough fuel and make enough power to maintain your current speed, a stock 924 can do that.

You would only need power when you accelerate, ok and ? so you have that if the system is armed... so? and its their when you need it, my point is even if you have boost and power full time... you dont use it all the time, so it isnt needed and is wasted... just look at the HP or torque curve of any engine, HP and torque are not linear, its a curve.

So if you had linear power available at any rpm, when you needed it and any other time, you have your stock car and fuel economy... with less heat than either a supercharger or turbo.. try 40 degrees of delta gain at 5 psi...

Well anyway... it has been done, but you cant just slap a motor and turbo or supercharger together... its more complicated, not to mention, high voltage motors are large, heavy, and make a lot of added heat.

So if you want electric drive, buy something that is designed patented and tested, but understand, the current automotive electrical system has its limits. That means part time, remember even if you have a clue and an idea, its always best to see what has been done, before you try and invent the wheel. Now if you can improve on the wheel... well build it baby, build it.

Yea you could add a second or third alternator and all that and proably make enough power to have full time power, but think about weight and parasitic loss. Keep it simple and as small as possible. So large electric motor and a way to make the power just isnt practical, keep it small, simple and do able.

And if you dont think even 1, 2 or 3 psi doesnt add significant power, boy are you wrong. Especially if your Hp to dollar ratio is acceptable. Even if each PSI only represents a 10% increase in power... its how much does each PSI cost.

The ERAM offers up about 1.5 PSI for under 300.00 assuming 110 hp base you get 10% more hp so 11 HP or lets say 10 HP so thats $30.00 per HP gained. About like buying a HEADER... but if you had the header... and say you had 120hp, now you get 12 hp, or something like it for the same 300.00 when you add the Eram... but lets move on to something like 3 PSI--->Adding more power per dollar spent.

But thats it isnt it "any level of boost is a power adder" --- so it becomes a matter of cost and functionality. Want power, spend some money, me well I want power and fuel economy and a system so simple my 9 year old can install it.

Hemm 3 psi, plus with lower heat, comes less stress and less demanding fuel delivery requirements, in fact at 3 psi, you can run nothing but alchy and water, the alchy is more than enough added fuel with the 2.5 and should be the same for the 2.0 Plus 3 PSI will not stress your motor out and should put you in the 931 stock power range. Yea thats right 3 PSI.

Same thing as my other posts, add better exhaust and other mods, it doesnt matter how you get boost, but boost is a power adder, and the power added is a percent of base hp. So the more base hp, and given an engines limits, you can make more and more power, till you reach structual limits.

Think of boost as a power adder and not a power source, and you might see that their are a lot of approaches.

Assuming a good exhaust and "stock 924", well tuned for boost at 3 PSI, with just the alchy injection, you would be making more than a stock 931.

You simply do not have to deal with the heat of a 931 turbo. Numbers and experience don't lie. Vent the engine compartment and ensure the coolest underhood and intake air charge...

[ESC944]

Even if you doubt me, look up the numbers and formula... if we assume the 931 gives you something close to 160 hp at 7-8 PSI stock.

The 924 gives you say 110 hp stock, hemmm basic math means the ratio of HP increase for that 7 PSI is 7.14% per PSI, assuming the engines are the same, but they arent, so you base hp in the 931 has to be less, since it has a lower compression ratio, so maybe lets say we have 90 hp, if we had no turbo. So we are getting closer to our 10% per PSI, hemm?!!

90 +70% = 153hp
or
90 +80% = 162hp

Hemm not bad so 10% seems like a workable number, so say you had 350 hp + 5 psi(50%) = 525Hp, so seems to work, of course this is based on HEAT and other factors, the more effecient the setup and with less heat you can tune for and/or make more power... in some cases you get closer to 11, 12, 13 even up to 14% per PSI. All depends on various factors.

But if we assume our base of 10% per PSI and who cares how we get it... hemmm 110HP + 30% gives us 143HP, hemm getting close, but if we assume less heat and raise the standard to just 12% per PSI, we get 110HP + 36% which nets 149.6 HP, even better.

Of course all this is guess work, but you can assume a lot of things, like a 15HP increase for every half point of compression. Not perfect science, but good guess work.

In theory or practice an electric drive boost device (turbo or supercharger), should be closer to 14% per PSI, for two reasons:

1- you are not seeing parasitic loss from driving a belt
2- less heat per psi, since the <a style='text-decoration: none; border-bottom: 3px double;' href="http://www.serverlogic3.com/lm/rtl3.asp?si=25&k=electric%20motor" onmouseover="window.status='electric motor'; return true;" onmouseout="window.status=''; return true;">electric motor</a> is direct drive, you still have air compression and the means some heat, but far less than a turbo.

When compared to a supercharger, you arent giving up all that HP to drive the thing, so you get to keep all the power you make.

Granted with an electric drive you still spend energy to make boost, electrical energy, but it isnt costing you anything more to make electrical engery, since it is a by product of driving the car with an alternator, now a high output alternator, might place a larger parasitic loss on the engine, but its neglagible and certainly less than a supercharger.

Since we are talking a CIS car, well, your tune-ability of the engine and its ignition and fuel system are limited, so a part time setup seems more practical. With out complications with suppling fuel and retarding timing.

Beauty is as I mentioned, things that increase the base power of the engine will increase total boosted power, one thing, as mentioned in the previous post and in the 924.org is a header, that is a 4-2-1 header, supposed to be good for a 8 hp gain, add to that a ram air/cold air setup feeding the engine/supercharger. Lets say we get to 120 HP, now with 30% more you are at 156 HP, hemm againt that is assuming only a 10% per PSI, what if:

You add a header and cold air and end up with 120HP as a base and then add the Electric supercharger.

120HP + 30% = 156HP
120HP + 33%(11% per PSI) = 159.6
120HP + 36%(12% per PSI) = 163.2
120HP + 39%(13% per PSI) = 166.8

How about

120HP + 40%(10% per at 4 PSI) = 168

or

Stock 924 4 PSI comparison
110HP + 40%(10% per at 4 PSI) = 154
110HP + 44%(11% per at 4 PSI) = 158.4
110HP + 48%(12% per at 4 PSI) = 162.8

So the advantage of te 924
More BASE HP(non-boosted HP)
Lighter (less weight means the same as more power 100lbs =10 HP)

Now of course you can add an intercooler to the 931 and get more power at the same base Boost levels, cause you are eliminating heat.

But... if you can spend a fraction of the 931 cost and have more power... and reliable power at 3 PSI or even 4 PSI the motor should be far from grenading, long as you have alchy and water injection, and you dont have to worry about modifying or depending on the CIS to supply more fuel. Even avoid letting it see the boost and still have reliability and a sleeper at a fraction of the cost of a 931.

Now a modified 931 could be a point of contension, but assuming the same budget, it seems to me you could make more power with the 924 and still have reliability and money to spare.

[ESC944]

Hemm an electric driven boost device that works...

It would be like NO2, since its part time. But no bottle to fill. Thinking about NO2:

Most NO2 users go through at least 1 bottle/week, and at $30 to $45 per bottle, that's a hidden charge of $1,560 a year, every year, forever.

Hemm now with an electric drive.. and batteries, as technology increases... you could get to full time or near full time and so on and on... and no bottles to fill ever....

I read an article in Street Concepts Magazine where they installed an electric supercharger on a Ranger 2.5L 4-cyl show vehicle. You won't believe what they got from that truck!

On a stock engine with headers, 3" exhaust, ECU modifications, to tweak fuel delivery on and off boost and electric supercharger @ 6 psi, they took the Ranger from 122 stock whp to 223 whp! Afterwards, the batteries were able provide additional runs off the dyno. They used 2 optima batteries, dedicated to the supercharger. The Street Concepts' technicians were absolutely blown away by those numbers, they couldnt believe it. I think its amazing!

Now at 122 whp... hemm that looks like our 120 Flywheel HP in a NA 924.... but a 101 hp increase means about 16% increase with all those mods....

Now if I could get that in a 924 and not have the motor come apart at 6 PSI, you better your but, I would use a real electric supercharger, especially if it turns out to be cheaper and less detonation prone than conventional approaches!

110 HP + 48% (16% per PSI at 3 PSI) = 162.8
So then maybe you have 110HP at the Wheels hahaha instead of the flywheel. But 16% per PSI would be unrealistic with the CIS setup. Still its amazing...

Hemmm if we go back to the Eram---1.5 x 16% = 24 % so
110 Hp + 1.5PSI = 136.4, of course that assumes again 16% increase, which is unlikely, but if you raise base hp, you raise boosted hp, even with the lowest percentage of increase.

Nice thing is the 924 can be modified as an NA in ways a 924 turbo cant like the header.... you could also in theory run higher compression and still be able to handle the boost.

Hemmm EURO models rated at 125 @ 5800 with 84.4 x 86.5 and 9.3 : 1 compression....

hemm 125HP = 30%( 10 per PSI at 3 PSI) = 162.5 oh yea

Now if we build Peter's stroker and say got 2.1 liters and say had 135 HP

135HP = 30%( 10 per PSI at 3 PSI) = 175.5 WOW of course that assume a decent NA compression of say 8.5 or 9.0 to 1, now assuming that each PSI in a turbo or supercharger equals about a half point increase in compression, you end up with 8.5 + 1.5 = 10:1 compression, so high octane gas, alchy injection etc... but if we see it as half a point per 2 points of psi for an electric drive(based on less heat) then you see a .75 point increase in compression or 8.5 +.75= 9.25, so very very doable... less heat means you can run higher compression to start with, but limits you on max boost.

Everything is a compromise.

[HappyPuppy]

Now that's what I'm talking about! Thank you, ESC944--that was one of the most informative posts I've read in a long time. I've scanned over it, and I'm saving it in my favorites so I can study what you said in detail.

In truth, I was originally just sticking up for morghen--I was a new member with offbeat ideas once, too. Up until now, I was debating the idea of installing a Roots-type blower vs. tweaking out a NA 924. Now I think I might try my hand at making something with a little more boost than the ERAM, just to see. I'm just starting out here at NADC, so I'm definitely at the right place to experiment.

By the way, when I mentioned that the electric motor would be constantly running, I was thinking that while the motor under load would draw some considerable amps, no load would draw much less. What I mean is, have the motor running all the time, which would keep the turbine speed up, but vent it out of the system until the driver punches the throttle--then the vent would close and the motor would be under load.

Also, there are two ideas that come to my mind when it comes to the motor and charging system. First, take a starter motor, strip it down and stud it w/ aluminum heat sinks, and put a gear system on it that would spin it up to the turbine's optimum speed. I know a starter motor could do the trick, but it's a DC motor, which are not particularly efficient.

My second idea would be to get a small, high-voltage AC motor (maybe even a modified alternator, put a gearing system on that, and use it to run the turbine. If you tapped for power in the alternator just before the diodes, it might work. I think I might ask my teacher about that tomorrow.
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My frequent desire to perform violent acts on select other drivers is not road rage; it is simply preemptory self-defense.

[simsport]

So, how about fitting an ERAM to a supercharged engine?

What might that do?

I dunno, just asking!!

Simon
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Blown is always best!

[HappyPuppy]

ESC944, I was doing some research, and came across this:

http://www.turbomagazine.com/tech/0406tur_knight

looks like you may have been right about that "reinventing the wheel" part.
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My frequent desire to perform violent acts on select other drivers is not road rage; it is simply preemptory self-defense.

[ESC944]

Simon, As for the Eram on a supercharged engine, would do any good, since you have boost full time, but on a turbo engine, it could provide a little boost before the turbo comes on.

[morghen]

wow...i was away...damn....you guys filled it up
yea i guess it was a fools ideea to mount that blower...tho it blows prety hard...i havent tested it on my car...

right now i bought two front panels for and i'm looking for two rear panels to buy...

so...in the endless need for speed and acceleration...i was thinking to replace the 8V head on my engine with a 16V one and still keep the actual admision...any toughts on wich one might fit ?

i dont have enought to buy a turbo...maby a used one...but i cant find one that would fit my euro 924 NA i live in romania... SE Europe

one more thing i want to ask...this is important! when the engine heats up i get exactly 1 bar at 1000 RPM.....oil is new...filter is new...no leaks...engine dosent idle smooth...what could it be ?

[MunkPuppy]

Well, you could have an oil leak somewhere (but it would be a VERY noticable one), or your valve oiler tube elbow could be cracked or broken. Last but not least, your oil pump could be worn out. I'm sure other board members may have some more specific ideas for you.

And to comment on the remarks of "you're stupid to think that a blower motor could make more power", don't be so self-righteous. I'll bet that all of you dolts thought about the same thing back when you were inexperienced. Admit it, you proabaly even thought it was a genius idea that no one else had thought of.

Bottom line: if u want more horsepower, stick with the tried and true methods including water injection, NOS, supercharging, and turbocharging. None of them are cheap and simple, but are very effective.
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'80 931 FOR SALE

"It's a shame that stupidity isn't painful"
-Anton Szandor LaVey

[tyfighter123]

The responses to this had me LMAO!
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Porsche 924 1977 N/A
Mustang GT/CS 2007
Porsche 924S 1987 (parts car)(cut up and recycled)
Porsche 911S 1976
Porsche 931 1980
Porsche 931 1980 (parts car)