BLOWER tech???

[burndup]

I don't really have a question... maybe just school us on blowers? Post pix of setups and/or dissassembled ones? Different design types, like roots vs: uh, whatever other types there are? Problems encountered with particular levels of boost? Someone else take it from here...

-J

[ray]

sorry, i ain't much for typing out info, but i DID just read a really good book about this.

called SUPERCHARGED, Design, Installation...yadda...of superchargers, by Corky Bell...worked for bell helicopters so he seems to know his shit.

i thought it was a VERY good book, it tells you MUCH more than "bolt on this kit and go". after reading it, you will be ready to sit down with a calculator, and figure out what you need, and how well it should work. he gets down to the basics of engines that ANYBODY should know, blown or not. it "seems" real easy the way he explains the theory of how much heat you can put into the intake charge before detonation, etc.

now i just need to get my blown motor! http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

[burndup]

tech posts shalt not be on page 2...

[Psychobilly Boi]

hey all,

im really interested in this as well...although i like mine blown flathead flavour...so many questions...need more blower guys to chip in here and spread the info!

danny

[Jkustom]

[ QUOTE ]
tech posts shalt not be on page 2...

[/ QUOTE ]

Or page 9! Bttt... -J.

[burndup]

I'm really shocked and apalled that the "Durrrr, what is a pickup truck??" post is... well, WAS higher up than this one...

based upon a lot of the shit on page one, this tech week is off to a slower start... I hereby appoint myself to the "tech police."

---

On Washington Blvd in Whittier there is this rather industrial looking building, and it says "Blower Drive Service" and BDS on the side... often wondered if they meant superchargers...

[Mutt]

YUP..

http://www.blowerdriveservice.com/

and..

http://www.dyersblowers.com/

[Sam F.]

yes,,you need to go inside next time your by there! when you first walk in there is a line of engines on display with blowers,they used to(or still do power many of the hardcore blown race motors out there



back to the question,,,well sort of, im cuirious about the Frenzel blowers,in regards to how they work

[old beet]

Always thought a supercharger 'pushed' air and fuel down thru the carb as opposed to a blower, 'sucking' air and fuel down. Paxton supercharger-GMC Blower.....OLDBEET

[Fat Hack]

Well...

For starters, blower tech begins below the manifold, with the engine sitting under it. Unless you're Mel Gibson sportin' a fake blower with an on/off switch, or running it uselessly underdriven for noise and show, you need to make some modifications to the engine if you wanna get very far!

Forged pistons are a must for any halfway serious blower motor, and blower-specific pistons work best. You gain the most from running a blower by setting your static compression low, and letting the huffer do the work! Blower pistons are strong, dished forgings in most cases with extra meat on top for strength, and should have NO sharp edges that can create hot spots and lead to disasterous detonation.

Rings should be chrome moly at least, if not ceramic with the proper honing technique used to seat them properly and promote a good seal. Excessive blow-by in a blower motor equals an oily mess...as you'll be blowing out every gasket in the engine!

It goes without saying that connecting rod, crank and block prep are critical. Running substantial boost with weak internals is gonna be an expensive lesson in high speed and messy disassembly!

Most blower motors have o-ringed blocks to prevent the possibilites of a blown head gasket by insuring a superior cylinder-to-combustion chamber seal. Your machine shop can do this for you along with the rest of your machine work.

Camshaft profiles are often different for a blown engine than for a naturally aspirated one, too. You can use other performance grinds, but you'll gain more power with a blower-specific cam profile. You don't want alot of overlap, and most builders like higher lifts and shorter durations for supercharged mills. Check with your cam manufacturer and be sure that you are buying a camshaft that will take best advantage of your given combination. Nothing is cheap about running a big ol' blower, and a custom-ground cam is more the rule than the exception for people serious about building their motor to run lotsa boost!

Mounting the blower to the engine will either require a manifold designed for the blower, or an adapter that allows use of a blower on a 4v intake. Using a manifold designed for a blower is by far the better choice!

Some sort of pop-off valve, or blow-out window is required with a blower as well. This is an area usually incorporated into the intake that is designed to give way and "blow out" in the event of a backfire or blower explosion to help minimize the severity of the damage. Backfires are bad news with a blower!

Almost all blower set-ups will feature a screen below the carbs and on top of the blower. This is to help keep debris out of the blower casing...which could cause expensive damage to the case or rotor vanes.

Think rich when topping your blower with carbs. Dual quads work very well, but should be jetted up and dialed in to run richer than you think they probably should at first. Too rich will rob a little power...too LEAN will hit you in the pocketbook FAST!

Two 660 center squirters is a tough combo to beat on a blown small block Chevy, and they're worth the added cost over cheaper 450 "tunnel ram carbs" for your huffin' hauler, although properly tuned and calibrated vacuum secondaries carbs CAN work on the street, too.

Ignition is a big deal on a blower mill. All that extra fuel and air being forced into the cylinders and then compressed will need a hell of a kick to light it off! Spend the bucks to equip your engine with a powerfull coil, stable distributor and good quality wires. Go cold with your plugs to start with, and work up as you iron out your combination.

Timing is important as well...too much advance or too fast a curve will make pieces out of your engine, so be conservative and err to the side of caution while finding what your motor likes. You may want to start off at 0 degrees advanced with a stock advance rate for break-in and initial trial runs.

The systems that support your engine really have to be up to the task as well. You NEED a GOOD fuel pump with a 1/2" line running right from the tank to the regulator(s) to the carbs...a loss of fuel pressure...even for a second...will send your motor into Meltdown Mode!

Additionally, your exhaust system has to be able to flow well enough to get rid of the spent gasses and avoid excessive back pressure. Muffler explosions are common on street cars running blowers...and they will scare the hell outta ya!

Lastly, your cooling system has to be able to handle the additional heat that a blower motor builds, and still keep it cool! Your stock radiator is likely NOT going to cut it with a big 6-71 blower and a motor built to use it! Like I said, nuthin' CHEAP about gettin' blown!!!

And, I guess I should mention that a beefy drivetrain and strong motor mounts are a must, too, right? What good is all that power if you break stuff all the time???

When it comes to starting your blown engine, don't pump the gas pedal a bunch of times before cranking, and don't hose the carbs down with starting fluid. Push the pedal halfway to floor and let up, then crank the engine and give it a pat on the pedal as soon as it firesto keep it from popping back through the carbs. You should be rich enough for the engine to run cold with little coaxing.

If practical, break in your camshaft with a standard four barrel carb and intake on the motor temporarily, then bolt on the blower intake and induction system. That way, your not dealing with a fresh, untuned blower motor durring cam break-in.

After your cam break-in and initial test running with the blower to get the carbs sync'ed and adjusted, the timing set and other considerations met...change the oil and filter prior to that first test drive.

Make sure the tank is filled with good, high octane fuel and go easy on the motor at first. Make a few moderate, part-throttle acceleration runs and get a feel for what's happening. Take frequent plug readings to be sure you're not too lean before getting heavy with the throttle for the first time. You don't want any sudden surprises when you mash the pedal!

Keep an eye on your gauges, especially fuel pressure...if it dips below 6 or 7 psi, be prepared to shut down quickly to avoid a lean-out!

There's lots of other things to consider, but that oughtta get you at least a little more familiar with what it takes to run a blower! I had researched it quite a bit a few years back when considering a blower for one of my old project cars. Best to learn about them BEFORE you dive in and make expensive mistakes!

Anyone else got something to add???

(I'm getting typing cramps lately! http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif)

[burndup]

Dope, other than the hardware, it sounds just like a lesson on turbo...

[ray]

if you run a centrifugal blower, it is even more like a turbo, right down to adding a big ol intercooler so you can really get into the boost!

i'll add also that the roots type will give you gobs of low end torque, while the centrifugal typw will help you out on the upper end more.

[Jkustom]

FAT HACK, all that typing you just did reminds me of why I joined the HAMB! I owe you one! http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif -J.

[Machinos]

Does anyone make a Roots-type blower that has any kind of wastegate on it? I know superchargers are less "efficient" than turbochargers because they take engine power to operate, but how much, especially if all the pressure is being let off?

Basically, I'd LIKE to install a blower one day, but if it means having a car that gets 10mpg on the highway, forget it. Also, how reliable are they, generally, and what happens if you just disconnect the pulley?

[autocol]

a lot of roots type blowers, the eaton M series for example, have a solenoid valve on the side that is *usually* operated by a vacuum switch, but which could probably use a throttle position sensor also.

as i understand it, when you're not "on the gas" this solenoid acts like a wastegate and allows you to burn atmospheric pressure air/fuel when you're idling or at low throttle openings.

you're still wasting the energy to spin the blower mind you.

the toyota 1GGZE (i think) engine has a supercharger with a electro-magnetic clutch, which when disengaged allows the pulley to free-spin on the shaft without turning the blower. flick a switch and you're in business!

unfortunately, while those blowers (SC14 is their designation) are dirt cheap, they are only off a two litre motor so generally i guess you'd need two (possibly overdriven) on a half decent size motor.

i just bought this Eaton M90 (http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2453868917&category=33 741&rd=1&sspagename=STRK%3AMEBWN%3AIT) on ebay but the seller won't respond http://www.jalopyjournal.com/ubbthreads/images/graemlins/mad.gif

[Flatdog]

Hack great post.I will post some flathead 471 stuff if I can get my kid to do it.I am computer stupid.

[burndup]

Autocol, how cheap? I gots a 2.0L that would be very happy to have a blower.... if it'd fit under the hood...

[burndup]

Oh yeah, and which GMC's came outta the box with a blower???

[38Chevy454]

I agree wioth all that's been said, you need to understand what you are doing before putting a blower on your engine. It is not a bolt-on and go. It is not cheap if done right.

Stock engines can usually stand up to about 6 psi boost, even with cast pistons, as long as you don't have detonation. Higher boost levels is where you have to step up with the good parts.

The main thing that you have to deal with any blower is that when you compress air it heats up. So hot air also takes up more space. So in effect it may have only a bit more oxygen than an engine without a blower. This is why intercoolers are so important and also work so well. It is all about the amount of extra oxygen that is crammed into the cylinder.

Blower cams are kind of like a nitrous cam. They tend to have wider lobe separation (less overlap) and more exhaust duration to help get the extra quantity out. This is why roller cams are popular, they allow more lift for a given duration.

I have a centrifugal blower on a nailhead using a blow-through set-up, and a whipple blower as a suck-through set-up on my dually. Both methods work.

[Scotch]

Okay - Lots to talk about here.

First - I've worked on all different kinds of blower setups, from street Roots deals to full-competition alky huffers pushing 1,500 hp. I've run centrifugals on the street, but not raced them.

So, here's the dealio:

Blowers provide pressure (called "negative vacuum" by some) to make an engine more than 100 percent efficient. A normally-aspirated engine relies on the vacuum developed by the sealed piston moving down in the cylinder to draw air and fuel down into the engine. Superchargers force air and fuel down the throat of the engine like John Holmes did to Linda Lovelace. As has been stated, the engine should be modified to make the most of this postive pressure.
A larger port will allow more air and fuel into the engine. While porting and polishing is a pretty normal part of hot rodding, ports for a supercharged engine can be larger and less "picky" than naturally-aspirated (N/A) engines. The positive force behind the air and fuel is much less concerned about port flow efficiency. Also, as stated previously, blowers make heat. They're compressing air, and the friction of the molecules bumping into each other causes heat. Also, the additional valve lift (usually on the exhaust side) of the camshaft allows for the greater quantity of spent air and fuel to exit the engine, which is necesary to get the most out of your blower setup.

I've not specified any particular type of supercharger yet, since they all work on these same principles. Some varieties mix the air and fuel into a nice homogenous mixture prior to intoroducing it to the engine, while others just pump air and fuel is introduced later (like in EFI setups). There are pros and cons to each of these methods. While a good mix of fuel and air is effective, and the engine prefers a well-mixed batch (it burns better), introducing fuel just ahead of the intake valve (like EFI) is also beneficial, in that it cools the incoming charge.

I prefer EFI setups over carbs in blown applications due to the control factor. You really have more control over a supercharged arrangement with EFI, since you can control fuel distribution. With a carbureted setup (carbs over blower, or "draw through" design), the carb power valves should be referenced to the manifold for best performance. A draw-through design is the most common because it's the least expensive, but you sacrifice fuel distribution and if your intake manifold setup is less-than optimum, you run the risk of leaning out a cylinder and hurting the engine. But, this doesn't happen much on street setups. It's more common when you're pushing lots of boost and rpm levels are up there. Everything gets more critical with rpm.

There are also blow-through systems, where the boost is generated first, then pushed through the carb. I don't like these setups at all. I know many centrifugal huffers are being run this way, but I still don't like it. My reason is simple- I've never seen one that worked perfectly. There's always a weak spot somewhere, and I feel it's because the carb gets confused. Instead of being drawn upon from the baseplate with vacuum signal, the carb is being force-fed from the top, and cannot react the same way. When the engine is not in a "boost" condition, the carb can do what it does, but when you get into pressure and there is equality between the manifold pressure and the inlet pressure, the carb can't see any signal and can't feed the engine with precision.

So, for a draw-through setup, carbs or EFI is fine.

For a pressurized blow-through setup, I prefer EFI tremendously.

For a street setup, efficiency can be secondary to reliability. Street blowers can run a little fat (rich) and be just fine without ever hurting themselves. In fact, supercharging with a Roots often smoothes out the power curve and hides other "mistakes" inside the engine.

In a competition setup, tuning and distribution of fuel is key. Going lean is the worst-case scenario and EFI is king.

If you're running any kind of supercharger, a good exhaust system is also key. You're forcing more air and fuel into the engine, you've got to give it a good way out.

There's more (much more), but these are some basics. If you're considering any kind of blower, these guidelines should help you make some decisions. If anyone would like to talk further about this stuff, P/M me or post something. I'll share all I can if it'll help.

Scotch~!

[Psychobilly Boi]

hey flatdog,

im hanging for this info...get that kid typing!

danny

[ QUOTE ]
Hack great post.I will post some flathead 471 stuff if I can get my kid to do it.I am computer stupid.

[/ QUOTE ]

[stolenmojo]

scotch, what's your opinion of a true mechanical injected blown setup for a street car? is the barrel valve too picky to be on a car that isn't constantly tuned for conditions?

anyone know of good resources for mechanical injection information in general? seems like a lot of this knowledge is starting to disappear with the guys who ran the early fuel motors.

[autocol]

J-

search for "1GGZE", "SC14", or just "toyota" in the supercharger section of ebay... i've seen them sell for US$100, up to about 200...


cheap.

[Mutt]

[ QUOTE ]
scotch, what's your opinion of a true mechanical injected blown setup for a street car? is the barrel valve too picky to be on a car that isn't constantly tuned for conditions?

anyone know of good resources for mechanical injection information in general? seems like a lot of this knowledge is starting to disappear with the guys who ran the early fuel motors.

[/ QUOTE ]

Try:

http://www.hilborninjection.com/tech-support.asp

And:

http://hre.com/cgi-bin/discus/discus.cgi

Dan

[recycler]

I have both editions of HRE's fuel injection handbooks. They are very good to have around if you have a mechanical injection system.
Correct me if I'm wrong but roots type blowers were originally designed to pump air in volume. When you put one on an engine you are asking it to act as a compressor- therefore you have some problems. If you run carbs you are asking it to also pump liquid and vapor.BUT the benifits outweigh the drawbacks. I'd recomend a 2 lobe for the street for better fuel/air dist. I had the pleasure of having a blown and injected car and I can tell you that they work like an SOB when setup correctly.
The more modern "screw compressors" ,I beleive, were engineered to be air compressors and they are much more efficient than the roots type.At the plant where I work we have 2 belt driven screw compressors. One is roughly the size of a 471 and the other an 871. They supply our whole manufacturing plant with 119 psi of air 20 hrs a day in a little room and all you do is change the oil and water separators once in a while. They are excellent but they don't whine, they scream.
My 2 cents for what its worth. Brad

[Scotch]

Thanks to Mutt for the excellent links, and as they state, mechanical injection is no party on the street. The finicky nature of barrel valves (pills) and the need to prime before firing is a hassle. For some, it may be livable, and sharp tuners can make it work okay for a season before the weather changes and screws up your tune. There have been plenty of factory mechanical fuel injection systems that worked okay in street applications (the Rochester FI units used on Chevys from '57-'65 are a great example, as are early Porsche units by Bosch), but the traditional gasser-style stacks just don't like running at part-throttle. The trick is in synchronizing all 8 stacks to pull the same vacuum and see the same fuel throughout throttle travel. It's akin to synchronizing multiple carbs, but carbs are much more forgiving since they work on the vacuum they see. Injectors don't care about vacuum signal, they force-feed fuel to the ports. Since different engine designs, manifold designs, and cylinder head designs normally offer up different size or length ports from cylinder-to-cylinder, it's really tough to make stacks happy. The advent of EFI conversions on classic stack intakes has helped tremndously, as the injectors can be tailored to what each port wants and synchronized much more closely. The key is in the butterflies, as they all need to be fine-tuned for synchronicity. EFI tuners read exhaust gas temps to sync up the tune, where old-school guys used vacuum tools on each stack, which is not nearly as precise.

If I really wanted to run a set of injector stacks on the street, I'd buy an old Hilborn, Kinsler, or Crower setup and plumb it for EFI as stealthy as possible. It ain't cheap, but it ain't common either. Done correctly, you'll have a good running setup with absolutely killer eye appeal. Done wrong, it won't matter because no one will ever see it...it won't start or idle or hold a load in gear. FYI - the hardest thing for any engine to do is idle.

P.S. - Blower whine is not all from the blower. In fact, less than half of the noise you hear from a blower-equipped car comes from the blower itself. Most of it comes from the air escaping from the mahcined cog belt pulley as the belt fills the notches in the pulley while the blower turns. A good 50 percent of blower whine can be reduced by drilling holes in the cog belt pulley grooves, which allows this air to escape without "whistling" past the belt teeth.

Scotch~!

[ray]

on the blower whine, for centrifugal blowers its due to the internal gears that gear up the blower.

i just got the newest CAR CRAFT in the mail yesterday, they do an article on a guy that has a DIY electronic fuel injection computer kit, you actually solder up your own circuit board, and scavange the rest of the parts you need. still kinda spendy, but i think the point is, the day is here when those of us who actually care about how our engines perform have to shit or get off the pot.EFI is the way to go, and once you make the commitment and learn the basics, you will never want another carb again. and it still can be made to LOOK traditional.

[DrJ]

Some random thoughts on how and why they work;

A screw compressor works like a ducted fan, or the jet drive on a ski boat.
It "hit's" the air/liquid on an angle and forces it to either compress or accelerate in a tangent to the hitting blade.
(Right, Physicists?)
A root's type "blower" with the pair of three bladed rotors works more like the paddles on a Mississippi river paddle boat, scooping behind the air/liquid and collecting and transporting it somewhere else, relative to the paddle.
A typical engine's geared oil pump works that same way.
(The Roots type rotors turn "up" in the middle and "down" at both sides so that the air is gathered and pushed around the outside parts of the blower case too, for those who hadn't really thought that much about how it works...)

Vacuum doesn't "suck" anything. When a piston moves down in a cylinder it creates an area that has lower air pressure than outside the area. If a valve/door is open to that area, AMBIENT air pressure will PUSH air into the lower pressure area.

A "blower" increases the "ambient" air pressure in the manifold above the valves/cylinders, making the air move into the void, created by the moving piston, with more force/efficiency.
The intake of the blower is still relying on that outside ambient air pressure but is set up/geared to move the air/liquid at a higher volume than the engine is capable of using it at otherwise ambient air pressure, that's the only way it is a "compressor"

[Bugman]

So Stack type fuel injection is touchy on the street because the syncronizing of the stacks is so important right? What about a 4 hole injector on top of a blower. The air and fuel from each port dump into what is basically an open plenum. Wouldn't that mix it up better, and help equalize the air/fuel mixture from each port? Would that be more streetable than an 8 stack unblown engine?

-Bugman Jeff

[Scotch]

Bugman - Once we're talking about putting anything on top of a blower, all bets are off. The blower mixes up the air/fuel into a wonderfully-homogenous mixture and delivers it with force to the hungry (read: "low pressure" so Dr.J doesn't get pissed) intake ports - vacuum signal is no longer an issue.

Where mechanical FI gets limited is when each port is isolated (via stacks) so the vacuum (negative pressure) signal is no longer shared, and there's no blower to help get air and fuel inside the engine. With the old factory mechanical FI systems, the intake plenum was still a shared design, so manifold vacuum was steady. Once the ports are all isolated (by stacks) the signals become erratic and must be synchronized.

The 4-holer mechanical FI setups on top of a blower have issues too, but they're different again from non-blown setups. Still, the pill is critical and the needs of a supercharged engine dictate careful pill selection. Since we're hot rodders, we choose the pill dimension the engine needs at wide-open throttle (WOT) since that's where drag cars are designed to run. How that same dimension will work at idle, with the lower fuel pressure supplied by the cam-mounted mechanical fuel pump (which of course changes pressure in a direct relationship with engine RPM) is anyone's guess, depending on the application. Drag racers set it up to work great at the target rpm/fuel pressure/boost level, open it up to WOT and let it eat. What it does at idle or part-throttle doesn't really matter, but it's much easier to try and tune a mechanical 4-hole injector atop a blower for street use than it is to tune a non-blown, 8-stack mechanical injector setup. As I mentioned in my first post in this thread, blowers cover up mistakes with brute force and engines can run fairly well even if they're less than ideal. Naturally-aspirated (unblown) engines are much more finicky, especially at idle and part-throttle.

Scotch!~

[stolenmojo]

scotch, i was under the impression that the fuel introduced on the top side was also for cooling of the rotors in the supercharger. is this the case? in an efi setup could you inject 1 or 2 on top for cooling and then inject in the port of each cylinder for optimal mixture. seems to me that this would allow more volume to compress since there would be less fuel to displace air in the rotors? obviously it would be complicated, you'd need a custom ecu to drive 10 injectors instead of 8.

tech week rocks, ryan, could we have tech millenium next time?

[gettingreasy]

What about running a four or a two hole injector on a Tunnel ram? Now what about turbos and centrfugals? i would like to run one or the other(probably a turbo tho)on my slant six.
-Jesse

[Flatdog]

Here are the pics of my blower setup.

http://members.lycos.co.uk/zackbass/4-71Gallery.htm

The motor feels very strong as it is, but I'm only getting ~5lb boost and the carb is far from tuned. I just got a new 650CFM Holley to put on the motor and hopefully I'll get a smaller top pulley so I can get some more boost. The motor has forged pistons, a strong crank, and beefed up mains so it should be able to take bit more. The motor wasn't built to be a blower motor, it's got a very radical roller cam and an extremely long stroke, but it took to the blower very nicely. The motor has a 7:1 comp ratio. It idles very nicely and the blower makes a surprisingly little amount of noise.

[Psychobilly Boi]

flatdog,

whats your estimate on the HP output of that setup? i'm still wiaitng to get joe's book Blown Flathead for some more info. Apart from the main strengthening issues, how would an otherwise stock stroke/bore/heads flatmotor take to being supercharged?

danny

ps. where was the sources for your drive gear parts on the blower?

[Flatdog]

I am hopeing for 300 hp,it made 188hp without blower.It is too early in testing stage to realy know anything yet except seat of the pants,but that feels great.Blower drive parts where made by Ronnie Roadster out off Conn.He also made extened water pump shahts to clear the blower belt it not the first blower drive setup he bilt.

[Scotch]

Gettinggreasy,

Running mechanical injectors atop a tunnel ram presents it's own issues aside from tuning...which is a problem unto itself. First, I'll tell you why it wouldn't work well if it WAS tuneable, which it isn't.

Mechanical injection is always flowing fuel, just at varying pressures (with rpm). It's been called a "drool" system for this reason. Engineers have placed mechanical injectors close to the intake valve for this reason. The air flowing quickly toward and around the intake valve can pick up the fuel from the drooling jector and keep some of it in suspension in the airstream so it'll mix well. If it doesn't mix well, it won't burn well...(you know that if you toss a lit cigarette into a bucket of fuel, it'll extinguish, right? Trust me on this...).

So, the finer the fuel can be misted, the better. The more fuel that can stay in suspension, the better.

If you were to mount a 4-holer atop a tunnel ram, you'd get a constant flow of fuel into the intake, where it would subsequently puddle up on the floor of the intake and the motor won't run well.

Also, mechanical injection systems don't have accelerator pumps, so there's typically a "lag" wen you floor it, or even casually creep up on the pedal. Remember, these injection systems were designed to be run at WOT, so acceleration smoothness is not a primary concern.

Maybe you can already begin to see how tuning a less-than ideal system like this would be near impossible. Even if you could, temperature and air quality changes (humidity, barometric pressure, etc.) would all affect it, and keep the killer tune out of your reach.

EFI clears up all these issues.

With regard to the cooling effect of gasoline on a blower...

Yes, the introduction of gasoline to a draw-through system does serve to cool the blower assembly, which is trying to heat up due to the friction of compression. However..

Roots blowers were designed to be run "dry", and they don't need the cooling effect of the gasoline to work. In fact, this is one of the reasons "factory" specifications for GMC superchargers are so loose compared to those preferred by automotive enthusiasts. Big clearances exist to account for the swelling of parts and long-term life of the blower when it's used in it's original application (diesel engines).

Car guys prefer tight clearances for higher boost pressures, and with the addition of gasoline this can be done easily.

There are some enthusiasts experimenting with blower EFI systems where the blower is run "dry" and fuel is introduced above the valve. Expect to see things like this on the market in the near future.

Scotch~!

[Phil1934]

I've been looking at FI since I posted a few months ago about my desire to build one with an electric pump. Work causes things to take months instead of weeks, but I found encouragement in air atomizing nozzles. The ones from http://www.spray.com/pdf/b381_Air%20Atomizing%20Nozzles.pdf claim to put out 15 micron droplets. A human hair is 100 microns. The nozzles look just like the tip on a paint gun. I have looked at others where air flow affected fuel which made programming tough, and I have not gotten the specs on these yet, but a Sanden compressor set up to supply air like this http://www.onboardair.com/compressors.htm should supply the air. While finalizing electrical ideas I found http://www.aquamist.co.uk/ who sell water injectors that mimic fuel delivery so if seals are compatible, could be the pump and programming solution. Put all this on 97/Rochester throttle body bases on SBC intakes with plumbing and compressor and offer the pieces for the other engines.

[stealthcruiser]

phil1934,
whereabouts in jointsboro do ya' live?
i live in hampton,and would like to see some of your experimenting on this subject,if you are doing some that is,and don't mind someone seeing such.
might even do some brainstorming.
pm if interested.
thanks.

[Psychobilly Boi]

hey flatdog,

was was his pricing like?

danny

[ QUOTE ]
I am hopeing for 300 hp,it made 188hp without blower.It is too early in testing stage to realy know anything yet except seat of the pants,but that feels great.Blower drive parts where made by Ronnie Roadster out off Conn.He also made extened water pump shahts to clear the blower belt it not the first blower drive setup he bilt.

[/ QUOTE ]

[Blownolds]

Something was said on page one of this thread that roller cams are preferred because it allows for more lift with a certain duration. Actually, that's backward. Roller cams allow for longer duration due to the steeper ramps (quicker opening, quicker closing, meaning the valve can hang open longer).


As for mechanical injection on the street, I doubt it would work well on a stack injector naturally aspirated, but I happen to know some Willys guys doing this on supercharged street engines with good results. I will be using a 4-port on top of my blown 394. There are definite tricks to setting the system up though!