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  • Thrud
    replied
    Paul

    Plus, it would make a nifty sidewalk defroster! Or BBQ charcoal ignitor...

    Everyone needs on of them, eh!

    Leave a comment:


  • gunbuilder
    replied
    <font face="Verdana, Arial" size="2">Originally posted by Thrud:
    Oso:
    Well, the turbo itself can be turned into a jet engine - you can even throw an afterburner on them. You attach a combustion chamber to the turbine side and it drive the compressor that feeds the burner. A small one on a bicycle is a squirrely ride - it is easy to get them over 60mph!

    Oh, the joys of bastardizing an application to create another unconventional one!
    </font>
    I found a web site about building a jet engine from a turbo, cool site. I would try one myself but I don't need another project.

    Paul
    I found my typo error.

    [This message has been edited by gunbuilder (edited 04-16-2003).]

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  • Thrud
    replied
    Oso:
    Well, the turbo itself can be turned into a jet engine - you can even throw an afterburner on them. You attach a combustion chamber to the turbine side and it drive the compressor that feeds the burner. A small one on a bicycle is a squirrely ride - it is easy to get them over 60mph!

    Oh, the joys of bastardizing an application to create another unconventional one!

    Leave a comment:


  • Oso
    replied
    Oh, well, of course an engine is designed to use a certain fuel type, in general.

    But in essence they all are burned, so the differences are in the mechanical arrangements for fuel handling, and the effect those have on usability of certain fuels. Cetane rating is important for diesel, but good diesel makes a poor fuel for a gas car. Good gas would be a problem in a diesel, as they are optimized for different things.

    BTW:
    In the US I rarely if ever see a diesel with white smoke, unless it is construction equipment just being warmed up on a cold morning.

    Mostly it is the trash collector trucks blowing thick black smoke because some bozo mechanic can't manage to adjust the injector pump, and the drivers all put the pedal to the floor. Diesels are "smoke limited" when there isn't any more oxygen in teh cylinder to burn the fuel completely.

    The Feds have always let big trucks pollute like crazy (partly burned fuel= carcinogens out the wazoo) but have stuck it to the auto driver twice as much to compensate.

    Of course, the auto is probably driven for 20-30 min twice a day, and the truck is on the road all day. Which do YOU think has the bigger pollution potential????

    Now, the fuel additives just take up space with lower energy (alcohol), or are "pre-burned". That is what "oxygenated" fuel amounts to....fewer bonding sites for oxygen as some are already full.

    Or, some fuel additives which are mandated, but are major pollutants, like MTBE. We still use it (by law) here in St Louis, but it is illegal everywhere else in the USA.

    Governments are committees, and comittees are inherently stupid. You can lower your effective IQ by just being on one. This must account for the stupid laws...........

    I dunno what this all has to do with turbochargers for small engines. But, since when have we EVER stayed on topic around here?

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  • Thrud
    replied
    Oso:

    I am not really arguing with you, but I would like to clarify my thoughts.

    What I was trying to get across was that some fuels are better choices than others for differing reasons. Today's gasoline is almost stoddard solvent - very low octane, and worse yet, they add butane in cold weather to make it more flammable for cold starts. If the daily temperature hovers close to 32F or 0C the butane makes the fuel line vapour lock. So fuels here in Alberta are not a constant formula during winter - they blend daily based on 3-4 day weather predictions. The addition of oxigenates (MEEP or Alchohol) is there to aid in cleaner burning fuel but cause injector and oil life problems.

    In diesels Cetane is important - a diesel that blows white smoke (even though the pump is set up correctly) is a direct sign of low Cetane in the fuel. The cetane advances the ingnition curve and makes cold weather starts easier for diesels.

    As complicated as engines have become, fuel is a major issue. Fuel effeciency of the motor is also dependant on fuel quality and its molar heat value. You cannot dismiss one or the other in the search for effeciency - they are co-dependent.

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  • Oso
    replied
    I think you missed the point.....

    The efficiency is how well the engine uses the available energy.

    If one gives more total energy output than another per gallon, or per KG or whatever of fuel, that is irrelevant UNLESS they are both using identical fuel. Not both using gasoline, or whatever, but IDENTICAL gasoline.

    Otherwise you have no idea what the comparative efficiency is. You are measuring with two different "measuring sticks", as fuels vary in available energy per unit.

    Even alcohol, which appears to be a lower grade fuel, apparently has a slight advantage per unit weight. Trouble is, it is pretty light stuff, so volume is bigger. Therefore, mixing alcohol with gas lowers the energy density on a volume basis.

    Your fuel mileage per gallon reflects that on a "gasohol" fuel as is used in the states. My truck will burn "E85", 85% alky and 15% gas (available in 2 pumps here). But my mileage will be worse on it, gallon-wise, due to the poorer energy density.

    You have to determine how much available energy there was in the fuel used, and how well the engine converted that to mechanical output.
    Only then can you state an efficiency, unless you are not talking about the same sort of efficiency.

    [This message has been edited by Oso (edited 04-12-2003).]

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  • Thrud
    replied
    Oso:
    Perfect does not exist. THE only way to get equal power out of a wide variety of fuels is to use total mass to enegy conversion. So far we don't even have Fusion, never mind.

    My point was that fuel does have an important key in effeciency - the motor needs to be optimised to that fuel for highest performance. Im my defense, Alcohol and diesel have been blended and produces considerably more power than just the #2 fuel oil by itself can produce (in the same motor). Stuff looks like liquid bear poo. They still have not determined if the injectors and pumps can take this abuse - they aded a surfactant to make the alcohol blend with the oil.

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  • Oso
    replied
    Thrud:

    Efficiency should NOT be in any way related to the fuel. It should be the power out vs power available, and is a dimensionless number.

    That means that if a fuel with more available energy is used, the power out should indeed go up. But the ratio of avaliable to output should ONLY be afffected by the engine's ability to utilize the energy of the fuel.

    So a perfect engine would be equally efficient on alcohol OR gasoline OR bunker 2. The actual power output would be dependent on the fuel.

    Leave a comment:


  • Thrud
    replied
    Ken
    Part of the reason diesels are more effecient is because they actually use a fuel with a higher molar heat value heavy oils like #2 fuel produce more power in highway tractors than the lighter #1. The #1 flows better in the cold because there are less paraffins than the #2 fuels. At cold temps the heavier fuels "gel" due to the waxes present. By removing the waxes in the fuel, they depress the pour point of the fuel at the cost of lost power.

    There are no free lunches - everything is a comprimise. Propane injection in diesels is akin to nitrous. Because propane has about 138 Rankin Octane Number (RON, MON is Motor Octane Number) it performs better under very high compression (diesels). These is why propane conversions do not get better fuel economy than they should as they are often slapped onto a 8:1 smog motor. It was mentioned gasoline was a good fuel - not so, as RPMs increase, the combustion rate of the fuel limits maximum RPMs long before its energy potention is realised. Alchohol, is much like propane - they both have a extremely fast flame front, but require high compression to get the power out. Nitromethane is used to get reciprocating engines above the 10,000RPM as it has a flame velocity far in excess of 60,000mps (Nitroglycerin is over 500,000mps).

    This is why as the speed and power go up we move from gas to methanol to nitromethane. Some racers put nitromethane in the 2 strokes for added power - the danger in that is Nitromethane polymerizes almost all 2 cycle oils (the reason Castor oil ss used in Nitro fuel for model airplanes is unaffected by Nitromethane) - some synthetics can stand up to 10% Nitromethane before they polymerize. It should be noted that High performance BB SP racing model airplane engines can get over 6HP/cid naturally aspirated (60-80% nitro)! Top fuel blown dragsters get around 5HP/cid for comparison (3000HP/600cid).

    Leave a comment:


  • Carl
    replied
    Steve, have you tried http://www.ihi-turbo.com/

    Leave a comment:


  • kgarver
    replied
    The old Hot Rod addage still applies, "When in doubt, bore it out"!

    However, a turbocharger is only used when its needed so you don't have to pay for the loss of mileage and more pollution (from a larger displacement engine) when its not in use. It has been found when the turbocharger's compressor just sits and spins in a "no boost condition", around 10,000 to 25,000 RPM the mileage will actually GO UP! It is believed that this phenomenon is caused by the turbos action of:

    1) The impellor's blades physically beating (mixing) the air/fuel charge up better (more homegenous) and

    2) Having the fuel/air mass "swireling" and not just simply "tumbeling" (falling) into the combustion chamber.

    Simple tumbeling is kinda like pouring a bucket of sand into an open window. It just piles up on the base board. The turbos action even when its just "idleing" is desireable as hell in getting more mileage (and lower emissions!) out of ANY engine. Now when it starts to produce boost you still keep these good points AND then you get a far denser mixture and the HP/torque can go right out of sight. Along with the pistons, rods, and bottom end if you're not too careful!

    Do any of you recall the small diesel engined VW Rabbits (and small VW P/U trucks) of the 80"s. If memory serves they were about 1200cc (73 CID). Stock they got 35 to 40 MPG and couldn't merge onto a freeway safely. Bog slow acceleration! Diesels will ALWAYS get better mileage than a comparable sized gas engine because they compress the fuel/air charge so much harder. More compression = more HP; simple as that. They can go as high as 23:1 CR. When after market turbochargers were added to get better performance out of those little VW's (a NA diesel powered car is a stone and a 73 CID one will grow moss!!) they suddenly found that their milage went up as high as 75 MPG when they were NOT under any boost! Talk about a Win - Win situation!

    FYI the highest horsepower NA gas motors (for their size) that will last for 1000 to 2000 miles using just pump gas and a 4-barrel carburetor are the 366 CID Nascar motors. Presently they can make a little over 650HP but have to run a CR as high as 15.00:1 or even 16.00:1 turning as high as 10,000 RPM. There is some serious engineering to make that much HP and get them to hang together at that speed. Trust me!

    Leave a comment:


  • ibewgypsie
    replied
    No replacement for displacement, I put a 900 kawasaki sectioned frame into a suzuki 4 wheeler
    front, and a honda big red rear axle. Knobs on the tires lasted less than 5 minutes.

    Leave a comment:


  • jeep_32
    replied
    Steve I would start with CB performance and also try dennis kirk. google it...
    archie =) =) =)
    <font face="Verdana, Arial" size="2">Originally posted by steve schaeffer:
    forrest,
    i didnt mean to be abrasive, i was a little cranky when i wrote that, i had just got up. and yes, it is good for someone to read to benefit. any info is good info.
    no hard ones,

    steve
    </font>

    Leave a comment:


  • kgarver
    replied
    Hi Forrest:

    RE: ..............There was a cartoon in one of the mags showing "trombone" tuning of the induction stacks and the exhaust complete with flyball governor Rube Goldberg operating mechanism. Hilarious.

    They are called venturis or velocity stacks when they are on just about on all racing NA fuel injected engines. Whenever an engine is being run on a dynometer (called a "Pull" BTW) they will always have a venturi on their inlet NA, turgocharged makes no difference. It is used to smooth out the centrifigual forces on the column of air as it enters the intake and is suddenly stopped by the intake valve slamming shut. FYI a Big Block (500 + CID) turning 6,000 RPM will make about 25 - 30 more HP with a venturi than w/o one! At least on the dyno.

    Early on the racer/tuners found that velocity stacks made more HP both on the dyno and the track. They just naturally assumed that it would do the same on the exhaust side. They were mistaken. It was later found that the diameter and length of the exhaust pipes, RPM, piping bends and having each side of the engines exhaust (V-8's) meet in a "cross over" would have the biggest effect of scaveraging the exhaust. Even the intake manifold pleneum (sp)size affected it.

    Back in the late 1950's my Dad worked for Ford Motor Co. in Dearborn, Michigan in the experimental engine division. His job was to take the experimental motors (literally handed to him a piece at a time from the machine shop[s]), assemble and tune them and do runs (pulls) on them to determine their torque, HP, and fuel consumption. A production engine (then) was run at WOT for 100 hours and then disassembled to check for any signs of wear.

    One of the experimental motors that Ford was working on at that time (1958-59) was the "Indy 4-Cam" engine. He had one all set up to run one day and he had me wait in the car until all of the "straw bosses" went home. He snuck me in the back door one night and fired one of them up. The engine "cells" then were all steel about 10' X 8'X 9' high completely enclosed. The exhaust went out the top of the cell as I recall. He needed to make some small adjustment and he let me in the cell while it was running. After he made the (fuel adjustment?) whatever he reached over and started to rev up the motor. When that motor hit a certain speed (sorry I can't recall what speed) suddenly your pant legs and shirt sleeves began snapping back and forth at the exact same speed as the air in that cell. That engine had caused (tuned)the air in that room to hit a harmonic and EVERYTHING move at the same speed! You could actually feel it. It is somthing that I'll never forget.
    Regards, Ken

    Leave a comment:


  • steve schaeffer
    replied
    actually i am sick and twisted. this is for my little "fx lawnmower racer" just a little something for my home use. haha i wonder, because it already does 60 mph, will put you on your back in a flash, and makes you pee blood the next day because @60 ;with no suspension, running over a small bump makes your head spin. haha.
    steve

    Leave a comment:

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