ratman

i was wondering if say 1200 turbo motors are getting better fuel mileage than an equal size equal hp and tq screw blower engine. i would think you would with the insane amount of parasitic hp loss seen from tuning a big blower... thx for you input, rm

boostbros

well theres one way to find out...... put one on each side in the same hull bet there would be some interesting results!

phragle

iTrader: (3)

Seriously?? What the hell have you been smoking down there?? Banging 10 peso whores and the syphillis is attacking your brain?? I know before you abondoned the good old US you were smart enough to know that if you have to ask about fuel consumption, you cant afford it anyways!!!!! Oldest rule in the book, well second oldest, first rule is that water is supposed to be on the outside of the boat...

ratman

no... not losing my marbles, i think its a valid question. i would go with a turbo set over a blower set up any day, now that the guys really seem to have the turbo engines sorted out. i hear numbers from top fuel teams that it takes a couple thousand ponies to turn those big over driven blowers on the top fuel cars, and gas isnt getting any cheaper anywhere. if you have a big hp boat running say 1200 hp a side and can see a 15 or 18 % reduction in fuel costs, that has to appeal to anyone...

PigNaPoke

I thought it was 4-500hp to turn the big blowers... thats 1000hp on a twin setup in a boat but boats are nowhere near top fuel... about ¼ - even for the big power.

ratman

those top fuel guys running nitro are over driving their blower like crazy, after doing some searching i found it takes 800 or 900 hp to turn a top fuel blower, so say its 200 or 250 on a blown gas engine for marine application but even so if you are saving 4 or 500 hp worth of fuel for the weekend it should save a ton of coin on fuel... something to consider as gas prices climb

Top Fuel Drag Racing Put Into Perspective:

* One Top Fuel dragster makes more horsepower than the first 4 rows of the Daytona 500.

* At full throttle, a Top Fuel dragster consumes 11.5 gallons of Nitromethane per run; a fully loaded 747 consumes jet fuel at the same rate but produces 25% less energy.

* A stock 426 HEMI does not produce enough horsepower to drive a Top Fuel supercharger

* At full throttle the supercharger is ramming 3000 CFM of air into the cylinders. The mixture is so compressed that the engine is on the verge of hydraulic lock.

* Nitromethane burns yellow. The white flames seen above the exhaust stacks is actually Hydrogen, which has been dissociated from water by the heat of combustion.

* At stoichiometric, the nitromethane air/fuel ratio is 1.7:1. Flame front temperature is 7050 degrees.

* The dual magnetos produce 44 amps to each plug. This is enough current to arc weld.

* Spark plugs are totally consumed during a run. In fact, after half way, the engine is dieseling from the compression and the glow of the exhaust valves. After this point, the engine can only be shut down by cutting the fuel flow.

* To accelerate to over 300 MPH in 4.5 seconds the dragster must average 4 Gs. For the dragster to reach 200 MPH by half-track required 8 Gs.

* A Top Fuel engine only turns approximately 540 revolutions from light to light. Including the burnout, the engine must survive only 900 revolutions!

* Redline is quite high at 9500 RPM.

* Assuming all the equipment is paid off, the crew is working for free, and nothing blows up, each run costs $1000 per second.

Perspective:
So you take your specially tuned $140,000 Lingerfelter “Twin Turbo” Corvette, and start back about a mile or so, accelerating as fast as you can, reaching your top speed of 200 MPH. This is really moving and would be something anyone would be proud of. You’re approaching the starting line where the Top Fuel dragster is sitting – stopped – waiting for you. As you cross the starting line, the light turns green.

Within 3 seconds you are deafened by the incredible whine of the dragster, which has caught up to you. He passes and beats you to the end of the 1320-foot quarter mile.
THAT is acceleration …

boostbros

ill bet there pretty close on fuel burn if you match horsepower you can turn a blower or restrict the exaust but there is no free hp unless you are running hydrazine and thats a whole nother interesting thread that scared me from ever trying it!

hogie roll

Turbos will be more efficient

Randy Nielsen

iTrader: (4)

Interesting facts on the dragsters RM. A guy I used to work with used to race in super gas class then decided to switch to a top alcohol funny car. He would turn his head to look at the other driver with 1 eye on the tree, then launch when the light turned green. Worked great at messing with his competitors. He tried the same thing in the funny car & had to let off the throttle to turn his head!! He told me that launching the car would shove him into the seat so hard it would almost pull his hands off the wheel, then pulling the chute was like getting kicked in the head by a Clydesdale. Lol I'm sure top fuel is even more intense.

wannabe

Ratman= Top fuel dragsters are making 6000 HP and are pumping so much nitro they are on the verge of hydro=locking their cylinders. The parasitic losses they have are enormous but it's the only way to get that much power to the wheels in 4 second 1/4 miles. Trying to use this as an example is not really relevant.

The difference between the roots and screw type have been discussed. The roots type -ie; 8-71 etc produce more heat but are excellent at low rpms as are the screw type. The parasitic losses of the 2 types are fairly close as engines are "tuned" for the type of motor and desired power.

Wannabe