Reply With Quoteis that english
nice finish there lv!
jw
is that english
Ya, "Get him Rex!"
I was not talking about a scientific explaination of what the dyno measures. I stopped at the measurement actually used to rate the engine.
To get scientific we can go all the way to the chemical energy in the fuel converted into heat energy by combustion. That heat energy transformed into a reciprocating mechanical energy. That reciprocating motion converted to a rotational mechanical motion. This is given to the dyno.
We can start at the beginning of dinosaur crap and remains converted into oil if necessary.
Is this fun or what? I think some of us need a life. Myself included.
I don't believe you can get the hp you're looking for without the necessary tq at a particular rpm.
The bottom line is look at torque. It moves mass. HP carrys the mass after the torque gets it moving. I have no clue what Jer said. Most of the time I don't. But the heavier you are the more torque you need to get the boat moving before HP takes over to carry that momentum(SP). So weight plays a big factor. The lighter the vehical/boat the less torque it needs to push it to that point where HP takes over to carry it.
So, here is the point that I continually see missed in these discussions.
Yes tq gets mass moving, what happens when you hit the gas in your boat? The RPMs jump way up and the boat begins to move. The only time tq was a working force was when the motor needed to begin that drive system spinning. Once it was spinning, all the "mass" that it needed to get started, had been started, tq is no longer a factor.
At this point it is up to hp to keep that mass spinning.
So how does tq relate (IMHO), the more tq you have, the larger imp. you can spin up. Larger imp. = more speed.
my .03$
FingerTight is right.
Some confused by car dynamics thinking same as jet boat dynamics.
A car engine is directly connected to the road assuming traction and no clutch spin. Therefore, the car engine has to deal with the mass of the car as it spins it's way to peak hp.
By contrast a jet boat engine is directly connected to an impeller and spins quickly to maximum hp regardless of boat mass. There's a difference here in what "mass" you are accelerating, and the effect of that "mass" on engine performance as FingerTight posted.
"I have no clue what Jer said."
Is that pretty clear Bense? If not let me know. These are my opinions right or wrong and I'd be happy to debate them, just wanna make sure I clearly state my thoughts for you.
First ya got to read carefully...past the earth is flat stuff
Urban myth:
"We measure torque on the dyno not power, so torque is more important!"
This is a myth that circulates both car and boat forums from time to time...
Truth:
Dynos actually measure things like force or pressure (sometimes temperature) and convert to torque by multiplying by the lever arm. I'm assuming it's clear what a lever arm is Bense? The mathematical relationship is:
Torque = F X d where d is the lever arm.
Those dyno measurements of force or pressure can just as easily be converted to power by multiplying by lever arm and measured rpm. So the myth implying that torque is more important because somehow it's a more basic measurement on the dyno is bogus. Both torque and power in the end are "mathematically derived" from what is actually measured on the dyno.
Note: The above "truth" does not imply power is more important, just that neither power or torque is more important based on what is measured on a dyno or how that quantity is derived.
There are other (non-bogus) reasons for which property (torque or power) is more important to jet boat performance, but I won't get into that right now
Info, I stopped short of dyno crap too. That and the meaning of life. Just focusing on which engine property is more important to jet performance...and exploding urban myths...
jer
[ May 29, 2003, 02:59 PM: Message edited by: LVjetboy ]
pops1:
jim lee:
It seems that there will never be an answer will there? On and on the old fight continues. Well, its time to take sides and put your money where your mouth is.
What camp are you in? Horsepower? Or would it be Torque?
Now, when entering those internet flame wars, you can display your camp's official Torque Vs Horsepower battle gear.
-jim lee JIM LEE-THE ONLY TIME THIS FIGHT COMES UP IS WHEN YOU TALK TO A SLOW ASS PROPERs.
NOW FAST JETS -BY THE WAY SPRAY PROPPERS JUST LIKE SKUNKS DO, THEN GO OFF EAT LUNCH,HAVE A NICE SOCIAL TALKING TO THE WOMAN,PUT THE COOLERS BACK IN THE BOATS, JUST ABOUT THE TIME THE PROPERS SLIP UP.
NOW I KNOW TONY THE JET BOAT GURU- STILL WILL NOT AGREE TO THIS, BUT SINCE THE SQUIRTERS SPANKED THE HYDRO @ THE 1,000 FOOTER THIS PAST YEAR. WE HAVE NOT HAD THEM VISITING OUR BOARDs -SO I SHALL CAST THE FIRST STONE-
PROPERS THOSE LEG CHOPING,HOLE DIGGING,STUFFING BOXES WHICH ARE SLOWER THEN SAIL BOATS ARE IN BIG TROUBLE AGAIN THIS YEAR- JETS- THE TORQUE GETS BIGGER WE GET MEANER AND SO DO OUR VANES!
NOW PROPERS YOU CAN CALL ME DAVE OR YOU CAN CALL ME POPs OR YOU CAN CALL ME FULL OF IT. BUT JETS AND TORQUE ARE GOING TO GIVE YOU SUCH BAD DREAMS.
JIM- SELL THEM HATS, AND TELL ALL THE ONES WHICH BUY THE WING, WING, WING,H/P HATS TO WATCH OUT FOR THE BIG DOGs "WHO DO NOT SPRAY LIKE A PUPPY"
THEY WILL SWAMP YOU AS THEY GO BUY.
(I WOULD HAVE SAID "AT THE LINE" EXCEPT IT TAKE'S PROPERS TWO OR THREE BOUNCES TO PLANE THE BOAT, SO THEY LEAVE THE LINE REAL EARLY. THATS WHY I SAID "GO BY" INSTEAD).
NOW THIS COULD START SOMETHING! HA HA This is a great post.
Now pops posts a challenge...just need a couple brews and reread several times to get the flow.
jer
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