730 Hp

[miketsouth]

Torque is twisting force. I can get 300ft/lbs torque out of my 18" torque wrench with no extension. I aint got no horsepower.
Torque X RPM = HP
Horsepower is the ability to do work. Bottom line. Forget torque. It might be usefull in deciding how strong a shaft must be to transmit the horsepower, but thats all.
In a drag car where you need to put power out between the shifting points, you might look at the torque curve to adjust the shifting points/differential ratios etc. In a jet boat you look at the HP curve to set the impeller which sets the max WOT rpm.
http://mywebpages.comcast.net/mikejet/forgettorque.JPG
mikeT
(Hey Jer, Jack was right, "Jim Lee will sell some T-shirts")

[Danhercules]

I am gonna throw somthin in the mix......
1st off, I dont know stuff about HP, Q, and all the above. I am just gonna ask somthin,
If Q is not improtant, and HP is, Why not run a Mazda Rotary in a jet boat. You could turn 9,000 RPM NO problem. The rotary can make a lot of HP but really sucks on the Q, so if its all about HP and RPM, wouldn't the rotary be the best jet boat motor out there?

[victorfb]

well, if you had a rotary pushing 500 HP to match up to the small block and BBC, id say your the winner. but id still bet on the BBC.
its all in the RPMs right? so at equal HP they all should be exactly the same.

[Danhercules]

I wanna see a lakeboat with a SBC or a BBC spin 9000RPM.
As you can tell I am a huge fan of the Rotary, but I was told it would not work in a jet. Ya need torque.
So what would happen, if ya had 3 identical boats, exept the motors, all made 500 HP
SBC, BBC, and Rotary

[miketsouth]

So what would happen, if ya had 3 identical boats, exept the motors, all made 500 HP
GREAT QUESTION
but you forgot some details, like weight of engine and RPM
Sooo...i will guess
BBC 500HP @5400 RPM 625lbs A imp
SBC 500HP @5700 RPM 525lbs B imp
ROT 500HP @9000 RPM 200lbs (dont know)
There has been lots of discussion about pump efficiency with various impellers. I read it all and i still dont know. I do know 9000rpm is off the scale so that it would need a gear reduction box.
Lets put a good gear reduction box (95%eff) on the rotary and get
ROT 475HP @ 5300RPM A imp
The ROT will walk both the BBC and the SBC from the git
The SBC will creep the BBC from the git
Top speeds will be very similar, within 2mph
Not bad for a bench racer, hey Jer
If you put them in a P/F jet they will probably go 130mph. Thats what some of the insurance companies told me.
mikeT

[Blown 472]

Originally posted by LVjetboy
Myth #2. "An engine produces the same hp no matter what rpm it turns" Wrong. Most engines have a power peak. Some more defined than others. Operate off that power peak and you don't get the same performance. Now think about the fact that I didn't say off-torque peak. Why? Because torque peak is not important for impeller matching or performance. Think about that a bit then tell me why torque is the same as power. Torque and power peak at different rpm's...where you gonna match your impeller? Oh wait, let's not look at charts, let's just do trial and error and stumble on the answer maybe. It's only money.
Myth #3. "Hp is calculated and Q is measured on the dyno, therefore Q is more important since Hp is a derived term" Wrong. Q is not measured on the dyno. It is also derived. Oh pray tell...how could that be? I quess from Myth #3 since Q is also a derived term, it isn't important? Faulty reasoning.
Myth #4. "An engine makes both Q and Hp, you need both therefore neither one is more important than the other for performance" Wrong. A typical Ghandi response. Just match your impeller to your Q peak rpm and see what you get for performance.
Myth #5. "AT the SAME RPM, you will run the same speed with either an A impeller or a B impeller." Wrong. You will run a different speed with the same rpm on an A versus the same rpm on a B. Why? Because at 5000 rpm, the A will absorb more power and flow more water than a B at 5000 rpm. The A will go faster. Assuming your engine can turn it 5000 rpm. But that assumption is inherent in the Myth #5 statement.
Can a small block putting 500 hp to an impeller match a big block putting 500 hp to an impeller? You bet. In fact the small block would win because it weighs less yet puts the same 500 hp to the impeller (neglecting efficiency losses) Why? Because it's all about power not torque. If you don't understand why this is then you won't understand why power is more important than torque.
Can you build a 500 hp small block as cheap as a 500 hp big block? Who cares? That's not the question here...copy?
PCrat. I never said I didn't want torque. Obviously, a running engine will have both...takes no brain surgeon to figure that out. Also takes no brain surgeon to quote the equation for Q and Hp.
I said focusing on torque is misleading...you should focus on power to the impeller. I said knowing an engine's power output is more important than knowing an engine's torque output. You don't think this topic is important? Then talk to the racer who didn't understand why power was more important than torque and matched his impeller to his engine's torque peak. See what he thinks now about the difference between torque and power.
I'm think I'm wasting my time.
jer
Ifin you didn't want torque, why did you build a stroker?? why not a 30 over 427??

[skeepwerkzaz]

Sorry guys, but I am going to go all science up in here! Some oldies but goodies. (definitions that is)
This is going to be long and painfull but........
Power is the rate of doing work. Or a measure of the rate at which work is performed--i.e., the amount of work accomplished per unit of time.
Horsepower is the amount of force needed to move 33,000lb through a distance of 1 ft in 1 min (or 550ftxlb/s). hp = K x torque (ft x lb) x rpm; hp = 0.0001904 x (ft x lb) x rpm
Torque is the force which is produced by a turning effort; it is measured is foot pounds.
The prony brake, or dynamometer, is a device used to measure the torque, or turning moment, produced by an engine. This moment acts upon a lever arm of a given length or L.
The force measured on the dynamometer equals F.
The known values are then F L and the rpm of the engine driving the brake. To obtain Brake horsepower, these values are used in the following formula:
Brake horsepower= F X L X 2pi X rpm/ 33,000
So you guys want more???????
Clay

[canuck1]

Originally posted by Danhercules
I wanna see a lakeboat with a SBC or a BBC spin 9000RPM.
As you can tell I am a huge fan of the Rotary, but I was told it would not work in a jet. Ya need torque.
So what would happen, if ya had 3 identical boats, exept the motors, all made 500 HP
SBC, BBC, and Rotary
Well I hate to bring this up but thats what got me into the alum hulls. I got my ass handed to me by a 14' alum hull with a ROTARY engine in it, ya I had more power but I also had twice the weight

[TRG]

so if i build a "TORQUE MONSTER" im lookin for some MPH or ET"s?
"BOTTOM LINE PLEASE"?

[cheech]

thankx cyclone you answerd my question perfectly. very good #'s the chassis dyno does not measure acceleration it measure the amount of hp to hold at a specific speed, the torque is what accelerate's and the horsepower will sustain and still pull but not as quickly.my next question is more to the drag car guy's. now when you put nitrous to the motor( for reference 300 shot fogger) your hp goes up 300 but the torque is almost multiplied by 3. now don't the drivers gear there final ratio to a taller number and lug the motors.