Torque vs. Horsepower

[Garucci]

Hey guys I am new to all this v-drive stuff but I am loving every bit about it!! My questions for someone is-- I have a 74 Sanger Flatbottom with a BBC 496 with 1.22 gears. I am being told that with all the torque my motor has is that I should put more gear into my box. How much gear would you try to start with?
And why I say sacrifice horsepower is because i am looking at putting a new cam shaft that will raise my torque even more and lower my horsepower.
Any advice would be appreciated.
Thanks

[Kindsvater Flat]

Mr T on the boards has a brother that has a white sanger flat bottom. He also runs a big block chevy in his with 22% gears. Now if you ask him he will tell you it turns 7500 rpm at 120 but ..... thats really another story in itself.
What rpm are you turning? What prop? More info on the motor? What do you want to do with it?

[Garucci]

I am running a 11.25x16 meikens prop. brodix alum heads, tunnel ram, two holley 750's, lunatti roller cam-.312,.320,.722,.722---the boat only pulls to 5500 rpm and it is running 84 mph. I am looking a either putting gears to slow my rpm's of the motor alittle bit and spin the prop faster, or changing out the prop?? The cam in the motor now for what i can figure off of desk top dyno isnt even in the power band of the cam until 7500 rpm, and tops out at 5500 rpm on the torque. So that is why i thought about putting a cam that will be more torque and less horsepower on the top end.
I am wanting to go as fast as this boat will go without supercharging it. I just feel that the boat has alot more potential.
Thanks for any input

[Kindsvater Flat]

Go to an 18 gear... less pitch. Get your motor in the top rpm range.

[BGMAN203]

Might even go to a 15% gear.

[Garucci]

yes that would be true to drop gears and let the motor come up into the power band of the horsepower, but what i have been told about boats, and correct me if i am wrong but horsepower dont mean s**t, its all about torque, so that is why i have been thinking about a cam that will drop my total horsepower by 24 horses, but i will gain about 150 ftlbs of torque, and then having to spin my motor at a less rpm to be safter in the internal parts??
Thanks for the input.

[WaterBox]

yes that would be true to drop gears and let the motor come up into the power band of the horsepower, but what i have been told about boats, and correct me if i am wrong but horsepower dont mean s**t, its all about torque, so that is why i have been thinking about a cam that will drop my total horsepower by 24 horses, but i will gain about 150 ftlbs of torque, and then having to spin my motor at a less rpm to be safter in the internal parts??
Thanks for the input.
Like K-Flat said, Put some 18's in it and go and run it, See what it dose, may suprise ya. And it will give you more info. to work with. It's good to have some comparisons to work with before ya make engine changes. And even if it dose spin up to 7000 or 7200 If it's put together half way decent it shouldn't make change. You probably won't be running it wide-open for 5 miles at a time like the S.S. Boats do. :idea:

[AzMandella]

I would drop to 18% gears.Your basicaly running a 454 not a stroker motor that is creating gobs of torque.I run a stroked 514 with 18% and a 11-1/2 x 15 and turning 7000 rpm,but now that I have the stroker motor I am putting the 22% gears in because she tops out too quick.Besides with the parts you have said you have that motor should run at least in th 6500-7000 range with no problem if it was assembled properly.And if you still don't see 6500 after the gear change try dropping the pitch or shaving the diameter of the prop till it does rev.

[Morg]

Garucci,
Nice avatar, c'mon.
A smaller gear will wake that deal up. Most lake races are over in the first 200'.
If I were running your deal here is what I would want.
-Out of the hole your motor should spin up to at least 6500. Let the prop. burn(spin). this allows you to get into the power of the motor. Think of it as slipping the clutch in a car. The gear size will allow the motor to get close to achieving this. Prop diameter will control how much slip you get.
-Prop. hook. After the burn & the boat starts to roll over. You should not drop below lets say 5500 rpm. This is where the torque comes into play. If the rpm drops to much goto a smaller gear. Not enough maybe a lttle more pitch or diameter on the prop.
-Top end pull. If you want the top end speed. You need to use you tunnel ram. If you get your out of the hole combo & prop. hook combo to work your top end should be pretty much set. somewhere between 7000-7500 rpms.
Now. This is a conservative set up. If you want to got big. out of the hole 8000 rpm, burn 7000 rpm. top end 8000 rpm.
The big dog race teams are doing over 9000 out of the hole.
This is how I would start. There many that will tell you different. Just my opiniun.
Morg

[Brodie]

Mr T on the boards has a brother that has a white sanger flat bottom. He also runs a big block chevy in his with 22% gears. Now if you ask him he will tell you it turns 7500 rpm at 120
i seen that boat, it be bad ass,,,,maybee 117m but it aint goieng 120

[Morg]

Oh
& one ore thing.
Like I said you will get many opiniuns in here.
You need to watch out for some of the jokesters who come in here under falls names & try to stir up the shehite. Sometimes they even act like new members & ask boat set up questions just to get people to fall on their face & post some lame information.
Amazing but true :eat: :eat: :eat:
Kid Morg.

[78Eliminator]

"Kid Morg"
Are you a rock star now?

[Garucci]

Hey Brodie
This guy with the 120mph flat bottom, is the motor blown ? Or about how many horse is the motor? He is probably running in alot less elevation also.
Here where I run it is about 3450' elevation but the air really sucks. The air is like 5500' of elevation, so i dont think a flat bottom would EVER run 120 here.
Thanks to all you guys for all the info.
It gave me a place to start!!

[Morg]

"Kid Morg"
Are you a rock star now?
Obviously you have missed some of my best moments.
In time glasshoppa

[058]

Oh
Sometimes they even act like new members & ask boat set up questions just to get people to fall on their face & post some lame information.
Amazing but true :eat: :eat: :eat:
Kid Morg.
Would they do that???...I'm shocked, stunned and amazed. :jawdrop:

[NitroMan]

I am running a 11.25x16 meikens prop. brodix alum heads, tunnel ram, two holley 750's, lunatti roller cam-.312,.320,.722,.722---the boat only pulls to 5500 rpm and it is running 84 mph. I am looking a either putting gears to slow my rpm's of the motor alittle bit and spin the prop faster, or changing out the prop?? The cam in the motor now for what i can figure off of desk top dyno isnt even in the power band of the cam until 7500 rpm, and tops out at 5500 rpm on the torque. So that is why i thought about putting a cam that will be more torque and less horsepower on the top end.
I am wanting to go as fast as this boat will go without supercharging it. I just feel that the boat has alot more potential.
Thanks for any input
Hook up your secondarys and head for a tune-up station. All those good parts aren't making any power, or your boats made of lead.

[MR.T]

Mr T on the boards has a brother that has a white sanger flat bottom. He also runs a big block chevy in his with 22% gears. Now if you ask him he will tell you it turns 7500 rpm at 120 but ..... thats really another story in itself.
What rpm are you turning? What prop? More info on the motor? What do you want to do with it?
I've got your brother hangin. I told him and your other brother [with the yellow snager] to switch the GPS back to MPH instead of KPH.

[riverbrat]

brother?

[MR.T]

Brother Joe Dirt.

[riverbrat]

Brother Joe Dirt.
???

[MR.T]

K-Flat is talking about Rob and his brother is Clayton.

[riverbrat]

he said MrT has a brother. When are you going to put your boat for your avatar?

[steelcomp]

yes that would be true to drop gears and let the motor come up into the power band of the horsepower, but what i have been told about boats, and correct me if i am wrong but horsepower dont mean s**t, its all about torque, so that is why i have been thinking about a cam that will drop my total horsepower by 24 horses, but i will gain about 150 ftlbs of torque, and then having to spin my motor at a less rpm to be safter in the internal parts??
Thanks for the input.
You can loook at HP and torque this way...Torque is what it takes to get a boulder rolling, HP is what it takes to keep it rolling. Torque and HP on a graph will always cross at 5250 rpm. (That's how you get hp: tq X rpm dev. by 5250= hp.) As you go through the rpm, your torque and hp are rising, but most always the torque is rising faster than the hp, but at 5250, the hp takes over and passes the torque. Your torque won't fall off very fast, and the hp goes up overcoming the loss of torque. Your motor has a VERY flat hp curve at 5250, so the amount of torque that's dropping off at 5500 isn't being replaced by the hp yet. Your HP probably won't start really climbing untill after 6000, which is where you need to get for the hp to start taking over for the torque. If I could draw you a graph, you'd be able to see wht I'm trying to tell you.
My jet boat used to turn a standard B impeller to about 6200 rpm, making about 650+ hp, and could red line the motor easily out of the hole. I had my impeller bluprinted, which basically made it bite harder. Now I haven't been able to slip the impeller, since it hooks up so much better, and the motor only pulls 5500. If I could buzz the motor a little out of the hole, I think the motor would carry untill the boat hooked up, and may hold that rpm. But since I can't slip the motor past 5500, I need to cut my impeller again (sort of like you putting in shorter gears) to let the motor buz back into the hp.
Bottom line is, you need to buzz your motor to a good 7000+ and like Morg said, no less than 6500 out of the hole.

[V-Drive Tom]

Garucci, You can't pull the 1.22 gear with your power, especialy at that altitude. You need to drop the gear,1.15 and try it. You have to get your RPM up to the high end working range of your cam.
ITS ALL ABOUT PROP SPEED... RPM+ gear overdrive =Prop Speed.
TOM.. :D

[Garucci]

Thanks guys,
You have just saved me 400 bucks on a new cam!! I will change out my gears and see if that helps me out.
Thanks for the help
Garrett

[voodooCanoe]

Thanks guys,
You have just saved me 400 bucks on a new cam!! I will change out my gears and see if that helps me out.
Thanks for the help
Garrett
Good answer!

[LVjetboy]

SteelComp posted: "Torque and HP on a graph will always cross at 5250 rpm."
Who cares? Is that important or hold some significant to boat performance or engine combination no matter the drive choice? I think not. Where do they cross in metric units? Does anyone here know? Is that magic rpm crossing point a matter of unit choice or some intrinsic performance truth based on fluid dynamics, engine performance and span all matter of drive choice and medium?? :confused:
So...as long as we understand that torque and power cross at 5250 in English units then we know the truth?
I think not.
The fact they cross at 5250 in English units has no bearing on engine building or performance. That's an artifact of the units chosen, not some physical property that drives acceleration or top speed performance in v or jet. You may read some opinions on the web that say different...urban legend.
"As you go through the rpm, your torque and hp are rising, but most always the torque is rising faster than the hp, but at 5250, the hp takes over and passes the torque."
So what? Jeez. 5250's a magic number now? At least in English units. In Metric, should European performance engine builders build to a higher rpm standard since their power and torque cross higher than 5250? Steelcomp, do you know at what rpm hp and torque cross in metric? Do you even understand torque and power? Or how that equation is influenced by the units chosen? Just curious. Think about it. Is 500 foot-pounds the same as 500 ft-pounds per second? Why are you trying to compare torque magnitude to power magnitude? Or place some significance to, "torque is rising faster than the hp, but at 5250, the hp takes over and passes the torque."
500 ft-lbs torque has little to do with 500 ft-lbs/s power.
Trust me. Or not...then question me. :D
jer

[V-Drive Tom]

MAN,,, are YOU a piece of Work!!!
Here is the BLUE RIBBON for Knowledge and Understanding. :220v:

[Morg]

LV,
I think he is just trying to give the guy an idea of when the torque falls off & when the HP comes into play. Which makes it more clear what you are dealing with at a given rpm.
You guys are both talking theory that is above my knowledge in motor dynamics.
Don't get to excitted, but I don't think the pool (Knowledge) needs to be that deep on this one.
I mean look what you are dealing with. I can't even spell. :D :D
Oh & btw, you do run a jet don't you?? ;)
Morg

[Roman 1]

SteelComp posted: "Torque and HP on a graph will always cross at 5250 rpm."
Who cares? Is that important or hold some significant to boat performance or engine combination no matter the drive choice? I think not. Where do they cross in metric units? Does anyone here know? Is that magic rpm crossing point a matter of unit choice or some intrinsic performance truth based on fluid dynamics, engine performance and span all matter of drive choice and medium?? :confused:
So...as long as we understand that torque and power cross at 5250 in English units then we know the truth?
I think not.
The fact they cross at 5250 in English units has no bearing on engine building or performance. That's an artifact of the units chosen, not some physical property that drives acceleration or top speed performance in v or jet. You may read some opinions on the web that say different...urban legend.
"As you go through the rpm, your torque and hp are rising, but most always the torque is rising faster than the hp, but at 5250, the hp takes over and passes the torque."
So what? Jeez. 5250's a magic number now? At least in English units. In Metric, should European performance engine builders build to a higher rpm standard since their power and torque cross higher than 5250? Steelcomp, do you know at what rpm hp and torque cross in metric? Do you even understand torque and power? Or how that equation is influenced by the units chosen? Just curious. Think about it. Is 500 foot-pounds the same as 500 ft-pounds per second? Why are you trying to compare torque magnitude to power magnitude? Or place some significance to, "torque is rising faster than the hp, but at 5250, the hp takes over and passes the torque."
500 ft-lbs torque has little to do with 500 ft-lbs/s power.
Trust me. Or not...then question me. :D
jer
This boy luv jet guy is a textbook neanderthal. He responds to the 5250 tq & hp intersection with "Who cares?", then proceeds to dissect it! :rolleyes:
What a windbag...
R1 :notam: :coffeycup

[WaterBox]

SteelComp posted: "Torque and HP on a graph will always cross at 5250 rpm."
Who cares? Is that important or hold some significant to boat performance or engine combination no matter the drive choice? I think not. Where do they cross in metric units? Does anyone here know? Is that magic rpm crossing point a matter of unit choice or some intrinsic performance truth based on fluid dynamics, engine performance and span all matter of drive choice and medium?? :confused:
So...as long as we understand that torque and power cross at 5250 in English units then we know the truth?
I think not.
The fact they cross at 5250 in English units has no bearing on engine building or performance. That's an artifact of the units chosen, not some physical property that drives acceleration or top speed performance in v or jet. You may read some opinions on the web that say different...urban legend.
"As you go through the rpm, your torque and hp are rising, but most always the torque is rising faster than the hp, but at 5250, the hp takes over and passes the torque."
So what? Jeez. 5250's a magic number now? At least in English units. In Metric, should European performance engine builders build to a higher rpm standard since their power and torque cross higher than 5250? Steelcomp, do you know at what rpm hp and torque cross in metric? Do you even understand torque and power? Or how that equation is influenced by the units chosen? Just curious. Think about it. Is 500 foot-pounds the same as 500 ft-pounds per second? Why are you trying to compare torque magnitude to power magnitude? Or place some significance to, "torque is rising faster than the hp, but at 5250, the hp takes over and passes the torque."
500 ft-lbs torque has little to do with 500 ft-lbs/s power.
Trust me. Or not...then question me. :D
jer
:burningm: W.T.F... I doubt anyone on these boards give a Aeronautical Fornication what the Metric values are! This is the U.S.A. We're talking about American made motors, So Pi$$ on your Metric and Euroiean Crap...

[steelcomp]

Windbag...that's a good one. Once again, Jer, the only one impressed here is yourself.
Yeah, I understand all that, but the guy I was explaining what I was trying to explain here dosen't. I was just trying to give him a layman's understanding of HP and torque in simple terms, and in the terms we use here, (as opposed to whatever planet it is you're on) not trying to impress anyone. What's wrong with that? I bet you get a BIG ol stiffy when you post shit like that, huh Jer? Big blu vein? Cold blu steel..cat couldn't scratch it...gonna knock some bark off a tree!
Why you gotta be that way Jer? Never mind...PLEASE don't answer...it was rhetorical.
Blue Ribbon...PLEASE!!! Don't encourage him!
BTW...European performance engine builders usually do build to a higher rpm standard.SteelComp posted: "Torque and HP on a graph will always cross at 5250 rpm."
Who cares? Is that important or hold some significant to boat performance or engine combination no matter the drive choice? I think not. Where do they cross in metric units? Does anyone here know? Is that magic rpm crossing point a matter of unit choice or some intrinsic performance truth based on fluid dynamics, engine performance and span all matter of drive choice and medium?? :confused:
So...as long as we understand that torque and power cross at 5250 in English units then we know the truth?
I think not.
The fact they cross at 5250 in English units has no bearing on engine building or performance. That's an artifact of the units chosen, not some physical property that drives acceleration or top speed performance in v or jet. You may read some opinions on the web that say different...urban legend.
"As you go through the rpm, your torque and hp are rising, but most always the torque is rising faster than the hp, but at 5250, the hp takes over and passes the torque."
So what? Jeez. 5250's a magic number now? At least in English units. In Metric, should European performance engine builders build to a higher rpm standard since their power and torque cross higher than 5250? Steelcomp, do you know at what rpm hp and torque cross in metric? Do you even understand torque and power? Or how that equation is influenced by the units chosen? Just curious. Think about it. Is 500 foot-pounds the same as 500 ft-pounds per second? Why are you trying to compare torque magnitude to power magnitude? Or place some significance to, "torque is rising faster than the hp, but at 5250, the hp takes over and passes the torque."
500 ft-lbs torque has little to do with 500 ft-lbs/s power.
Trust me. Or not...then question me. :D
jer

[Floored]

http://auto.howstuffworks.com/framed.htm?parent=horsepower.htm&url=http://www.revsearch.com/dynamometer/torque_vs_horsepower.html :confused: here is a simple explanation of torque and HP. in car terms take out your 3.08's and put in 4.11's and kick a$$. :idea: and one more explanation of the 5250 rpm figure http://auto.howstuffworks.com/question622.htm

[LVjetboy]

SteelComp, the torque and 5250 hp crossing thing is bogus. It means nothing to performance. Just a meaningless number of units. But some still think 5250's important to engines and performance thanks to urban legend and the internet. I was just trying to open some minds...be they v or jet drive, physics still physics. Neither drive works by different rules.
Floored, your links ok for basic definitions and equations but not answering the original post...Torque vs. Horsepower. In that they are misleading.
In fact your first link propagates the legend that power is calculated while torque is measured so torque is somehow more important than power? Excuse me? Just how does that "torque arm" figure torque? It's a calculation just like power trust me. No better or worse just a number.
Most posts to this thread avoid the original question instead jumping to recommend gears plus the usual v-drive cool funny factor. Go with this or that gear or switch the GPS back to MPH instead of KPH. Ha ha.
If you read Garucci's original post plus his follow on, I think he's asking a serious question and looking for a serious answer. That answer's a bit technical like it or not.
Here's one attempt: "...yes that would be true to drop gears and let the motor come up into the power band of the horsepower, but what i have been told about boats, and correct me if i am wrong but horsepower dont mean s**t, its all about torque, so that is why i have been thinking about a cam that will drop my total horsepower by 24 horses, but i will gain about 150 ftlbs of torque, and then having to spin my motor at a less rpm to be safter in the internal parts??"
The essence of misunderstanding or confusion about hp vs Q and the reason for urban legend hp vs Q discussions. According to that post, he was told gear to the power band, but no wait, focus on xxx torque and not xxx hp for best performance 'cause power don't mean shit. Oh jeez which is it? You agree?
Isn't that question the topic of Garucci's original post not what gear he should run or where does hp and Q cross in English units?
There's a truth here. It has to do with power applied to the drive and drive efficiency not torque. It spans both jet and v-drives. If you want to be cool, dismiss my posts as windbag aeronautical fornication, anal etc. At least you'll seem cool to your buddies. If instead you want to learn something or discuss Garucci's original post...let's talk.
jer

[steelcomp]

Jer, as usual, when you just talk like a regular guy, you have good things to say. It's when you jump in a thread and have this way of insulting the intelligence of every letter that was written up to this point that gets old. Real old. You answer the question by asking a bunch of other questions in a real insulting "boy, you guys are stupid" manner that dosen't do anyone any good at all.
I understand that power is power, and that HP and Q are just labels.
So, go on and try and explain here, without insulting and belittling. Good info and good answers are always welcome. KISS.

[058]

Damn....here we go again, the age old arguement of which is best....well here's a newsflash...they are both important. Torque is work and horsepower is a calculation of torque and rpm. The "5252" is nothing but a mathamatical constanant to calculate horsepower from torque and rpm. It has nothing to do with where the torque curve and hp curve intersect. If that were the case then how do large diesel engines calculate horsepower when they do not turn over 1000 rpms or less depending on size. Ship diesel engines don't turn more than 90-100 rpms so do they need to be spun to 5252 rpms to figure a HP rating? Don't think so. 'horse-power'[hors'pou-r] n. A unit of power equal to 745.7 watts or 33,000 ft lbs per minute. Extra points bonus question...Why does HP continue to rise as torque falls off as rpms increase?

[steelcomp]

Damn....here we go again, the age old arguement of which is best....well here's a newsflash...they are both important. Torque is work and horsepower is a calculation of torque and rpm. The "5252" is nothing but a mathamatical constanant to calculate horsepower from torque and rpm. It has nothing to do with where the torque curve and hp curve intersect. If that were the case then how do large diesel engines calculate horsepower when they do not turn over 1000 rpms or less depending on size. Ship diesel engines don't turn more than 90-100 rpms so do they need to be spun to 5252 rpms to figure a HP rating? Don't think so. 'horse-power'[hors'pou-r] n. A unit of power equal to 745.7 watts or 33,000 ft lbs per minute. Extra points bonus question...Why does HP continue to rise as torque falls off as rpms increase?
Oh man...not another car craf expert.
Funny...I've seen lots of power curves where hp and q both continue to rise, just not at the same level, but I'll bight...explain to us why that is??
So how would you figure the HP rating on a "ship diesel"? No motor has to be spun to any RPM to figure anything. That's why they call it figuring. You can do it with , now check this out, NUMBERS!! No spinning involved!
BTW...5252 is exactly where hp and q intersect, when using them as units of measure. That's their given values. Different for NM, KW, KG/Angstrom, etc.

[058]

I shoulda known better not to get involved with any thread that the All knowing, All seeing Steelcomp was bestowing his infinite wisdom on us mere mortals here. Perhaps we can just sit back and let Steelcomp take over these forums as none of us has anything useful to contribute. Soooooooo without further adoooo....take it away STEELCOMP! The forum is now yours.

[INEEDAV]

I remember back in the good old days when you could set down read the v-drive section of the ***boat forums and get something besides indigestion......

[LVjetboy]

Ineedav, with your 360 posts, how long ago were those good ol days?
SteelComp posted: "You answer the question by asking a bunch of other questions in a real insulting "boy, you guys are stupid" manner that dosen't do anyone any good at all."
So? Sometimes it takes an abrasive style to get people thinking instead of herding in front of the local sheep dog.
O58 posted: "The "5252" is nothing but a mathamatical constanant to calculate horsepower from torque and rpm. It has nothing to do with where the torque curve and hp curve intersect."
Yes and no. Yes, 5250 is just a math constant based on units. No, it actually does have to do with where the hp and Q curves cross as SteelComp posted.
And the crossing point is of no performance significance...as a link posted earlier by floored may lead some to believe. Urban legend. Change to metric units? The rpm crossing point goes thru the roof. Does that mean European engines work different than ours? No. My intent with this point is to dispel the myth, "you need more torque below 5250 and more power above 5250." I've seen that thinking. Some actually believe that. As well as others sighting 5250 as some sort of magic crossing point mantra explaining how torque is more important than power. As well as some who focus on maximum torque to the prop/impeller instead of power. Even others who suggest there's a magic blend of power and torque say maybe where they intersect or at 1/3 gives best performance. Those are misconceptions...faulty reasoning does not lead to better insight and performance.
Apply maximum torque or power to your drive. Which property gives more performance? There is a difference btw...some will say no it's all the same.
jer

[058]

LV, the 5252 constanant is a reduced number from 33,000 lb/ft/min that James Watt derived when he made a "work" measurement based on torque & time. If the hp and torque intersects at 5252 rpm as you say it does it is a nothing more than a coincedence. If what you say is true about the torque and hp intersecting at 5252 rpms then how do you account for a large engine, say a diesel that peak torque is developed at 1200 rpm and maximum hp is made at 2000 rpm? It seems to me the intersecting point of torque & hp would be somewhere around 1550 to 1600 rpms.

[INEEDAV]

Ineedav, with your 360 posts, how long ago were those good ol days?
jer
You are correct LVjetboy, I do not have a whole lot of posts. You can also ispect them and see that there is not a single one of them where I am talking shit or trying to force my ideas or theorys on people who are obviously as smart as I am. People do not appreciate someone running up and talking smack about what they know or believe.
I am sure that if you can give some truely wonderful information that would settle the torque v. horsepower issue you would be up for a Peace Prize or something:rolleyes: .
Billy

[steelcomp]

I shoulda known better not to get involved with any thread that the All knowing, All seeing Steelcomp was bestowing his infinite wisdom on us mere mortals here. Perhaps we can just sit back and let Steelcomp take over these forums as none of us has anything useful to contribute. Soooooooo without further adoooo....take it away STEELCOMP! The forum is now yours.
I didn't think you could answer the question. :hammerhea
And you contributed what, that was useful??

[steelcomp]

LV, the 5252 constanant is a reduced number from 33,000 lb/ft/min that James Watt derived when he made a "work" measurement based on torque & time. If the hp and torque intersects at 5252 rpm as you say it does it is a nothing more than a coincedence. If what you say is true about the torque and hp intersecting at 5252 rpms then how do you account for a large engine, say a diesel that peak torque is developed at 1200 rpm and maximum hp is made at 2000 rpm? It seems to me the intersecting point of torque & hp would be somewhere around 1550 to 1600 rpms.
What number do you seem to think they would intersect at? (how much hp and q)?

[Boy Named Sue]

Don't want to crash your thread. What up EHSGS? 058 keep on truckin.
later.

[steelcomp]

SteelComp posted: "You answer the question by asking a bunch of other questions in a real insulting "boy, you guys are stupid" manner that dosen't do anyone any good at all."
So? Sometimes it takes an abrasive style to get people thinking instead of herding in front of the local sheep dog.
Sorry Jer. :notam:

[steelcomp]

Don't want to crash your thread. What up EHSGS? 058 keep on truckin.
later.
'sup sue

[Boy Named Sue]

nuttin. just sayin hey to a hillbilly. :redface:

[Boy Named Sue]

and its Suey to you redneck.

[Roman 1]

...faulty reasoning does not lead to better insight and performance.
Well that explains why your boats a pig. :notam:
R1

[steelcomp]

and its Suey to you redneck.
That's Mr Redneck, to you, Sueeeeeeeeeeeeeeeeeeeeeeey :lightsabe

[Fiat48]

I am running a 11.25x16 meikens prop. brodix alum heads, tunnel ram, two holley 750's, lunatti roller cam-.312,.320,.722,.722---the boat only pulls to 5500 rpm and it is running 84 mph. I am looking a either putting gears to slow my rpm's of the motor alittle bit and spin the prop faster, or changing out the prop?? The cam in the motor now for what i can figure off of desk top dyno isnt even in the power band of the cam until 7500 rpm, and tops out at 5500 rpm on the torque. So that is why i thought about putting a cam that will be more torque and less horsepower on the top end.
I am wanting to go as fast as this boat will go without supercharging it. I just feel that the boat has alot more potential.
Thanks for any input
Pm me with the following information:
Engine:
Compression ratio
Camshaft specs @.050 or Lunati's camshaft number
Valve spring pressure
Ignition system
Boat:
True flat or runner bottom?
Boat bottom condition (hooks?)
Rpm when you first nail the throttle to set the boat.
Fuel pressure reading at wide open throttle at top rpm (5500?)
PS: Never...ever...post a thread on any forum with the title "Torque vs Horsepower" if you want real answers. Go stand in the corner.

[LVjetboy]

O58, yes I understand the 33,000 lb/ft/min, James Watt, and where the 5250 comes from. Read on...
O58 posted: "If what you say is true about the torque and hp intersecting at 5252 rpms then how do you account for a large engine, say a diesel that peak torque is developed at 1200 rpm and maximum hp is made at 2000 rpm? It seems to me the intersecting point of torque & hp would be somewhere around 1550 to 1600 rpms."
What I said was the 5250 crossing point is based on units chosen and has no significance to performance. It is a math constant and will not change unless you change units. The "crossing point" is an artifact of the units chosen and has no significance to predicting engine/drive performance in cars or boats or airplanes or dirigibles. In other words, if you choose English units for power and torque, then yes, power and torque will always cross at 5250 no matter the engine design or fuel...gas, diesel, propane or freaking electric. If instead you choose metric units then power and torque will always cross considerably higher...usually off the chart. Do you know where?
Consider...
English:
Power (Hp) = Q (ft-lbs) X Rpm/5250
Metric:
Power (Kw) = Q (Nm) X Rpm/9543
Any guess where Metric power and torque cross...for the same engine run compared to English?
Yes a diesel develops big time torque low and power peaks low too. But guess where they cross? Hp and Q equations don't magically change with the engine design. But the crossing point does change depending on units chosen to display results. That's why the fabled "crossing point" is of no significance other than in the world of urban legend where some trumpet the "crossing point" as proof they understand what's up with power and torque. You think?
And you can bet you'll see that legend repeated on more than one site. As well as the mantra "torque is measured" and "power is calculated" Nonsense. Both are calculated does anyone know why?
Instead, why not be open to understanding physics, what's really happening, and how power and efficiency affect performance? Why blindly follow the sheep dog?
jer

[LVjetboy]

INEEDAV posted: "People do not appreciate someone running up and talking smack about what they know or believe."
No doubt, epecially if what they think they know or believe based on what their sheep dog leader says is different than the outsider who questions their beliefs or their leader? Have you ever read history? The earth's still flat right? Leaders of the time swore it and punished those who doubted. No useful exchange of ideas back then.
On the other hand, if you have a different technical opinion on this thread "Torque vs. Horsepower" and would like to post something worthwhile then feel free. Challenge what I've posted and let's exchange ideas.
Otherwise, I suppose it's all just "talking smack" as you say.
jer

[LVjetboy]

Fiat48 posted: "PS: Never...ever...post a thread on any forum with the title "Torque vs Horsepower" if you want real answers. Go stand in the corner."
But if you want to understand, then go ahead and question "Torque vs Horsepower." Or, if you just want the trial and error answer, pick gears and a prop based on what the sheep dog says. Trial and error eventually leads to a solution...without real understanding.
jer

[LVjetboy]

Roman1 posted: "Well that explains why your boats a pig."
Quality post as usual. If that explains, then half the v-drivers reading this thread are also pigs. Including the author of this thread, poor Garucci who only runs 84 mph, a rather slow pig by your definition? Actually, that explains why your boat's a pig and my boat's a pig focker.
Which would you rather be farmboy?
jer

[Roman 1]

Roman1 posted: "Well that explains why your boats a pig."
If that explains, then half the v-drivers reading this thread are also pigs.
jer
Poindexter,
Can you break down your hypothesis and formulate an equation explaining all steps involved in achieving the facts from the quote listed above? Please include your condescending tone that so successfully fortifies your popularity.
Come out to needles in april and we'll see who gets focked...
R1 :notam: :coffeycup

[Fiat48]

INEEDAV posted: "People do not appreciate someone running up and talking smack about what they know or believe."
No doubt, epecially if what they think they know or believe based on what their sheep dog leader says is different than the outsider who questions their beliefs or their leader? Have you ever read history? The earth's still flat right? Leaders of the time swore it and punished those who doubted. No useful exchange of ideas back then.
On the other hand, if you have a different technical opinion on this thread "Torque vs. Horsepower" and would like to post something worthwhile then feel free. Challenge what I've posted and let's exchange ideas.
Otherwise, I suppose it's all just "talking smack" as you say.
jer
Who is this "sheep dog" leader to whom you refer?

[058]

Well put INEEDAV! LV Why the hell would you use "urban legends" or old wives tales in your arguements? In your own words they meant nothing lets leave it at just that, old wive's tales. 5252 is nothing more than a math constinant used to find hp from torque and rpm. No different than Pi is used as a transcendental number that represents the ratio of the circumference of a circle to its diameter...thats no urban legend or silly wive's tale. As such a stickler for fact this surprises me that you would resort to using this tactic to try to support your arguement.....LV, stick to dazzling us with your brillance and not baffiling us with your bulls*it.

[Roman 1]

LV, stick to dazzling us with your brillance and not baffiling us with your bulls*it.
If he takes that advise, we'll never hear from him again :jawdrop:
R1 :notam:

[steelcomp]

Fiat48 posted: "PS: Never...ever...post a thread on any forum with the title "Torque vs Horsepower" if you want real answers. Go stand in the corner."
But if you want to understand, then go ahead and question "Torque vs Horsepower." Or, if you just want the trial and error answer, pick gears and a prop based on what the sheep dog says. Trial and error eventually leads to a solution...without real understanding.
jer
There are those who really don't need to understand, nor do they really care. They just want to get their shiot runnin right and go have some fun the easiest way possible. Nothing wrong with that. It's not always necessary to re invent the wheel just to make something roll. There are those who have already done that, and are willing to share their hard found answers and results without charging those seeking the answers to their questions with "understanding". Let's face it...the truth is what's so, but it's also so what. :idea:

[LVjetboy]

SteelComp posted: "There are those who have already done that, and are willing to share their hard found answers and results without charging those seeking the answers to their questions with "understanding". Let's face it...the truth is what's so, but it's also so what."
Good point and well said Steel. If Garucci just wants "throw in this or that gear" advice from someone who's been there done that he may not give a sh*t about theory or care to understanding why. But he named the thread "Torque vs. Horsepower" and mentioned both in his first post. So I figured he was open to discussion and questioning why this or that gear...or debating torque vs. power.
INEEDAV posted: "5250 is simply a constant in a mathematical formula...mathematically it is not the RPM at which they cross, only a constant in the formula."
We all agree it's a constant, not sure if you caught that. Not an issue. But with your follow-up statement, "...it is not the rpm where they cross" I don't agree. If power and torque are plotted using the same axis scale as they nomally are, that constant will always be the crossing point. The reason IS math and nothing else. For English units, power and torque always cross at 5250 no matter the engine...even diesel. With Metric, they always cross at 9540 no matter the engine.
So why dwell on a seemingly trivial point? Because if understood, the meaninglessnesss of assigning any performance significance to that crossing point becomes clear...and that understanding's not so trivial. But it goes deeper. Plotting torque and power on the same axis with similar magnitudes leads some to incorrectly concluding magnitude of torque applied to the prop (or impeller or wheel) is of equal if not more important than power applied. Take Garucci's 496 BBC for example, the question from someone confused by this may be, "Should I gear for more power or more torque to the prop?"
Gear for power. For performance, the focus should be maximum power output at full throttle not max torque. In the real world, things like gear box and prop efficiency may modify target rpm because drive-train and propulsion efficiency change with rpm. But those real world factors don't change only modify the primary focus...power. And efficiency is measured in power not torque...for a good reason.
The only thing torque's good for is calculating which gear ratio gets you max power.
Also in the real world, most don't even know their engine's true power curve let alone details like propulsion or gear box efficiency. Not saying we can calculate or predict everything. There's always test and tune, trial and error. But I think in the end, understanding basic principles can lead to better performance decisions regardless of knowing every last detail.
Just my thoughts. Obviously I dont gear or think much about props. You think different let me know...and be ready to explain why. The same physics applies to both jets and props...so also the answer to power vs torque applies to both.
jer

[LVjetboy]

Roman posted: "Please include your condescending tone that so successfully fortifies your popularity."
Was this a popularity contest? Not that I give a sh*t. You think a jet guy posting in v-drive what I post worries about popularity? For that matter what I post in jet tech or anywhere else? I just post what I think take it or leave it. Come to think of it why should I care? Gear all you sh*t to max torque.
jer

[LVjetboy]

"Who is this "sheep dog" leader to whom you refer?"
Not me. I'm the wolf growling at a couple dogs. And stiring up a bunch of blind sheep.
Think outside the herd.
jer

[Fiat48]

I see. I was just trying to help the man fix his boat.

[Roman 1]

"Who is this "sheep dog" leader to whom you refer?"
Not me. I'm the wolf growling at a couple dogs. And stiring up a bunch of blind sheep.
jer
You may be a wolf in the jet forums, but over here your more like an annoying chuahua trying to stir up a bunch of lions :notam:
R1 :sleeping:

[lucky]

Poindexter,
Can you break down your hypothesis and formulate an equation explaining all steps involved in achieving the facts from the quote listed above? Please include your condescending tone that so successfully fortifies your popularity.
Come out to needles in april and we'll see who gets focked...
R1 :notam: :coffeycup
how long did it tak you to look up dem werds ! lmao :eek: :cool: :eek:

[LVjetboy]

"...over here your more like an annoying chuahua trying to stir up a bunch of lions"
Then go back to your dens...nothing to see hear, nothing to learn...move along.
jer