How much power is enough?

[xb-60]

Just thinking out load here (it's been a quiet night)

How much power is enough?
I know, I’ve read Mark Donohue’s gem "If you can make black marks on a straight from the time you turn out of a corner until the braking point of the next turn, then you have enough horsepower" enough times, but how much really is enough?

So, what is the horsepower crossover point in a light weight, short wheelbase, front-mid engined car like a Cobra replica, where adding more power actually detracts from the driveability and maybe even makes the car slower for virtually everybody except a professional racing driver?

At what (HP) point does the knowledge that flooring it will just create lots of tyre smoke without a proportional amount of forward motion?

Cheers,
Glen

[tin-man]

Originally Posted by xb-60

Just thinking out load here (it's been a quiet night)

How much power is enough?
I know, I’ve read Mark Donohue’s gem "If you can make black marks on a straight from the time you turn out of a corner until the braking point of the next turn, then you have enough horsepower" enough times, but how much really is enough?

So, what is the horsepower crossover point in a light weight, short wheelbase, front-mid engined car like a Cobra replica, where adding more power actually detracts from the driveability and maybe even makes the car slower for virtually everybody except a professional racing driver?

At what (HP) point does the knowledge that flooring it will just create lots of tyre smoke without a proportional amount of forward motion?

Cheers,
Glen

always want more, can never get enough. Just my two cents... Cheers, tin-man

[undy]

Too much power is not quite enough...

[tuska]

land speed records are still being broken....tells us there is never too much...just keeping it all together is the problem

[mdross1]

Like any machine with too much power,trying to conquer them is half the excitement.Honestly, having a lot of torque and power in a properly set up suspension and decent rubber can be an addrenaline rush you will always feel the need for more of.Just because you have more than you think you might need does not mean you have to drive it to the point of not having control.But when the conditions are right big power is addicting.I use my car to it's fullest potential,road racing is a blast having the tail wag out in the turns keeps me very focused.Rollons out on the highway alone or passing is an absolute thrill.The very reason why I wanted a Cobra in the first place.

[tin-man]

Originally Posted by mdross1

Like any machine with too much power,trying to conquer them is half the excitement.Honestly, having a lot of torque and power in a properly set up suspension and decent rubber can be an addrenaline rush you will always feel the need for more of.Just because you have more than you think you might need does not mean you have to drive it to the point of not having control.But when the conditions are right big power is addicting.I use my car to it's fullest potential,road racing is a blast having the tail wag out in the turns keeps me very focused.Rollons out on the highway alone or passing is an absolute thrill.The very reason why I wanted a Cobra in the first place.

Help this poor sinner understand "Rollons" never heard this before, guess I've been in China too long.

Cheers, John, AKA, tin-man, Zhuhai, P.R.C.

[xb-60]

So far, the score is...tinman with Roush 511 IR with 572HP, there's undy with a KC 482, tuska with a KC 427 and mdross1 with a 460 and 525hp.....very predictably saying nup, can't have too much.
Makes me feel like a bit of a girlie for even asking the question

Cheers fellers,
Glen

[tin-man]

Originally Posted by xb-60

So far, the score is...tinman with Roush 511 IR with 572HP, there's undy with a KC 482, tuska with a KC 427 and mdross1 with a 460 and 525hp.....very predictably saying nup, can't have too much.
Makes me feel like a bit of a girlie for even asking the question

Cheers fellers,
Glen

Glen, I'm betting you are the type of guy that asked the question since you have already made up your mind you will have the meanest nasty sounding high powered rocket in OZ that's gonna cause your sphincter muscle to pucker every time you take it out for a spin. did I get that right?

The girlies come later.

Cheers, tin-man

[mreid]

For most people, anything over 400hp at the rear wheels is too much in one of these cars. Unless it is primarily used on the track, you will rarely use that level of power and the car will be scary fast and easily capable of spining out of control quickly if you get on it too fast. Now I'll speak for me personally. It seems that every car I build gets more radical in the power department. My GT40 had a 500hp 347, my daytona coupe before that, a 430hp 392w (both rated at the flywheel). All the cars before them were in the 300 to 400 range. They were both scary to drive at first, but quickly became the ultimate adrenaline rush, but I also respected the power and rarely used it all. That said, I'm aiming for 500hp at the rear wheels in my Kirkham simply because HP is so damned addicting!

[lnfletcher]

Bank account balance = $0 = enough power!

[charles roybal]

"First of all, from a driver's perspective, torque, is the only thing that a driver feels, and horsepower is just sort of an esoteric measurement in that context. 300 foot pounds of torque will accelerate you just as hard at 2000 rpm as it would if you were making that torque at 4000 rpm in the same gear, yet, per the formula, the horsepower would be *double* at 4000 rpm. Therefore, horsepower isn't particularly meaningful from a driver's perspective, and the two numbers only get friendly at 5252 rpm, where horsepower and torque always come out the same"

[bobcowan]

How much is enough? Tough question, with no real answer. You need enough power to get the job done. So, first, you have to decide what the job is: Road racing, drag racing, autocross, street cruising, turning your hair white, etc.

I'm putting about 510hp to the pavement. On the street, I never use all that. But on the track I use every one of them, and I'm looking for more.

There's no such thing as too much power. Only not enough control.

Don't worry about building the engine to a certain power number. Instead, build the engine for what you're comfortable with driving./ Big nasty radical cam with a Holley Dominater carb, or a stock DD. Then let the power numbers fall where they may.

[Tommy]

The most high performance Cobra I know of that is running today is Bruce Cambern's # 3170. He spoke of the challenge of driving it in this thread: Click here. See comment #56 to read how he had to modify his throttle to make it possible for the driver to handle his 600+ HP. ... My point is that "enough power" is not an absolute quantity. It depends on the driver, the environment and all the components that must work together in the car.

[charles roybal]

Sorry wrong post

[RestoCreations]

I have to agree with Mr Reid on all points. I tend to be going up on cubic inches and power each time i build a car as well, but i am also going up in quality. I think 400 at the wheels is probably a good number, but it also really depends on which replica you are building and the quality of their suspension and frame.

[skippy]

Well again its still a good question.

After 8 years owning my SPF i tired of the 500hp of my old 392ci.

After long talks with Keith Craft we decided to up the Cubes and all the little goodies to bring that X-factor feeling back.

After now driving its first 1000 miles that factor has certainly come back, but also at a price, im now as we talk upgrading all the components to handle such power, ie front brakes SPF upgrade, upgrade axel and now suspension.

Is it all worth it ? So far a massive yes, will only know the full x-factor feeling when all the upgrades are done.

I say go big from the start, we always grow into old shoes..

Skippy.

[ItBites]

I regularly use all 700 hp from my 540cid. I can use it on the street or at the track. Don't know what folks are talking about with too much... If I had 200 more, I'd use that as well. Maybe N2O next!

I think most folks use substandard tires so they just spin, or maybe have bad rear suspension geometry? Anyhow, if you know more than a box of rocks, 700 hp is fun and controllable.

[xb-60]

Originally Posted by tin-man

Glen, I'm betting you are the type of guy that asked the question since you have already made up your mind you will have the meanest nasty sounding high powered rocket in OZ that's gonna cause your sphincter muscle to pucker every time you take it out for a spin. did I get that right?

The girlies come later.

Cheers, tin-man

tin-man, you should be a psychologist; you've got me worked out. Yes I do have certain requirements and I suspect they will be expensive....particularly where I live.
Cheers,
Glen

[Silverback51]

I have said it before, but I will say it again.

The throttle is a rheostat, not an off/on switch. What fun is a car that you can flat foot it in any gear and not break the tires loose.

My wifes JEEP SRT/8 is fast, but anyone can drive it. All you have to do is push the pedal to the floor and point it in the direction you want to go. It's not very exciting.

With the Cobra you cannot flat foot it in 1st or 2nd, and sometimes 3rd depending on the conditions. You have to learn how to apply the throttle to acheive the maximum results. That's fun.

So, in my opinion you can never have to much power. You can however misuse what you have and get in trouble because of it.

[lovehamr]

Originally Posted by charles roybal

"First of all, from a driver's perspective, torque, is the only thing that a driver feels, and horsepower is just sort of an esoteric measurement in that context. 300 foot pounds of torque will accelerate you just as hard at 2000 rpm as it would if you were making that torque at 4000 rpm in the same gear, yet, per the formula, the horsepower would be *double* at 4000 rpm. Therefore, horsepower isn't particularly meaningful from a driver's perspective, and the two numbers only get friendly at 5252 rpm, where horsepower and torque always come out the same"

I just can't help it, maybe it's all the math classes, I don't know, but every time I see one of these "it's all about torque" rants I just have to break it down. This is a misnomer; “torque, is the only thing that a driver feels" and then follow that up with "horsepower is just sort of an esoteric measurement"?? I got news for ya, the human butt can no more distinguish torque from HP than it can blue light from red light. In simplest terms we are dealing with power or energy, a force that moves you. These forces are best expressed in mathematical terms (rather than internet colloquialisms) thusly;

1 HP = 33,000 foot-pounds per minute
Or it could be P/hp=[T/(ft lb)][w/(r/min)] over 5252
By the way, THAT 5252 is why all dyno charts show the HP and torque curves crossing at that RPM.
Or it could be 746 watts
Or maybe 2,545 BTUs (British thermal units)
One BTU being equal to 1,055 joules, or 252 gram-calories or 0.252 food calories.
This means that 1 HP is also equal to 2684975 joules, or 63504 gram-calories, or 641.34 food calories
Presumably, a horse producing 1 horsepower would burn about 641 Calories in one hour if it were 100% efficient.
The point is that its energy, a force, what moves you, not some "esoteric" calculation.

Torque, on the other hand, is a static force applied to a lever, multiplied by its distance from the lever's fulcrum in our case a theoretical lever and a rotating fulcrum, or more simply:
T = r x F (whadaya know another calculated "esoteric" number)
Which is linier force multiplied by a radius. Of course this formula always assumes a perpendicular force axis to the fulcrum. And we all know that this is NOT the case in a reciprocating engine right?

To put this into perspective the next time you want to accelerate really fast try shifting at your engine’s torque peak rather than the HP peak. It doesn’t take a rocket surgeon to figure out using which shift point will accelerate the car faster. This is because we’re talking about energy expended over time (HP) not a static applied force (TQ). To say that another way; I could put 100 pounds of torque on your crank shaft with a ratchet handle, but I don’t think you’re going to accelerate too quickly and I doubt that you’d feel it to much in the seat of your pants either.

In summary, to poo poo on HP and bow to torque is like saying that you really like chocolate cake but that chocolate is over rated. It's disassociating 2 mathematical formulae which are expressions of force, just one is static and the other is expressed over time. And the more power you have over time the faster you go, period.

Steve

I should add Einstein and quantum entanglement not withstanding!