HP vs. laptimes vs. driveability/fun
 

I am sure someone has posted a version of this before but here we go... Recently some posted about how proud he was about having 750HP and only pressing the gas pedal half way... That's exactly what I want to debate here.

I race Karts on a competitive level. I race a stock moto 125cc honda (NCKroadracing.com my videos can be seen there). Our lap times at Laguna seca are around 1:36 and our lap times at Sears Point are around 1:45 just to give you an Idea of what we do..They often put us together with the super karts (250cc and above) The 125cc guys usually (i say usually because there some rare occasions) smoke the super karts largely because of handling, braking and usable power. The analogy I am referring too is very similar to the 289 cars vs. the 427 cars.

The 289 cars would constantly beat the 427 cars because the 427 cars would not be able to manage the HP to the track and spin the tires. In other words the 289 cars would smoke the 427 cars much like the 125cc karts smoke the 250cc karts. Assuming driving skills are equal.

I find it entertaining that some guys love to brag about how much HP they have while they have no idea why they built a street novice driven car with 700+ HP maybe they just enjoy bragging and deal with a car that is much slower and less fun to drive than a 450 HP car that is set up properly. A car that is not manageable on the street much less the track.

I get it, It is fun to have 700-800HP in a 2400lb car and brag to your buddies until a 289 car comes up and puts an ass whuppin on you... then what... LOL

I want to be able to push my car and my driving skills to a point where I am having fun with out spinning my tires and swapping ends while a miata blows past me... just saying... thoughts?

Mike,

Mine's a 289....so I like what you're sayin' :3DSMILE:
Lighter, better balanced, more fun because the engine power suits the chassis.
Got to qualify this though, as mine hasn't turned a wheel yet....however weight, balance and grip all have to be 'talking' to each other.

I started a thread here on CC quite a few years ago titled something like "How much power is enough" and quite a number of respondents weren't in agreement that too much power could be counterproductive.

Cheers!
Glen

edit: found it....
http://www.clubcobra.com/forums/all-...er-enough.html

Hello Mike,

I fully agree there.

I too, have raced Karts in a few forms, including 250cc International SuperKart.

My 250 was faster than all of the Group C and Group A touring cars of the era, back in 1990. Top speed by only calculated 10km/hr, lap time near 2 seconds. Lakeside International Raceway.

My current road car has only 330 rear wheel horsepower, but is much more useable, and faster overall than some of my mates with "500 plus horsepower".

Just enough to break traction in 3rd is ample for me, compared to some cars that smoke the tyres in 3rd.

Gary

I had a kart too, back in my teenage years. The kart was a homebuilt, and 'raced' on a dirt figure-eight track. The most fun was in the wet, with the hard packed, super-slippery surface.
The kart could also usually make it across a ploughed paddock if the entry speed was high enough. Downside to that was that it would need attention from the welder after most outings. The rear wing, of course for show only, was usually the problem. Sorry Mike. Off 'track' a little :D

Cheers!
Glen

I agree about your post overall as there are some that want a lot of HP for whatever reason. It’s their car so they are good to do what they want. As for HP, I think 400-450 is plenty. Some the faster guys that race replicas I have come across a few had 347’s as they are lighter and with a Dart block, they had no issues with 450-525hp. Some prefer a 331 over the 347.

I have a big block NASCAR Cobra and a Daytona Coupe with a 351 stroked out to 408. I have always liked the small blocks because the only type of racing I ever did was road racing and the small blocks would beat the big blocks most of the time. Also they are much more street friendly as due to age and health I had to give up racing so I had the small block detuned to where it just puts out 385 horsepower at the rear wheels and that is more than enough for just fun driving.

Ron

Yeah. Your 289 story happened 55 years ago? With engine technology, transmission technology, rear end technology, handling technology, and most of all, tire technology all taking a massive leap, it would be really hard to make that comparison today.

Take 800 hp, with a modern suspension set-up and some pretty sticky tires and it is a whole different world.

My first hand experience of actually racing a small block is they are competitive with a big block to a point. If the course has enough slow sections and only short straightaways they can keep up, usually under braking. But at the next straightaway the big blocks regain their advantage.
I race a period correct small block making about 438 HP in B Production vintage races, whereas the A Production Corvettes are making 700+ HP, something the 60's Corvettes never achieved but that has as much to do with the manner the GCR's are written as the specific race course.
A track like Sebring, Road Atlanta and Road America cubic inches wins out due to their configuration. A track like Sears Point with it's less technical aspects a small block can keep up with a big block, all things being "equal".
The big 427 came to be as a means to try to overcome the Shelby's drag coefficient and achieve a higher top end on the courses with the long straightaways. But in doing so it presented additional issues with brakes, front end lift and cooling.
Not taking sides, both motors have their place, and I enjoy both equally.

Well, from what I remember about 20 years ago, I performed some research, looking at the race results from 1965 / 66, races that included both 427 and 289 cobra's racing simultaneously, at the same track, under the same conditions, but obviously in different classes. From all the races that I was able to review the data ( maybe 10 races), the 427 cobra (s) always finished ahead of all the 289 cobra's. I did not include DNF's.

I think that any power level that requires you to constantly reign in your enthusiasm to prevent too much wheel spin is too much power and not very much long term fun to drive.

The right amount of power gives you a tyre chirp with a little wiggle when changing from second to third and allows you to keep your foot flat without risking a Mustang like excursion into the surrounding countryside.

The latter to my mind would be a lot more fun on the track.

If you want to drive the car and not constantly worry about whether it's going to exchange ass and head, then you want about no more power than what the 289 gave. The 427 was put in the car to push it around a track with an experienced driver. It's not really a street engine, nor are the high horsepower variants. Horsepower in a Cobra is about bragging rights. You can't get it (safely) to the ground. That's why if (when?) I get another Cobra it will be a small block car.

First, it's the Tim Allen caveman grunting thing. Why did I buy a power washer that I have to be careful not to cut my vinyl siding in two? Why do people buy the top of the line laptop computer to play solitaire?

Now to Cobra's. It depends on the track as to when more Hp wins. A longer straightaway track, where higher speeds can be reached, the 427 Cobra will beat the 289 Cobra, at high speeds, every time. A shorter track with sharper corners and lower speeds would favor the 289 Cobra, but better drivers may change that outcome.

You can make as much power as you like with a small block, but the torque curve starts to look like a mountain shape, and it becomes very difficult to control. Flatter torque curves are much easier to control. Big blocks can make more power with a flatter torque curve than a small block, generally speaking. In the end, it is matching the right engine to the track for the drivers skill level.

If a track required 500 Hp to reach the top speeds, you could build a 289 to get there. You can easily get there with a 427. I would expect the 427 would be much easier for an average driver to use. It would also allow more low end torque and would not need to shift down as much in the corners. If I were a betting man I would bet on the 427, but the right driver in the 289 could win, which is why they race instead of calculating who would win, and why I don't bet.

Like Mark Donahue said.....”If you can burn rubber from one corner to the next corner, .....then you have enough HP”.

When you have suspension & Chassis and Knowledge like we have today....

The HP wins every time....to win a Championship it takes 3 items.....
1. A good Car =Dedication
2. A good Driver = Determination
3. A good Crew = Desire

That’s How we did it 3 times with 3 different cars....

perhaps my analogy was not correct with regards to a 289 vs a 427. the point I was (am) trying to make is I feel a properly set up car with 500+ hp will do well against a car with 750+ HP, on a technical track that requires some driving skills. The car with 750+ HP will simply spin the tires and you will wind up taking a trip into the weeds or even worse, the wall. Yea I agree a track like willow springs with Long down hill straight the high HP car will most likely prevail. There is not a ton of talent required to run with leader group on that track. Typically guys drive over their head when suddenly in the leader group when never really been there before... LOL

Csx 3170 and KMP 259 would be hard to beat on the track I would think.

....and that's the point. Horses for courses.

If I'm on a KART track with lots of corners then weight and set-up counts, if I'm on a drag strip, then all things being equal I'll take the horses. :cool:

...and if I'm on the street, well it's all kind of irrelevant bc even a Prius can be issued a speeding ticket.:o

I don't know of any 750+HP Cobras with naturally aspirated engines. If you want a reliable street engine the limits are considerably lower. 302/347 ~ 500 HP, 482 FE ~ 600 HP, and my choice 351W/427 ~ 585 HP. With the 351W/427 and a Performer RPM Air-Gap manifold I have the big flat torque curve of a big block and about 570 HP. I am curious of the benefits of destroking to 3.75" ~ 401" with higher rpm, but it's a street car and it runs well to 6000 RPM. With 300 traction compound tires, I could blow them loose all the way through third gear if I gave it full throttle. I switched to 100 series traction compound now I only have to worry about first gear.
Someone mentioned CSX 3170. I actually spoke to Bruce at a Good Guys event in Scottsdale. He talked about numerous things he did to make the car handle better, some of them things I've never heard anyone else even discuss. Stiffening the frame, roll over ratio, sticky tires (CSX 3170 has been used to test tires for manufacturers), and high reving FE engine to accelerate faster. These are all things that require extreme engineering knowledge and dollars that most of us don't have access to.
500 vs 750, it depends on the chassis. You can build a 460" small block and still capture the weight benefit. Comparing our replicas with the originals, is apples and oranges. As previously mentioned, the technology has improved everywhere.
A final thought, Carroll Shelby had AC build the Mk III chassis for a reason, Carroll Shelby quote: Horsepower sells cars, torque wins races.

Absolutely the same results as I found in my own research years ago. The myth that the 289 Cobras consistently beat the 427's is just that - a big myth.

The truth is that the 289's won more races before the 427's came along because they enjoyed a longer period of factory support, while the 427 program never really took off due to focus in other directions (Daytona Coupe & GT40) and the changing face of racing itself that rendered open roadsters like the Cobra generally less competitive overall.

In the hands of privateer racers, when they were raced against each other, the big block Cobras with their greater power and improved suspension almost always blew the 289's into the weeds. The legacy of the 289 is that it brought home the championship trophies. The 427 just never really got the opportunity.