Cobra power, how much is enough?

[PHC1]

What do you guys think is the "sweet spot" for powering a typical Cobra replica? If the car is to be enjoyed mostly on the streets and driven semi-aggressively on back roads, how much is enough to keep the car fun to drive and feel you have neither over-powered or under-powered the car with the choice of engine? Bragging rights aside, being realistic and keeping driveability in mind for your answer!

Horsepower is fun, especially when you can put it down! Driving a Nissan GT-R with 535HP and 0-60 of 2.8 sec with all wheel drive, dual clutch tranny and launch computer is nothing like driving a Cobra replica with the same HP! Of course the GT-R can't compare to the raw and exciting experience the Cobra brings either...

So then, would most agree that between 400-500HP is more than enough? Or do many feel between 500-600 is where the sweet spot is? Perhaps below 400 or above 600 for some???

[patrickt]

I have a 428 bored .025 over and stroked to 4.125 (not 4.250). Solid lifters, old fashioned cam, 10.6 compression, Edel. heads, aluminum flywheel -- it was spec'd to be a fast-revving, medium powered FE mill. It has under 500 "true horsepower" and I can't begin to use it all on the street. With my 3.54 rear and Yokohama Avids, if I give it any more than, maybe, half throttle the tires will break loose. Above 3000 RPM you really can't give it WOT much at all. I have the rev limiter set at 6400 RPM and occasionally bounce off it. Not because there's extra power past six grand (there really isn't much), I just really love the way it sounds up there -- but, believe me, I'm not using WOT to run past six grand on the street. Once you get past a certain mark on your engine power (and I'm not saying what that mark is) all you do is shorten the life of your components, create excess heat, and make it less drivable on the street. Hope that helps.

[Got the Bug]

My guess is that the sweet spot for enjoyment and driveability is in the 500 hp/500 tq range at the crank. Guess it depends on what you're looking for. I'm sure others will say the more the better.

[Silverback51]

Well I'm one of those that feel to much is just right.

The throttle is a rheostat, not an On/Off switch. Just because you have 650+ HP does not mean you have to use it all the time. But it's nice to have when you want it.

[mreid]

x2. I started with 340hp, then 430, then 475, and now 540. Each seemed enough at the time until I learned how to use it. Now 540 seems just right, but I barely use a fraction of it most times. It's those few times I really want it that makes it all worthwhile...

[mdross1]

My big block was dynoed at a tad over 525hp will be stepping it up near 560/570hp with some topend work and solid roller,It's all about taking advantage of what your packing,learning how to best use it.The more power you make the more you have to focus on the perriferals,brakes,suspension,cooling etc.Having a car built this way makes the rides so much more fun.

[patrickt]

PHC1 -- also keep in mind that there are a lot of games with dyno numbers. When I say "true horsepower," that's being dyno'ed with the side pipes bolted on, water pump pumping, no goofy adjustments to the machine, etc... but dyno games are for another thread. It's important for you to understand that though when you start comparing/contrasting builds for your car. And it's not like the engine builders are trying to "pull one over on you" either -- imagine if you were building engines and your competitor's numbers were with open pipes and yours weren't. You'd look like a lousy builder unless you got a chance to 'splain. Someone on here had a pretty funny thread a couple of years back when he insisted that his new FE be dyno'ed with his sidepipes bolted on. The builder really didn't want to do that, but he eventually got his way.

[undy]

Enough horsepower is sort of like absolute zero... Once it's attained you find out it really wasn't the right number (too low). At least that's my slice on it.

[mdross1]

I had never been into the dyno thing until the Cobra always tuned by seat of the pants and the way the cylinders were burning.Caved to it just to see what I might be dealing with.Actually since the dyno run have done many upgrades to the motor and drivetrain.Will stick with seat of the pants and the way I learned a long time ago.Course always open to new ideas,part of the fun of owning these hot rods.

[twobjshelbys]

Bartender training: A bartender shall never ask "do you need another drink". The bartender shall ask "do you want another drink".

Gearhed training: Noone shall ever ask "how much horsepower is enough, or how much horsepower do you need" (The answer, is infinite, and there is never enough, and I'll always need more). The proper question is then deferred to bartender rules, and the proper question is "how much horsepower do you want".

In the end I didn't want more than about 500HP on the 427, and really only wanted a 289 style car as it was too easy to get the 427 to start acting like a squirrel crossing the street.

[B.M.B.C]

Remember a 428 street cobra was packing about 375hp and a 427 engined car was 425hp..... And thats the power the legend was built on!

[GRUF78]

My motor dyno'd at 594 HP and 601 TQ on the initial break-in. Installed in the car , it probably makes 450 HP at the wheels or so.

The car is 99.9% correct, every nut and bolt. (427 SO/Toploader/rear/etc, etc)

Near uncontrollable in the first 2 gears, but OK in 3rd and 4th. It will still spin the tires at 60-70 MPH in 3rd.

500 HP in a 2200 # car is way enough IMO unless your going to road race it on big tracks or drag it.

If I do another 427 (Will be a street car vice S/C), it will have 100 less HP than the one I have now.

GRUFF

[Stentor]

The amount of HP that is enough/feasible is to a large degree dependent on getting the suspension of the car dialed in and investing in a good set of tires.

A quick query--how many guys posting that 400/500 hp is too much are running good tires (e.g., Avons, drag radials, Billboards)?

For whatever reason, a lot of guys settle for running junk tires (e.g., Radial T/A)--which can be downright dangerous in these cars.

[olddog]

Two points:

1) Peak Hp tells nothing about the torque over the entire rpm range. The low end torque of a stroked FE is way more than a high strung SB that make it's peak Hp at 7000, even if they make the same peak Hp.

2) Rear end and suspension makes a huge difference in traction. IRS vs straight axle. 4 link 3 link also matter.

If you listen to what the guys on here say, you get the impression that a stroked FE connected to an IRS is a very difficult thing to launch.

[fordracing65]

Originally Posted by Stentor

The amount of HP that is enough/feasible is to a large degree dependent on getting the suspension of the car dialed in and investing in a good set of tires.

A quick query--how many guys posting that 400/500 hp is too much are running good tires (e.g., Avons, drag radials, Billboards)?

For whatever reason, a lot of guys settle for running junk tires (e.g., Radial T/A)--which can be downright dangerous in these cars.

Hey, I use BFG radials T/A on my van, and they are fine.

[rpatton3]

Did you see the $400,000 drag race with the FE powered Kirkham smoke the Ferrari 458?

The Kirkham was is middle tens and 133 mph; much faster than the Ferrari with launch control that was middle elevens at 125 or so.

It is on youTube.

[garyjettrike]

with toyo R 888 tyres around 500 HP and 500 ft lbs i will let my mum drive it on a dry day , big torq engine and stiky tires makes easy driving

[Silverback51]

Originally Posted by Stentor

The amount of HP that is enough/feasible is to a large degree dependent on getting the suspension of the car dialed in and investing in a good set of tires.

A quick query--how many guys posting that 400/500 hp is too much are running good tires (e.g., Avons, drag radials, Billboards)?

For whatever reason, a lot of guys settle for running junk tires (e.g., Radial T/A)--which can be downright dangerous in these cars.

It never ceases to amaze me the number of Cobra owners that will invest thousands in their car increase the HP, but won't invest in a good set of tires.

Mine had Goodyear GTII's on it when bought it. Not a bad tire, but they are garbage on a higher HP Cobra. As stated, you could break them lose at 60 MPH in 3rd gear. Generally the BB's or Avons will never do that.

[wideglidejoe]

If you listen to what the guys on here say, you get the impression that a stroked FE connected to an IRS is a very difficult thing to launch.

I've got a stroked FE (428 bore 4.13 X 4.25 stroke) in a 3.27 IRS car. I'm not sure how it compares upon launching compared to 3 or 4 link, but its not like its out of control or unmanageable. Then again, I'm used to 11 sec 1/4's on 2 wheels too. I haven't driven a roadster w/FE in a 3 or 4 link to compare it to my IRS. Granted, I don't do a water burnout like at the strip then pull into the staging area where its super-sticky, but as long as the tires are warmed up, spirited street driving and launches aren't a problem. I think it is what you get used to.

My engine wasn't dyno'd, but with a list of all the parts in it, most experienced engine folks tell me it would probably be 520-530 at the flywheel.

Anyway, it is a moot point now, as I blew the whole bottom end out of it last Sat at Hallett Raceway west of Tulsa. Now I'm planning my next FE stroker.

Anyway, my opinion........500-600 hp at the flywheel is about right, but you know how opinions are.

[vatdevil]

Torque and tires are more important than HP. Cobras are so traction limited. My car at 450ft/lb flywheel and sticky 315 Nittos is very manageable. Could probably go to 550 ft/lb. Would need stickier tires above that.