Longevity & Reliability vs. Power

[zrayr]

for a street driven FE 427, at what point do power modifications begin to seriously degrade longevity & reliability? 500 HP, 550 HP, 600+ HP ?

Z.

[blykins]

For an engine of that displacement, it's not hard to get 500hp with good cylinder heads, hydraulic roller cam, etc.

When you start approaching 600hp, you need to start using the larger, rowdier cams, little higher compression, etc. Peak horsepower rpms go up, better valvetrain components are necessary, etc.

Of course the larger the displacement, the easier to make more horsepower.

The 428FE that I built for my own Cobra used Edelbrock heads, a Tunnel Wedge intake, a solid roller camshaft, and it was about 11:1 compression. Peak horsepower was about 550 @ 6500. If you were running this car hard, you would need to shift at about 7000. A solid roller cam needs a little more attention than a hydraulic cam and the lifters don't live as long. I would consider that a minus in the longevity department.

Where reliability starts becoming an issue is if you're drag racing with hard launches, spinning the engine really high, etc.

[Tom Kirkham]

At about 5,500 RPMs

[Wbulk]

“5,500 RPMs”, I agree.
The higher the RPMs the greater the cost to build and the longevity goes down. It’s literally diminishing returns.

[blykins]

I wouldn't call it diminishing returns since rpms make horsepower, but in terms of reliability, I would say anything over 6400-6500 would start to see a decline.

[patrickt]

Originally Posted by zrayr

for a street driven FE 427, at what point do power modifications begin to seriously degrade longevity & reliability? 500 HP, 550 HP, 600+ HP ?

Z.

If it's street driven, you will not notice the difference between 600 and 500 horsepower. Plus, any of the FE builders on this forum can build you a 500+ HP FE that will last your lifetime.

[CobraEd]

If you put Royal Purple oil in it with a ZDDP additive, it may physicaly break, but it will never wear out!




.

[patrickt]

Personally, for a predominantly street-driven car, I think the "sweet spot" is mid to upper 400's in horsepower at the flywheel, measured with all accessories and pipes attached.

[RodKnock]

Originally Posted by patrickt

Personally, for a predominantly street-driven car, I think the "sweet spot" is mid to upper 400's in horsepower at the flywheel, measured with all accessories and pipes attached.

And this is based on...............................personal experience with one engine?

(just giving you a hard time).

[patrickt]

Originally Posted by RodKnock

And this is based on...............................personal experience with one engine?

(just giving you a hard time).

Awwww, man. In a Cobra, I guess that's true. But, I always try and get my engine running at its tippy-top right before I put her away in her seal-a-meal bag for the winter (which I did last week). I took her out for the last drive of the year and it was in the 50's (which is arctic weather, in my book). With the cold air, and the cold tires, I could not safely push the throttle more than half way to the floor for more than a second or two. I don't know how an additional dose of horsepower would do a thing for me. And, if there was the slightest bit of "streetability"* taken away by the horsepower fairy that wanted to wave her magic wand and give me a magic extra 100 horsepower, I would politely decline the gesture.

EDIT -- *streetability, longevity, or increased maintenance. (I need the last one like a I need a hole in the head.)

[Tom Kirkham]

So, it all boils down to:

Performance, Reliability, or Cost.
Pick any two.

[Stentor]

Originally Posted by patrickt

With the cold air, and the cold tires, I could not safely push the throttle more than half way to the floor for more than a second or two. I don't know how an additional dose of horsepower would do a thing for me. And, if there was the slightest bit of "streetability"* taken away by the horsepower fairy that wanted to wave her magic wand and give me a magic extra 100 horsepower, I would politely decline the gesture.

Perhaps you should ask Santa for a new set of Avons or Billboards for your ERA. You could get a bit more performance out of your FE with a better set of tires.

[patrickt]

Originally Posted by Stentor

Perhaps you should ask Santa for a new set of Avons or Billboards for your ERA. You could get a bit more performance out of your FE with a better set of tires.

Well thank you very much. Didn't Steve Sunshine post an in-depth analysis that concluded that anything over 525HP was wasted and useless? I seem to remember something like that from, like, four years ago and it was not just spouted-BS. It was a well researched and nicely presented post. Either that or I'm just imagining it ... but I don't think so.

[RodKnock]

Originally Posted by patrickt

Well thank you very much. Didn't Steve Sunshine post an in-depth analysis that concluded that anything over 525HP was wasted and useless? I seem to remember something like that from, like, four years ago and it was not just spouted-BS. It was a well researched and nicely presented post. Either that or I'm just imagining it ... but I don't think so.

Personally, I think it boils down to what the Matrix will allow you to do. The Architect may have changed the program in the last four years.

[patrickt]

Originally Posted by RodKnock

Personally, I think it boils down to what the Matrix will allow you to do. The Architect may have changed the program in the last four years.

I dunno. I imagined that I had bought out all of Stephen Becker's inventory last night at a firesale price, but then nobody would buy any of the cars from me. Fortunately I woke up from that nightmare....

[Stentor]

Originally Posted by patrickt

Well thank you very much. Didn't Steve Sunshine post an in-depth analysis that concluded that anything over 525HP was wasted and useless? I seem to remember something like that from, like, four years ago and it was not just spouted-BS. It was a well researched and nicely presented post. Either that or I'm just imagining it ... but I don't think so.

I am not familiar with the aforementioned post, but would be interested in reading it.

Are you suggesting that--ceteris paribus--a Cobra with 525 FWHP would accelerate as quickly as the same Cobra with 700 FWHP (assuming decent tires and suspension setup)?

[RICK LAKE]

zrayr Z this will turn into a questionable answer. From my own personal 14 years of owning a cobra and abuse at the track 95% of the time, here is what I have found. Matching parts for an rpm range is most important. If the power range is between 2,000 rpms and 5,800 rpms you build a motor for this range with parts. Intake manifold, compression, exhaust system and most important, CAMSHAFT design and valve springs. I built a shelby block and head motor with a 9.2 compression, 501/533" hydro camshaft and stock ERA exhaust. Car made 368 HP and 420 ft of torque at the rear wheels. This was with a stroker crankshaft from a stock 428 motor. 3.98" The cylinders are bore of 4.25". I build torque motors, this is was moves the cars, HP is for topend speed. I also believe in a peroiler system for the motor. Car will pull just under 1 "G" on a skid pad. I have learned that anything over 500 rpms past max hp numbers is all you need to spin the motor up to. ANY THING more than tis is just wasting motor life. Maintainance of checking bearings each sprring and looking for any damage or metal flakes in the oil pan are important to longer life of the motor. If you are running an FE bottom end, which I was, I run high oil pressure when racing. Between 65-80 psi hot on the track. I ran this motor for 8 years and have no failures. I run a 15w-40 oil and Lucas oil suppliment and small bottle of EOS. 75% of the wear to a motor is on startup after the motor has been sitting for a week. prelube with giving the motor a 35 psi pressure before starting saves alot of wear and tear. I have only $14K in this motor. The motor now with the same block and heads is a 482 motor. Same principles apply to this motor. I have gone to a hydro roller camshaft with a .586-.607". I have also gone to beehive springs that have less weight than the stock valvesprings and top caps. The couple of oz's has increased the rpm range 300 rpm more and raised the valve float to 5,800 rpm, the motor just pushes through this spot. Max rpm is 6,200.
Here's the thing, if you want to build an FE motor, stroker it with a 4.25 crank and chevy rods. This will make it just about bullet proof. I would still not rev this over 6,500 rpms. HVHP oil pump with an #80 pound spring. This will work good for street and a little track fun. Having ports on the intake and heads will make 10-30 hp more that stock. The exhaust is the big choker of the power. If noise is not an issue, go for loud pipes, low back pressure, and ear plugs. forget about talking and driving. Watch out for the cops with DB meters in town after dusk. You can also buy 2 sets of pipes, one for track and one for street. Run a lite flywheel on the car 20-22 lb one,not the 40 pounds that comes stock on most motors. Rearend ratios and trans ratio need to work togeather to get the most power to the ground. Barry R. has a book out about max hp from an FE motor. BUY IT and read. Jay Brown is also coming out with a book in a couple of weeks with more info on each part and which ones work better than others. You can build a nice 445-482 make great power, run on hightest gas 91 0ctane. Smoke the rear tires in 3 gears. Make about 600ft, of torque and 540hp. This is what my 482 makes. idles at 750 rpm with a little lope sound. running for 5 years now and no problems. I did have 2 failures of rocker shafts and have fix this with running ersons now. limit to 6,000 rpms, motor will last for many years with basic service. Have to remembeer the car ownly weights about 2,500 pounds. TOO much power is as bad as not enough, only different is one makes you look silly the other one could get you kill. Rick L.

[patrickt]

Originally Posted by Stentor

Are you suggesting that--ceteris paribus--a Cobra with 525 FWHP would accelerate as quickly as the same Cobra with 700 FWHP (assuming decent tires and suspension setup)?

In all seriousness, it was something pretty close to that -- yes. And hopefully somebody else can remember it, or maybe even find it. But it did conclude that anything over like 525/535 HP, even in racing conditions, was of no help.

[Hotfingrs]

But it did conclude that anything over like 525/535 HP, even in racing conditions, was of no help.

So Donohue didn't really need 1400 horse in his 917-30 ??

[patrickt]

Originally Posted by Hotfingrs

So Donohue didn't really need 1400 horse in his 917-30 ??

One has nothing to do with the other -- you know that. If I could find his post, I'd paste it here, but I think it may have gone down in one of the crashes we had a couple years ago. I bet Ernie remembers it, though. I have a vague recollection of him discussing it in that thread. I'm sure there are others who might it recall it.