Longevity & Reliability vs. Power

[RodKnock]

Originally Posted by patrickt

Uhhh, ok then... "thank you" for my pipes, and if I want kiss Lykins, that's my own business.

Always call for back up.

[rodneym]

To the experts (EXPERTS!!!):

Doesn't it stand to reason that if you have a set of pipes (no matter the brand, let's just keep them constant in this example), and you have 20-25% HP loss on average (expert opined), wouldn't you get a higher percentage of HP LOSS on a 800 HP engine vs a 400 HP engine? Remember, the headers and pipes are the same for both engines in this case. It would seem to me that the same headers/pipes would do more choking on a higher powered car.

Or is the difference negligible?

[blykins]

Yes, you're correct....

If you start at 500 fwhp and lose 20%, you've lost 100 and you're down to 400.

If you start with 700 and lose 20%, you've lost 140 and you're down to 560.

And I believe that if a certain size exhaust system is restrictive to a 500hp 400ci engine, it's going to be even more restrictive to a 700hp 500ci engine.

[patrickt]

Originally Posted by rodneym

To the experts (EXPERTS!!!):

Doesn't it stand to reason that if you have a set of pipes (no matter the brand, let's just keep them constant in this example), and you have 20-25% HP loss on average (expert opined), wouldn't you get a higher percentage of HP LOSS on a 800 HP engine vs a 400 HP engine?

I think you're absolutely right, and I think Keth is being painfully honest in his post. I know Barry R. is busy with his cammer (from the FordFe thread), but it would be interesting to get his input on it, as well as Jerry C.'s input.

[RodKnock]

I'm not ready to believe that there's a linear relationship like that without some dyno testing using all the same equipment, but for the engine.

[patrickt]

Originally Posted by RodKnock

I'm not ready to believe that there's a linear relationship like that without some dyno testing using all the same equipment, but for the engine.

Absolutely correct. The loss will not be linear, it will be exponential. The larger the engine, the larger percentage of loss.

[blykins]

Yep.

Take a 302....you can run a 1-5/8" header tube on that one....try running 1-5/8" headers on a 557

[patrickt]

Yep, Rod... I'm going to have to start drawing you graphs. I am just loving this thread.

[RodKnock]

Couldn't you design, let's say, and 850 HP SOHC engine, employing concepts of quench, piston/chamber design, cam and EFI technology, etc., etc., that would lose less HP through the sidepipes, as a %, than other 850HP FE engines? Are all 850 HP FE engines created equal.

[CobraEd]

When I upgraded from my original PoS Classic Roadsters sidepipes to a custom set of stainles pipes, I picked up a ton of power. I did not dyno it but seat of the pants was day and night. Anyway, . . . I now have 4" oustide diameter stainless glasspack sidepipe mufflers with 3" inside diameter. We keep talking about hp losses of sidepipes, but it is hard for me to imagine that I am losing a lot with a straight thru 3" ID glasspack. The case is about 30" long, it is not a shortie. It sounds very good to me


.

[rodneym]

Originally Posted by patrickt

Absolutely correct. The loss will not be linear, it will be exponential. The larger the engine, the larger percentage of loss.

That's what I was getting at. All pipes being the same, you might get 20% loss on a 500 HP build and 25% HP loss on a 700 HP build. So you would lose 100 HP on the first engine and 175 HP on the second (just an example).

[Z-linkCobra]

Originally Posted by blykins

Yes, you're correct....

If you start at 500 fwhp and lose 20%, you've lost 100 and you're down to 400.

If you start with 700 and lose 20%, you've lost 140 and you're down to 560.

And I believe that if a certain size exhaust system is restrictive to a 500hp 400ci engine, it's going to be even more restrictive to a 700hp 500ci engine.

In my mind you cant do the math correctly based on percentages. If you have a motor that builds 500 hp and you put it on a chassis dyno and say that it looses 100 hp through the drivetrain. Now if you swap motors to more hp then the drivetrain still only takes 100 hp to turn. It doesnt take more hp to turn with a bigger motor...the tranny and dif dont know the difference.

So with the 500 hp motor you lost 20% or 100 hp. With the 700 hp motor you lost 14.3% or a 100 hp....again the drivetrain doesnt know the difference. It takes X amount of force to turn X amount of weight...right?

Now if you go trying to make that 700hp motor breathe through them 500hp headers and pipes....then the drivetrain is no longer a consideration.

Im confused....lol

Gene

[LRRCobradreamer]

So, it all boils down to:

Performance, Reliability, or Cost.
Pick any two.
__________________
Thomas L. Kirkham, Jr.,
Vice President
Kirkham Motorsports


When designing any new parts, if you do not consider all three above, it is like designing a "three legged stool with only two legs". This is one of my "old" sayings.

Lee

[zrayr]

Originally Posted by Z-linkCobra

"...........So with the 500 hp motor you lost 20% or 100 hp. With the 700 hp motor you lost 14.3% or a 100 hp....again the drivetrain doesnt know the difference. It takes X amount of force to turn X amount of weight...right?........."

Im confused....lol

Gene

you're confused? I'm so confused I'm tempted to un-subscribe, and I'm the numbskull who started this thread .

all I want(ed) to know is can I have a 427 FE motor (stock displacement) that can reliably hit the red line as often I choose and still have enough reliability to drive across the country w/o undue worry. Or do I need to limit my fun to low & midrange torque-type excitement?

Z.

[patrickt]

Originally Posted by zrayr

all I want(ed) to know is can I have a 427 FE motor (stock displacement) that can reliably hit the red line as often I choose and still have enough reliability to drive across the country w/o undue worry.

I think it would be a coin flip as to whether my FE would make it cross-country without something breaking on it.

[392cobra]

Originally Posted by zrayr

all I want(ed) to know is can I have a 427 FE motor (stock displacement) that can reliably hit the red line as often I choose and still have enough reliability to drive across the country w/o undue worry.
Z.

The key to the answer depends on how often you choose to hit redline.

[RodKnock]

Originally Posted by zrayr

all I want(ed) to know is can I have a 427 FE motor (stock displacement) that can reliably hit the red line as often I choose and still have enough reliability to drive across the country w/o undue worry. Or do I need to limit my fun to low & midrange torque-type excitement?

Z.

Depends on how much of a worrier you too. Personally, I would worry plenty about driving any FE across country. Unless I had Patrick tailing me with a tool chest and a bunch of spare parts, I wouldn't do it. But that's me.

If you can fix anything at anytime, you know a McGruber type, then you da man.

[Z-linkCobra]

Originally Posted by zrayr

you're confused? I'm so confused I'm tempted to un-subscribe, and I'm the numbskull who started this thread .

all I want(ed) to know is can I have a 427 FE motor (stock displacement) that can reliably hit the red line as often I choose and still have enough reliability to drive across the country w/o undue worry. Or do I need to limit my fun to low & midrange torque-type excitement?

Z.

Driving cross country back when those motors were new was still somewhat of a gamble..lol. Put together with the right parts and taken care of(water temps,oil pressure etc) there is no reason why you couldnt drive one cross country and hit red line every now and then.

Long story short the more hp you want to make the bigger the fire you gonna have to build. A 427 will make more hp and tq then you will ever be able to hook up anyway. Put it toggether with some good rod bolts, good head bolts and gaskets, a mild cam and let it go.

Just my thoughts

[patrickt]

... and to think how much we've spent on our FEs and now most of us would just be happy if they went an entire summer driving season without breaking down. My car *might* make it coast-to-coast, but if I was going to place a heavy bet, I'd put my money on a break-down. Nothing terribly serious, but something requiring a garage and time. And it would be out in the middle of a cornfield somewhere, too....

[zrayr]

so the consensus is, consistently hitting a 6000 rpm redline in a 427 FE will put cross country reliability at risk.

Z.