Roush vs 427FE vs Keith Craft

[AL427SBF]

Might as well jump into the fray, and generalities do apply because on balance they apply to most engines.

It takes more energy to spin up a BB's rotating mass versus SB rotating mass because the SB has less mass to spin up, basic physics. That energy comes from your motor and is stored as kinetic energy in the rotating assembly.

The BB guys do better at the 1/4 mile because they can rev it up, dump the clutch - and use all that kinetic energy stored in the rotating assembly for a good launch and let the BB HP do the rest.

The SB guys do better on road courses because it's accelerate & brake driving, less rotating mass to slow down and speed up means the SB can stop and go faster as well as corner better*.

Yeah the BB makes more power earlier in the RPM range, but the SB revs faster than the BB (and typically revs higher than the BB). Hypothetically, if one were to stomp it at say 3000 RPM in some gear, if it takes the BB 2 seconds to get to ~5000 RPM, then those 2 seconds will put the SB at ~6000 RPM ( again hypothetical). In other words, both would be at or near their respective peak horse power levels in the same amount of time.

*That can be debated later, but real road course men prefer SBs

[blykins]

Originally Posted by AL427SBF

...but the SB revs faster than the BB (and typically revs higher than the BB)

We may want to start a new thread to get away from taking over this guy's thread.

However, this statement is again a generality that's not true at all.

[jhv48]

Alright you guys, leave Brent alone.

He has engines that need building!

[hercf16]

Originally Posted by blykins

We may want to start a new thread to get away from taking over this guy's thread.

However, this statement is again a generality that's not true at all.

No problem, good discussion on the differences and issues. I am a little color limited in my search; black, black with stripe, silver with stripe, darker blue
With stripe in that order. A few are starting to pop up with different engines
So the more info the better.

Should have bought Sharpatas? Black with champaign stripes and 638 hp
Keith Craft stroker a few years back, brand new in the low 60s

Herc

[Dimis]

Originally Posted by hercf16

No problem, good discussion on the differences and issues. I am a little color limited in my search; black, black with stripe, silver with stripe, darker blue
With stripe in that order. A few are starting to pop up with different engines
So the more info the better.

Should have bought Sharpatas? Black with champaign stripes and 638 hp
Keith Craft stroker a few years back, brand new in the low 60s

Herc

Herc,

A couple of things.

1. A New paint job isn't that expensive. Body work is mostly done so labour costs aren't as high as they otherwise could be. Perhaps broaden your search with his in mind.

2. SPFs are great, and while you can put anything in them, making for a great cobra. They do recommend going SBF.

3. ERA arguably the gold standard in fibre glass cobras. So if you were set on an FE, then perhaps investigate this option also.

4. If you are having an custom engine built and wanted a boutique, non-cookie-cutter engine, you'd be hard pressed to go past Brent (George Anderson, Barry R, others can add to this list).

5. If buying an FE built by KC, You'd be wise to double check the build isn't using an eagle crank, they are offered as standard equipment in KC builds (see their website). There's documented history of them failing.


I hope that helps. Enjoy your hunt.
It's all part of the fun.

[hercf16]

Originally Posted by Dimis

Herc,

A couple of things.

1. A New paint job isn't that expensive. Body work is mostly done so labour costs aren't as high as they otherwise could be. Perhaps broaden your search with his in mind.

2. SPFs are great, and while you can put anything in them, making for a great cobra. They do recommend going SBF.

3. ERA arguably the gold standard in fibre glass cobras. So if you were set on an FE, then perhaps investigate this option also.

4. If you are having an custom engine built and wanted a boutique, non-cookie-cutter engine, you'd be hard pressed to go past Brent (George Anderson, Barry R, others can add to this list).

5. If buying an FE built by KC, You'd be wise to double check the build isn't using an eagle crank, they are offered as standard equipment in KC builds (see their website). There's documented history of them failing.


I hope that helps. Enjoy your hunt.
It's all part of the fun.

Thanks for the input. I have been looking at Superformance for years, I like
factory built roller idea and components but one of the biggest reasons is the
leg room in a Superformance compared to the others.

Herc

[CobraEd]

Originally Posted by AL427SBF

Might as well jump into the fray, and generalities do apply because on balance they apply to most engines.

It takes more energy to spin up a BB's rotating mass versus SB rotating mass because the SB has less mass to spin up, basic physics. That energy comes from your motor and is stored as kinetic energy in the rotating assembly.

The BB guys do better at the 1/4 mile because they can rev it up, dump the clutch - and use all that kinetic energy stored in the rotating assembly for a good launch and let the BB HP do the rest.

The SB guys do better on road courses because it's accelerate & brake driving, less rotating mass to slow down and speed up means the SB can stop and go faster as well as corner better*.

Yeah the BB makes more power earlier in the RPM range, but the SB revs faster than the BB (and typically revs higher than the BB). Hypothetically, if one were to stomp it at say 3000 RPM in some gear, if it takes the BB 2 seconds to get to ~5000 RPM, then those 2 seconds will put the SB at ~6000 RPM ( again hypothetical). In other words, both would be at or near their respective peak horse power levels in the same amount of time.

*That can be debated later, but real road course men prefer SBs

AL427SBF gets it. It is not about how high an engine can rev, it is about how fast an engine can rev. And of course you can build a 385 series that can rev faster than a SBF, but the statement assumes all things being roughly equal. Apples to apples. Dynos only show torque and HP (a derivitive of torque) They cannot and do not show how quickly an engine can rev. This is not about selecting parts and assembling engines. It is about internal combustion physics. AL427SBF gets it 100% completely. He is correct.


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