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Old 03-26-2005, 11:02   #1 (permalink)
CobraJet
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Stock Cobra Jet Dyno Figs

Here's a dyno chart by one of the guys in the FE forum. This is the
closest to stock 428 CJ engine I've seen tested so far. The compression
is down half a point over original, which may be losing 10 or 12
horsepower. The Lunati 10503 is their replacement CJ grind.

http://www.network54.com/Forum/messa...geid=111175957
0

You can see where Ford's figure of 440 lbs at 3400 rpm was pretty
much on the money. It has long been said that the 335 hp was
underrated, and here's the skinny. The 335 was quoted at 5600 rpm. We
see here that the hp peak is actually earlier, at around 5100, in the
375 range. After that it drops, and in this case it looks like it might
be at 335 in the 5600-5700 range. So did Ford lie? Not really.

The NHRA factored this engine somewhere between 390 and 400
horsepower for legal competition. I've seen both figures; not sure
which one is accurate. But if you add back the compression loss on this
test engine, you are once again in the ball park.

What's interesting here is that the stock manifolds are not giving
up much of anything against the small-tube Hooker headers. That's a
good testament despite their compromised design.

If you check out the entire thread you will see more dyno info on
more serious engines. See that this forum regular Jay Brown is running
a 1030-horse supercharged FE in his Shelby. Kinda makes all those
huffed smal blocks look a little weak.

CobraJet

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Old 03-26-2005, 13:01   #2 (permalink)
Wound Up
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Re: Stock Cobra Jet Dyno Figs

CobraJet wrote:
> Here's a dyno chart by one of the guys in the FE forum. This is the
> closest to stock 428 CJ engine I've seen tested so far. The compression
> is down half a point over original, which may be losing 10 or 12
> horsepower. The Lunati 10503 is their replacement CJ grind.
>
> http://www.network54.com/Forum/messa...geid=111175957
> 0
>
> You can see where Ford's figure of 440 lbs at 3400 rpm was pretty
> much on the money. It has long been said that the 335 hp was
> underrated, and here's the skinny. The 335 was quoted at 5600 rpm. We
> see here that the hp peak is actually earlier, at around 5100, in the
> 375 range. After that it drops, and in this case it looks like it might
> be at 335 in the 5600-5700 range. So did Ford lie? Not really.
>
> The NHRA factored this engine somewhere between 390 and 400
> horsepower for legal competition. I've seen both figures; not sure
> which one is accurate. But if you add back the compression loss on this
> test engine, you are once again in the ball park.
>
> What's interesting here is that the stock manifolds are not giving
> up much of anything against the small-tube Hooker headers. That's a
> good testament despite their compromised design.
>
> If you check out the entire thread you will see more dyno info on
> more serious engines. See that this forum regular Jay Brown is running
> a 1030-horse supercharged FE in his Shelby. Kinda makes all those
> huffed smal blocks look a little weak.
>
> CobraJet


Interesting stuff, especially about the exhaust manifolds. This is a
topic of endless debate, but I have heard some say no gains (and some
losses due to underhood temp., even) are to be found with some BB
manifolds, assuming stock cam and induction. It makes me wonder why
some of them choked engines so badly, and some didn't. Yanking stock
manifolds has been such an automatic mod for so long...

I've poked around a bit, and it seems like there some real hardcore
types over there. I'd say a blown 1000 hp FE would make most anything
look weak.

One thing I've noticed, at least using Netscape, is that the URLs
provided have been cut off the last zero. Dunno why; it appears on a
separate line, just so ya know...

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Old 03-26-2005, 14:01   #3 (permalink)
CobraJet
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Re: Stock Cobra Jet Dyno Figs

In article <4245C013.8030505@your.disposal>, Wound Up <none@your.disposal> wrote:

> CobraJet wrote:
> > Here's a dyno chart by one of the guys in the FE forum. This is the
> > closest to stock 428 CJ engine I've seen tested so far. The compression
> > is down half a point over original, which may be losing 10 or 12
> > horsepower. The Lunati 10503 is their replacement CJ grind.
> >
> > http://www.network54.com/Forum/messa...geid=111175957
> > 0
> >
> > You can see where Ford's figure of 440 lbs at 3400 rpm was pretty
> > much on the money. It has long been said that the 335 hp was
> > underrated, and here's the skinny. The 335 was quoted at 5600 rpm. We
> > see here that the hp peak is actually earlier, at around 5100, in the
> > 375 range. After that it drops, and in this case it looks like it might
> > be at 335 in the 5600-5700 range. So did Ford lie? Not really.
> >
> > The NHRA factored this engine somewhere between 390 and 400
> > horsepower for legal competition. I've seen both figures; not sure
> > which one is accurate. But if you add back the compression loss on this
> > test engine, you are once again in the ball park.
> >
> > What's interesting here is that the stock manifolds are not giving
> > up much of anything against the small-tube Hooker headers. That's a
> > good testament despite their compromised design.
> >
> > If you check out the entire thread you will see more dyno info on
> > more serious engines. See that this forum regular Jay Brown is running
> > a 1030-horse supercharged FE in his Shelby. Kinda makes all those
> > huffed smal blocks look a little weak.
> >
> > CobraJet

>
> Interesting stuff, especially about the exhaust manifolds. This is a
> topic of endless debate, but I have heard some say no gains (and some
> losses due to underhood temp., even) are to be found with some BB
> manifolds, assuming stock cam and induction. It makes me wonder why
> some of them choked engines so badly, and some didn't. Yanking stock
> manifolds has been such an automatic mod for so long...


There are a lot of restrictive manifolds, and some that aren't as bad. There was another
thread that showed how the angled exits in the FE exhaust ports caused turbulence in some
of the manifold designs. Basically, the "ideal" layout for the FE would be the small block Chevy
ram's horn. Although nobody actually said that, that's what the situation amounts to. Sanderson
might make such a manifold; been while since I looked.

>
> I've poked around a bit, and it seems like there some real hardcore
> types over there. I'd say a blown 1000 hp FE would make most anything
> look weak.
>
> One thing I've noticed, at least using Netscape, is that the URLs
> provided have been cut off the last zero. Dunno why; it appears on a
> separate line, just so ya know...


It's the word wrap feature of this program. It's very inconsistent, if you look at the line lengths of
my posts. It happens to be one space short on a lot of URL's, worse on others. In this post I turned off
the word wrap and you can see that I can keep going on line length until I manually shift down. It's a real pain
to type this way. Oh well.

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