[DeTomaso] Ford 392 rev limit?

michael@michaelshortt.com michaelsavga at gmail.com
Fri Sep 6 14:49:51 EDT 2013


Boom!
Please get off the racing line.

Michael Shortt
On Sep 6, 2013 2:17 PM, "Boyd Casey" <boyd411 at gmail.com> wrote:

> Once again the laws of physics make the call . Newtons second law;
> Momentum = mass X velocity.
> So the momentum of the piston will be effected by it's mass X it's
> velocity, so a piston assembly of greater mass will be more inclined to
> continue traveling in the same direction the greater it's velocity. So the
> key in designing the Piston and connecting rod assembly capable of
> withstanding the greatest RPM (piston speed) is to make them from the
>  strongest *yet* *lightest (lowest mass) * material available.  It also
> calls to mind the adage that "a chain is only as strong as it's weakest
> link. So as an example if you attempted to build a Cleveland engine using
> the best possible (strongest) crank, the best main bearings the strongest
> lightest valve train , strongest everything possible but you built it on a
> Cleveland block with a two bolt main your still going to self destruct at
> an RPM that an engine with a four bolt main would be able to withstand. An
> engine or any machine for that matter is equal to the sum of it's parts.
> You can't just throw in a forged crank and H rods and ignore everything
> else. An engine  is like the best detective in the world, push it past it's
> limits and it will find it's weakest point just like Sherlock Holmes always
> finds the culprit.. Piston speed is just a guide line that gives an idea of
> what level of build you are going to need if you have expectations of
> exceeding a given piston speed (RPM). Also if you have an engine that
> develops it's peak torque and horsepower at a given RPM range there is not
> allot of point in exceeding it by very much ( as Dan Jones Pointed out)
> because you won't go any faster. (By the way Dan Jones is an engineer and
> is the most knowledgeable person that I am aware of when it comes to
> Cleveland and Windsor builds). I have spoken about the Laws of Physics now
> I am going to quote the laws (or more precisely the "Rules" of Mad Dawg  )
> ( who I believe has been the most successful at campaigning Cleveland
> Powered Panteras in the Silver state and other ORR events)
> They are Rule #1 Dan Jones is always right, Rule #2 See Rule # 1. :>)
> I think like an under built engine we have over revved this subject line
> and it's ready to throw a rod!
> LOL!
> Boyd
>
>
> On Fri, Sep 6, 2013 at 12:25 PM, Doug Scott <doug at pickbbs.com> wrote:
>
>> When you jump out of a plane, there is nothing said about how fast you
>> are going, they only talk about how well you stick the landing.  The reason
>> I brought this up was simply to make sure all, that are reading this,
>> understand the actual issue with piston speed.  Not everyone has a good
>> understanding of the benefit and detriment of a longer stroke.****
>>
>> ** **
>>
>> Generally, the stronger parts are forged, but, the forged parts are
>> heavier as well.  So they put forged pistons and connecting rods in to help
>> keep the engine together, and in doing so, they add more weight that makes
>> the effect of piston speed more dramatic.  ****
>>
>> ** **
>>
>> *doug*
>>
>> ** **
>>
>> *From:* Boyd Casey [mailto:boyd411 at gmail.com]
>> *Sent:* Friday, September 6, 2013 11:32 AM
>> *To:* Melanie Disco
>> *Cc:* Doug Scott; mike Drew; detomaso at poca.com; Pantdino; Jeff Cobb
>>
>> *Subject:* Re: [DeTomaso] Ford 392 rev limit?****
>>
>> ** **
>>
>> Saying piston speed is not the issue is like saying jumping out of an
>> airplane is not what kills you , it's the sudden stop when you hit the
>> ground! The faster the piston is moving the more stress is induced when it
>> has to stop and change direction ****
>>
>> It's simple physics A body in motion tends to stay in motion  When a
>> piston hits the bottom of its power stroke and is traveling at 5000 fps it
>> wants to keep going, so if you have a weak crank, weak wrist pin  or weak
>> mains (to name just a few potential areas of stress it will keep going! You
>> can break criminal laws, you can break civil laws, but you can't break the
>> laws of Physics.****
>>
>> Boyd****
>>
>> ** **
>>
>> On Fri, Sep 6, 2013 at 11:07 AM, michael at michaelshortt.com <
>> michaelsavga at gmail.com> wrote:****
>>
>> I think because Buick had a 425 back then, Dodge had already made 426
>> famous, they (Ford) had 428 ...so 427 was left available. Marketing
>> probably made that decision is my guess.
>>
>> Michael Shortt****
>>
>> On Sep 6, 2013 11:02 AM, "Doug Scott" <doug at pickbbs.com> wrote:
>>
>> > Ford has known since the early 60s that short stroke, big bore is the
>> > recipe
>> > for race engines.  Take a look at the bore and stroke of the 427
>> compared
>> > to
>> > the 428.  Don't know why they call the 427 a 427 though, the
>> displacement
>> > is
>> > closer to a 425.
>> >
>> > doug
>> >
>> > -----Original Message-----
>> > From: detomaso-bounces at poca.com [mailto:detomaso-bounces at poca.com] On
>> > Behalf
>> > Of MikeLDrew at aol.com
>> > Sent: Friday, September 6, 2013 10:50 AM
>> > To: cengles at cox.net
>> > Cc: detomaso at poca.com; pantdino at aol.com; zumzum at cox.net
>> > Subject: Re: [DeTomaso] Ford 392 rev limit?
>> >
>> >
>> > In a message dated 9/6/13 6 44 23, cengles at cox.net writes:
>> >
>> >
>> > > FWIW: on the Speed Talk website Engine Forum, the professional
>> > > machinists and engine builders have commented that the factory crate
>> > > engines have been found to have, ahem, factory seconds used as parts.
>> > > It is perhaps not in all the engines, but it has happened often enough
>> > > that the pros have commented on it.
>> > >
>> >
>> > >>>They do make one hell of a spec sheet though:
>> >
>> >
>> http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=10757
>> >
>> > I don't know if the engine in Jeff's car is *this* 392 or if they sold a
>> > lower-spec version.   It appears Ford has gotten out of the 392 business
>> > and
>> >
>> > gone completely over to 427 Windsors now:
>> >
>> > http://www.fordracingparts.com/crateengine/main.asp#tfo
>> >
>> > I've heard enough bad things about Ford crate motors from people who
>> have
>> > had them, that I would never get one.   They are absolutely fine for
>> street
>> > rods and things like that, or even for a Pantera that will only be
>> driven
>> > on
>> > the street, but for a Pantera that would see track duty (abuse) as mine
>> > does, there's just too much likelihood that something would let go....
>> >
>> > Mike
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