[DeTomaso] Question about modifying ZF gearing for high performanceengine.

Julian Kift julian_kift at hotmail.com
Sat Mar 13 00:56:32 EST 2010


A lot depends how you are going to get the HP you are talking about. If it's through stroking then rpm is dictated by piston speed. A 6800 rpm stock 3.5" stroke is just under 4,000 ft/min piston speed. To maintain that your are down to 6,000 rpm for a 408 stroker. Same reason a Ford 302 with same 4.00" bore, but 3" stroke is such a revving little motor. IMO the higher the piston speed you want to attain the more $$ exponentially you have to throw into the build and on a Cleveland you have to be really careful in block selection for adequate cylinder wall thickness.

 

Julian

 

 
> Date: Fri, 12 Mar 2010 22:48:41 -0500
> From: boyd411 at gmail.com
> To: teampantera at yahoo.com
> CC: detomaso at realbig.com
> Subject: Re: [DeTomaso] Question about modifying ZF gearing for high performanceengine.
> 
> Dawg,
> I only mention 6800 rpm because thats the RPM thats quoted when the original
> Pantera top end is mentioned. 168 mph in 5th gear at 6800 rpm. I would
> rather count on more horsepower and torque at lower rpm then increase the
> chances of throwing a rod by over reving the motor for long hauls at top
> speed (like your runs at the silver state).
> Boyd
> 
> On Fri, Mar 12, 2010 at 10:10 PM, Mad Dog Antenucci
> <teampantera at yahoo.com>wrote:
> 
> > I have to agree except I'd do the taller 5th.
> >
> >
> > Mad Dawg Antenucci
> > Team Pantera Racing
> > The 1st & still the only vintage race team in open road racing
> > www.teampanteraracing.com
> >
> >
> >
> >
> > ________________________________
> > From: Will Demelo <wdemelo at cogeco.ca>
> > To: detomaso at realbig.com
> > Sent: Fri, March 12, 2010 1:44:04 PM
> > Subject: Re: [DeTomaso] Question about modifying ZF gearing for high
> > performanceengine.
> >
> > I have the 3:77 R&P and taller 5th gear. I wouldn't do both again. I would
> > be happy with the 3:77s alone as the revs in 5th are a tad low at highway
> > cruising speed. I absolutely love the taller gearing on the street running
> > through the gears.
> > Will
> >
> > --------------------------------------------------
> > From: "boyd casey" <boyd411 at gmail.com>
> > Sent: Friday, March 12, 2010 4:25 PM
> > To: "De Tomaso List" <detomaso at realbig.com>
> > Subject: [DeTomaso] Question about modifying ZF gearing for high
> > performanceengine.
> >
> > > I was wondering when one repowers their Pantera with an engine that
> > > generates allot more Tourque and Horsepower as well as possibly higher
> > > revs
> > > and you goal is higher top speed as well as faster acceleration do people
> > > usually only change the pinion gear to change the final gear ratio or do
> > > they also change the gears1st thru 5 or just one or some of them? From
> > > looking at the calculator on the RBT transmission web sight, it seems
> > like
> > > you can accomplish the end result of raising your top speed available
> > with
> > > the higher horsepower of of a more powerfull engine. To get the optimum
> > > gearing at every gear you could change the gears and the pinion gear but
> > > the
> > > cost would be very substanntial.The gear sets for 2nd, 3rd, 4th, and 5th
> > > are $1068.75 apiece. That's $4275.00 for 2nd thru 5th ( plus labor) The
> > > ring
> > > and pinion set is $2801.25 (plus labor) Thats $7076.25 just for parts to
> > > change the gears and ring and pinion set. So my question is what have
> > > other
> > > people done when they made engine mods that produced large horsepower
> > > increases and possibly increased revs acheive the desiredgearing to
> > > provide
> > > the right gear ratios to provide both reasonable accelleration as well as
> > > top speed. (above the 168 mph limatation of the stock set up at 6800
> > rpm).
> > >
> > > Boyd
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