[DeTomaso] stroker kit????

[GOW2]

There are several instances in an airplane; both piston airplane and turbine
where a prop has cracked loosing a portion of the blade has caused enough
vibration to cause the engine to immediately vacate the airplane. I think
balance components really has to be important.

Gary


----- Original Message ----- 
From: "Mad Dog Antenucci" <teampantera at yahoo.com>
To: "Daniel C Jones" <daniel.c.jones2 at gmail.com>; <detomaso at realbig.com>
Sent: Thursday, March 02, 2006 12:33 PM
Subject: Re: [DeTomaso] stroker kit????


> As usual, excellent points Dr. Dan....I'm not pointing any fingers at
anyone except maybe myself on those 3, 393's that didn't work for me....
>
>   Your right, engine failure #1 was a snapped cam shaft!  Engine #2 was a
lifter...and the same builder built all 3 strokers. I'll leave it at that
except to say none of those motors were ever raced at more then 5500-6000
RPM and as you and Gary point out that may be the weak link....running above
5500........then again russ Fulps tells me he doesn't generally have any
problems with the 393-400+ strokers he builds for racing and/or street.
>
>   MD
>
>
> Daniel C Jones <daniel.c.jones2 at gmail.com> wrote:
>   > My experience with the three 393 Cleveland Strokers was not good. They
all
> > felt from day one like they were going to grenade....Allot more
vibration
>
> Mad Dog, can any of those failures be attributed to the increased stroke?
> As I recall, these engines were built by a different engine builder and
> the one that had the block I sent you was blamed on a broken camshaft.
> If you felt vibration, there was something wrong from the get go which
> I doubt can be blamed on the 3.85" stroke. I've driven a 4.1" stroke 418
> that was nice and smooth and made 556 HP on the dyno under 6000 RPM.
> The piston speed at 6000 RPM of that engine may be the same as a 3.7"
stroke
> engine at 6600 RPM so the stress on the rods is similar but the rest of
the
> parts (valvetrain in particular) benefit from the reduced RPM.
>
> Rod stress increases in proportion to stroke and by the square of rpm.
> While we often speak of RPM, it's really the piston speed that counts.
> Increasing stroke means increased piston speed at the same RPM so, all
> other things considered, the maximum RPM the short block can sustain will
> be decreased. A stroker offsets this since you can make power at a lower
> RPM level which has benefits when it comes to valve train life.
> Short rods increase acceleration near top dead center which is a little
> harder on the rods but helps flow in large port cylinder heads. Longer
> rods are easier on cylinder walls but the trade-off is in pin location
> and ring pack. Gas loads dominate at low rpm, inertia loads at high rpm.
> Excessively high piston speed will exceed the mechanical limitations of
the
> materials. Excessive side loading will create increased friction on the
> bore and the pin/rod and rod pin on the crank. The load on the crank is
> a function of the RPM, the weight of the rods and pistons, the stroke, and
> the balancing/counterweighting. Reducing RPM, reducing stroke, reducing
> piston and rod weight will all help, as will a stronger crank.
>
> Longevity is dictated by the power the engine makes, the strength
> of the components, piston speed (a function of RPM and stroke), rod
> to stroke ratio (side wall loading) and rin pack (narrow ring packs
> don't seal as well, tend to rock at TDC) and the RPM you turn, not to
> mention tuning factors (pinging, additional thermal loads due to running
> lean, etc.).
>
> > If I don't expect to rev 7500 rpm.. and seldom see 5500 rpm.. then I can
> > go with the 393 and make sure of my 4V heads and ITB? :)
>
> Yes. For lower RPM like that, I'd jump to a 4" stroke for 400+ cubes.
>
> > What type of parts should I be looking for and would it basically fit
the
> > 351C without much modification? I just don't want to run into unexpected
> > issue where the machine shop has to do a bunch of other things to make
it
> > all work out...
>
> You gotta do your homework. A number of small issues, no major shopw
stoppers.
> Most of the inexpensive aftermarket cranks are not true Cleveland
dimension
> cranks, rather they are listed as "Cleveland style" because they use the
351C
> main diameter ut in most other regards are Windsor. They are cranks
originally
> designed to go in Ford Motorsport hybrid blocks (or other race block)
which
> combine the 2.75" Cleveland mains with a Windsor architecture. The
Cleveland
> snout is longer than the Windsor one. Most aftermarket "Cleveland style"
> cranks use the Windsor snout. Cleveland cranks have a "snout ring" ahead
of
> the #1 main, to space the lower sprocket out to clear the journal.
Windsors
> have a collar on the back of the sprocket and are machined flat ahead of
the
> journal. When using a "Cleveland style" crank in a 351C iron block, a Ford
> Motorsport spacer (part number M-19009-A341C, required with 351 SVO
crankshaft
> when used in production iron 351C engine), will fix the problem. The
spacer
> is not a press-fit and you can push it on by hand. There are true
Cleveland
> spec aftermarket cranks but they tend to be custom order. Also, RDI stocks
a
> hybrid 351W/351C timing set from Dynatech to match the Windsor crank snout
in
> a Cleveland block. Some have reported balancer fit issues but Dave
Williams
> said my Romac balancer fit snugly on my SCAT 4340 crank as did the FRPP
> balancer on a friend's stroker.
>
> The Cleveland #3 (thrust) main is narrower by approximately 0.009" (as
> measured by Jim Sams). Most aftermarket cranks with 2.75" diameter mains
> use the narrower Cleveland thrust width which allows the use of Cleveland
> main bearings but ask before ordering. The main bearing spacer kit that
> allows 351W blocks to use 2.75" diameter cranks uses the 351W thrust width
> which requires a special thrust bearing (available from Ford Motorsport).
> The cast iron 2.75" diameter main Ford Motorsport Sportsman cranks have
the
> 351W thrust width to match the spacer kit. The 4000 series SCAT "Cleveland
> Style" cranks have the Windsor snout but have 2.75" diameter mains and
take
> 351C bearing, including the thrust bearing.
>
> Most aftermarket cranks use small block Chevy 2.1" diameter rod journals
and
> 0.940" width rods. However, Ford Sportsman and certain 3.85" SCAT and
Eagle
> cranks are set up for 2.311" diameter 351W rods.
>
> SCAT offers their cranks in versions to use with 6.000, 6.125, and 6.200
> inch long rods, the difference being in the OD of the counterweights.
> My engine builder wanted to external balance to 28.2 oz-in and suggested
> ordering the 6.2" version, even though we are using 6.0" rods. That way
> he wouldn't need to use any expensive Mallory metal for balancing (could
> grind down the counterweights as needed). The tech at SCAT (Brian)
> insisted this was a mistake. He said that the 6.0" version would likely
> need to be lightened. Furthermore, he said the counterweights are cam
> profiled on a CNC machine and that turning them down on a lathe would ruin
> the balance and not have the desired effect. Dave mentioned he had to
spend
> a lot of time lightening the crank throws to get the crank into balance.
>
> Canted valve Cleveland heads require uniquely positioned valve notches
> at the edges of the pistons. The limiting factor for Cleveland stroker
> pistons is often the valve notch in the block and pistons. Cleveland
> blocks are usually notched at the tops of their bores for valve
> clearance/shrouding which can place a limit on the top ring placement
> (needs to be below the valve notch at TDC plus rod stretch). The depth of
> the notch varies from block to block but on my Aussie XE block, it was
about
> 0.27" down from the deck. If running quench heads on pump gas, you'll
> probably want a dished piston for anything over 3.7" stroke. If so, don't
> use a circular dish. A d-dish is better and a mirror image of the
combustion
> chamber is better yet. Wiseco will do a mirror dish if you send them an
> image. You need a flat pad on the piston where the quench pad is on the
> head to maximize the quench effect.
>
> > If I believe correctly.. a stroker basically has a longer stroke and
that's
> > via a modified or different crank that's larger in diameter... mm longer
> > rod?...
>
> Stroker math is simple :
>
> rod length + crank stroke/2 + piston pin height = deck height
>
> Of course, you can rearrange the equation anyway you want to solve for a
> particular variable. The deck height of the block is fixed so you have to
> juggle the other parameters to keep the same stack height. You could
shorten
> the rod but it's best to increase the rod length with increasing stroke to
> preserve the rod to stroke ratio. A good rule of thumb from Jon Kaaase is
> to keep the rods 2"+ longer than the stroke. What is usually done is to
move
> the pin up on the piston to offset the stroke and rod length increases. An
> example of a 4" stroke, 6" rod, and 4.030" bore for 408 cubes in a 9.2"
> deck height Cleveland block. Assuming zero deck, the stack up works out to
> be:
>
> piston pin height = deck height - (rod length + crank stroke/2)
> = 9.2 - (6.0 + 4.0/2)
> = 1.2 inches
>
> 331 and 347 cubic inch strokers are popular for 5.0L Ford V8's these days.
> 5.0L V8's have a deck height of 8.2", so plugging the pertinent values
into
> the formula yields:
>
> deck height - (rod length + stroke/2) = pin height
> 8.2 - (5.4 + 3.4/2 ) = 1.100 inches
> 8.2 - (5.4 + 3.25/2 ) = 1.175 inches
>
> so you can see the 1.2" pin height of a 408C stroker is better than the
> popular 5.0L stroker kits.
>
> Rod to stroke ratio for the 408C is:
> = 6.0/4.0
> = 1.5
>
> A r/s of 1.5 is on the low end of production Detroit V8's (slightly less
> than a Chevy 454 but slightly more than a Chevy 400), so should be fine
for
> a hot rod motor.
>
> > Would i need a custom piston or a normal forged 351C piston would be
fine?
>
> Custom pistons will be required due to the pin location.
>
> > And then of course i'll need new main and cam bearings... piston
rings...
> > etc for my typical engine rebuild right? :)
>
> Yes. You have the freedom to specify the ring widths and style with your
> custom pistons. The block or crank may need clearancing to fit a stroked
> reciprocating assembly and you have to verify the cam's not in the way as
the
> rods swing around. The 351C bottom end is roomier than a SBC so these are
> not generally big problems.
>
> Dan Jones
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