[Shotimes] (OT) Marauder

[Ron Nottingham]

The way you keep describing it (one cam lobe per valve), sure, it is almost
impossible to achieve.  You would go from 16 pushrods to 32, and from 16
rocker arms to 32, it would get VERY crowded very fast.  And you are right,
David, it wouldn't be a good arrangement (I never said that way would work).

Obviously, you have never subscribed to the KISS philosophy, because the
Y-rocker setup does work, has worked, and could work in the future.  It is
easier and more simple to implement than having all those lobes and rods and
rockers.  Sure, the valves would need to be lighter to be able to utilize
lighter load springs, but things are already going that way.  Smaller bores,
and using more slender rockers aren't a problem either, just look at some of
Honda's SOHC VTEC engines.  But also, as engines get smaller, they lose
torque, and I thought that was main reason to keep larger engines?  Untill
everyone is driving cars/trucks/suvs that are small enough, we will still
have large engines.

Still, the point is moot, as electrical valve opperation is the next logical
step...  Just as soon as a dual 14-volt/42-volt electrical system in cars
becomes practical.  Which looks to be at least 10 years away.

Ron N. - Dalton, GA
90 SHO

----- Original Message -----
From: "David P" <jpotter8@bellsouth.net>
To: <BJamesjr@aol.com>; <shotimes@autox.team.net>
Sent: Wednesday, November 06, 2002 7:31 AM
Subject: Re: [Shotimes] (OT) Marauder


> Not three cams profiles per cylinder. Three profiles per cylinder spacing.
The
> cylinders banks are offset from each other, so, looking at the total
length
> dedicated to one cylinder, you have to profile 1.5 cylinders (1 cylinder
plus
> 1/2 the cylinder from the opposite bank).
>
> I was wrong, though, as I was only thinking about the cylinders at the end
of
> the block. This would only work on a V3! (or less) You actually will have
four
> different profiles per cylinder spacing on a single-cam OHV setup (intake
and
> exhaust of the cylinder that falls in the measured length, and the intake
of
> one cylinder and exhaust of another cylinder on the opposite bank). You
can
> v-rocker the intake and exhaust to provide only four cams instead of
eight.
> Not a problem with large cylinder bore, but as motors get smaller, the cam
> lobe width has to decrease and the available length on the cam decreases.
A
> decrease in the width of the cam lobe requires a reduction in the spring
rate
> of the valve, which requires a lightening of the valve, or durability of
the
> cam lobe becomes an issue. There a definite alternatives like titanium and
> beryllium alloys, but cost can rise considerably. I am thinking they need
to
> find a way to coat carbon fibre with stainless  ; )
>
> The drawbacks of a little extra valvetrain mass is higher power
consumption
> and reduced rpm limit (unless money is no hindrance).
>
>
> David P
>
> 95MTX
>
>
>
> ~
> ----- Original Message -----
> From: <BJamesjr@aol.com>
> To: <shotimes@autox.team.net>
> Sent: Monday, November 04, 2002 17:34
> Subject: Re: [Shotimes] (OT) Marauder
>
>
> > > A 4V OHV motor has to operate three separate cam
> > > profiles per cylinder spacing vs SOHC operating only two.
> > > The cam gets a bit more crowded.
> >
> > 3 cam profiles per cylinder?  On the surface you would think 2 valves- 2
cam
> lobes, 4 valves- 4 cam lobes.  However since OHV engines use rocker arms I
> would think a Y-shaped rocker arm could easily operate 2 valves with one
> pushrod.  An enterprising person could have built a 4-valve head for a V8
> chevy long ago (may have even been done for all I know).  The only
drawback
> would be a little more valvetrain mass, but this would be counteracted by
2
> springs per cylinder instead of 1.
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