"Bernd D. Ratsch" wrote:
> Nothing much HP wise (even with the 1.7:1)...but added safety if you happen
> to "Over-Rev" the engine. MPG wise, I saw no change with the roller
> rockers.
Say what? Surely you jest. 1.7 to 1 rockers -vs- 1.6 to 1 don't add much HP?
Bone stock maybe not that much but for an engine that has been modded to intake
more air (upgraded air filter/inlet & throttle body) and exhaust more gases
(headers, high-flo cat, cat-back exhaust) I'd say it makes a nice difference in
HP. It would be like a camshaft with the same duration but with higher lift
because it has the EXACT same effect - raises the valve slightly higher on every
stroke to allow more breathing capability.
As far as added safety if you happen to "Over-Rev" the engine - hardly.
Aluminum ones might absorb some valvetrain harmonics over the stock stamped
steel ones and possibly keep the valvetrain geometry slightly more accurate but
there are more serious things to consider. I quote the following from Mopar
Muscle - July 1997 issue - article titled: "Inductive Reasoning"
"The other concern centers around the lifters. They're real heavy and overcome
the strength of
the lifter bore casting at high RPM. Spinning a Magnum to 5400 RPM is
borderline, 5800 RPM too
much, and above 6000 RPM can be the kiss of death. What happens is the heavy
lifters crack the
casting, start to wobble and the valve train self-destructs. When the valve
train starts to go
bonkers, you'll notice an upper RPM vibration, almost like the engine is out of
balance. Either
limit your shift points, buy a Fluidampr, or pray somebody develops a
lightweight lifter for the
Magnum."
No known upgrade will help this problem. This is also the reason lots of people
have to re-bore
and sleeve the lifter bores (costly). Very common on Mopar small-blocks due to
this design
flaw. If you have ever seen a bare shortblock (any year smallblock will do) -
it isn't hard to
see where the weakest part of the whole block is - the lifter galleys. Compare
them with the
race version block from MP - almost all the difference is there.
If you are going to put technical info out here for 700+ members to read - you
might want to check the accuracy of your statements first.
Latr,
Shane
-- '96 IndyRam-HisIndy-MPI/TB/Pulleys/Coil/Wires/CompTAs '96 IndyRam-HerIndy-numbered(#142)"Track Truck" '74 Triple-Black Dodge Challenger Rallye 360 home-brew EFI R&D vehicle '68 Black Corvette Convertible 427 (For Sale)
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