The other day I meantioned DRD's "OEM 043" cylinder heads. Since then,
I've stumbled across what they call the "L3" head, which appears to have
more suitable seat material ("high-chrome"), stainless valves, 4130
retainers, and a much larger chamber volume without a "step". This
means it's far easier to set up a tight quench volume (to facilitate
auto-fuel) and reasonable (low) compression ratio. I asked about the
valves and was told "they're high quality", but got no further details.
I've ordered a set of Manley exhaust valves just to be sure. I no
longer take chances with exhaust valves! It's amazing how folks sell
things that they don't know the details of, such as valve and seat
material. It's, uhh, important.
I'm not necessarily recommending these, just pointing out that they
appear to be a better choice than the OEM 043 heads, and are only
slightly more expensive ($499/pair). I have no idea if these have the
same large cooling passages as the 043 heads, however. My guess is that
they are different castings entirely, given the large chamber volume, so
they may be more limited in the air passage department. I really don't
know. See
http://www.drdracingheads.com/xcart/DRD-Stocker-plus-35.5X32mm.html
With Jeff Lang's experience on the Revmaster 049, that looks pretty good
too. Others are welcome to post their real world experience, with
details like CHT, OAT, fuel type, head type, compression ratio, etc, so
others can make informed decisions, rather than depend on marketing.
I will have another set of data points in a few weeks, just in time to
fly to OSH...
Mark Langford
ML at N56ML.com
http://www.n56ml.com
