Ed,
DIE at one single RPM is exactly what I want. The target RPM
would be what I get at something less than WOT at cruise altitude.
Perhaps if that was close to T/O RPM I would shoot for a "dual purpose" RPM,
but cruise is my objective. Takeoff should not be a major consideration
since if I can get anywhere near the cruise I want, I can take off (at
airports where I will operate) with room to spare.
If turbo rotor housings are ported symmetrically, how far off that would NA
housings be? Would "street porting" bring the path lengths (in the
block) closer together? If so, it might be possible to close the gap
between primary and secondary paths in the block so as to merge them
into a single runner and retain some DIE effect. Is it possible that DIE
might be enhanced if the closing of one port was a little later than the
closing of the other? Probably too much to ask. I guess I'll
understand a lot better when I get my engine torn down and get a look at the
porting.
It would be great to simplify the intake though ... Jim S.
Some good questions, Jim
Unfortunately I don't have definitive answers to
the questions. However, based on the DIE equations (and assuming they
are in the ball park), I would hazard an opinion that 13B NA 6 port engines
might be the one to use if you wanted an DIE effect at several different RPMs
- after all it already has three different port timings. Perhaps a turbo
block might be idea if only one RPM is wanted. However, there are any
number of options.
For instance if your primary and secondary are
ported the same that means they are in effect identical - timing wise.
So if your ports all have the same timing then the DIE effect for all
will happen at the (or at least very near) the same RPM point. I think
that would be easy on a turbo block but you would have to remove so much
metal to make the primary of a 13B NA port timing equal to the secondary+ Aux
ports that I don't even know if its doable. You would need to change the
primary on a 13B NA from IO 32 IC 40 to IC 32 IO 70 to get them at the same
timing. Probably doable, but you might harm the basic airflow by doing
so, in which case trying to get that DIE rpm would likely be
counterproductive.
So now you know more about the DIE effect, but,
that simple adds to the decisions/compromises you now have to
considered. Before, you knew about it - you didn't worry about it
{:>)
If I had the resources to hook 13Bs to dynos and
try out some of this it would be nice to further expand our knowledge and
answer such questions. However, that will have to wait until I win the
powerball lottery {:>) or someone who has such facitlites and equipment
might want to try such experiments.
Best Regards
Ed Anderson