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Message
With stock ports and
pulling off power to limit boost. I
think your only problem is the waste gate
size. Or flow, but that is the
Idea.
I certainly agree about the wastegate problem,
and I'm skeptical that porting it will help enough.
The cowl shape, or lack of a cowl is not
going to make much
difference in the climb at 100 KTS.
Thanks for the confirmation of this, and to
others who made it as well. It would seem that the cowl just can't be the
whole problem.
Taking out pitch, and then
limiting RPM, limits excess HP
required for climb. More typical would be
enough pitch to stall the prop on a
hot day and have to back off the power slightly
to unstall it until some
ground speed has built up.
I've been adjusting the throttle for 30
inches of MAP, rather than for a particular RPM, so the RPM has in fact gone up
with reducing pitch. Another reason to suspect that I'm not putting
out the proper amount of power is the pitch. Warp estimated that I would
need an 18 degree pitch setting, which is what I started out with. Static
RPM wasn't constant at 18 or even as low as 15 degrees, and I found out that the
prop was indeed stalled to some extent at those pitch settings. My first
climb RPM's were very low, 4700 with full throttle, 15 degrees of pitch, and 36
inches MAP. Reducing the pitch to 12 degrees, gave me 6300 RPM at full
throttle, 36 inches MAP. This is way below the pitch that Warp estimated,
and I'm betting that they wouldn't be off that much. It would seem to
indicate that I'm not making the power I should be.
Once you can lay into it at
WOT all the way up to 6,500, you
should see at least 160HP performance or more.
In my current
configuration, I have to limit the throttle opening to about half throttle, to
maintain 30 inches MAP. All along, I've been assuming that this give me
the same power as a NA engine using full throttle. I know there are some
losses with the higher temp of the intake, but I wouldn't expect them to add up
to that much.
Here's my question- Is my above
assumption correct? I've tried to follow some intake flow discussions in
the past on the RX-7 forum, where they were stating that pressure isn't
everything. The idea (as I think I understood it) was that
having good pressure registering on a gauge didn't guarantee anything,
since the gauge isn't fast enough to show you what's really happening.
They said that if the pipe was restrictive, or there was some other
obstacle to flow (throttle butterflies half closed), you wouldn't get the power
you should, because the pressure would drop instantaneously when the ports
opened. When that happens, I guess the engine doesn't get the charge that
it would appear to be getting from the gauge. Is this more or less what
you're getting at when you say I need to be a WOT to get good
power?
Thanks for all the
thoughts.
Rusty (still
baffled)
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