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Ok, thanks for the information, John
Yes, the 1/2 inch hole may have
contributed to more mass flow which would push you (in my opinion) closer to the
high speed part of the turbo curves at that operating condition. I just
wish I knew how much mass flow we could get through a 1/2 hole at say 7.5 psi
boost. I am certain that somebody out there would figure that out. I
probably could, but I don't want to have all the fun {: )
Of course, this is all just
speculation - but, I think its at a minimum pointing toward a possible
cause. I certainly wouldn't give up on the stock turbo - I think the
modifications that Max has to offer will certainly help considerably. I
personally believe they will eliminate this problem. Hopefully, we will
find out soon.
Ed
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
----- Original Message -----
Sent: Saturday, July 10, 2004 11:21
AM
Subject: [FlyRotary] Re: Turbo
Overspeed???
> Pressure ratio boost creep.
Ed,
More fascinating reading.
Thanks.
You might also want consider the air bleed on my intercooler. I
thought I'd mentioned this, but your analysis makes it more relevant so I'll
mention it again. There is a 1/2 inch outlet on the intercooler which vents to
atmosphere. Before getting the BOV I tried blocking it, and found that the
boost "went off the scale", so I unblocked it again. It left it unblocked when
I got the BOV think this was a "safety" measure. Perhaps it was with respect
to the engine & detonation, but not so, I think, with respect to
overspeeding the turbo. By the way I was at 11,500 doing 5200rpm when
the turbine wheel let go.
Oh, and for anyone thinking that this turbo stuff is
way too much complexity and trouble, let me point out that the 13B with 9PSI
of boost at only 4000 rpm is a truely powerful beast and well worth the
effort. (especially now I have the injectors wired correctly and the mixture
right). Sitting at 11k ft its VERY nice to add a couple of inches of map
and see an instant 1000 fpm, and if I can get the rpm up a bit more at sea
level with the new turbo I'm going to need a G suit for take off.
:)
Regards,
John
JTD? (Johns Turbo Demise). Is this what fame feels
like???
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