Today's Message Index:
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1. 10:24 AM - Re: Disappointment in Rotax 9 series (rv6ejguy)
2. 10:51 AM - Re: Re: Disappointment in Rotax 9 series (Gilles Thesee)
3. 01:34 PM - Re: Re: Disappointment in Rotax 9 series (Duncan & Ami McFadyean)
4. 02:48 PM - Re: Disappointment in Rotax 9 series (rv6ejguy)
5. 04:05 PM - Re: Re: Disappointment in Rotax 9 series (Dave Austin)
Message 1
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| Subject: | Re: Disappointment in Rotax 9 series |
EGT is not, strictly speaking, a measure of mixture. Many factors affect EGTs so
this is not a valid way to determine AFRs. You can fit a wideband O2 meter to
determine AFR changes with altitude.
Programmable fuel injection is now available for for 912UL and 912ULS engines if you dislike the carbs: http://www.sdsefi.com/rotax2.htm
--------
Subaru EJ22 turbo RV6A Flying
Subaru EG33 twin turbo RV10 building
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=163701#163701
Message 2
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| Subject: | Re: Disappointment in Rotax 9 series |
> EGT is not, strictly speaking, a measure of mixture. Many factors affect EGTs
so this is not a valid way to determine AFRs. You can fit a wideband O2 meter
to determine AFR changes with altitude.
>
I'll second that.
> Programmable fuel injection is now available for for 912UL and 912ULS engines if you dislike the carbs: http://www.sdsefi.com/rotax2.htm
>
>
Please be aware that electronic fuel injection means higher part count,
and increased complexity because of the need for electrical redundancy.
It is just the same with the 'electrically dependant' 914.
The injection kit you are referring to is most interesting.
Elsewhere on their site is a most interesting story about a subaru RV
project with fuel injection. Beautiful engineering, but unfortunately
the plane experienced an engine failure due to the lack of backup
electric supply.
Fuel injection in an airplane is inseperable from electrical redundancy.
Best regards,
--
Gilles
http://contrails.free.fr
Message 3
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| Subject: | Re: Disappointment in Rotax 9 series |
I think I would dislike this system even more than carbs.
The manifold design on the 912 provides uneven charge to the front and back
cylinders (except, I am told, at full throttle).
This EFI system, using the stock inlet manifolds will do exactly the same in
terms of the air delivered to the front and back cylinders.
But now, the mixture will be different front to back as well. Because the
injectors only meter according to the air demand of the whole engine, not
the air demand of individual cylinders. It gets worse still; the mixture for
all cylinders will need to be set up to the leanest cylinder, meaning the
others run rich.
The advantage of having individual and tuned inlet runners to each cylinder
has been lost with this specific arrangement.
Duncan McF.
Been there, done that (with other engines), not worth the hassle for the
benefit obtained (unless lower emissions is high on your list of
priorities).
----- Original Message -----
From: "rv6ejguy" <racetech1@telus.net>
Sent: Tuesday, February 12, 2008 6:21 PM
Subject: RotaxEngines-List: Re: Disappointment in Rotax 9 series
>
> EGT is not, strictly speaking, a measure of mixture. Many factors affect
> EGTs so this is not a valid way to determine AFRs. You can fit a wideband
> O2 meter to determine AFR changes with altitude.
>
> Programmable fuel injection is now available for for 912UL and 912ULS
> engines if you dislike the carbs: http://www.sdsefi.com/rotax2.htm
>
> --------
> Subaru EJ22 turbo RV6A Flying
> Subaru EG33 twin turbo RV10 building
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=163701#163701
>
>
>
Message 4
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| Subject: | Re: Disappointment in Rotax 9 series |
ami(at)MCFADYEAN.FREESERV wrote:
> I think I would dislike this system even more than carbs.
>
> The manifold design on the 912 provides uneven charge to the front and back
> cylinders (except, I am told, at full throttle).
> This EFI system, using the stock inlet manifolds will do exactly the same in
> terms of the air delivered to the front and back cylinders.
> But now, the mixture will be different front to back as well. Because the
> injectors only meter according to the air demand of the whole engine, not
> the air demand of individual cylinders. It gets worse still; the mixture for
> all cylinders will need to be set up to the leanest cylinder, meaning the
> others run rich.
>
> The advantage of having individual and tuned inlet runners to each cylinder
> has been lost with this specific arrangement.
>
> Duncan McF.
>
> Been there, done that (with other engines), not worth the hassle for the
> benefit obtained (unless lower emissions is high on your list of
> priorities).
>
>
> ---
By making an assumption like this, you'd be incorrect. Testing showed the EGT spread
was narrowed at 5750 rpm from 110F with carbs to 10F with the EFI. At 5500
rpm, spread was 60F with EFI and a whopping 130F with carbs. Intake length
tuning is largely unaffected typically with the siamesed runner design used on
this engine when only dry air is flowing through the manifolds. The EFI demonstrated
much better fuel distribution than the carbs at typically run rpms as
well as a power increase of about 4-6 hp depending upon ambient conditions.
--------
Subaru EJ22 turbo RV6A Flying
Subaru EG33 twin turbo RV10 building
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=163751#163751
Message 5
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| Subject: | Re: Disappointment in Rotax 9 series |
Hey folks.. Go flying! My 912 has sung with oil and coolant change each
year for 15 years!
Dave Austin 601HDS - 912, Spitfire Mk VIII
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