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rparigoris
Joined: 24 Nov 2009
Posts: 792
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 Posted: Sun Oct 24, 2021 9:04 am Post subject: Rotax Cooling Air Baffle |
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Hi Group Has anyone flying with Rotax Cooling Air Baffle modified the internal flow to give cylinders #3 and #4 a little more flow compared to the front two cylinders? How about with a 914 even giving #3 a little more flow compared to #4? This coming week going to test mine with a leaf blower. Thx. Ron
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Duncan McFadyean
Joined: 18 Jan 2011
Posts: 219
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| Posted: Sun Oct 24, 2021 9:46 am Post subject: Rotax Cooling Air Baffle |
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I have under-baffles with the airhood to split the air that passes down between each pair of cylinders (to direct this on to the underside of each cylinder) and therefore to maximise any benefit of the air passing through the airhood.
Don't know if they work or not, I've never instrumented the cylinders (apart from one cylinder wall thermocouple during commissioning, per Rotax recommendation).
Duncan Mcf.
| Quote: | On 24 October 2021 at 18:04 rparigoris <rparigor(at)hotmail.com> wrote:
Hi Group Has anyone flying with Rotax Cooling Air Baffle modified the internal flow to give cylinders #3 and #4 a little more flow compared to the front two cylinders? How about with a 914 even giving #3 a little more flow compared to #4? This coming week going to test mine with a leaf blower. Thx. Ron
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=503607#503607
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rparigoris
Joined: 24 Nov 2009
Posts: 792
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| Posted: Sun Oct 24, 2021 11:27 am Post subject: Re: Rotax Cooling Air Baffle |
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Hi Duncan Thank you for reply. Do you by chance have any pics or documentation of under baffles? What Rotax document speaks of using a cylinder thermocouple for monitoring cylinder wall temp? Thx. Ron P.
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Gilles
Joined: 16 May 2020
Posts: 33
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| Posted: Mon Oct 25, 2021 12:55 am Post subject: Rotax Cooling Air Baffle |
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Le 24/10/2021 à 19:04, rparigoris a écrit :
| Quote: | | Quote: | --> Europa-List message posted by: "rparigoris" <rparigor(at)hotmail.com> (rparigor(at)hotmail.com)
Hi Group Has anyone flying with Rotax Cooling Air Baffle modified the internal flow to give cylinders #3 and #4 a little more flow compared to the front two cylinders? How about with a 914 even giving #3 a little more flow compared to #4? This coming week going to test mine with a leaf blower. Thx. Ron
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Hello Ron and all,
We installed the Rotax air baffle on our 914 and made some measurements at the time.
Here are some considerations :
With adequate sealing around the baffle and some pressure recovery (expanding inlet), all 4 cylinders get enough cooling air.
Only the #1 gets some extra blast from the "bizarre" Rotax inlet.
Due to liquid cooling, the cylinder heads are good "temperature sources" and the cylinder temps never exceeded 100/120 °C.
[img]cid:part1.B6BB1D9E.6AD7895F(at)free.fr[/img]
FWIW, --
Best regards
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
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Best regards,
Gilles
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Duncan McFadyean
Joined: 18 Jan 2011
Posts: 219
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| Posted: Mon Oct 25, 2021 10:22 am Post subject: Rotax Cooling Air Baffle |
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https://www.rotax-owner.com/pdf/IM_912_Series_Ed3_R0.pdf
Page 132 et seq.
Duncan Mcf.
| Quote: | On 24 October 2021 at 20:27 rparigoris <rparigor(at)hotmail.com> wrote:
Hi Duncan Thank you for reply. Do you by chance have any pics or documentation of under baffles? What Rotax document speaks of using a cylinder thermocouple for monitoring cylinder wall temp? Thx. Ron P.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=503612#503612
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rparigoris
Joined: 24 Nov 2009
Posts: 792
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| Posted: Tue Oct 26, 2021 10:41 pm Post subject: Re: Rotax Cooling Air Baffle |
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Hi Duncan and Gilles Thank you for information you provided. For the past several days we have been evaluating the flow characteristics of Rotax CAB on our 914. We did not remove the engine from the mounting ring to install the CAB but made slits to go over ring. Perhaps that caused a little leaking, but don't think too much. We used a shop vac with an airspeed of 35mph and a leaf blower with airspeeds of 50mph, 75mph and 100mph. First test was not too impressive. We purchase the CAB from Lockwood, looked like it was run at the factory for an hour. #1 cylinder where the baffle touched the fins was pretty brown indicating high heat. #2 cylinder was somewhat showing brown. Flow was almost nonexistent on #1 and only a little on #2. Aft of #4 wasn't too bad and #3 aft was very bad, a little more than #2. Between cylinders was dismal. There was a ton of air exiting aft of cylinders mostly on the stbd side where Rotax kinda has an exit to blow some air on ignitions, but it was grossly overdone. We now have flow where 35mph is giving us at least as much on cylinder #3 and 4 as 75mph was on stock configuration, even more air between cylinders and #1 and #2 is getting same as 100mph stock configuration. In process of glassing cutout for alternator and install of baffle and scoop. Stock configuration with 100mph and the CAB just sits there. With modified CAB even at 35mph it lifts in back! We will be installing 1 bolt ontop the center of case to hold it in position. If engine was removed from ring, the ring may have held the CAB down? Will post pics when complete. If I'm going to take a drag hit adding a third air scoop on the snout, might as well make it count. Net is we now have good airflow to #4, a little more airflow to #3 than #4, really good airflow between cylinders, perhaps a tiny bit more on starboard side (turbo side), and lesser airflow to front cylinders compared to #3 and #4, but way better than stock configuration. Because we have 2 eyeballs that's blowing air on front cylinders, We're OK having a little less airflow from CAB on front cylinders and we are going to cut off 3/4" of the CAB to allow some of the eyeball air to better hit fins. Stay tuned. Ron P.
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rparigoris
Joined: 24 Nov 2009
Posts: 792
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| Posted: Thu Nov 18, 2021 1:30 pm Post subject: Re: Rotax Cooling Air Baffle |
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Hi Group We completed our CAB for 914 XS mono. It has rebate for B&C SD20S alternator, #1 cylinder has a scoop, gap #1 cylinder inboard top crankcase sealed, sealed between cylinders inboard of fins and on 3 cylinders inboard of fins to CAB, dammed a huge leak aft and near cylinder #3 and used Silicone foam most aft central to slow leak: https://1drv.ms/u/s!Ah1S270Nwg9VgeIUVBgsSTq-KOL22w
We mutilated the intake of the CAB and moved flange way back and have it plumbed with a SCAT Duct: https://1drv.ms/u/s!Ah1S270Nwg9VgeILZu1KhZulPMJUuw
To install, using a Snow Globe that gives us one fingers worth of clearance for taking cowl off or putting it on:
https://1drv.ms/u/s!Ah1S270Nwg9VgeIKHAHKF743qDzKVg?e=Td3Y7B
https://1drv.ms/u/s!Ah1S270Nwg9VgeIJjp4k4b03VBlHhg?e=Hre97E
https://1drv.ms/u/s!Ah1S270Nwg9VgeIObtNSh8mzCvURkA?e=II78TM
We are holding the CAB down with 1 central bolt and spacer to crankcase and welded a tab to the ignition bracket to hold it down in back. Ron P.
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rparigoris
Joined: 24 Nov 2009
Posts: 792
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| Posted: Fri Nov 19, 2021 8:17 am Post subject: Re: Rotax Cooling Air Baffle |
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Hi Group For some reason Matronics cuts off some of the URL on links I post. To view it's necessary to copy entire link and paste into browser.
Here's a single link to an Overview Folder for CAB:
https://1drv.ms/u/s!Ah1S270Nwg9VgeFAfoDVhV9zD9n3JQ?e=chHzat
Ron P.
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