Topics

Q2 Revmaster Cooling


Joe Hood
 


Jay Scheevel
 

I think that Dave Dugas is your best source on this. His Revmaster has been flying a long time and he seems to cool it adequately.   Dave, you out there?

 

Cheers,

Jay

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Joe Hood
Sent: Monday, June 29, 2020 3:09 PM
To: main@Q-List.groups.io
Subject: [Q-List] Q2 Revmaster Cooling

 

Q-talk 119 had a cowl mod. Is that the best way to cool a Revmaster?

 

http://www.quickheads.com/index.php?option=com_content&view=article&id=1301:q-talk-119-cowl-mod-increases-cooling-and-mph-for-revmaster-turbo&catid=48&Itemid=101


Joe Hood
 

I see the Citabria uses the same design.

IMG_3018.HEIC

On Mon, Jun 29, 2020 at 6:50 PM Jay Scheevel <jay@...> wrote:

I think that Dave Dugas is your best source on this. His Revmaster has been flying a long time and he seems to cool it adequately.   Dave, you out there?

 

Cheers,

Jay

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Joe Hood
Sent: Monday, June 29, 2020 3:09 PM
To: main@Q-List.groups.io
Subject: [Q-List] Q2 Revmaster Cooling

 

Q-talk 119 had a cowl mod. Is that the best way to cool a Revmaster?

 

http://www.quickheads.com/index.php?option=com_content&view=article&id=1301:q-talk-119-cowl-mod-increases-cooling-and-mph-for-revmaster-turbo&catid=48&Itemid=101


Dave Dugas
 

Hi Joe
I can't say whether or not the pictured outlet design is any better than the plans built cowl flap, which is what I have. By having nice fitting engine baffling really made the biggest difference in cooling, both CHT and oil temperature. In cool or cold OATs my oil temperature struggles to reach 160, so the option to close the flap to me is a benefit. My CHTs are steady at 340 to 350 degrees, and my oil temperature at cruise is 200 on the hottest days, never exceeding 210 degrees. If you purchased your Q2 with either version, it wouldn't be worth it to change it until you know how the climate and type of flying you do affects engine temps.
 I will be hosting the August Zoom meeting, and it will coincide with my annual so it would be a good time for you to see my setup. It's been a lot of trial and error over the 20 years or so that I've been flying my Q2, so hopefully some of the things I've done can save some time for you. I'm going to be going to Enid in September so if you fly in with your Q2, I'd love to see it. Even if you drive to FOD I can remove the cowl and try to help you out. 
Dave D


On Mon, Jun 29, 2020 at 11:27 PM, Joe Hood
<joe.hood@...> wrote:
I see the Citabria uses the same design.

IMG_3018.HEIC

On Mon, Jun 29, 2020 at 6:50 PM Jay Scheevel <jay@...> wrote:

I think that Dave Dugas is your best source on this. His Revmaster has been flying a long time and he seems to cool it adequately.   Dave, you out there?

 

Cheers,

Jay

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Joe Hood
Sent: Monday, June 29, 2020 3:09 PM
To: main@Q-List.groups.io
Subject: [Q-List] Q2 Revmaster Cooling

 

Q-talk 119 had a cowl mod. Is that the best way to cool a Revmaster?

 

http://www.quickheads.com/index.php?option=com_content&view=article&id=1301:q-talk-119-cowl-mod-increases-cooling-and-mph-for-revmaster-turbo&catid=48&Itemid=101


Joe Hood
 

I'll look forward to August. The previous owner said he always flew with the cowl flap open. 


On Tue, Jun 30, 2020 at 10:23 AM Dave Dugas via groups.io <davedq2=yahoo.com@groups.io> wrote:
Hi Joe
I can't say whether or not the pictured outlet design is any better than the plans built cowl flap, which is what I have. By having nice fitting engine baffling really made the biggest difference in cooling, both CHT and oil temperature. In cool or cold OATs my oil temperature struggles to reach 160, so the option to close the flap to me is a benefit. My CHTs are steady at 340 to 350 degrees, and my oil temperature at cruise is 200 on the hottest days, never exceeding 210 degrees. If you purchased your Q2 with either version, it wouldn't be worth it to change it until you know how the climate and type of flying you do affects engine temps.
 I will be hosting the August Zoom meeting, and it will coincide with my annual so it would be a good time for you to see my setup. It's been a lot of trial and error over the 20 years or so that I've been flying my Q2, so hopefully some of the things I've done can save some time for you. I'm going to be going to Enid in September so if you fly in with your Q2, I'd love to see it. Even if you drive to FOD I can remove the cowl and try to help you out. 
Dave D


On Mon, Jun 29, 2020 at 11:27 PM, Joe Hood
<joe.hood@...> wrote:
I see the Citabria uses the same design.

IMG_3018.HEIC

On Mon, Jun 29, 2020 at 6:50 PM Jay Scheevel <jay@...> wrote:

I think that Dave Dugas is your best source on this. His Revmaster has been flying a long time and he seems to cool it adequately.   Dave, you out there?

 

Cheers,

Jay

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Joe Hood
Sent: Monday, June 29, 2020 3:09 PM
To: main@Q-List.groups.io
Subject: [Q-List] Q2 Revmaster Cooling

 

Q-talk 119 had a cowl mod. Is that the best way to cool a Revmaster?

 

http://www.quickheads.com/index.php?option=com_content&view=article&id=1301:q-talk-119-cowl-mod-increases-cooling-and-mph-for-revmaster-turbo&catid=48&Itemid=101


Jon Finley
 

Joe,

 

The basic premise of efficient engine cooling is to get the air into the cowling, slow it down/increase pressure, get it thru the cooling fins, speed it up/reduce pressure, and get it out of the cowling.  Sounds easy but it isn’t – especially with limited space.  Air wants to move from high pressure to low pressure. So, the cowl exit needs to provide that. The Citabria photo is a classic example of little to no engineering/design – just a big hole with a lip at the front to create low pressure. Probably works fine at 80mph and with no regard to efficiency.  At cruise, air tends to hit the nose of the aircraft at a slightly upward angle.  This means the lowest pressure area (near the firewall) is the top of the cowling and not the bottom.  I experimented top air exits years ago but just didn’t have enough instrumentation.  Most don’t do that because ‘it just isn’t done that way.’  As Dave says, very good baffles are important.  After that, I would focus on the cowling exit – much to be gained there IMO.

 

Oh, also… The VW engine was designed to cool something around 30hp with a fan. When extracting 70hp (stock heads), there just aren’t enough cooling fins for all situations.

 

Years ago, most of us had no idea what our engine was doing. We had one cylinder instrumented and assumed all were the same (they aren’t). Instrumentation is cheap these days (e.g. GRT EIS with all four cylinders instrumented) so no need to repeat those omissions (which led to problems).

 

Cowling design (and baffles) has been beat pretty severely by numerous groups – especially the boys doing the racing (check out Sam’s setup while at FOD). I suspect lots of good stuff can be found with a bit of Googling.


Jon Finley
Somewhere in the Southwest flying an RV-4


Michael
 

You may also want to take a look at Mark Langford's website for info on VW heads and his mention in there on plenums. If you do a search on quickheads you can find some similar articles.

http://www.n56ml.com/n891jf/vw/

http://www.n56ml.com/corvair/plenum/
--
-MD
#2827 (still thinking about planning on visualizing how to finish building)