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  #1  
Old 09-27-2022, 05:55 AM
kens_cockpit kens_cockpit is offline
 
Join Date: Jan 2005
Location: Launceston, Tasmania, Australia
Posts: 89
Default Cowl modifications with engine change

I originally planned on an IO 360 with a constant speed prop. I have the IO360 cowl

Fora number of reasons I have decided to change course as I have acquired an 0320 and I will put a fixed pitch or ground adjustable prop on it, at least initially.

I need to add the scoop to the bottom cowl for the vertical induction. It looks like I can buy that from Vans and attach it.

Are there other differences I need to look out for? For example will I need to modify the baffling etc

Are the external dimensions of the engines essentially the same?

What size prop spacer will I need?

Thanks for your thoughts.
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RV8 QB started 2004

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  #2  
Old 09-27-2022, 07:43 AM
Southern Pete Southern Pete is offline
 
Join Date: Jul 2015
Location: England
Posts: 210
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Installing a smaller engine will not give you any problems. The scoop is available, it may be a fair amount of work to bond on. Have you considered an injected IO-320 with horizontal induction, perhaps with a Superior sump? The baffling will be high enough to fit with your cowl, you may have some work at the front outboard corners. An O-320 is slightly narrower than a 360 otherwise similar dimensions. The injected cowl is wider than the vertical induction cowl. As you will have to cut down the rear of the cowl it doesn't matter what size spacer is used. Typically longer is better with a lightweight prop. Is there enough cowl length to take a 4" extension? Otherwise you may be limited to 2.25 or 2.5".
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  #3  
Old 09-27-2022, 07:44 AM
Joeyo68 Joeyo68 is offline
 
Join Date: May 2015
Location: Frankston, Victoria, Australia
Posts: 152
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Hi Ken,
I suspect you will need a different mount. I have the custom 320 mount for the RV7, which I have fitted an IO-360 to. I have a GT propellers 3 blade GA prop, so this combo was to help move the CofG forward. Speaking for an RV7, the mount for the 320 is 2 inches longer, so you need to add 2 inches to your cowl for it to fit, also control cables, and fuel lines need to be longer. Standard spacer is used for the prop, so nothing special at the front. 320 baffle kit will be needed, 320 FAB, but I suspect you could use your 360 FAB, as it will be bigger than the 320 FAB.
Feel free to call me tomorrow if you want to discuss. PM me and I can send my number to you.
Here is a pic of my 7 with the longer cowl.
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  #4  
Old 09-27-2022, 08:52 PM
bbsdad bbsdad is offline
 
Join Date: Oct 2018
Location: tx
Posts: 147
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I have a 320 induction scoop New never used. Pm me if interested.

RD
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  #5  
Old 09-27-2022, 08:58 PM
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wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 5,698
Default Mount

Standard mount or 320 mount?
I don't know anything about it but have read issues with aft CG that some resolved by using the longer 320 mount.
Adding material is easy.
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I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #6  
Old 09-29-2022, 08:06 AM
Southern Pete Southern Pete is offline
 
Join Date: Jul 2015
Location: England
Posts: 210
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Use a thick steel crush plate rather than buying a new motor mount!
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  #7  
Old 09-29-2022, 06:36 PM
kens_cockpit kens_cockpit is offline
 
Join Date: Jan 2005
Location: Launceston, Tasmania, Australia
Posts: 89
Default The engines are essentially interchangeable in the 8

Thank you all for your input.

I made the same inquiry of Vans

In the 8 the same mount is used for both engines.

I suspect that is because the 8 tends to be nose heavy without a rear pax so lowering the weight and keeping it back helps that. I am hoping the handling will be a little sweeter even if the performance isn't as brisk.

I can buy a scooped lower cowl at significantly greater cost or buy the scoop and install it with significantly greater work. But it seems doable and I plan to do that. There are some posts of that on the forums such as this https://vansairforce.net/community/s...ght=cowl+scoop

Looks like I will just need whatever the standard spacer is for the ground adjustable prop I choose.

I should be able to use the standard FWF kit for the O320 in the 8.
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  #8  
Old 09-29-2022, 07:11 PM
Ralph Inkster Ralph Inkster is offline
 
Join Date: Feb 2008
Location: Calgary, Alberta
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Quote:
Originally Posted by kens_cockpit View Post
Thank you all for your input....

Looks like I will just need whatever the standard spacer is for the ground adjustable prop I choose.

.
Not as popular these days (for whatever reason), you might consider using a Sensenich aluminum prop up front instead to preserve some extra weight up front.
As you are starting with less HP, supposed slight performance losses using these props shouldn't matter.
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