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Offline Painlesstom

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Air Shroud and Engine Cooling
« on: May 26, 2016, 10:49:47 PM »
I've been trying to squeeze as much as I can from this ES-kape as you all well know, but I feel like I've been chasing my tail since no matter what I do I have not been able to retain RPM once the engine gets hot. Water cooled muffler helped a little, cold air intake did too, but nothing like my 2003 or 2011 boats. So I started thinking outside the box and realized the air coming INTO the "box" was coming in through a smaller volume shroud, so I held the two up for comparison and sure enough the ES-kape shroud is only 2/3rds the size of the previous models shroud. These engines NEED lots of air, as much as that flywheel can suck in. Restricting that flow has got to be causing the heat issues, so I went to town chopping up the shroud and making it deeper. Opened up the hood and made a new scoop to accommodate as well. Will have more pictures and test results Saturday.  \./8
Tom

  >:D    

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Offline Odie

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Re: Air Shroud and Engine Cooling
« Reply #1 on: May 27, 2016, 01:29:29 AM »
I've often wondered how the Honda flywheel intake volume capacity compares to the Robin Subaru flywheel intake volume since mine is a Honda to Robin conversion. I believe you have each, how do they compare Tom?

Offline Painlesstom

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Re: Air Shroud and Engine Cooling
« Reply #2 on: May 27, 2016, 07:04:13 AM »
I've not had any cooling issues with my 2003, it will hold it's RPM all day like my 2011, so I would be willing to bet it is comparable to the Subaru. I'll get some pictures later today for comparison sake.



*Update*

Old hull plenum is comparable in size, yet not as tall, so air has a more direct path into the flywheel. The two old models provided suitable cooling ability, the Subaru models needed to have the hood opened up though so the inlet was the same size as the tunnel.
Tom

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Offline Painlesstom

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Re: Air Shroud and Engine Cooling
« Reply #3 on: May 28, 2016, 01:11:46 PM »
Larger plenum worked like a charm. Zero heat issues today, motor ran beautifully. Now I know that all the performance loss issues I've had with all of these ES-kapes is related to overheating. Air cooled motors need lots of air and the stock plenum chokes that down to a fraction of what is needed for sustained running. I always wondered why they made that inlet so tiny, I guess they skipped the testing part since it looked cool.  :D

<a href="http://www.youtube.com/watch?v=AXBV3niWgZk" target="_blank">http://www.youtube.com/watch?v=AXBV3niWgZk</a>

<a href="http://www.youtube.com/watch?v=8iDMSmTUIc4" target="_blank">http://www.youtube.com/watch?v=8iDMSmTUIc4</a>
Tom

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Offline riverman

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Re: Air Shroud and Engine Cooling
« Reply #4 on: May 28, 2016, 04:23:35 PM »
That's interesting,  is there any way to modify the stock plenum on the es-kape without too much chopping  and altering to attain  that extra air flow, or is it a total redo? Would adding a flared scoop to the outside be enough or is it the necking down that's causing the air restriction?

Offline Odie

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Re: Air Shroud and Engine Cooling
« Reply #5 on: May 28, 2016, 04:29:44 PM »
Great work Tom. Congrats!

Offline Painlesstom

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Re: Air Shroud and Engine Cooling
« Reply #6 on: May 28, 2016, 04:37:34 PM »
The plenum is just physically too small to flow the amount of air required. It needs to be cut down the middle and widened at least 1-1.5", and the inlet opening removed since there is no real way to enlarge that. Oh, I also do not have the recoil starter on. With electric start there is no reason to have that there interfering with air flow, the more the better.  \./8

Great work Tom. Congrats!

 :)
Tom

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Offline riverman

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Re: Air Shroud and Engine Cooling
« Reply #7 on: May 28, 2016, 04:43:37 PM »
I see what you're saying, I guess to keep the low profile the trade off was performance loss, or like you said they just never put it through the proper testing.

Offline Odie

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Re: Air Shroud and Engine Cooling
« Reply #8 on: May 29, 2016, 11:25:06 AM »
Tom, you ought to consider making a one size fits all intake shroud. Designed with more intake volume for all models. An ABS plate could adapt the plenum to the compartment cover. The shroud could be longer/taller  than necessary and custom fit if so desired.

Offline Painlesstom

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Re: Air Shroud and Engine Cooling
« Reply #9 on: May 29, 2016, 11:41:58 AM »
The one size fits all concept isn't viable as all the models have different flywheel cover mounting designs and different hoods. There isn't any similarity between models, they are all quite different. I'm working on another plenum for a customer now, opening it up like I did mine but will be retaining the "cold air" aspect with a variation of my divider installed. Will post pics once it's done.
Tom

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Offline Painlesstom

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Re: Air Shroud and Engine Cooling
« Reply #10 on: May 29, 2016, 07:50:42 PM »
Here is one I just finished for a customer. Should work wonders for his motor w/ EX17 head. Looking at the comparison pictures, I still can't believe anyone thought that inlet size was going to let that flywheel breath. It's literally a fraction of the size in volume!  :D
Tom

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Offline Odie

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Re: Air Shroud and Engine Cooling
« Reply #11 on: May 30, 2016, 08:20:53 AM »
What synthetic is it? Looks like polypropelene, very difficult to glue. The Honda shroud is the same as compartment cover on mine, abs I believe, the abs glue I used for it worked well.

Offline Painlesstom

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Re: Air Shroud and Engine Cooling
« Reply #12 on: May 30, 2016, 08:37:15 AM »
The plenum is HDPE like the hull, earlier Honda plenums were ABS.

I cut the plenum then rejoined it with fiberglass. Easiest method I could think of, works great.
Tom

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Offline Odie

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Re: Air Shroud and Engine Cooling
« Reply #13 on: May 30, 2016, 09:01:00 AM »
Very interesting, thanks for sharing. I recall when you made your intercooler mentioning "grafting" to the air box using fiberglass. So fiberglass + resin bonds to prepped hdpe/pp or does it completely wrap/enclose the plastic?

Offline Painlesstom

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Re: Air Shroud and Engine Cooling
« Reply #14 on: May 30, 2016, 09:07:51 AM »
The idea is to wrap, resin doesn't bond to the plastic so enveloping the union well is the trick. Roughing up the plastic is a good idea too. Resin will attack ABS though, so a better bond would take place when that is the material being joined.
Tom

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