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Thanks Ed, is there any reason not to trust the standard formulas for determining injector size for the rotary? I ask only because running those formulas the #42 seems to be just about right for my p port (220 hp) unless the BSFC goes above .60. Eighty per cent duty cycle is 41 lbs. With a lower BSFC no problem at all, of course. I was surprised to learn that the 42 lb injectors were stock on older 13B NA. Does this point to a higher BSFC than recips? Jerry
On Wednesday, March 23, 2005, at 10:58 AM, Ed Anderson wrote:
Jerry, the older 13B NA (post 1986) used 460 cc/min (Peak and Hold - Low resistance) injectors approx 42 lbs/hr (this is what I fly with). The first turbo units used 550 cc/min injectors (saturated types - higher resistance), I have flown with these but found I did not like the idle as well as the 460 cc/min units so reverted.
Ed A
----- Original Message -----
From: Jerry Hey
To: Rotary motors in aircraft
Sent: Wednesday, March 23, 2005 10:45 AM
Subject: [FlyRotary] Re: fuel injector size, and redrive losses
Mark, is your engine a N/A 13B? Do the 550s equate to a little more than 50 lbs/hr? That is hugh. Did you find the 42 lb/hr injectors to be too small? Lastly, can someone tell me the size of the stock Mazda injectors? Thanks, Jerry
On Wednesday, March 23, 2005, at 09:25 AM, Mark R Steitle wrote:
Jerry,
I bought a set of eight 42# Ford injectors but in the end, wasn’t able to use them and went with the 550’s.. I gave $320 for the set and would let them go for my cost. I’ll split the set if someone else wants the other four. They have about 5 hours on them. If you’re interested contact me off line.
Mark S.
mark.steitle&Austin.utexas.edu (replace & with @)
<image.tiff>
From:Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf OfJerry Hey
Sent: Wednesday, March 23, 2005 8:12 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: fuel injector size, and redrive losses
Ken, after spending the day calculating injector sizes, I ended up coming to the same conclusion that you did. The Ford 42 lb are perfect for my application. P.L. recommended 50 lb injectors but for 225 hp they are too much in my opinion. Unfortunately Ford Racing is out of stock. Damn. Jerry
On Tuesday, March 22, 2005, at 06:06 PM, kenpowell@comcast.net wrote:
Jerry, the Ford injectors are not directly compatible. Here are the details:
ENGINE SIDE FUEL RAIL SIDE
Ford 0.55" 0.55
Mazda 0.65 (with the FAT Mazda rubber ring)
0.435
Note that the electrical connector is the same (center spline top/inside and center lower outside). So, the Ford injector will hook up electrically but the fuel connectors must be different.
Ken Powell
Bryant, Arkansas
501-847-4721
-------------- Original message --------------
> Ken, are the Ford injectors interchangeable with the stock Mazda
> injectors as far as size, plug and so on? If so, do you have a part
> number? BTW sorry but there is no way you can run a p port at 7500
> rpm and only get 225 hp. Can you accept 240? Jerry
>
>
>
>
>
> On Tuesday, March 22, 2005, at 03:48 PM, kenpowell@comcast.net wrote:
>
>
> But this graph was for a carburated engine so it really
> proves nothing. Besides, the engine only needs to be as rich as we
> want to run - you can't hurt the engine by running lean (I know, if
> you run it into the trees on a 100 F. day that will HURT it!!!). I
> have not seen any graphs showing power improvement beyond 0.6 on a NA
> engine and with very little to be gained by going beyond .55. If
> anyone can educate me differently please do so (no kidding, I'm trying
> to learn). I'm planning on using 42 lb Ford injectors for my P-Port
> motor, if this isn't enough I want to know (planning on 225 HP at 7500
> RPM).
>
> Ken Powell
>
> Bryant, Arkansas
>
> 501-847-4721
>
>
>
>
> -------------- Original message --------------
>
>
> v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);}
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> Arial0000,0000,8080Rus
> ty,
>
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> Arial0000,0000,8080Are
> you sure youĚre allowing yourself enough margin on the top end by
> using .55 bsfc. This chart (snitched from the other list) indicates
> that .55 is about right up to around 7500, but at 8000 rpm bsfc will
> be up around .60. What does that do to your hp numbers?
>
>
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> Arial0000,0000,8080
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> Arial0000,0000,8080Mar
> k
> S.
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Times New Roman
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> From:Rotary motors in
> aircraft [mailto:flyrotary@lancaironline.net] On Behalf
> OfRussell Duffy
>
> Sent: Tuesday, March 22, 2005 2:25 PM
>
> To: Rotary motors in aircraft
>
> Subject: [FlyRotary] Re: fuel injector size, and redrive
> losses
>
>
> Times New Roman
>
>
> Times New RomanRC Engineering's calcs show
> that you are good to 302 HP at 43 psi fuel pressure, .50 BSFC, and
> 100% duty cycle. Of course you can't run the injectors at 100%
> (except maybe briefly like a drag race, not applicable to aircraft).
> So at 80% duty cycle the 38 lb injectors should be good for 242 HP.
> Enjoy your idle!!! Your injectors are big enough unless you P-Port
> and turn at least 8000 RPM.
>
>
>
> ArialFFFF,0000,0000Hi
> Ken,
>
>
> Times New Roman
>
>
> ArialFFFF,0000,0000RC
> Engineering's calc shows the same as the fuel calculator that I
> posted the other day. Four 38 lb/hr injectors, at 80% duty cycle, .55
> BSFC, should be good for about 220 HP at the flywheel. I imagine that
> will be enough for the current engine, but not by a wide margin. I
> plan to run this engine as high as 8000 if I can, though I'll be
> amazed if I can get beyond 7500. Don't need no stinkin' P-Port for
> these rpms :-)
>
>
> Times New Roman
>
>
> ArialFFFF,0000,0000On
> the fuel spreadsheet that I posted (stolen) the other day, it gives a
> HP figure for the flywheel, and rear wheels. The estimate for
> the power loss due to a manual trans and diff is 15% on this
> spreadsheet. Anyone know what this amounts to for our redrive, and
> prop?
>
>
> Times New Roman
>
>
> ArialFFFF,0000,0000Cheers,
> or>
>
>
> ArialFFFF,0000,0000Rusty
> (hoping Ed out types me)
>
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