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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
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Rusty,
Are you sure youíre 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?
Mark S.
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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
RC 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.
Hi Ken,
RC 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 :-)
On 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?
Cheers,
Rusty (hoping Ed out types me)
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