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06-25-2009, 05:03 AM
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Join Date: Jan 2005
Location: Hazlehurst, GA
Posts: 1,359
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Don't worry Pierre, I'll still buy lunch if show up in Sandersville Saturday! I can look past your comedically challenged issues!
__________________
IHN,
2020 Dues Paid
Robby Knox
THEM: Why do you always carry a knife?
ME: I can't open a bag of chips with my Glock!
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06-25-2009, 06:39 AM
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Join Date: Oct 2005
Location: Savannah, GA
Posts: 1,849
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Quote:
Originally Posted by fmarino1976
The stock LS1 puts out 200 HP and 350 ft-lbs at 3000 rpm (according to
http://www.gmperformanceparts.com/En...4322&engCat=ls ).
Could it be possible to match it to a prop that would allow the engine to spin up to 3000 rpm for takeoff?
Weight might still be an issue, I couldn't find the weight of the LS1 really easily so I can't tell what the difference would be.
Any engine gurus care to say yay or nay?
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The LS2 weight is about 345lbs. You would probably have to go with a short 3 blade prop which would let you run the rpm's up. I would move the radiator to the rear and use an electric water pump that could be put in rear.
__________________
Todd
N110TD
RV-10 Vesta V8 LS2/BMA EFIS/One formerly flying at 3J1 Hobbs stopped at 150 hours
Savannah, GA and Ridgeland, SC
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06-25-2009, 05:59 PM
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Join Date: Jan 2005
Location: Central California
Posts: 388
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Not a rational thing to do. RV-7 not a RV-10
Quote:
Originally Posted by TSwezey
The LS2 weight is about 345lbs. You would probably have to go with a short 3 blade prop which would let you run the rpm's up. I would move the radiator to the rear and use an electric water pump that could be put in rear.
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Group,
First of all I have to say that considering the crankshaft center line there is NO WAY you can fit an LS-2 without an offset drive or a completely new cowl. Even if you could this is a case of what I call, "Spec sheet daydreaming." If you read the spec sheet the engine is supposed to make X horsepower at a given RPM. In reality that engine probably has poor performance at that RPM because it wasn't designed to operate there continously. The reality is that there can be a multitude of issues, tortional vibration, bearing oil feed, etc. You are MUCH better off if you run the engine in a normal operating range. This is where we get into the problem with automotive conversions by spec sheet readers. There are lots of now belly-up companies that thought, "I'll make a motor mount for this engine and run it at lower speed and it will be fine." Most of the time they find out that the engine will make nowhere near the sheet HP when max loaded by a prop to make only 3000 RPM. Typically those numbers are simply connected dots on a dyno chart when the operator is spinning through that range on the way to maximum hp! Often the dyno operator won't even dial down the water brake until the engine is in the intended range. I have been there many times and seen exactly that proceedure. If you can get it to run in those lower ranges and make the published hp it is usually because the engine has re-designed manifolds and carbs to run there. That isn't an easy or cheap task either.
Lastly does that weight include a PSRU? Does that weight include a prop shaft extension with the proper bearings to withstand 800 pounds of end thrust? Does that include the Radiators and the coolant? Will the stock water pump be OK? Even if you don't run a reduction box most auto engines require a prop adapter that can handle the prop thrust. If you can get even a aluminum V8 to come in under the weight of an IO-540 you have done an excellent job of systems design. It isn't impossible but like LYC you must account for every nut and bolt to get the designed result. You have just turned your self into the systems engineer. Some people can do this, and others are not up to the job. (I'm speaking as a guy that intends to run an auto conversion in my aircraft!)
The point I'm making here is this will not be a bolt in conversion even if, (and it is a BIG if), the engine will produce specified HP when loaded down to that RPM by a prop. The casual disregard for the engineering involved is what gets a lot of people in trouble. The W&B will just be wrong for a RV-7. Sorry but I have to say this anybody doing this on an RV-7 is just ignorant, or possibly stupid! The difference is that if only ignorant they can probably be cured of the idea. DO NOT EVEN THINK ABOUT THIS CONVERSION. Period.
Bill Jepson
Last edited by Rotary10-RV : 06-25-2009 at 06:08 PM.
Reason: redirection
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06-25-2009, 08:34 PM
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Join Date: Oct 2005
Location: Savannah, GA
Posts: 1,849
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Quote:
Originally Posted by rv6ejguy
Not a good choice for a -7, way too heavy.
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Bill did you miss one?
__________________
Todd
N110TD
RV-10 Vesta V8 LS2/BMA EFIS/One formerly flying at 3J1 Hobbs stopped at 150 hours
Savannah, GA and Ridgeland, SC
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06-25-2009, 08:35 PM
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Join Date: Oct 2005
Location: Savannah, GA
Posts: 1,849
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Quote:
Originally Posted by TSwezey
Ditto. .
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And this one following Ross'.
__________________
Todd
N110TD
RV-10 Vesta V8 LS2/BMA EFIS/One formerly flying at 3J1 Hobbs stopped at 150 hours
Savannah, GA and Ridgeland, SC
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06-25-2009, 08:38 PM
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Join Date: Oct 2005
Location: Savannah, GA
Posts: 1,849
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My quote you quoted had nothing to do with putting the engine in a RV-7. It is stupid. Plain and simple.
__________________
Todd
N110TD
RV-10 Vesta V8 LS2/BMA EFIS/One formerly flying at 3J1 Hobbs stopped at 150 hours
Savannah, GA and Ridgeland, SC
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06-25-2009, 08:59 PM
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Join Date: Nov 2006
Location: Waco, Texas
Posts: 1,658
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I think you would have way too much power......
The LS1 is really too much power for the -10, but mangagable.
From what I've heard (direct reports) the LS1 will push the RV-10 over VNE in straight and level flight. It's a power house.
Can't imagine what it would do to a -7.
Phil
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06-26-2009, 12:21 PM
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Join Date: Jan 2005
Location: Central California
Posts: 388
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Sorry Todd, but...
Quote:
Originally Posted by TSwezey
Bill did you miss one?
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Todd,
No I didn't miss that one, but the later post just gave the engine weight. Somebody reading the thread by using the "first unread" click could misconstrue the post since it seems an acceptable starting weight. I posted the reply to "group" and I didn't want to imply that you didn't understand Todd. Sorry, since it does seem to imply that you condoned the idea, and I KNOW that you don't. You, more than anyone, know what the all up system weighs. I probably should have used a link and started my rant in a new thread. I always get upset when the idea of using a mismached engine, of any kind, in experimental aircraft. RVs have considerable reserve built in and can also be successfully modified for different engines. (Like the various Rockets for instance) The trouble starts when non-mechanical people are convinced by someone, (or themselves), that these changes are easy or safe. Mostly it just results in someone being parted from their money. That is bad but not as bad as when it puts a low-time pilot in comand of a "hot rock" of an airplane. Bad decisions or lack of knowledge can cause even a proven good flying machine to become deadly. I always feel the need to inform the mechanically-challenged who are lurking on the list. I say this all the time, but
it bears repeating, If you can't work out the mechanics of an alternate engine design you are better off using a Lyc or a clone.
Bill Jepson
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