Gm engine weights

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skydawg

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Jul 26, 2016
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148
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All good ideas, and most tried in the past with exp community. i spoke with many owners of conversions, as well as engine builders and even many airboat manufacturers which use the same basic engines as many experimental aircraft do. we spoke to exp builders with a lot of aero experience and degrees yet experienced inflight failures simply because more than one issue happened at the same time as another seemingly unrelated issue occurred, or simply because they didn’t think of that. I’ll say this:.. figuring this stuff out properly is expensive and requires a lot of skill sets, training and fancy education. most pilots don’t have all these traits, so hiring out the right help gets real expensive, and Quick. We underestimated the cost and time by a huge margin, and most skill sets were in house.

We initially looked for a kit that had already gone through the R&D, flight testing, etc for the c172 or c182, but none existed; so we built our own. When we started to get a lot of inquires from folks wanting to buy one, we figured the cost could work as most of the development was already complete.

we tested many setups and came to a few fundamental conclusions, many we posted on website. There has been enough service history on common conversion problems that almost all new entrants would not need to be starting from a blank drawing board. But many still fall into same traps, regardless. If anyone does plan on building a Auto conversion….spend a significant amount of time learning from others mistakes and do research. Such topics are often engineering driven with many esoteric terms used in publications, so be ready to learn a lot of new and boring stuff, as well.

But, it’s not rocket science. Anyone can make a reliable conversion if they have the resources, and maybe make it even better. Just be committed to doing it right…. I think for most, however, buying an engine that’s been through most of the challenges Is more practical.
 

Winginitt

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Apr 5, 2019
Messages
197
In the power to weight ratio thing, the nice thing about the LS3/480 is that simply moving from 2700 rpms/200 HP up to 3000 rpms provides 250 HP . Thats a nice change in power for 300 more rpms and a slightly smaller prop. A three blade composite would be my choice.

Or, someone wishing to scratch build could use the block and add the stroker crank. No real change in weight but 282 [email protected] and 329 HP at 3000.

So a range from 200 HP to 329 HP for the same weight engine. Also, remember that neither of these engines were optimized for aviation use which could wring even a little more power in the correct power range. Another thing to notice with the stroker engine is that even at 2500 rpms it makes 252 HP
 

Sonny Furman

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Feb 23, 2011
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Punta Gorda FL
I converted a 63 Buick 215 engine, along with reduction drive of 1.6 for my full scale SE5a replica. All aluminum block & heads, and with a few basic mods, boring, head work, cam & carburetion, dyno readings of 237 HP at 4800 rpm. Complete weight with redrive 318 lbs. These engines are still around and not costly to rebuild provided one can find parts,
Irv "Sonny" Furman, Lt. Col. USAF ret.
 

Pops

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Jan 1, 2013
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10,799
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USA.
I converted a 63 Buick 215 engine, along with reduction drive of 1.6 for my full scale SE5a replica. All aluminum block & heads, and with a few basic mods, boring, head work, cam & carburetion, dyno readings of 237 HP at 4800 rpm. Complete weight with redrive 318 lbs. These engines are still around and not costly to rebuild provided one can find parts,
Irv "Sonny" Furman, Lt. Col. USAF ret.
I built a 215 ci , 1963 Buick, alum block V-8 for my box framed 1968 VW Bug. Stock with 4 barrel carb, except for the HEI ignition dist. Nice engine.
 

rv6ejguy

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Joined
Jun 26, 2012
Messages
4,752
Location
Calgary, Alberta, Canada
In the power to weight ratio thing, the nice thing about the LS3/480 is that simply moving from 2700 rpms/200 HP up to 3000 rpms provides 250 HP . Thats a nice change in power for 300 more rpms and a slightly smaller prop. A three blade composite would be my choice.

Or, someone wishing to scratch build could use the block and add the stroker crank. No real change in weight but 282 [email protected] and 329 HP at 3000.

So a range from 200 HP to 329 HP for the same weight engine. Also, remember that neither of these engines were optimized for aviation use which could wring even a little more power in the correct power range. Another thing to notice with the stroker engine is that even at 2500 rpms it makes 252 HP

The problem is there are few airframes which can use a 450lb engine in that 200-250hp range. The LS is more suitable to replace 520/540/550 Lyconentals. Too heavy to replace 320/360 engines even without a PSRU.
 

rv7charlie

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Nov 17, 2014
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3,001
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Pocahontas MS
Agree. Which means we need an airframe designed around the engine, not unlike what was happening back in the beginning with the Pietenpol & other early designs. Pick the powerplant, and design the airframe around it. Not just the weight, but cooling architecture, firewall height/shape, etc.

Ross, I'm sure you can testify about how much fun it is fitting water cooling onto an air cooled airframe, right?
 

Winginitt

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Apr 5, 2019
Messages
197
The problem is there are few airframes which can use a 450lb engine in that 200-250hp range. The LS is more suitable to replace 520/540/550 Lyconentals. Too heavy to replace 320/360 engines even without a PSRU.


I agree that its somewhat heavy compared to what its replacing, but I think careful planning could reduce that somewhat. The airplane would definitely loose some of its weight capacity, but the additional power might offset that. As I mentioned earlier, the oil pan weighs 15 lbs. Replacing it with a small fabricated alum pan would get that weight off the nose somewhat and allow it to transfer to a sump on the firewall. Still forward, but still better. I have a propellor from a 175 and it weighs 32 lbs. Perhaps a composite replacement . Its like the old saying, "the devil is in the details". Skydawg published a picture of a 172 that he says flys well with an LS but they had other issues they were having trouble resolving. So I guess its doable, just a matter of someone working thru the details.


As I went back in the thread to doublecheck some info, I noticed that apparently I had been banned from HBA. This is the first time I was aware of that, but I definitely don't want to participate any further after seeing that.......... Best of Luck to the many good people who use this site.
 
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