Direct drive SBC

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MARCVINI

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I agree with you in this case I was referring to the ford being in the middle and not being able to take the thrust.
Well, as I said before, believe it or not, practice has been showing that Ford V8s and other engines with thrust bearing in the middle CAN take the thrust with no problems. This particular plane has loged more than 1400hs and conting!!! LongEZ V8

Tailwinds.
 

Doggzilla

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I have a question...

What parts would be required to use NOS, without reducing reliability? Because there must be an optimal trade off between the power and additional weight required for reliability. How much heavier would the crank, pistons, and rods have to be? And any other components, as well?

Thanks, and keep up the great work and mentoring!
 

MARCVINI

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I have a question...

What parts would be required to use NOS, without reducing reliability? Because there must be an optimal trade off between the power and additional weight required for reliability. How much heavier would the crank, pistons, and rods have to be? And any other components, as well?

Thanks, and keep up the great work and mentoring!
Jesus Christ!!! Is it "Drag Flying" you are talking about??? Well, not nonsense as a power add on for, say, shortest take offs in "special" ocasions. Something to be thought about...

Cheers.
 

MARCVINI

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Stol, this one is for you, regarding SBFs:

Since Windsor cranks are the beefiest on the business (3.000 mains), and, therefore, they certainly favor a simple prop extension set up, my question is: is it possible to use one of those in a SBF aluminum block whose main caps and stuff are made for Cleveland (2.750) mains by virtue of boring them to 3.000 inch?

Tailwinds.
 
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Vigilant1

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Jesus Christ!!! Is it "Drag Flying" you are talking about??? Well, not nonsense as a power add on for, say, shortest take offs in "special" ocasions. Something to be thought about...

Cheers.
I have heard of at least one amphibian that has a Mazda 13B Wankel and NOS as a boost to get up on the step and take off. It's lighter than a turbo or any other means of boosting HP. The setup provides the "kick" for the short time it is needed without a lot of extra weight and complexity for the other 99% of his flying time.
 

Doggzilla

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Usually I dont like NOS, its usually considered cheating by most muscle car guys... but weight is weight. If you need to use the lightest boost system, you need the lightest boost system.
 

jac

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The Long Eze has an alloy SVO RD1 block of 8.2 deck height and therefore very likely to have a crank with 2.250" main brg dia, its bored & stroked to ~360 cubic inch, so that will be 3.4" stroke x 4.125 + OS bore. He mentions occasions of valve seat recession so I dont believe that the 1000+ hours can have been entirely maintainance free.
More of a consideration, these aftermarket steel cranks have either 2.125" SBF or 2.100" dia crankpin/rod sizes being used so your asking the thrust forces to pass thru a smaller pin overlap area in 4 places before reaching the thrust bearing face.
 

MARCVINI

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The Long Eze has an alloy SVO RD1 block of 8.2 deck height and therefore very likely to have a crank with 2.250" main brg dia, its bored & stroked to ~360 cubic inch, so that will be 3.4" stroke x 4.125 + OS bore. He mentions occasions of valve seat recession so I dont believe that the 1000+ hours can have been entirely maintainance free.
More of a consideration, these aftermarket steel cranks have either 2.125" SBF or 2.100" dia crankpin/rod sizes being used so your asking the thrust forces to pass thru a smaller pin overlap area in 4 places before reaching the thrust bearing face.
Hey, thanks for your contribution!!!

You see, given the dimensions of that engine, mainly crankshaft´s, and that its propeller extension is 9 inches long, it is something to be impressed with. And more importantly, those details show how better a beefier crank can take the propeller´s thrust and radial forces. Not that those forces were causing any problem to that engine.

I have been doing some research and I got amazed by the fact that, in general, Lycomings have 2.375 inch mains for 360s and "smaller" 540s (260 and 290hp) , and 2.625 inch mains for 540-Ks and up. On the other hand, SBC 350s have 2.45 inch mains, SBC400s have 2.65 mains and BBCs have 2.75 mains. Except for 302 derived engines, Fords have even beefier cranks: 2.75 inch mains for 351 Cs (Clevelands), 3.00 inch for 351Ws (Windsors) and 3.00 inch for Big Blocks. Rod journals and thrust bearing thrust faces are bigger accordingly.

So, in general, I am sure that a 351C like crank, or even a 351w like crank, may give me quite a safety margin for a simple prop extension set up. I do not intend to use a bigger than 6 inches a prop extension.

As for the cylinder head problems Gary Spencer reported, they certainly happened because of the tremendous high compression ratio he used (11:1), its correlated heating and, of course, the fact that he spins his engine till 3400 rpm while racing. And he races a lot. Another factor to be considered is that he might have used 100 LL without lead scavenger. You see that even 3400 rpm is mild reving for that engine, so there must be something, or, many things in that engine that´ve led to that problem.

I intend use valve seat materials that are capable of handling 100LL as aeronautical engines´cylinder heads are. I also intend to spin my engine considerably slower than Garys, as well as use milder compression ratio. Those things will certainly add up to more reliability and less heat.

I have seen that you have quite an experience with that p76 engine in inverted form. How is it faring so far?

Marcvini
 
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jac

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Not so sure that the seat erosion is directly related to compression ratio, ( used to build jet boat engines in the tourist industry that ran all day @~3800 rpm ), we had terrible valve seat erosion on those that was tracked down to valve spring & camshaft lobe profile. Was not spring pressure but more a case of selecting a spring and camshaft that were compatible with no harmonic issues in the rev range used. Also had to remove any valve train hardware that promoted valve rotation, IMHO the industry has this factor wrong now that lead has been removed/reduced and I now build everything using narrow seats, tighter valve lash settings and cam lobe profiles with gentle open/close ramps, so far it working!:)

The P76 has been good in terms of flying, A/C down at this time for change to Ellison TB from previous auto 2bbl electronic TB which was not performing up to spec.
A/C has nose gear like RV6A and IMHO could do with a rethink especially for use on the grass strips use locally, not a problem, just 'looks' wrong!:)
 

MARCVINI

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Usually I dont like NOS, its usually considered cheating by most muscle car guys... but weight is weight. If you need to use the lightest boost system, you need the lightest boost system.
I really liked your idea. It certainly has its place in certain circunstances. Worth looking at it.

Cheers
 
E

ekimneirbo

Hey, thanks for your contribution!!!

You see, given the dimensions of that engine, mainly crankshaft´s, and that its propeller extension is 9 inches long, it is something to be impressed with. And more importantly, those details show how better a beefier crank can take the propeller´s thrust and radial forces. Not that those forces were causing any problem to that engine.

I have been doing some research and I got amazed by the fact that, in general, Lycomings have 2.375 inch mains for 360s and "smaller" 540s (260 and 290hp) , and 2.625 inch mains for 540-Ks and up. On the other hand, SBC 350s have 2.45 inch mains, SBC400s have 2.65 mains and BBCs have 2.75 mains. Except for 302 derived engines, Fords have even beefier cranks: 2.75 inch mains for 351 Cs (Clevelands), 3.00 inch for 351Ws (Windsors) and 3.00 inch for Big Blocks. Rod journals and thrust bearing thrust faces are bigger accordingly.

So, in general, I am sure that a 351C like crank, or even a 351w like crank, may give me quite a safety margin for a simple prop extension set up. I do not intend to use a bigger than 6 inches a prop extension.

As for the cylinder head problems Gary Spencer reported, they certainly happened because of the tremendous high compression ratio he used (11:1), its correlated heating and, of course, the fact that he spins his engine till 3400 rpm while racing. And he races a lot. Another factor to be considered is that he might have used 100 LL without lead scavenger. You see that even 3400 rpm is mild reving for that engine, so there must be something, or, many things in that engine that´ve led to that problem.

Reply: Something to consider here about crankshaft selection. I think within reason your choice of a short prop adapter is a good idea in respect to its ability to act as a lever on the crank. Not sure how it plays out aerodynamically. Earlier you had mentioned possibly not using a full flywheel as you felt that the momentum of the prop would be sufficient. Not sure if you are still leaning in that direction. I would use a regular flywheel (maybe lightened some with most mass toward the outer diameter where its more effective. If you rely on a prop for rotational momentum you may need a heavy prop....and I don't think that would be a good choice. Heavier flywheel(not real heavy)and lite prop (wood or composite) would be my recommendation. As for the crankshaft, I would look for a good aftermarket forged crank as the aftermarket ones are usually better quality and material than factory units and be sure to get large fillet radaii on all journals...which usually requires narrower bearings to accomodate the fillets. IMHO, large fillets are major players in crankshaft durability.
 

MARCVINI

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Something to consider here about crankshaft selection. I think within reason your choice of a short prop adapter is a good idea in respect to its ability to act as a lever on the crank. Not sure how it plays out aerodynamically. Earlier you had mentioned possibly not using a full flywheel as you felt that the momentum of the prop would be sufficient. Not sure if you are still leaning in that direction. I would use a regular flywheel (maybe lightened some with most mass toward the outer diameter where its more effective. If you rely on a prop for rotational momentum you may need a heavy prop....and I don't think that would be a good choice. Heavier flywheel(not real heavy)and lite prop (wood or composite) would be my recommendation. As for the crankshaft, I would look for a good aftermarket forged crank as the aftermarket ones are usually better quality and material than factory units and be sure to get large fillet radaii on all journals...which usually requires narrower bearings to accomodate the fillets. IMHO, large fillets are major players in crankshaft durability.
Hy, ekimneirbo,

A 6 inch prop extension seem to provide a good set up for keeping most of the original lines of the Sportsman untouched. Of course, as for what my "projections" show, the original cowling would have to be lenghtened to 5 or 6 inches, as well as the lower cowling would have to be changed a little bit in order to accomodate the lower part of the engine. But, all in all, no big deal aerodynamically wise.

Wittman´s inverted V8 instalations, wich use light wood props, as well as the miriads of 540s and 360s with the same set up and almost no flywheel to tame their pulses seem to be a good indicator that a full size or even a lightened flywheel wouldn´t be necessary in my instaltion, specially considering that it is going to be a much more smooth running engine than its aeronautical counterparts. Specially the Canard crowd use those engine/prop combinations, some of them with 8 inc prop extensions and seem to have no problems at all. Even Gary Spencer´s Long EZ has the same set up. Another factor to be taken into account is that with a projected 240/250 hp I will be able to use a prop that is pitched enough to counteract engine pulses by a fair amount and, on the other hand, provide decent thrust during climb.

Another insteresting element for comparison is that a Lycs stroke, be it 360 or 540, is 4.375 inches. I foresee that my proposed engine will not be more than 4.170 inch stroke. So, appart from the bigger number of cylinders and, therefore, bigger number of pulses per crank revolution, that reduced stroke (in comparison to 360s and 540s) play a good role on providing a much more smooth running engine.

But this is MY THEORY and precaution says that your observations have to be taken into account once I start testing that proposed installation. So, thank you again for your contribution "for the cause".

As for crank selection, a good forged one is mandatory and nothing less is acceptable. If I go the SBF way, a Windsor derivative would be my favorite, since it has 3.000 inch mains (!!!) and all other dimensions are bigger accordingly. For comparison sake, a 260hp 540 has 2.375 inc mains (!!!). This seems to indicate that I will have a ratherly beefy instalation. You see, I believe that even a Cleveland derivative would do the job, since it has 2.75 inch mains. And if I go the SBC way, a 400 derivative is high priority, since it has 2.65 mains.

Cheers.
 
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blainepga

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Stol, this one is for you, regarding SBFs:

Since Windsor cranks are the beefiest on the business (3.000 mains), and, therefore, they certainly favor a simple prop extension set up, my question is: is it possible to use one of those in a SBF aluminum block whose main caps and stuff are made for Cleveland (2.750) mains by virtue of boring them to 3.000 inch?

Tailwinds.

The larger crank is a cast crank. Use the other (2.75 mains) crank, I believe it is a forging and still stronger than the cast crank.

Blaine
 

MARCVINI

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The larger crank is a cast crank. Use the other (2.75 mains) crank, I believe it is a forging and still stronger than the cast crank.

Blaine
Scat has them forged. Biggest stroke seems to be 4.100 inch, wich allows to get a 427 plus stroker. With 2.75 mains I can get up to 4.250 stroke.

Cheers.
 

MARCVINI

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MARCVINI

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I have found little information about the Sauser P6E Hawk, a 80% Curtiss Hawk Replica, powered by a DD SBC 350. The most I have found is that one exemplary belongs to Keith Roof, from EAA Chapter 33. Anyone has more details about this airplane??? Maybe Mr. Roof´s email? Here are some videos of this aircraft: http://alexisparkinn.com/photogallery/Videos/2007-3-27-KeithRoofsP6EHawk.wmv
http://www.ameliaslanding.com/images/Videos/2007-4-29-P6E-2nd-flight.wmv

Tailwinds
Well, this aircraft crashed after 45 hours total time. It seems that pilot error was the accident cause. Thank God the pilot seems to be is alive and well, although had sustained serious injuries. Anybody has contact with Mr. Roof?

Marcvini
 

jac

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Couple of articles on that P6e replica A/C or the original in Sport Aviation IIRC (Feb 1998).
Ford factory cranks for both 351c/351w are cast, some with higher nodular content. I have see enough broken cast cranks to know I wouldnt want a cast crank to be the only means of prop thrust control in an aircraft application:)..
Forged examples are available from Ford Motorsport, SVO etc as bare forgings, semi finished, & finished @ several stroke options. IIRC these do not have enough material to allow 3" mains,Scat & others do have the 3" main option. The 4.25" stroke version requires extra mods in the cam/con rod clearance and bottom of the cylinder & pan rail area.
 
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Toobuilder

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I have found little information about the Sauser P6E Hawk, a 80% Curtiss Hawk Replica, powered by a DD SBC 350....
Talked to a P6 replica owner in Corona a few years ago and he said the DD350 was adequate, but if he were to do it over, he would build a 500 inch Cadillac instead. Not much heavier, but a lot more low end grunt.
 
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