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PostPosted: March 31, 2012, 12:29 am 
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Driven5 wrote:
You're probably more well aware of the intricacies than I am, but I don't know that I'd be looking too closely at the Model A engine for design inspiration. :wink:
http://www.modelaengine.com/

Only for the water jacket, as the A has easy access to that part of the design.
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So which way did you ultimately end up going with the overall head layout and design, or are you still not 100% certain yet?

It's a 90 degree V engine, initially a V-twin or V4, depending on if I can get two more liners. Head layout will be overhead valve, I think I have that nailed down in how to do it. The rods will be a Fork and Blade connecting rod. Huron head design, to keep it simple. I am keeping the stroke low, and the rods long, to reduce side-stresses and improve performance. The head flow was designed by my friend around his racing engines porting, which gives them a lot of breathing room. Two valve per engine, due to the needs of the casting method being used. Any more would be too complex. As it is now, will be pushing the limits of my small foundry's abilities.
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I have to say your updates keep me coming up with crazy ideas of building an engine someday too...Of course then I either decide there's already something too similar already available, or even for all of its unique glory can't justify the expense for something that will likely never perform (horsepower, torque, fuel economy, emissions, reliability, or longevity) anywhere near as well as most any of the previously mentioned production engines in addition to probably costing an order of magnitude more when all is said and done.

IKWYM, but at the same time, there's that inner voice going "You can do it your own way" and then suddenly I feel like putting on some Sinatra...
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Aren't you in the Seattle area, or nearby? If you ever want to grab a beer and talk engines or whatnot, shoot me a PM

Just north of it in Lynnwood, and sure.


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PostPosted: March 31, 2012, 2:47 am 
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Downix wrote:
It's a 90 degree V engine, initially a V-twin or V4, depending on if I can get two more liners. Head layout will be overhead valve, I think I have that nailed down in how to do it. The rods will be a Fork and Blade connecting rod. Huron head design, to keep it simple. I am keeping the stroke low, and the rods long, to reduce side-stresses and improve performance. The head flow was designed by my friend around his racing engines porting, which gives them a lot of breathing room. Two valve per engine, due to the needs of the casting method being used. Any more would be too complex. As it is now, will be pushing the limits of my small foundry's abilities.
That sounds like a rather practical starting point. It will certainly be exciting to follow along as you start getting cast pieces out.


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IKWYM, but at the same time, there's that inner voice going "You can do it your own way" and then suddenly I feel like putting on some Sinatra...
Yes, and maybe once you get your design proven out we'll have to start discussions about the possibility of a small displacement V12. :mrgreen:


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Just north of it in Lynnwood, and sure.
I'm right down on the border of Kirkland/Bothell. :cheers:

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PostPosted: April 2, 2012, 10:23 am 
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Learned yesterday of a way to run an aluminum cylinder wall, chrome plated pistons and rings. Opens up more options. Wears out faster but for a proof of concept may work.

Finished the crankshaft design for the V4 last night. If my calculation is right I should have a ~70hp engine at the end of this. The Model A water jacket has been very educational. Although once done, anyone know someone rebuilding a Model A?


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PostPosted: April 2, 2012, 10:48 am 
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Interesting, I would not have thought to run chrome pistons/rings on bare aluminum. How many cc's will this V4 displace for that ~70hp proof of concept?

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PostPosted: April 2, 2012, 11:06 am 
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Driven5 wrote:
Interesting, I would not have thought to run chrome pistons/rings on bare aluminum. How many cc's will this V4 displace for that ~70hp proof of concept?

Some cheap B&S motors use the bare aluminum method and Çhevy also used it in a few smaller engines.

Calculated displacement is 1166 CC. The short stroke would allow higher rpm to keep the HP up.


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PostPosted: April 3, 2012, 9:06 pm 
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Downix wrote:
Some cheap B&S motors use the bare aluminum method and Çhevy also used it in a few smaller engines.


Downix,

I'm not aware of the B&S + Chevy examples, but I'd have presumed they would require some sort of coating.
e.g. Nikasil.
.. in which case they're very tough, yet don't have the weight & hassle of a steel lining.

Cheers - Gavin.


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PostPosted: April 4, 2012, 4:51 am 
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gavin_eakins wrote:

I'm not aware of the B&S + Chevy examples, but I'd have presumed they would require some sort of coating.
e.g. Nikasil.
.. in which case they're very tough, yet don't have the weight & hassle of a steel lining.


B&S are plain aluminium, very short life engines.

The Chevy Vega engine problems and development is interesting reading, it's on the net because that's where I read it :-)

Here's one I found in 20 seconds ... http://ateupwithmotor.com/model-histori ... worth.html


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PostPosted: April 4, 2012, 5:26 am 
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cheapracer wrote:
B&S are plain aluminium, very short life

For quick and dirty testing it would be adequate. Or can chrome the liners, tun iron rings and plain pistons like tractor engines.


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PostPosted: April 8, 2012, 3:18 am 
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Driven5 wrote:
Yes, and maybe once you get your design proven out we'll have to start discussions about the possibility of a small displacement V12. :mrgreen:

You *Had* to say V12 didn't you! V12 requires a 60 degree, not 90 degree, to balance, and cannot use a flat crankshaft due to balance as well....

And just finished designing the crankshaft for a 60 degree V12...

GAH!


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PostPosted: April 8, 2012, 3:49 am 
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Really? Everything I've read on V12's indicates that since I6's are inherently balanced, and that a V12 is just 2 I6's that share crank pins...That they can be configured at essentially any angle, but are generally 60* or 90* with a few 180* "flat" (not horizontally opposed/"boxer") variants thrown in for good measure. But you are definitely correct that they do not use a flat plane crank, but rather a 120* offset between crank pins

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PostPosted: April 8, 2012, 1:38 pm 
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Driven5 wrote:
Really? Everything I've read on V12's indicates that since I6's are inherently balanced, and that a V12 is just 2 I6's that share crank pins...That they can be configured at essentially any angle, but are generally 60* or 90* with a few 180* "flat" (not horizontally opposed/"boxer") variants thrown in for good measure. But you are definitely correct that they do not use a flat plane crank, but rather a 120* offset between crank pins


I'm going by the details on the Jaguar V12 I've found, which says that 90 degree was more difficult to balance the exhaust, not by much but still more. I should have been more clear there.

I think I'll just stick to the V-twin, but now, 90 degree for V4/V-8, or 60 degree for V12 / V6 / slant-6? 60 degree would make the engine narrower, that is for certain, and easier to fit into the Locost body.


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PostPosted: April 8, 2012, 3:19 pm 
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Height is the biggest issue for fitting in a Locost. Modern I4 don't seem to fit without hood bulges or oil pans hanging below the frame a good distance.

A V4 is so short it fits in the widest part of the engine bay. Maybe you could use some heads from a pushrod Subaru. I'm not sure if you want to build every piece yourself right, that could be a help.

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PostPosted: April 8, 2012, 8:24 pm 
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horizenjob wrote:
Height is the biggest issue for fitting in a Locost. Modern I4 don't seem to fit without hood bulges or oil pans hanging below the frame a good distance.

A V4 is so short it fits in the widest part of the engine bay. Maybe you could use some heads from a pushrod Subaru. I'm not sure if you want to build every piece yourself right, that could be a help.

The head is the part I am least concerned about, as I have a head builder on speed dial who is already pretty close to finished with the custom head.

Height is very much on my mind, hence the off-center OHC design (which the Heron head valve design allows). From the front, it looks like a DOHC setup, but missing the exhaust valve cam, narrowing the engine. As the cam is lifting up, rather than pushing down, it is located lower in the head than the typical cam-in-head layout (something stolen from another Chevy engine design I saw).

I did, however, mis-speak. I said 60 degree, but I was still in design mode, where the bore was 60 degrees off-center. As both cylinders are 60 degrees off center, it is 120 degrees if I do the V12/V6-optimized design, or a 60 degree slant if I do a slant-6 (which is quite appealing once I sat down and studied it some). I still have the V4 and V-twin pretty close to completion and should have the twin up tonight after dinner. (I am being realistic, using the twin will tell us just as much as the 4, and be a lot simpler to build).


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PostPosted: April 8, 2012, 11:53 pm 
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The balanced exhaust comment makes sense, as the angle which produces the most even single-cylinder exhaust pulse spacing for a V12 is 60 degrees. But to the best of my knowledge, which is admittedly not as all-encompassing as I would sometimes like it to be, the fully balanced first and second order forces of each I6 within the engine are unaffected by the angle of the V12. Very interesting that you've actually decided to go 120* on the V6/V12 architecture...With a small displacement and compact heads to keep it to a reasonable width, the reduced height of the 120* angle just adds intrigue. With that shallow of an angle, will the oiling system design be borrowing anything from Subaru? Don't want to design in any deficiencies that could cause trouble like GM has had with the Gen III/IV small blocks when really going around corners.

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PostPosted: April 9, 2012, 1:30 am 
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Driven5 wrote:
The balanced exhaust comment makes sense, as the angle which produces the most even single-cylinder exhaust pulse spacing for a V12 is 60 degrees. But to the best of my knowledge, which is admittedly not as all-encompassing as I would sometimes like it to be, the fully balanced first and second order forces of each I6 within the engine are unaffected by the angle of the V12. Very interesting that you've actually decided to go 120* on the V6/V12 architecture...With a small displacement and compact heads to keep it to a reasonable width, the reduced height of the 120* angle just adds intrigue. With that shallow of an angle, will the oiling system design be borrowing anything from Subaru? Don't want to design in any deficiencies that could cause trouble like GM has had with the Gen III/IV small blocks when really going around corners.


Now, if you run twin tailpipes, the angle doesn't really matter, but why limit the design to only twin pipes when an up front design could allow either?

The oiling system I baselined to a dry sump system, for two reasons:

1) the deeper wet sump pan hurts overall engine height and I want to make sure I don't scrape the pan when bottoming out.

2) My first motorized vehicle was a Suzuki motorcycle which ran a dry sump, and it spoiled me for when I ran a normal sump later on. With it's multipoint direct injection, and multiple pickups, I could out-corner anything else without concern about oil flow.

The Mopar Slant 6 ran at the same 60 degree off center angle, and had a reputation for reliability even in racing configurations for its oil delivery system. Between it, the Subaru and my old Suzuki, I am not taking risks, although I may be over-zealous in working to ensure proper oil delivery. The oil pump itself would sit in the traditional pushrod camshaft location, allowing an extra pickup pump per engine cylinder pair. For the V-twin, only the single pickup and sending pump would be present while the V4 would have two pickup and the sending, V6 having three pickup, and so forth. It would also be the gear used to transfer from the crankshaft to the camshafts.


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