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Learning how to build Lotus Seven replicas...together!
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PostPosted: Tue Nov 09, 2010 12:23 am 
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oldejack wrote:
i think you're making more work for yourself than you need to. why start with too high of a compression for example? thats just one more thing to overcome. .. if you plan on shutting off (port) fuel injectors during (di) water injection events you don't need to change the cam just be able to switch between injectors as appropriate. a megasquirt can handle that easily after proper programming (no different than using an existing injector emulator on a gaseous fuel system really) the steam expansion will provide more power than the compression stroke used, then it becomes a question of "is it enough of a return?". back to the days of steam for power output calculation formulae :P you would want some sort of demand based steam cycle shutoff of course, and probably a minimum engine temp for operation. .. corrosion of course will be an issue, as would minerals buildup.
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" You need a camshaft of course to suit the 3 cycles, I'm sure Crower Cams have that info :). "?

you don't honestly expect crower cams to give away currently unused intellectual property do you, i like open source but selling "the fruits of employee and owner labor" is how they make their money. ..
besides, what would you do with the "third cycle" when you aren't using the steam, such as during warmup, have power drains?
.


I believe skimming a few mm off the top of a piston and adding a carby is a lot simpler than what you propose, seems like an afternoons work to me.

Yeah I do expect Crower to help out when you order the cam from them actually especially as Mr Crower left it as an open source. Other than the cams being reduced by 33% in their timing and split to suit the extra cycle I don't see whats difficult about it anyway?

Well most people warm their cars up anyway for a minute or 2, I don't see what the problem is there really?

Anyway this is a bit off topic, back on topic is the "Block 8" I propose ;

Motorcycle engines are a source of lightweight big hp for cars as some of you are aware.

Couple of problems, clutches are made to move 300kgs rather 1000kgs, same for the transmission, chain drive and no reverse.

We know there is a few V8's getting around that not only solve this problem but they also lighten your pocket by around $50,000USD

There is also the 4 cylinder case conversion that also solves all the problems and like the V8 you can bolt a normal RWD gearbox to it...

http://www.holeshot-racing.co.uk/index. ... =h2-4-busa (you can find one of the V8's there as well)


So I was thinking, why not a "Block 8" in the same concept as the 4 above - a casing made to accept 2 x bike engine internals saving you a truck load of cash through not requiring special crankshaft and rods. A dummy output shaft would be required.

It would still be compact and lightweight, less vibes, management systems can still be rolled into one etc...


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PostPosted: Tue Nov 09, 2010 8:23 am 
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cheapracer wrote:
So I was thinking, why not a "Block 8" in the same concept as the 4 above - a casing made to accept 2 x bike engine internals saving you a truck load of cash through not requiring special crankshaft and rods. A dummy output shaft would be required.

It would still be compact and lightweight, less vibes, management systems can still be rolled into one etc...

I still really like this idea. A V8 around 1.2 to 1.6L would be pretty sweet.

I had another idea for an engine design - a flat inline four with an integral gear set that brings the output shaft to the centerline of the engine. Laying an inline four flat wouldn't work alone, as it would be hanging off one side seriously screwing with where you'd want frame members to go, but if the block was made with an integral gear set that brought the output to the centerline (or center of mass), then you'd have an engine a lot narrower than a typical flat four, but with most of its benefits. Exhaust might be tricky... so perhaps it would have to be a slant-4 with 15 degrees off horizontal to allow for an exhaust header... Anyway, that's the idea. I would imagine one could use internals from an existing engine and simply redesign the block and head for proper oil flow while horizontal. Crazy? Needlessly complicated?

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PostPosted: Tue Nov 09, 2010 11:04 am 
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cheapracer wrote:
Well most people warm their cars up anyway for a minute or 2, I don't see what the problem is there really?


In the dead of winter, maybe. Otherwise 99.99% of the time it's start and go.


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PostPosted: Tue Nov 09, 2010 12:51 pm 
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nether10 wrote:
I still really like this idea. A V8 around 1.2 to 1.6L would be pretty sweet.

I had another idea for an engine design - a flat inline four with an integral gear set that brings the output shaft to the centerline of the engine. Laying an inline four flat wouldn't work alone,


It's not a V8, read it again please.

The biggest weight of an inline engine is the crankshaft along with it's rotational mass, people have tried this and it's not worth it for the very small % of lowered CG you get but around 45 degrees is ok to improve room for inlet tract flow as almost all sports bike manufacturers have proven. Chrysler did a lot of work slanting engines over for inlet tract gains in the 60's and 70's too.


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PostPosted: Tue Nov 09, 2010 1:53 pm 
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cheapracer wrote:
It's not a V8, read it again please.

So I was thinking, why not a "Block 8" in the same concept as the 4 above - a casing made to accept 2 x bike engine internals saving you a truck load of cash through not requiring special crankshaft and rods. A dummy output shaft would be required.


Oh. Missed that. So... basically you're proposing making a 2-input 1-output gearbox of sorts? Perhaps making this as the oil pan? Sorry, your description isn't painting a clear picture for me.

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PostPosted: Tue Nov 09, 2010 6:09 pm 
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Quote:
I believe skimming a few mm off the top of a piston and adding a carby is a lot simpler than what you propose, seems like an afternoons work to me.


ya know i gotta stop being snippy when my pain meds ain' working, i apologise for sounding that way.
with further thought would be pretty easy if you could shut off the oil supply to the lifters and therefore the resulting action just as chrysler is doing now on the hemi and cadillac did years ago. if you didn't open the intake valve at all on steam cycles and only gained the energy released from the block turning water into steam that would work and allow you to use a carb with no major problems(a bit of overcapacity at light load but so what. ..). you'd need to be putting in 2 steam production cycles for every combustion cycle to keep everything lined up so that would truly be a 6 cycle. a second lobe 180 degrees out from the stock one on the exhaust cycle, shut off the oil pressure when its not used and you're back to a 4 stroke cam, shut off the oil pressure again when you're in a steam cycle so the intake doesn't open and inject water(using what would be an intake stroke as a power stroke), then dump the steam using the added lobe on the exhaust valve and run a second steam cycle on what would be the 4 stroke power stroke then run a normal 4 stroke cycle then repeat. very repeatable, and not too hard to do using existing sensors (cam position, throttle position, engine temp, etc) and a fairly small microprocessor (or a rather large stack of opamps) to control a dump solenoid in the oil feed line to hydraulic lifters. you'd have something that would operate without any input from the driver other than throttle request making engine behavior controllable, repeatable and verifiable. unfortunately i disagree with it being "only a few millimeters" considering you'd be wanting to drop the mechanical compression by 1/2 which in my experience is rather larger than that and diesels typically have what in the gasoline world would be considered to be very mild cams therefore a high dynamic compression as well. possibly a severe dish? compression ignition pistons are a LOT stronger than spark ignition so there would be a lot you could remove but they are quite a bit heavier in every part than a spark ignition engine which massively increases the reciprocating mass.

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PostPosted: Wed Nov 10, 2010 12:23 pm 
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nether10 wrote:

Oh. Missed that. So... basically you're proposing making a 2-input 1-output gearbox of sorts? Perhaps making this as the oil pan? Sorry, your description isn't painting a clear picture for me.


maybe this will help ...

As my Dad always says to me - "It's been done before".

Here is 2 American Bantam engines stitched together in the exact way I propose the Block 8, dummy shaft and all ... it's got 2 whole engines in there, 2 cranks and all....

1938!!

Image

Image


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PostPosted: Wed Nov 10, 2010 12:38 pm 
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oldejack wrote:
Quote:
I believe skimming a few mm off the top of a piston and adding a carby is a lot simpler than what you propose, seems like an afternoons work to me.


ya know i gotta stop being snippy when my pain meds ain' working, i apologise for sounding that way.
with further thought would be pretty easy if you could shut off the oil supply to the lifters and therefore the resulting action just as chrysler is doing now on the hemi and cadillac did years ago. if you didn't open the intake valve at all on steam cycles and only gained the energy released from the block turning water into steam that would work and allow you to use a carb with no major problems(a bit of overcapacity at light load but so what. ..). you'd need to be putting in 2 steam production cycles for every combustion cycle to keep everything lined up so that would truly be a 6 cycle. a second lobe 180 degrees out from the stock one on the exhaust cycle, shut off the oil pressure when its not used and you're back to a 4 stroke cam, shut off the oil pressure again when you're in a steam cycle so the intake doesn't open and inject water(using what would be an intake stroke as a power stroke), then dump the steam using the added lobe on the exhaust valve and run a second steam cycle on what would be the 4 stroke power stroke then run a normal 4 stroke cycle then repeat. very repeatable, and not too hard to do using existing sensors (cam position, throttle position, engine temp, etc) and a fairly small microprocessor (or a rather large stack of opamps) to control a dump solenoid in the oil feed line to hydraulic lifters. you'd have something that would operate without any input from the driver other than throttle request making engine behavior controllable, repeatable and verifiable. unfortunately i disagree with it being "only a few millimeters" considering you'd be wanting to drop the mechanical compression by 1/2 which in my experience is rather larger than that and diesels typically have what in the gasoline world would be considered to be very mild cams therefore a high dynamic compression as well. possibly a severe dish? compression ignition pistons are a LOT stronger than spark ignition so there would be a lot you could remove but they are quite a bit heavier in every part than a spark ignition engine which massively increases the reciprocating mass.

Wouldn't keeping the intake valve closed on the steam cycle create a large power loss due to unneeded vacuum?

Bill


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PostPosted: Wed Nov 10, 2010 12:44 pm 
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cheapracer wrote:
nether10 wrote:

Oh. Missed that. So... basically you're proposing making a 2-input 1-output gearbox of sorts? Perhaps making this as the oil pan? Sorry, your description isn't painting a clear picture for me.


maybe this will help ...

As my Dad always says to me - "It's been done before".

Here is 2 American Bantam engines stitched together in the exact way I propose the Block 8, dummy shaft and all ... it's got 2 whole engines in there, 2 cranks and all....

1938!!

Image

Image


i knew i'd seen this before in a production motorcycle, had to go back to being a teenager to find it.
produced for over 20 years i present to you the Ar-i-el square four;http://www.arielnorthamerica.org/squarefour.htm

Quote:
Turner’s innovative design featured chain-driven single overhead camshafts, and was effectively two parallel-twin engines with their crankshafts geared together and turning in opposite directions. This had the advantage of being not only very well-balanced but also compact, which allowed the original 497cc engine to be fitted to a slightly modified Ar-i-el single-cylinder chassis, saving the firm from Selly Oak in Birmingham both money and development time.

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PostPosted: Wed Nov 10, 2010 12:55 pm 
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Quote:
Wouldn't keeping the intake valve closed on the steam cycle create a large power loss due to unneeded vacuum?
Bill

i think it would sort of but the steam should be creating a positive pressure, i suspect it become a question of water injection event timing to a large degree. there has to be some point of diminishing returns but calculating them?

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PostPosted: Wed Nov 10, 2010 4:21 pm 
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oldejack wrote:
Quote:
Wouldn't keeping the intake valve closed on the steam cycle create a large power loss due to unneeded vacuum?
Bill

i think it would sort of but the steam should be creating a positive pressure, i suspect it become a question of water injection event timing to a large degree. there has to be some point of diminishing returns but calculating them?

I think you have to decide why you are designing such a hybrid engine. To me, the whole point is to achieve maximum efficiency. Otherwise, its a lot of complications and for what? If efficiency is the goal, why settle for half a loaf? There comes a time when pencil and paper has to put away and DATA created. I think this would one of those times. I would then say "220, 221. Whatever works."

Bill


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PostPosted: Wed Nov 10, 2010 5:17 pm 
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In the spirit of the Bantam engines stitched together, that's probably the best way to approach this project.

Use existing pieces in a way the factory didn't. 2 cranks isn't the ideal set up from the stand point of rotating weight but it's a heck of a lot easier and cheaper than machining or casting special pieces.

Motorcycle engine pieces would seem to be the easiest and lightest way to do this. Simply use more cylinders than the bikes used.

Transition to transmission is probably the toughest part to get right and to get light.

To make 4+ rotor Wankel engines they use some sort of 2 piece connector. Your side by side cranks is in that vein.

From a car engine concept something like the wet sleeve block of the Alfa engine in another thread would be a way to increase capacities of an older engine thru special sleeves. I can't believe that would be all that expensive to cut down a sleeve from one engine and fit it in another. Then add newer/different heads & a megasquirt to get modern day power levels.

Pick from the parts bin instead of from thin air.

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PostPosted: Wed Nov 10, 2010 8:58 pm 
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carguy123 wrote:
In the spirit of the Bantam engines stitched together, that's probably the best way to approach this project.

I do like it, but I see one issue right away: your new output would be spinning backwards, unless you can figure out how to mount the existing crankshafts in backwards to put their output on the other side.

Hmmm... now that I'm thinking about it, I can't say I know for sure which way a bike engine spins, as compared to a car engine. I can only assume the same way, but can anyone confirm that?

Of course, you could always make lemons into lemonade... take a couple of Honda D or B series engines, apply them in this same manner, and have yourself the sweetest-revving 3.2L V8 that has tons of aftermarket support. Hmmm!!

Actually... wait, those engine blocks are flipped 180 degrees to each other, so only one crankshaft would have to be flipped... but then you wouldn't need the middle output shaft, you could simply gear one with the other... aaaaand now my head hurts. :BH:

Regardless of my confusion, this seems like a good way to go.

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PostPosted: Wed Nov 10, 2010 9:39 pm 
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There's also the not-insignificant issue of harmonics. Where I work we tried building our own twin-crank Diesel, and after several million on developement, we shelved it due to harmonics causing havoc on the crank and bearings. Just because something can be bolted together with existing parts doesn't guarantee no issues. Just sayin'.

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PostPosted: Wed Nov 10, 2010 10:47 pm 
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KB58 wrote:
There's also the not-insignificant issue of harmonics. Where I work we tried building our own twin-crank Diesel, and after several million on developement, we shelved it due to harmonics causing havoc on the crank and bearings. Just because something can be bolted together with existing parts doesn't guarantee no issues. Just sayin'.


well thats one killer issue with multiple crankshaft engines. its simpler if the power strokes cancel each other out. easier to do in a 2 stroke than a 4 stroke.


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