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Learning how to build Lotus Seven replicas...together!
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PostPosted: Sun Feb 12, 2012 3:05 pm 
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horizenjob wrote:
If you want to make something that is better for a locost then what is available that is a pretty high bar these days. That said we do have different needs. Lots of horsepower per displacement is pretty useless as a primary goal for us, but it is good for advertising so that's a lot of what is available in the junk yards or donors. For us small physical size and light weight are the big primary factors. So I would expect pushrods and relatively large displacement. A typical airplane engine can be 6 liters and under 300 pounds...

Another approach would be to get something fun. So a small V8 of 2+ liters. Again pushrods for size.

I remember a Lotus designed engine for a light airplane from years ago. It had one piece cylinder and head to avoid head gaskets. That would help for boost and might be simpler. You could also use a combustion chamber in piston design with that like the Ford Kent engines. Pistons for those are easy to come by and would produce simple machining, one of the goals.

I think pollution requirements are a non starter. You could pass the tests, maybe. Those tests are to check the engine is sort of complying with the certification though. That certification is a many million dollar prospect, I would imagine.

Just for fun here's a picture of a downsized Cosworth V8 for an FSAE car. It's a small picture, sorry.


I was unaware of the Kent piston design, it simplifies things dramatically, and doing some checking it is readily available and quite simple to cast oneself if desired. The one piece cylinder/head design is part of the Corvair documents I ran across, as GM was experimenting with just such a design as part of their Modular Engine program, and is one of the pieces I am very interested in due to the elimination of head gaskets. Was unaware Lotus was working on a similar idea. I still like overhead cams, but pushrods do simplify things.

I have Californias emissions target rules, but not the full manual. The goal for me would be to hit the target, even if proper testing cannot be done. The target, just to put it out there would be to hit this result (in grams/mile):

Non-Methane Organic Gasses: 0.25
Carbon Monoxide: 3.4
Nitrogen Oxides: 0.4
Particulate Matter: 0.08

I've found a lot of tricks to address these, such as dual sparkplugs and using a three-way catalytic converter. Controlling the temperature is also important, to reduce the NOx emissions.


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PostPosted: Mon Feb 13, 2012 9:05 am 
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Downix wrote:

I was unaware of the Kent piston design, it simplifies things dramatically,


It's called a Heron Head, cheap for production but inefficient, bad for fuel economy and emissions and you won't find it on anything anymore. Had some minor success in racing in the 60's but on small bore, hi revving engines. Look up the history of the Jaguar XJS V12.

And sure it runs on every Formula Ford engine in the world (until recently) but that's because they have no choice.


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PostPosted: Mon Feb 13, 2012 9:09 am 
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There's a BIG topic on it over at speed talk:

http://speedtalk.com/forum/viewtopic.php?f=15&t=28861

I stumbled into here over the weekend and was surprised to see this topic had "taken off" to some degree. Should I reopoen the "Open Engine Design Project" forum again?


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PostPosted: Mon Feb 13, 2012 11:03 am 
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Quote:
It's called a Heron Head, cheap for production but inefficient, bad for fuel economy and emissions and you won't find it on anything anymore.


The cheap for production part makes it efficient for home made engines, would it not? If you're going to measure efficiency the same way major manufacturers do, there is little point to making your own engine. This is partly why engines don't fit in our cars and tend to be so heavy. Those are not factors which manufactures want or need to measure.

If you're not going to be passing an emissions test or only drive the car on the track bad fuel economy or emissions may not matter. It isn't efficient to measure things that don't matter in your efficiency...

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PostPosted: Mon Feb 13, 2012 12:07 pm 
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cheapracer wrote:
Downix wrote:

I was unaware of the Kent piston design, it simplifies things dramatically,


It's called a Heron Head, cheap for production but inefficient, bad for fuel economy and emissions and you won't find it on anything anymore. Had some minor success in racing in the 60's but on small bore, hi revving engines. Look up the history of the Jaguar XJS V12.

And sure it runs on every Formula Ford engine in the world (until recently) but that's because they have no choice.

I checked and the Heron is listed as a way to improve both efficiency and emissions over other systems of the day and was used until a decade ago by Peugeot ans Volvo until modern computer fabrication made a better solution.


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PostPosted: Mon Feb 13, 2012 12:41 pm 
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This may be a dumb question Downix, but what exactly are your goals and desired outcomes with this engine project? It appears that you're anxious to further prove out your casting methods and skills, but beyond that I really haven't seen any method to your madness since you restarted this thread...Which subsequently seems be fueling much of your indecision. What you need to do if you're just looking for a 1-off DIY project to prove that you can construct a running engine is completely different than if you're looking to develop something saleable to fill some perceived gap in the market. If you start out by asking yourself the right questions at the beginning of any project, the answers are what will help narrow your options and guide you towards the decisions that will ultimately determine your plan of action.

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PostPosted: Mon Feb 13, 2012 2:05 pm 
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Driven5 wrote:
This may be a dumb question Downix, but what exactly are your goals and desired outcomes with this engine project? It appears that you're anxious to further prove out your casting methods and skills, but beyond that I really haven't seen any method to your madness since you restarted this thread...Which subsequently seems be fueling much of your indecision. What you need to do if you're just looking for a 1-off DIY project to prove that you can construct a running engine is completely different than if you're looking to develop something saleable to fill some perceived gap in the market. If you start out by asking yourself the right questions at the beginning of any project, the answers are what will help narrow your options and guide you towards the decisions that will ultimately determine your plan of action.

I hit some fustration awhile back in finding that while engine technology knowledge is available, there is little actual material on the fabrication. I am a firm believer in open systems, which means having a system which can be fabricated should be there, if nothing else as a reference point. I see the rise of small scale CNC and 3D printshops as a sign of the future, but one which needs the embers to be fed to it, embers in this case being items which can be fabricated. While personally I see something I can cast, my eye beyond that is to give a small seed for others to build off of if they so choose. If it was just for my pleasure, I'd just pull a negative sand mold off of my EJ22 and be done with it. As it is right now, there is more fabrication source material for a jet engine or nuclear reactor than a car engine. I want to at least see the ability for someone who has the skills and tools to be able to fabricate every single piece of his or her own vehicle at home, which is the ultimate sign of open independence. The Locost in its own way is an open platform, something in which we all are experimenting, some ideas working, some not, but the sharing of that information makes the platform itself better in the long term.

As for method to my madness, I do tend to drive people crazy during the run-up period as I cover every base until I've isolated things down to a final concept. I only put final-stage bits here, which should give you an idea how many pieces I began with. I could show you the wankel and turbine designs I studied earlier and eliminated due to one piece or another. But once finished, I get things done fast.


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PostPosted: Mon Feb 13, 2012 2:08 pm 
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horizenjob wrote:
If you're not going to be passing an emissions test or only drive the car on the track bad fuel economy or emissions may not matter. It isn't efficient to measure things that don't matter in your efficiency...


Sure but I only responded when the subject of emissions was mentioned - and California ones at that ....

Downix wrote:
I checked and the Heron is listed as a way to improve both efficiency and emissions over other systems of the day



Pages 3 and 4 ..

http://www.jagweb.com/jagworld/v12-engine/page3.html

http://www.jagweb.com/jagworld/v12-engine/page4.html

Paragraphs 4 and 5 .....

http://www.pumaracing.co.uk/cflow.htm


Downix wrote:
and was used until a decade ago by Peugeot ans Volvo until modern computer fabrication made a better solution.


You can still buy cars with carburetors and points ignition too, hell Morgan's still have wooden frame parts :lol:


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PostPosted: Mon Feb 13, 2012 2:50 pm 
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cheapracer wrote:
horizenjob wrote:
If you're not going to be passing an emissions test or only drive the car on the track bad fuel economy or emissions may not matter. It isn't efficient to measure things that don't matter in your efficiency...


Sure but I only responded when the subject of emissions was mentioned - and California ones at that ....

Downix wrote:
I checked and the Heron is listed as a way to improve both efficiency and emissions over other systems of the day



Pages 3 and 4 ..

http://www.jagweb.com/jagworld/v12-engine/page3.html

http://www.jagweb.com/jagworld/v12-engine/page4.html

Paragraphs 4 and 5 .....

http://www.pumaracing.co.uk/cflow.htm


Downix wrote:
and was used until a decade ago by Peugeot ans Volvo until modern computer fabrication made a better solution.


You can still buy cars with carburetors and points ignition too, hell Morgan's still have wooden frame parts :lol:

Points taken. I suppose you can compare my thinking about Emissions in the same vein as Toby Hooper did on "The Texas Chainsaw Massacres" MPAA rating during production. While producing TCM, Hooper would regularly call the MPAA ratings board asking such questions as "Ok, to get a PG rating for my movie, I have one shot where a guy is hanging from a hook dropping blood." Of course the MPAA would say absolutely not, where he would counter with "If you saw the hook, the look on the guys face, then a quick shot to the bucket below, would that work for PG?" Getting his answer, he went about shooting it. Of course he never expected to get a PG rating, but by mentioning it, and working by what they said, he did get only an R rating and not the X which would have meant the death of his movie. Aim for a target you cannot hit so you can hit the target you need to hit. I know a homemade engine won't likely get California emissions, but by aiming for it, I know it would hit the target of being a solid performing engine that won't be belching out clouds of black smoke everywhere.


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PostPosted: Mon Feb 13, 2012 3:45 pm 
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CR, I haven't been doubting your points are valid. In the context of trying to make a home made engine and especially if you consider not having a head gasket, it still seems a reasonable choice compared to trying to machine combustion chambers into heads, making head gaskets etc.

On the other hand if you're going to have CNC code and printed mold parts perhaps you can do fancier things....

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PostPosted: Mon Feb 13, 2012 4:43 pm 
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horizenjob wrote:
CR, I haven't been doubting your points are valid. In the context of trying to make a home made engine and especially if you consider not having a head gasket, it still seems a reasonable choice compared to trying to machine combustion chambers into heads, making head gaskets etc.

On the other hand if you're going to have CNC code and printed mold parts perhaps you can do fancier things....

You could indeed, but not everyone has access to a CNC. You plan around a CNC, you set a minimum level capability which is still set quite high. You could also plan around Direct Metal Laser Sintering as well, but then you would set the bar even higher. By setting to sand casting, you can still use die casting, forging, CNC or DMLS to build it, giving you maximum flexibility for getting it produced on a local level.

I almost have a first test unified head/cylinder design together, should have something up tonight.


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PostPosted: Thu Feb 16, 2012 5:58 pm 
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Showed my head design to a friend who builds racing engines ans he called my ports rubbish. He then redesigned them on paper for me. So in the middle of making his design of port flow work.


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PostPosted: Fri Feb 17, 2012 1:20 am 
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killer_siller wrote:
There's a BIG topic on it over at speed talk:

http://speedtalk.com/forum/viewtopic.php?f=15&t=28861

I stumbled into here over the weekend and was surprised to see this topic had "taken off" to some degree. Should I reopoen the "Open Engine Design Project" forum again?


Finally had time to sit down and read this, lots of information there which can be useful in the future. Right now my focus is a working system, even if not the most ideal, which can then be improved over time. (Although the recessed exhaust port from the Jag is not a bad idea, and would make the rocker arm assembly a bit easier)


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PostPosted: Fri Feb 17, 2012 2:07 am 
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I have seen a lot of engines being built, commercial available ones, miniatures, custom engines race engines... all that stuff (it is some kind of popular over here)
I´d definitely recommend some of the old Porsche designs (I still have tons of blueprints) since they are easy and quickly build, reliable and make good power. Before Radical (long time before radical) there have been a lot of engines consisting of two BE blocks mated together on a custom crankcase ... I once read an very interesting article (sad, it was not really a engineers point of view / interest) - I will try to dig it up.
However as mentioned the Porsche designs have several benefits like the cylinders that can easily be produced and exchanged, the independent heads, the air-cooling - and if you take a look at the people who are really into building engines from ground up - most of them go this route
I´d stay away from pushrods

Sorry, I´m in a hurry - will get clear on this later

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PostPosted: Fri Feb 17, 2012 8:38 am 
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horizenjob wrote:
CR, I haven't been doubting your points are valid.


Valid from an emmissions POV otherwise I agree with you. Jack Brabham/Phil Irving chose the Heron Head for the Repco Brabham '66 and '67 F1 WDC winning cars for the reasons you mention, was easier to build that way ....

http://www.racemagazine.com.au/index.ph ... 4&Itemid=1


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