Engine Hypotheticals

[Wideband mindeD]

This post is a thank you for the members contributions that have kept me very busy reading about a sport I am very passionate about. And I hope that the more knowledgeable and visual presenters on this forum will indulge me by answering a few hypothetical questions about engines in general.

1. What benefits, if any, would a mono-block engine have over regular ICE design?

2. If an engine were to be cast in place with all internals already installed, what effect would that have on the operation, design criteria, and expected wear?

3. Why don't the engine manufacturers use lapped pistons like RC engines?

4. Is it a strength problem, or a dynamic heterogeneous environment?

5. What would be the benefits of integrating a turbo unit into the intake plenum, if you could guarantee isolation of heat from the exhaust turbine?

I have always asked myself these questions while reading through the more respectable, and well detailed posts on this wonderful technical site, and I would like to know what the speculation may be as to these questions.

Thank you kindly.

[Wideband mindeD]

Maybe I went too far with my original post.

What, if any, would be the benefit of being able to produce an engine that is a single piece?

Thermal, compression, efficiency?

Would there be a benefit to having these 3d printed when the tech allows for it?

[hardingfv32]

Why don't the engine manufacturers use lapped pistons like RC engines?

Describe this process.

Brian

[Shrek]

i think having a monobloc(one piece block and head) is lighter and stronger, i don't know the disadvantages though

[matt21]

1. What benefits, if any, would a mono-block engine have over regular ICE design?

You don´t have to deal with head bolts and a gasket. But you have to machine the valve seats from below. Brian Hart has this done on his turbo engine.

2. If an engine were to be cast in place with all internals already installed, what effect would that have on the operation, design criteria, and expected wear?

What would be the advantage execpt you can do without bolts and sealings. But then you have a throw-away engine.

3. Why don't the engine manufacturers use lapped pistons like RC engines?

Lapped pistons? Never heard of. Cylinder bores are honed to get asurface retaining oil.

4. Is it a strength problem, or a dynamic heterogeneous environment?

To what does this refer

5. What would be the benefits of integrating a turbo unit into the intake plenum, if you could guarantee isolation of heat from the exhaust turbine?

We will see interesting solutions in 2014. But if you have the turbo integral with the plenum you get a high CoG.

If you need more detailed stuff just ask or PM me.

[superdread]

1. What benefits, if any, would a mono-block engine have over regular ICE design?

You don´t have to deal with head bolts and a gasket. But you have to machine the valve seats from below. Brian Hart has this done on his turbo engine.

You can insert them through the inlet/outlet holes, by using thermal contraction (I know of Ferrari and Ducati doing that).

[Wideband mindeD]

I was more thinking of the future of 3D printing.

We are probably no more than 10 years away from being able to literally pull anything out of a bucket of goo with the new light curing resins out there. It's only a matter of time before they figure out how to add proper surfacants to various elements to allow them to be selectively placed/sintered.

Lapped pistons are the ones that are polished to perfection, and run with no rings. The RC car engines reach about 40k RPM and they have no piston rings. I always wondered why this treatment wasn't part of the F1 engines..

It has always struck me when reading about design compromise strategies, how the future of 3d printing has the ability to overcome a large part of them. Heck, if the teams can simply print up parts out of a solution, F1 suddenly gets exponentially cheaper. It is definitely coming, just look at the rapid-prototype parts that are already on the brake ducts.. It will not be long before the entire chassis is built the same way.

[Wideband mindeD]

This was more geared to look at the possibility of 3d printing engines, which I suspect will be available within the next 15 years.

Costs would come way down, and using an engine per session will not matter.

PS: Lapped pistons = pistons with no rings, like the RC engines that spin close to 40k RPM...

Another unique aspect of a typical nitro RC engine is that the piston does not have rings like most conventional piston engines. In most conventional internal combustion piston engines, the rings help to seal and keep the combustion gases inside the combustion chamber instead of leaking past the piston. However, a nitro engine is different. Instead of piston rings, nitro rc engines will typically just have a precision fit with the cylinder sleeve. To ensure a good seal during the compression stroke, the cylinder liner is actually slightly tapered so that the piston fits tighter at the top of the cylinder stroke. Many nitro engines have pistons with at least 1 small groove at the top of the piston which act as an oil retainer and is supposed to help keep the piston to cylinder contact well lubricated. Click link to see more about the operation of 2 stroke engines.

Most nitro rc engines are of the "ABC" type design. The ABC stands for ALUMINUM BRASS CHROME. This means that the piston is aluminum, the cylinder liner is brass, and the internal wear surface of the cylinder is plated with chrome. This hard chrome plating offers a much better wear surface than the soft brass underneath, and helps to prolong engine life. Sometimes, you will see an ABN engine. Usually the N stands for NICKEL plating in the cylinder liner which is cheaper and less durable. However, occasionally expensive, high end rc nitro engines will have an "ABN" design in which case the N stands for a NICASIL plated cylinder sleeve. This is a premium plating found on only a very few very expensive engines, because it offers even better wear resistance than chrome plating. This tougher Nicasil plating comes at additional expense. By far, the majority of good rc nitro engines utilize ABC technology with excellent results and long life potential.

The picture below shows some of the internal parts of a typical reciprocating 2 cycle nitro engine including the crankshaft, connecting rod, piston, & cylinder sleeve.

Is it because it is only a 2 stroke that they can use this type of piston?

[matt21]

I doubt that the contract to such an extend that you can insert them from above and that the seats are fixed properly afterwards. But can you provide some more details on the Ferrari and Ducati way.

Why should they o this? Are they using monobloc engines somewhere?

[superdread]

I doubt that the contract to such an extend that you can insert them from above and that the seats are fixed properly afterwards. But can you provide some more details on the Ferrari and Ducati way.

Why should they o this? Are they using monobloc engines somewhere?

Sorry, I misremebered they insert them from the underside: http://www.youtube.com/watch?feature=pl ... Y30#t=271s.

The reason the cool them is to get a bond, rather like tires of trains are heat shrinked on their wheels. The contraction would be large enough for that, but not large enough to insert them from above (using 0.00002 1/K (arbitrary value for steel) and 220K, the relative expansion is 0.0044).

[Tommy Cookers]

valve seats would normally be installed by differential expansion/contraction from below (we know this ?)

the valve seat is to be as usual installed into a machined precision counterbore in the head (or equivalent)

this machining is the problem with '1 piece' engine ? ..... any answers on how people are treating this problem ?

[matt21]

valve seats would normally be installed by differential expansion/contraction from below (we know this ?)

the valve seat is to be as usual installed into a machined precision counterbore in the head (or equivalent)

this machining is the problem with '1 piece' engine ? ..... any answers on how people are treating this problem ?

Brian Hart as this solved by machining the seats from below. Complicated but managable.

By the way, the term "monobloc" just means that parts of the engine are casted in one piece. So strictly spoken every engine with combined cylinders and crankcase or even with cylinders casted as one piece (so 99% of all road engines) are monoblocs.

[hardingfv32]

The Offenhauser was built this way in the 40's, so I would assume that the process is not to difficult as to require computer controlled machine centers.

Isn't 'differential expansion/contraction' the standard valve seat installation process?

Brian

[Tommy Cookers]

it had an iron cylinder/head 1 piece casting ie there were no valve seat inserts to be fitted and no counterbores

valve seat inserts (allowing aluminium alloy heads) only came in after head gaskets became viable around 1930
before this, in GP etc or aircraft engines the cylinder wall/liner was closed at the top to form the combustion chamber and valve seats (to allow an al alloy 'head'), or the cylinder/head was made by fabrication and welding (or was Offy-like)

true, the Hart 415T did have this machining of the counterbores
true, modern very high bore:stroke ratios ease access for the machining, hence my interest in any current development

[langwadt]

1. What benefits, if any, would a mono-block engine have over regular ICE design?

You don´t have to deal with head bolts and a gasket. But you have to machine the valve seats from below. Brian Hart has this done on his turbo engine.

I believe Porsche welded the heads on some of their engines, aircooled I guess