29 replies to this topic

[stevew]

I posted this memory/question over on the Nostalgia Forum, and someone suggested I post it over here:


I'm going from memory here, but I remember reading a little blurb in AutoWeek magazine in 1986 or 1987 that Honda had developed a 1.5 liter V6 turbo F1 engine which had oval-shaped pistons.

This engine had 8 tiny valves per "oval" and only ran on the dyno, but reportedly produced "2,000hp at 20,000rpm"!

Does anyone have more info???

[desmo]

That sounds like the NR500 GP500 bike engine. I cannot recall hearing about any F1 developments based on the oval piston concept. The fascinating NR500 and it's later developments were, as far as I am aware, designed with "oval" pistons to circumvent the FIM's maximum of 4 "cylinders" rather than any intrinsic technical merit the design may have had.



Here's a piston-rod(s!) set from the NR500.

[AdamLarnachJr]

That is amazing looking. What type of material is that piston made of?

http://www.atlasf1.c...&highlight=oval

[Chui]

Actually, the press report stated "1.5L turbocharged V6 producing 1,000 bhp per liter."

FIA promptly banned it by requiring all pistons to be circular when viewed from the x-y plane.

Very interesting concept, though. Too bad no SAE Paper was produced - at least no technical papers translated into English.

[Ali_G]

Ands what would be the advantage of such an oval piston.

A circular piston had the best weight to area ratio. Going oval would mean that extra material would be needed to have the same surface are.

Also, can F1 cars still have 2 con rods per piston. I could see teams using that instead of just 1 con rod. Wouldn't there be a bit of a weight advantage if done properly.

Niall

[Halfwitt]

Originally posted by Ali_G
Also, can F1 cars still have 2 con rods per piston. I could see teams using that instead of just 1 con rod. Wouldn't there be a bit of a weight advantage if done properly.

Niall

An interesting idea. Please elaborate on this. I can't see it myself.

[Ali_G]

Well i just saw that on the oval piston there seemed to be 2 con rods.

i could see a few possible advantages.

1. Instead of having one point of pressure on the crankshaft, there would be 2 for each piston. Wouldn't this even out the straing more over the lenght of the camshaft. I'm no expert but this has to have some positive effects.
2. 2 Con Rods could be lighter than just having 1. (not sure about that0

Niall

[P1 Senna]

The 2 rod design probably has to do with stabilizing the piston in the bore, and a better distribution of forces to the piston pin.

I've seen the NR500 described as a V8 in V4 clothing, which seems appropriate if you think of the cylinders as 2 round cylinders siamesed together. And as Desmo pointed out, it was an effort by Honda to get around the 4 cylinders max limit.

[H. Eckener]

Ali_G,

Check out http://www.cycleworl...ts/0800_tdc.xml and do an internet search on the old Lanchester automobile. Probably not something you will ever see in F1, but interesting engine history.

[desmo]

The Baindl twin rod/crank solution is intriguing for a single, if heavy and complex sounding. I want images of it! Kevin Cameron's writing is excellent, here's a list of articles he has written for Cycle World that I recommend reading:

TDC Kevin Cameron

I must say i think he has F1 rod ratios wrong though as I expect ratios well above 2.5:1 are now universal even though engines can be theoretically smaller and lighter with shorter rods.

[Ali_G]

GUys I have another idea.

How about an engine with 2 pistons per cylender.

Here's the idea. At the moment F1 engines have to have 10 cylenders or less.

But as was seen, loads of companies were supposed to be testing with V12's.

Well here's my idea. Instad of a V10 create a V6. Except have 2 pistons per cylender. I've been thinking the logic through all mornign and I can't see an reason why it would produce the same performance as a V12.

1. The rotating mass of the pistons is the same as in a V10.
2. Same number of pistons.

The only thing I can see is that more air and fuel will have to be put into the cylender at each revolution of the engine. WOuld this be a problem ?

Niall

[david_martin]

Article 5 : Engine

5.1 Specifications

5.1.1 Only four-stroke engines with reciprocating pistons are permitted
5.1.2 Engine capacity must not exceed 3000cc
5.1.3 Supercharging is forbidden
5.1.4 All engines must have 10 cylinders and the normal section of each cylinder must be circular
5.1.5 Engine may have no more that 5 valves per cylinder

[Ben]

Do we need the FIA regs to shitcan it?

Ben

[Ali_G]

Thanks ben

But anyway guys. WOuld it be practically possible anyway without the rules.

FOr example, you could have 2 round pistons going into the same cylender. (Cylender si a bad name for what i've got coming) Instead of a normal shape cylender, a sort of double cylender would be need. Both would be side to side, and only a tiny little gap (opening) would lay between them to confirm that they are essentially 1 cylender.

Niall

[int2str]

So just for fun:

What would the two pistons do? Talk us through the full cycle. Where would the combustion be? Above every piston - at the same time? How would you get both parts of the chambers filled/emptied? And what would be the benefit of this again???

Cheers,
Andre

[Ben]

Two circular pistons in an oval hole - big gap at the sides for gas to get around. That would appear to be the problem with the idea Ali.

When you have an idea like this which is so obviously of no advantage whatsoever you are going to get shitcanned. You can roll your eyes as much as you like but it's still a dumb idea.

Ben

[Ali_G]

Ben: My idea wasn't using 2 circular pistons in an oval cylender is was having a cylender which would look like this.



Each side could have its own valves, and each side could have its own spark plug.
The gap between the 2 cylenders could be very very small, much smaller than what my drawing shows.

BTW: I know I'm flogging a dead horse but if I'm still getting it wrong at least I'm putting over the idea I originally wanted to put over.

int2str: 1. Both pistons go down.
2. Fuel goes into both halves of the cylender
3. Pistons come back up and fuel is compressed.
4. Ignition
5. Pistons pushed down.
6. Pistons come back up and exhuast escapes.
7. Cycle repeated.

The benefit as I see it is that you could make a V6 have near enough to the perfomance of a V12. The engine would be a lot shorter than a V12, but as the pistons and con rods are so light better perfomance could be obtained. The only problem is that with a limit of 5 valves per cylender, and the fact that each cylender is still the size of a V6 cylender, the fuel would have to enter and the exhuast would have to exit at very high speeds.

Niall

[P1 Senna]

Ali - the other problem is that it is not a maximum of 10 cylinders, but rather a requirement to have 10 cylinders - not 9, not 11, not 6, but 10. So from that perspective your idea cannot proceed.

My take on this is that there are an awful lot of extremely smart people designing these engines within the format of the rules, and they will explore every avenue, resources permitting. Like the Renault camless solution, if it ever makes it to the racetrack. These people are brilliant, and that's why F1 rocks!

[Ali_G]

P1: I heard about the 10 cylender thing alright. At the moment i'm just seeing if the other board members even think this engine is viable at all.

Niall

[Duckers]

Ali would the tips of the gaps being so thin, heat up excessively and then present potential pre-ignition problems?

Duckers

[Ben]

The regulations are framed at the moment with the implicit assumption that when they say 'cylinder' they mean 'a single cylinder with a single reciprocating piston within it'. I suspect that any ruling body would decide that your engine has 12 pistons and is therefore a 12 cylinder engine.

I think Duckers has a point as well. You would get a very uneven temperature gradient in that thin tip section and that could distort a fair bit.

Ben

[Top Fuel F1]

I think some good points were made here regarding oval pistons:

http://www.atlasf1.c...val AND pistons

[Ursus]

Originally posted by Ben
The regulations are framed at the moment with the implicit assumption that when they say 'cylinder' they mean 'a single cylinder with a single reciprocating piston within it'. I suspect that any ruling body would decide that your engine has 12 pistons and is therefore a 12 cylinder engine.

Ben

And if not, the cylinder is hardly circular.

[H. Eckener]

Hello,

Although, you could round the edges on Ali_G's drawing to reduce thermal stresses and the like, I think you will still face the same problem that thwarted the oval pistons, and that is pistion rings, combustion chamber sealing, and blowby. The problem could even be worse on this configuration. And even if you could go ringless you still may find that there really isn't much of an advantage or that the rules committee doesn't like your interpetation of cylinders.
On an earlier subject of the twin crankshaft engines, if we believe the rotational velocity of the crankshaft at the bearings is limiting the rpm of F1 engines, a twin crankshaft engine could push that barrier up higher in the revs, by lowering the bearing velocity. I'll let someone else imagine how you could pull this off in a V-10 and still maintain good packaging and engine weight.

[AS110]

Ali_G,the closest I can think of to what you propose is the split single that was made by Puch,this was a 2 stroke single with two pistons,two rods on one crankpin,with a common combustion chamber.Taking out the cylinder wall would give the layout you have given.But somehow I think a round cyl is best.
Twin cyl 2 & 4 stroke motors have often been set up firing at the same time to give the effect of a single cyl of the same capacity.But the cyls are completly separate.

[Croaky]

Aw, come on guys, I think Ali_G's onto something here. Those are valid points about the thermal stresses and blow-by. All that needs doing is a small modification. Simply insert a thin wall of metal in between the two halfs of the combustion chamber. This would solve the minor problems that have been raised. The two pistons would still share a common crankcase. Do you think I'd be infringing Ali_G's patent though?

[Manson]

No "ovals" period in F1!

[Halfwitt]

Originally posted by Croaky
Aw, come on guys, I think Ali_G's onto something here. Those are valid points about the thermal stresses and blow-by. All that needs doing is a small modification. Simply insert a thin wall of metal in between the two halfs of the combustion chamber. This would solve the minor problems that have been raised. The two pistons would still share a common crankcase. Do you think I'd be infringing Ali_G's patent though?

Croaky, this might involve using only one rod per 'half piston' though. I supppose it is a form of Ali's design though. I think BMW may be using a 5-cylinder Ali engine for their F1 campaign, but a sort of fully split type as you suggest. I think Ali might be on to something here. I think I'm going to bed with a stiff drink

[Ali_G]

Originally posted by Halfwitt


Croaky, this might involve using only one rod per 'half piston' though. I supppose it is a form of Ali's design though. I think BMW may be using a 5-cylinder Ali engine for their F1 campaign, but a sort of fully split type as you suggest. I think Ali might be on to something here. I think I'm going to bed with a stiff drink

Is this a joke or are you being serious.

I really can't tell

Niall

[Halfwitt]

No, it wasn't a joke. I really did go to bed with a stiff drink.