28 replies to this topic

[Formula1_Fan]

Hello everybody! Does anyone knows some details about F1 pistons? For example their weight. In a prevoious F1Racing magazine issue it has been told that Renault's pistons weighs about 250 gr. Any thoughts about that? Also which is the clearance between piston and cylinder liner, such as the clearance between piston ring and liner? What about the material and coatings? Also which is the height and diameter of an F1 engine's piston? All details and information are welcomed!

[30ft penguin]

You might look here:

http://www.atlasf1.c...&threadid=46802

and here:

http://www.atlasf1.c...&threadid=47412

[marion5drsn]

250 gr. x .002205 = .551 pounds/.102 = 5.404 cubic inches = a cube of aluminum 1.755 inches (44.574mm) on a side. Hummm, not a very large piece of metal. Remember this piston's outside diameter is 97.0mm (3.819 inches).
A piece of aluminum 97mm (3.819 inches) in diameter would be 7389.8 sq. mm area (11.454 sq. inches area). This would make the thickness 11.984mm(.4732 inches).
One has to visualize that this is not very thick considering the piston crown thickness. Also one must remember that the area around the piston pin is very thick.

Are pistons weighted with the piston pins in place? All pistons pins that I know of are made of steel. Something is wrong here with this weight figure if that's the case!!! Piston pins are heavy. Is there any record of piston pins being made of something other than steel? I don't know of any myself. Piston rings, two per piston, are usually also made of steel and altho they also don't weight much they are still there. Pistons are usually delivered with pins installed but not piston rings (U.S.A.).

Density of Aluminum per cubic inch is .102 pounds.

Anyone who has picked up a box of V-8 piston pins knows just how heavy eight of those little things are. M.L. Anderson

[Formula1_Fan]

I have designed an F1 style piston in CAD software. Also i analyze this solid model in finite element analysis software. My first model was weighing 326 gr. and it had a max. deformation of 3.70e-2 mm and a Stress Von Mises figure of 1.81e8 N/m**2. Then with some improving and developing work i finally designed a piston that weighs 271 gr and with a deformation of 4.39 e-2 and a Max streess Von Mises of 2.42e8. The stress is not a problem. The main problem is the max. deformation which occurs in the edge of the crown of the piston. I would like here to ask if this deformation is acceptable and how much is the clearance number between the piston and the cylinder liner, such as between the piston rings and the cylinder liner in a real engine (not indispensably an F1 engine). Thanks in advance!

[marion5drsn]

Formula1_Fan; I don't believe I would worry about the piston to cylinder wall clearance , I would worry about the piston crown bending down and pinching on the only piston compression ring and the resulting crankcase explosion! Could that happen? M.L Anderson

[Formula1_Fan]

Originally posted by marion5drsn
Formula1_Fan; I don't believe I would worry about the piston to cylinder wall clearance , I would worry about the piston crown bending down and pinching on the only piston compression ring and the resulting crankcase explosion! Could that happen? M.L /anderson

Let me ask you with your question... Should i worry for anything having a maximum deformation of 4.39e-2 mm? If yes, then for what have i to worry about and why? Thank you very much marion5drsn. Would you like to post my piston design into this thread...?

[12.9:1]

Formula1

I'd like to see it !

I'll bet you have some nice displacement contour plots.

[Formula1_Fan]

Here are the images:

Piston plots

The two first images are the deformation plots and the third is the Stress Von Mises plot. Please don't look at the results because this piston is not my last optimized model!
12.9:1, could you tell me whether the deformation of 4.39e-2mm is acceptable for a piston or not? Thanks in advance!

[12.9:1]

Formula1

I can't answer your question but I'll bet the folks at Omega Pistons ltd would help you.
Massimo Bordi - the man who made Ducati + eight valves = victory, has said of - Omega (who supply pistons to minor F1 teams) "we decided to use the services of Omega, In their small workshop, they have perfected the metallurgic technology of aluminium to such an extent that we still use their excellent products today."
Tell them your situation, and ask for the engineer. Good Luck

[Formula1_Fan]

Originally posted by 12.9:1
Formula1

I can't answer your question but I'll bet the folks at Omega Pistons ltd would help you.
Massimo Bordi - the man who made Ducati + eight valves = victory, has said of - Omega (who supply pistons to minor F1 teams) "we decided to use the services of Omega, In their small workshop, they have perfected the metallurgic technology of aluminium to such an extent that we still use their excellent products today."
Tell them your situation, and ask for the engineer. Good Luck

Thank you 12.9:1 ! May i take the opportunity to ask you what is your opinion about my plots such as the piston model design...

[12.9:1]

Your C O L O R selection reminds me of a shirt I had Quite some time ago, real eye jazz

I might suggest that you model that Mahle - Ferrari piston, then subject it to the same loads as your design. This could give you a glimpse into their thinking

[Formula1_Fan]

There is no colour selection from me. The colours are the original ones that the software gives you in a deformation contour plot!

[blkirk]

F1_Fan,

I can't imagine that an out-of-plane deflection of 0.0439mm (0.00173in for the metrically challenged) would matter that much. You're talking about something of the same magnitude as most machining tolerances. As Mr. Anderson pointed out, the change in diameter is probably much more important.

The other area you might want to look at is fatigue. In a two-hour race, although most don't last that long these days, the piston will see approx. 1 million power strokes. You'll need to find the stresses caused by acceleration and reduced bore pressure during the intake stroke and subtract one stress state from the other. There should be a way to do this in Patran. That will give you the total stress amplitude that the piston sees during a full cycle.

I found a fatigue curve at http://www.darpa.mil...df/Spa Chen.pdf for 7075-T6 Aluminum. Whatever material you use is certain to have a different S-N curve. I'm just using this one for illustration. From the 7075-T6 AL curve, it looks like the maximum allowable stress for 10e6 cycles is around 50 ksi (3.45e8 N/mm**2). You're already 70% of the way there without accounting for stress reversal when the con rod yanks the piston down during the intake stroke.

You don't have much of a factor of safety, but you have several things that may be in your favor. The grade of Aluminum you use may have a better S-N curve. The piston is very light which will keep acceleration stresses to a minimum. If the peak stress is in the webbing on the back face, there might be a surface treatment you can use to locally increase the fatigue life. Steel can be shot-peened to improve its fatigue performance. I don't know if Aluminum responds the same way.

Good luck,
Brian

[Formula1_Fan]

Originally posted by blkirk
F1_Fan,

I can't imagine that an out-of-plane deflection of 0.0439mm (0.00173in for the metrically challenged) would matter that much. You're talking about something of the same magnitude as most machining tolerances. As Mr. Anderson pointed out, the change in diameter is probably much more important.

The other area you might want to look at is fatigue. In a two-hour race, although most don't last that long these days, the piston will see approx. 1 million power strokes. You'll need to find the stresses caused by acceleration and reduced bore pressure during the intake stroke and subtract one stress state from the other. There should be a way to do this in Patran. That will give you the total stress amplitude that the piston sees during a full cycle.

I found a fatigue curve at http://www.darpa.mil...df/Spa Chen.pdf for 7075-T6 Aluminum. Whatever material you use is certain to have a different S-N curve. I'm just using this one for illustration. From the 7075-T6 AL curve, it looks like the maximum allowable stress for 10e6 cycles is around 50 ksi (3.45e8 N/mm**2). You're already 70% of the way there without accounting for stress reversal when the con rod yanks the piston down during the intake stroke.

You don't have much of a factor of safety, but you have several things that may be in your favor. The grade of Aluminum you use may have a better S-N curve. The piston is very light which will keep acceleration stresses to a minimum. If the peak stress is in the webbing on the back face, there might be a surface treatment you can use to locally increase the fatigue life. Steel can be shot-peened to improve its fatigue performance. I don't know if Aluminum responds the same way.

Good luck,
Brian

Hello Brian and many thanks for your interest! I am really grateful for your help. Have in mind that in my analysis i have not included the thermal deformation, because doing structural and thermal analysis at a time requires a veryvery powerful computer. So then is this deformation number acceptable agian? Thanks in advance!

[Formula1_Fan]

Brian, could you give me a normal figure of the clearance between piston and cylinder liner, or piston rng and cyl. liner? Thanks

[blkirk]

I can't say what the clearances are in an F-1 engine, but in my race car, the bore is 82.00mm and I just measured one of my old pistons at 81.94mm.

Hope that helps.
-B

[Formula1_Fan]

Originally posted by blkirk
I can't say what the clearances are in an F-1 engine, but in my race car, the bore is 82.00mm and I just measured one of my old pistons at 81.94mm.

Hope that helps.
-B

In your race car the clearance is (82.00 - 81.94)/2 = 0.03mm. In my analysis the deformation is 0.0439mm. I think that i am over the limits...What's your opinion?

[blkirk]

Depends on the direction. Is that total deflection, or is it the axial or radial component? As long as your radial deflection is less than the clearance, you should be okay.

BTW, it just occured to me that unless Patran is mirroring your model, you did the analysis on the full piston. As far as I can see from the pictures you posted, both the geometry and loads have two planes of symmetry. One parallel to the pin axis and one perpendicular to it. You should be able to run only a quarter model and still get all the results you need.

Good luck
-B

[Formula1_Fan]

Originally posted by blkirk
Depends on the direction. Is that total deflection, or is it the axial or radial component? As long as your radial deflection is less than the clearance, you should be okay.

BTW, it just occured to me that unless Patran is mirroring your model, you did the analysis on the full piston. As far as I can see from the pictures you posted, both the geometry and loads have two planes of symmetry. One parallel to the pin axis and one perpendicular to it. You should be able to run only a quarter model and still get all the results you need.

Good luck
-B

blkirk, could you tell me the normal figure for the clearance between the piston and liner? Also could you give me a number of maximum cyl.pressure of an engine, racing and not?

[Formula1_Fan]

.

[desmo]

While I don't have figures at hand expect very normal- for a racing engine- in cylinder pressures in an F1 engine. BMEPs are higher in many other racing categories.

[Formula1_Fan]

What i would like to know is whether is a real thing to have a piston of 91.80mm and a liner of 92mm or not. Thanks

[Formula1_Fan]

Does anyone has any images of touring cars pistons (BTCC, ETCC...)?

[marion5drsn]

Go here for Honda piston F-1. Honda claims its expertise in Formula One racing enabled it to produce a 96-mm (3.7795-in) diameter piston that is 33.6 mm (1.322 in) tall and has a mass of only 261 g (9.2 oz).

http://www.motorspor...feb02-honda.htm

M.L. Anderson

[Formula1_Fan]

Originally posted by marion5drsn
Go here for Honda piston F-1. Honda claims its expertise in Formula One racing enabled it to produce a 96-mm (3.8-in) diameter piston that is 33.6 mm (1.3 in) tall and has a mass of only 261 g (9.2 oz).

http://www.motorspor...feb02-honda.htm

M.L. Anderson

This piston indeed seems like a disk with wrist pin bosses. I would bet that this piston would be lighter than 261 gr. Probably there is more metal betweeen the "disk" and wrist pin bosses. Thank you very much for the information!

[pstnspd]

I have measured or reviewed cylinder pressure data in a 4 stroke gasoline lawn mower engine to be a maximum of 30bar, modern gasoline passenger car ~70bar, modern diesel medium displacement ~220bar, and methanol fueled racing engines to ~140bar.

[Formula1_Fan]

Originally posted by pstnspd
I have measured or reviewed cylinder pressure data in a 4 stroke gasoline lawn mower engine to be a maximum of 30bar, modern gasoline passenger car ~70bar, modern diesel medium displacement ~220bar, and methanol fueled racing engines to ~140bar.

Thank you very much pstnspd! Have you any figure about maximum piston deformation in any of these circumstances (i mean for pass.car, or for diesel engine etc.) ?

[pstnspd]

Most of my work has been in physical testing, so there is surely someone else out there better qualified to speak to what values you would expect from FEA for this type of thing. From my experience though I would say the focus is more on managing the shape of the pressure distribution between the skirt and cylinder bore or the wrist pin and pin bore than any specific value for deformation. Furthermore, these locations are just as important to heat transfer as they are to lubrication or load transfer.

[Greg Locock]

You should also consider the elastic deformation of the cylinder wall. It will be expanding outwards due to gas pressure, and the lateral force from the piston will also push it outwards. I can imagine that this is significant in the case of a wet liner engine.