Bret, although I can not name names if you asked a lot about the F1 cranks they would have told you or you would have seen the bobweight numbers. Some run as heavy as a 290g piston even in 2003 if you know the balance and the other parts etc. The guy at Chambon with JE said he had seen even 300g lately on some other stuff in F1 and they are the ones that made that stuff on display at CP. Pankl made the rods on that engine but CP makes nothing else on that.

I was told that at least one good running BMW piston lately still weighed over 230G and was MMC so even though the stuff is light that is on display doesn not mean it will go the whole distance at a lot or power and rpm. I also heard that some other MMC pistons were as low as 200g on a smaller bore motor. I don't follow it as much as I should but I do know the guys that make those pistons very well but they will lose their job if they actually talk about anything current.

I absolutely agree that the MMC stuff is lighter and in the current form it is legal in F1! But the whole discussion that you are changing was whether piston speed was a good indicator of mechanical stress which limits race engines or whether as I said it was an airflow limitation that kills power at a certain piston speed and it IS airflow as far as why no one can usually get over a certain piston speed. To find mechanical stresses we use the variable in this form (RPM^2 X Stroke) and piston speed uses the same variables in this form (RPM X Stroke) so there is a very big difference between the two as RPM is MUCH more important to mechanical stress and cycle life than piston speed is.

 

Yeah, Yeah Mahle makes F1 pistons we know that. But then again you would remind me if I didn't dot my i's and cross my t's if this was hand written.
The Asiatech motor was weak and not even current but that's not the point. The piston mass was for that and other F1 motors. You still said that they were 275-300g's for a Al piston. Mahle stated that Al pistons were at the most 230gs in what they do now. They also said they used other alloys but it's not like they are going to say what they use. I don't blame them.

Go up the page and I think you will see you explicitly said that Cup motors were valvetrain limited. Now you are just stepping on your toes about it changing what you said about it. Your new postion just copies what I said in new language.

Both of those things you've taken a 180deg position on. For your posts to be that YOU are right all the time, don't you think you need to at least be right?

As for the PS piston...I just picked up the PS piston at CP and talked with them about it, maybe they don't run them in PS, but that's what it was made for. If they do or don't run them I don't know, but the only real way to know would be to be WJ, Grumpy or Anderson. The piston didn't have a super thin crown so it might have worked but they can't run them anyways so it makes sense that they show it since the new piston mass has to be 460g's now.

Bret

 

Wouldn't that basically be piston g's?

When did you say before this that "an airflow limitation that kills power at a certain piston speed and it IS airflow as far as why no one can usually get over a certain piston speed. "

 

I wasn't talking about Mahle.

 

Bret,

I said that I remembered MMCs being banned back then which they were temporarily. Now different MMCs are back. This thread was about finding piston velocity and then it was discussed that piston speed was synonomous to stress and it is not. I know people that make F1 pistons but have not talked with them in around 2 years but I knew at that time that everyone thought stuff was lighter than it really was and that is still the case.

Piston "Gs" are not directly tied to piston speed at all but rather another formula as they increase exponentially with RPM whereas piston speed does NOT. This is simple.

Also Bret the valvetrain LIMITS airflow when it starts causing false motion and airflow is no longer happening in the right direction so valvetrain limitations causes airflow limitations and power falls off.

 

WOW, I want to thank all you fellows for a lively interchange of ideas and information and I want to thank Damon in particular for his explanation of max piston velocity. His exercise with wire/t-square/protractor made me smile as it all came clear to me about the rod being 90* to the crank throw at 75* ATDC. Short of being a degreed engineer, that's the way I find myself understanding how things work, by laying them out and looking at them. I'm now further asssuming that the only way to get max piston velocity at 90* ATDC would be to offset the main journal a distance equal to the radius of the crank throw in relation to the bore centerline. I realize this wouldn't work well coming back from BDC to TDC, I'm just visualizing it to bring it all together in my mind. Although I've been building motors for myself and friends on a hobbyist level for over 40 years, it's just something I never thought much about.

I'm coming over to the camaroz28 site from another forum where I've become bored and stifled with the inane chatter served up there. There seems to be a very good collection of sharp minds here and I'm looking forward to learning from you fellows.

I'm 62, semi-retired and living with my wife of 34 years in Phoenix. I began tech inspecting in 1958 at a little airport runway/Sunday drag strip called Dahio just outside of Dayton, Ohio. I currently inspect at Firebird Int'l Raceway in Chandler, AZ where I've been since 1990 (that's the "semi-retired" part of it).

 

Nice to have you Richard and you are basically correct about offseting the rod a crazy amount like that (although then on the stroke back up you would have a really crazy rod angle!) or you could use an infinitely long rod and then you would basically be back to sinusoidal motion with the max piston speed at 90 degrees. That rod would be really heavy though!

 

Yeah Erik, it would have to be made of "unobtainium"