Top Fuel Piston and Rod Assembly

[bdcardinal]

Originally Posted by 02SE
Look at the pic I posted of the rack ready to be installed, from one of the past teams I worked on. It is for the oil control ring. The wristpin is inboard as you see in the OPs pic. What you can see installed in my pic are called 'buttons' which keep the wristpin centered. They are clearanced for the oil control rings.


Do they even bother to run a support rail on the coil control ring since the pin extends into the ring groove? Or is it one of those things where it runs for such a short amount of time that the additional rotating mass isn't worth it?

Also another random question, one of my close friends swears that when I build the engine for my 95 Mustang I have to spend the money and get the wrist pins casidium/DLC coated. He has a sprint car and swears by it. Do any of the teams you have worked with do it and is it worth it if they do? I know you can't really dyno a top fuel engine to get concrete data but I understand the theory behind them.

 

[02SE]

If you can blow up the pic I posted, you'll see the oil control ring support rails.

Re: The coated wrist pins. Some use it, some don't. With the short expected life of the parts, it's kind of a toss-up. In a high-performance street engine, I'd probably use the coating on the pins. I'm using it on my all-motor Hayabusa. Most Fuel teams do use an aluminum oxide coating on the pistons, as it does help the piston survive to the end of the run.

 

[ZeeOSix]

Originally Posted by 02SE
Look at the pic I posted of the rack ready to be installed, from one of the past teams I worked on. It is for the oil control ring. The wristpin is inboard as you see in the OPs pic. What you can see installed in my pic are called 'buttons' which keep the wristpin centered. They are clearanced for the oil control rings.


Originally Posted by 02SE
If you can blow up the pic I posted, you'll see the oil control ring support rails.


So looks like there a groove in the wrist pin end "buttons" for the oil control rings. I'm assuming the wrist pins are interference fit with the piston and there's no movement between the wrist pin and piston (ie, it's not a full floating wrist pin)? Guess if the wrist pin was full floating, the pin and end buttons could still move independent of each other.

 

[02SE]

Let's just say they are more of an interference fit, eventually...