stayer

Hi friends!
Continue your project. I wrote earlier that for the construction of necessary engineering approach. That is, first done structural calculations. After that begins the process of compiling details. In this topic I want to talk about the pistons.
To obtain a power of about 300 HP (N/A) for the 4G69, I need to get a CR 11.8 : 1. This cannot be done with stock pistons. Therefore, I need custom pistons.
I considered various options. For example, well-known companies (Wiseco, CP, Cosworth, etc.) do the pistons. The problem is that all these pistons are forged. Don't think forged pistons are cool. Doubt?
In this case, ask yourself the question, why not install forged pistons from the factory? Why the best and the most powerful cars from the factory, have the cast pistons?
Yes, forged pistons are more durable. But they have a significant disadvantage. This thermal expansion.
Cast pistons have the clearance 0.02-0.04 mm.
Forged pistons have the clearance 0.06-0.10 mm.
A lot or a little? Because of this, forged pistons have a higher noise level. And most importantly, they do not go more than 30k miles. Further, the oil flow rate becomes simply monstrous. Drops the compression in the cylinders. There is a sharp engine wear.
While cast pistons will run 200k miles (or more)
Also, if you make cast pistons for modern technologies, the strength can be increased significantly. In this topic, I want to tell you how to make pistons.

stayer

First comes the design stage. I did the calculation, I need to CR 11.8
Is measurement of the volume of the combustion chamber, the volume of the cylinder-head gasket recess in the piston, etc.
Further work in the computer.

stayer

Next, we obtain a drawing of what we need to.

I have done porting the cylinder head. I have big valves on the inlet and outlet. Therefore, the undercut valves are oversized.
When all drawings are ready, we can start production. I mean, in Russia, it is possible to make a detail of any complexity. Originally done casting in a metal mold.

stayer

The pistons are cast under pressure. Aluminum alloy is very durable.
It has a large silicon content. This is called a hypereutectic alloy. I'm not sure that in English it sounds right.

stayer

Next you need to obtain high strength alloy. The pistons are hardened at a temperature of 520 ° C for 8 hours.
Further, the stage of aging. 14 hours at a temperature of 190* C.

The alloy is gaining a very high strength and hardness. The stock pistons do not have such strength.
Why is it done?
The factory, the stock pistons have very low resistance to detonation.
The stock piston will break the barriers between the rings. This is not my photo, I brought them for example.

stayer

After the pistons acquired a high strength, you can start machining.

This is done on precision machines.
Further, it is necessary to apply coatings. On the lateral surface of the piston to apply a Teflon coating black. This really reduces the resistance of the piston friction.





On the upper surface of the piston is applied with a ceramic coating zirconium oxide. In these pictures the top coating is not done yet. It will be up to the end of the week. After I show you the final version.

stayer

Ceramic coating on top, you need to reduce detonation zones. Reduce the temperature of the piston. The temperature of the gases remains in operation and is not dissipated in the atmosphere.

At the moment, that's all. If you have any questions, I will answer.
Stayer

stayer

If you are interested in the question of price? Full production cycle is worth $ 600. For 4 pieces

stayer

A slight extension.
In the upper part of the piston is made of ceramic coating. It keeps the temperature of the gases inside the cylinder and does not spread to the engine parts. On average, this gives an increase of 5-8% capacity. Now the pistons are ready to install.

bakuro117

iTrader: (5)

This is awesome. Nice work Stayer! Thank you for sharing this.

stayer

At the moment I have collected all the details. Now assemble the engine and set it up.