The connecting rods will be soooo much cooler and likely made of titanium (Ti-6Al-4V) which has a heat expansion of 75% of 15CDV6.Badger wrote: ↑20 Jan 2026, 19:59Again, much too high temperature. The expansion is a function of the average temperature across the whole length, not just the highest temperature spot. You'd do better by lowering the temperature and incorporating the con rod and cylinder head in your calculation. Those have more length to expand. I also believe the cylinder head can use aluminium.diffuser wrote: ↑20 Jan 2026, 19:12Not all lost .... The iron alloys specified in the rules include:
- AMS 6487
- 15 CDV6
- 42CrMo4
- X38CrMoV5-3
15CDV6 has a α (×10⁻⁶ /°C) of 11.5–12.5 about 35% lower than aluminum. Also 15CDV6 transfers heat 6 times slower than aluminum, therefore, it will run hotter than aluminum. So where an aluminum piston would run around 300C, a 15CDV6 would be near 360C.
| Material | Hot CR for 16.0:1 cold CR | | ------------------ | ------------------------- | | Aluminum piston | ~16.9–17.0 | | 15CDV6 iron piston | ~16.6–16.7 |
It's still something.The regs also have the same restrictions on material for Crankshafts and rods. They do allow titanium for rods.
Cylinder heads and main static structure:
- Aluminum or iron‑based alloys.
Cylinder Head Specific Requirements:
- Only one cylinder head per bank is permitted.
- Each head must be made from a single piece of material (exceptions only for defined inserts).
Pretty much leaves you with monkeying around with aluminum head geometry to increase compression.
The con rod is 120 mm, you can use 30 mm for the piston, and idk what the cylinder head is, at least a few cm. Say the alpha is on average 12 across the whole range, and the average temperature is 120 C.
Also I don't think the temps I mentioned are hot for F1, I think that's just normal temps at those spots.

