Fuel rail and radiating heat from the engine block..

[Patcon]

Our fuels are also vastly different today! They are designed to be more volatile so they burn cleaner. That volatility makes them more prone to vapor lock at lower fuel pressures. Its part of the reason modern cars run higher rail pressures

[Tirnipgreen]

So running non-ethanol REGULAR may be better than PREMIUM E10...?

[Patcon]

Ethanol definitely raises the volatility and it's also hard on a fuel system not designed for alcohol. I try to avoid Ethanol in my boat, mower and small engines. It just doesn't age as well as straight gas does

[AK260]

We are still lucky enough to have ethanol free super unleaded at Esso in the Southeast of England. That’s the ONLY fuel I use. But our other super unleaded is 5% ethanol.

Just been out for a blast to test some tuning I did today and when parked up I popped the bonnet to check the fuel rail. Front of engine mounting hanger (welded) without insulators, was cool to the touch. Mid part of the rail boiling hot! I appreciate the timing chain part of the head will be cooler but the fuel rail at that point was way cooler than that section of the head.

So I suspect the majority of the issue is radiated heat.

Isolating the rail hangers with fibre washers in the past - I found didn’t make much of a difference and over time they broke up and caused false air / vac leaks on the intake manifold. So better washers for insulation need to be thought about! Maybe mica washers!?


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[Jeff G 78]

1 hour ago, AK260 said:

...over time they broke up and caused false air / vac leaks on the intake manifold. So better washers for insulation need to be thought about! Maybe mica washers!?

Just make sure the bolt is also isolated.  The washers need to have a shoulder so the rail bracket hole doesn't ground against the bolt. Ideally, the washers would be pretty thick, but that will throw the rail alignment off. 

The better method would require a donor rail where a section of each vertical support is cut out and replaced with an isolating material to keep the heat from transferring up the support.  Think of an exhaust hanger, but in compression rather than tension and rigid material rather than rubber.  Once isolated from heat conduction, the rail could be properly wrapped to isolate it from radiant heat.  Right now, the sleeve only holds the conducted heat in.