intake runner lenght with ITBs discussion

[eight-six]

Bean – sounds like your going for some long stacks – might be worth checking they will fit. I have 75mm stacks on my OER ITB’s and they are literally right up against the inner wing, which cant be good for performance. I have decided to reduce the length of mine - IIRC 45mm. I couldn’t find any to fit my throttles without paying bum rape prices so started to make my own.

How long the stacks are …



My trimmed down FRP version … trying to source some carbon or carbon Kevlar to make the final version. This one was just a test.

Quote:The more usual materials for thermal insulators are "Phenolic" sheet (a fabric reinforced plastic similar to Tufnol) and the more expensive, but better performing "Teflon" sheet (virgin PTFE). I have an insulator water jet cut from 3.1 mm Teflon, but the engine has not run yet, so I cannot comment on the performance.

Do you need to bother with Phenolic insulator on ITB’s? Was under the impression this was a Carb thing, and the idea was to insulate the Carb from heat transferred through the engine, obviously the heat could cause issues with jetting / floats etc.

Cant see the point in doing it on a set of ITB’s or even with a conventional inlet plenum. The air will flow so quickly through the stacks / plenum the chance of a hot plenum heating the air is going to be very small – I would assume the plenum would need to be red hot for it to even come close to affecting the incoming charge temperature?