Sustained Engine bay temperature

[arseofbox]

'Loha.

Some of you know Ive been developing an inlet manifold for the 1108 and 1242cc FIRE (SPi) Engines.

The design is now finished and Im collecting fabrication quotes. Im looking at using plastics as it could end up more cost effective than using metal.

Problem Im having is temperatures...I know the coolant only reaches 130deg C max in most cars (and if it goes much over 100deg C the engine's kinda dead anyway..)...so theres not much chance that the manifold would have to sustain much more than 100deg C in normal operation (cos the head's gonna lose some heat and Ive bypassed the coolant in the manifold anyway...)

Its easy to find plastics rated for 120 deg C constant operation...but finding much above that is rather hard!!

Anyone else fancy throwing some opinion in!?

 

[arc]

i have a sensor that sits inside my air filter. I've never seen it read about 60c, sat in traffic in summer

I dont think its gonna get that hot round there. I'd be more concerned with the effects the fuel has on the plastic.

 

[arseofbox]

Nah Im not....I can easily find thermoplastics (needed for plastic welding) that are resistant to oil - both fuel oils and oil oil...Its the heat thats worrying me

 

[hmallett]

My thoughts would be:
The inlet manifold will not reach the temperature of the coolant (hopefully!).
The Ford Fiesta Mk4 has a plastic manifold (I think), so it's not that unusual.
By putting the manifold in metal, as it heats up, it will preheat your intake air, whereas you want it as cool as possible.

H

 

[arseofbox]

My thoughts would be:
The inlet manifold will not reach the temperature of the coolant (hopefully!).
The Ford Fiesta Mk4 has a plastic manifold (I think), so it's not that unusual.
By putting the manifold in metal, as it heats up, it will preheat your intake air, whereas you want it as cool as possible.

Yep, there will be some preheating anyway (pretty much everythng conducts heat to some degree)...but Ive taken measures to prevent that...

But plastic manifolds are fairly common yes...I just dont have a clue what plastic it is!!

 

[sediciRich]

the manifold wont see this temp, a gasket between it and the head insulates it against a lot more heat then you think, most of the heat is on the exhaust side, so with a cross flow this will not affect the inlet so much. How will you make this, most thermoplastics for drape forming wont stand up to the heat (they wont melt but will soften), perhaps look to a thermoset acrylic gpr construction. Im sure injection moulded abs will stand up to pretty sure this what most plastic inlets are.

rich

 

[smurfhead]

There are an inreasing amount of new cars on the market with plastic manifolds as standard, including turbocharged vehicles. alot of japanese cars and the odd ford has one