Water heated plenum on RB25 DET?

[r33fred]

Been making mods to get coolest air charge possible on a series 2 - R33.

Big FMIC from PWR , insulated turbo, cooler and intake pipes with Flashtac to reduce heat soak.

But notice on the throttle body and plenum, coolant piping routing hot water through both. I'm puzzled, would that not simply heat up the plenum and throttle body? Sure feels hot after a run.

Nissan engineers would know what they are doing and probably have reason for doing this. I guess the coolant is designed to cool down the plenum which would get very hot being bolted to the head.

Anyone disconnected these pipe or re routed them?

[raist60]

I thought it was the opposite, i thought their aim was to heat the runners up to increase atomisation of fuel when the engine is cold.

At high airflow i dont think it would make too much difference to the air temps that actually hit the cylinders.

[mabru]

I'm not 100% sure but I think the intent of the coolant passages in intake manifolds are to actually raise the temp of the intake charge during cold start.

[Guilt-Toy]

w0000t.. we gotta remove this crap!!!!

[Busky2k]

Not sure about the RB's, but the SR20 has the coolant hose to the TB because it has a 'fast idle cam' which keeps the TB slightly open when the engine is cold. As the coolant heats up, the cam slowly moves so that the TB is fully shut. I'd check for a device like that before you remove the coolant lines...

[r33fred]

I can understand coolant running through the injector rail to heat up the fuel so it atomises better but can't understand why you would want to heat up the air intake, unless the idea is to actually cool the plenum.

[raist60]

Sorry ill explain my POV. I dont think you want to heat the fuel per say, nor do i think they wanted to heat the intake air.

When you get a good squirt from an injector some bits of fuel would be bound to hit the lower part of the runners, if the runners are hot it would atomise instantly on touch.

Thats why i think its there for atomisation. Its only my opinion.

[dnb]

its so the throttle doesnt freeze shut in the snow i thought

[Guilt-Toy]

its so the throttle doesnt freeze shut in the snow i thought

just stop on it HARD

:microwave

[redline2003]

I was thinking about this a few weeks back too, getting the coldest air possible. Isnt there a way to have the plenum HPC coated or something similar to that used on intercooler piping, so it wouldnt be affected by the hot air around it?? Or is the air traveling through the pipes and plenum moving too fast to be affected by engine bay temps? How good is intercooler piping in keeping cold air cold, as it is still a conducter. Are carbon fibre or alloy with a rubber coating pipes possible? I have seen carbon fibre intake plenums and runners so surely this came from the idea that the plenum suffers heat soak as well, or maybe its just for wank factor? Because i know you can HPC coat the actual combustion chambers, although i dont know how much of a gain it would give, if any.