I once read an article that went in to some depth about why these don't work, I can't remember the specific details as it was a long time ago, but I recall it was essentially to do with the volume and speed of the air in the runners meant that heat transfer from the runner walls was essentially nothing anyway. - Once you were actually pulling some revs and throttle angle of course.
I'll try and find the article tomorrow.
I would say there could be a couple of things to consider specific to our engines though. That is both the plenum location above the engine and the location of our injectors.
-It may help to cover the underside of the plenum in reflective heat tape, my thoughts here are that as it's a larger surface area and when not under WOT the air speed in the plenum will be less - so more chance to transfer heat perhaps? Again though I think once you are actually pulling some revs and throttle then it's probably negligible from this too. I will be doing this on the inlet I'll be testing, but being honest it's because the gold tape will look pimp on a crackle black manifold, more than I think it'll do anything
-Regards injectors, as far as I recall then the injection and atomisation of fuel cools the intake charge. Obviously as our injectors are right at the port the spray is therefore after the spacer, so I think resulting charge temp won't have been altered much from negligible air temp change the spacer may or may not have provided. However just to think conversely though for a second, well I guess it could help to keep the injector body cooler, which may have a little effect!? But then small plastic injectors that are held in via a contact point of an o-ring....just how much heat are they actually going to pick up from the manifold?! And there is still the head next to them radiating heat!
Bit of musing there but overall though I'd be inclined to think the spacer will do nothing to very little - but I'll certainly look into them again more tomorrow, as I do need to be ordering some inlet gaskets within the next couple of weeks anyway.
