Quote:
Originally Posted by PTAddict
Not really sure why cylinder to cylinder fuel trim would be more important in an ITB setup. It is actually easier to make each cylinder "see" the same intake tract in a properly designed ITB setup than in a conventional common plenum intake. Adjusting the individual throttle blades to be consistent is obviously very important, of course.
Correct but I've done a few Hilborn systems that had blade problems on a couple of throats. Being able to change cyl to cyl trim kept it from popping at idle.
I have a slightly different point of view on your dirty air comment - I can easily envision a design that has big long runners with throttle blades at the very ends which will create just as much exhaust reversion as a common plenum intake. And most "street" intakes have some common vacuum channel as well. But it really isn't worth arguing - in practice ITB intakes suffer much less from exhaust reversion with big cams than conventional intakes do, and that's all people need to know to understand the advantages.
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If they're isolated then they don't share the others dirty air at the wrong time.
I've done a few where they had tunnel rams or other common plenum intakes first. Idle rpm's ranged from 1100-1400 rpm's and were rough no matter what. Once they got a properly tuned true isolated IR intake all of them idled at 800 and where as smooth as silk. Not sure what else it could be, you?
