Quote:
Originally Posted by bmorecam
longer runner length will definitely produce more torque in the lower power band, and shorter the length the more power you will produce up top and this is a proven method that racers and engine builders been using for years and years. The problem here is that we are talking about no bigger than an inch of extra length and differences of only 6mm, 9mm(RX), and 12mm. The question here is, is an inch of added length from the factory measurement really big enough to take advantage of runner length benefit.
a quick online calculation for 3.6L V6 engine showed that I need 24" of intake length and 1.44" square inch of intake runner area from valve head to plenum to have the best torque by 3500rpm. If we want more torque earlier than the intake length will have to get longer than 24"! I don't know what our factory intake length is from the valve head to plenum, but if anyone does then you might be able to get your answer.
One thing I do know for sure is that the insulator is seperating heat from the cylinder head and the intake manifold. I am seeing my IAT avg from ambient temp to about 4-5* over. I can do long and hard runs all day and my manifold stay cold. I can sit at the traffic light and the IAT creep up very very slow. We know that cooler charge of air will produce power, and the insulator does the job very well from what I can tell already. Another thing that's easy to understand is that a thicker insulator will isolate heat better than your thinner counter part.
At the end of the day, we know that the 25mm insulator is worth about 14ft lb of tq. Is that gain all from the temp drop or does the runner length also play a role? I wish I knew  |
Thanks for taking the time and doing this nice write-up. The reason for asking was with so many people hung up on the 25 mm and the height for under hood clearance, and being able to work with XXX intake systems. I figured I would see if we could get some answers. My guess is that any of the insulators will work well, some slightly better than others. Unless someone dynos all of them the same day (probably not going to happen) the difference between all of them are really unknown.
I agree the longer the runner the more torque but as you pointed out we are only talking the difference of 6 to 25 mm. Not like we are talking a low rise manifold vs. a high rise manifold with a spacers......
