What is the deal with a tubular turbo manifold? I know it is the best when the runners are as short as possible and should have equal length, right? The wastegate should be feed from all 4 cylinders too.

So, what is the deal of running a tubular manifold vs (let's say) an inlinepro stainless iron mani?

 

Personally, i dont know. Some people are making some damn good power off of the inlinepro manifold.


Rob

 

shorter runners are actually considered to be generally less effective than a longer runner. For example on identical motor setups, the full-race equal length spools a 60-1 to full boost by 4200/4300 rpm. However with a log style its more like 5400-5500 rpm.

Also a nicely tuned equal length manifold will have a far broader mid range torque band as well as a broader HP curve. The peaks are generally only about a 20 hp differnce while the midrange can be even bigger.

needless to say, longer runners do work better. A funny test that is interesting to do and mimics a flow bench is using compressed air from a compressor and a simple blow gun. Take the gun and pull the trigger then point the compressed air to come out of each head port. Then stick your hand at the turbo point and feel how much air comes out. Then put your hand at the other 3 exhaust ports on the head flange to feel for any reversion. On a log manifold/drag style there is quite a bit of air coming back out the exhaust flange. On a properly design equal length with a merge collector there is *no* air coming out and the air that is coming out of the turbo flange is hauling ***.

its pretty fun.

 

What your saying is true though. A turbo is not spooled on air flow but rather on heat energy. If the runners get to long, they loose heat and the turbo will not spool.

 

its a combination of the two. Length is not only to blame for lousy heat transfer. Heat transfer is mainly due to two things -- 1) surface area (length and diameter) as well as (more importantly) 2) the heat transfer properties and insulative properties of the material used. The thicker the material the better the heat retention. Also ceramic coating do wonders in these situations.

also ever wonder why a 60-1 will work so well on a super high revving honda but not so well on a lower revving sr20?