what yous think of this manifold?

[blaze]

hey all im thinkin about purchasing a manifold soon heres 1 i found. does any1 know anything about these? Twin Throttle Manifold - eBay Engine Modifications, Performance Parts, Car Parts, Accessories, Cars, Bikes, Boats. (end time 27-Mar-09 11:22:45 AEDST) i think they are no brand name

[VrWagz1]

Is your car turbo'ed, or heavily cammed. With alot of these i have seen the runners just seem too short for standard or even mildly modified application. Maybe ask them the runner legnth and post back up and hopfully foamy sees this and can tell you how it will perform roughly.

[blaze]

i asked the dude if the runners where long or short and he replied. "im not sure what u mean by runners" haha umm is there any easier way i could describe them? check out my ride n see if u rekon it would suit. hopefully it will go as good as it looks

[VrWagz1]

So the dude has no idea what he has built by the sounds of it, probably just copied another design. I seen plenty of them on ebay, it seems its fairly easy for people to just machine off the top of the standard banana manifold and weld up a new plenum ontop of it and call it a "performance manifold" without actually knowing why.

The runner length is important as it basically determines your peak power. There are web sites that explain this better(google some stuff) but i'll try and give you a quick 101 on my limited knowledge.
As you know the inlet valve is ultimatly at the end of the intake runner and the air rushes in there at a squillion miles an hour and then the valve slams shut. When it slams shut it bounces a pressure wave back up the runner. When it reaches the other end of the runner at the plenum chamber, it bounces off the plenum base(or roof in that ones case) and pulses back down the runner again. Now the trick is to have the inlet valve re-opening at the very point the pressure wave reaches it so it can slam itself into the cylinder. This assists with the cylinder not having to "drag" the air in basically and helps increase the efficiencey and power of the motor. One web site i was reading basically said if you have the runners tuned at the right length it can be almost like having a mini turbo fitted.

So if that sorta makes sensce, you'll see that its alot more than whacking twin t/b's onto a manifold and chopping the runners up to any ol' length that fits. They are a fairly precise, tuned device that manufactures and engineers put alot of time and calculations into, and if its modified without proper knowledge it can stuff all that stuff up and you will end up with alot less power then you have now and your torque and peak power curves could be anywhere.
Modified and built properly to your motors specs you can make a substantial power gain. Done wrong and it will cost power. The fact this guy has no idea of the runner length is concerning as it should be one of the only things he should be worried about.