nevermind

 

o man. geoff you dont like my pics. no comments??
just playing. whats up man. i got to send you some updated pics of the engine bay. WOW.

 

o get ready. winter is almost here and that means motor build and a GT40r twin scroll. maybe we can work something out

 

Holy crap, man. Doesn't seem like you stick with the same mods for long.

 

WOW read from start to finish havent done that in a while this was a great read and i think everyone brought up some great points and opinions and yes they were all very civil and respectful something hard to find in the forums nowadays i wont say any names that brings me to their level but i do not belive it is hype as for reading this i lean more toward a TS setup granted i don't have the knowledge that a lot of you do but IMHO i would say TS just from the read even though there is still doubt to it also fence sitter

 

Twin scroll turbine housings will often have different cross-sectional areas for the two volute paths. This is not because the turbocharger engineers are stupid.

Here is why: packaging often dictates that one of the two volutes is "laid over" somewhat. This places the radius of that volute's effective centroid (this is the "R" in A/R) closer to the axis of rotation. In short, the R gets smaller.

So to maintain the same A/R as the other volute, its "A" (or cross-sectional area) must be correspondingly smaller.

As for GT wheel trims, don't get too hung up on them. Once you start comparing different wheel aeros, it becomes essentially meaningless. Turbine flow is a function of not only of trim but also wheel size, blade wrap, blade thickness, b-width, number of blades, backdisk geometry, hubline, wheel axial length...

 

Your imagining a fictitious motor.

Scorke

 

A "180-degree" V8 is shorthand for a V8 with a flat-plane crank. It's real, and its firing order (unlike a traditional crossplane V8) is indeed exactly like two 4cyls mated to a common crank.

A 180-degree V8 can take advantage of twin scroll. A crossplane V8 cannot, unless you crisscross the exhaust manifolds together like those on a '60s Ford GT40.

 

E.G. the 'Bundle of Snakes' manifold.

This is why I question the value of equal length tubular manifolds on conventional American V8s. With two adjacent cylinders firing on each bank, this negates at least part of the benefit and disrupts pulse tuning. This is why the engineers went through the trouble of putting those elaborate criss-cross manifolds together.

 

Yup.

Those crisscross headers used on a conventional crossplane V8 are also called "180 degree headers". They're called that since their collectors experience the same pulse intervals as those on a flat-plane V8.

 

Well, I do have an active imagination, but, as mentioned, it's 100% truth.

 

And, they are the key element in making a typical American V8 sound much more like an exotic. That's why this GT40 doesn't sound like a Mustang:

http://www.youtube.com/watch?v=iN-J4Jydnkc

Anyway, it's all about finidng ways to isolate and maximize utilization of the 'free' energy of an exhaust pulse. Because the obvious power potential added with turbo covers a multitude of minor exhaust inadequacies, proper exhaust design tends to get neglected. Serious normally aspirated applications tend to give this far more consideration, and with good reason.