Aarons Drag CQ: 3-29 anodized and welded stuff. AN lines

hypothetical · Post by **hypothetical** » Sat May 16, 2009 6:27 am

bradyzq wrote:BTW, is this done to keep exhaust pulses as separated as possible to help the turbo spool, or is it for some sort of scavenging dealio?

It follows the firing order, one pulse to the turbo right after the other back to front and back again. The pulses in theory never compete with each other therefore they loose very little velocity.

speeding-g60 · Post by **speeding-g60** » Sat May 16, 2009 6:55 am

hypothetical wrote:Aaron. You are crazy... Ha ha.

Looks like it is coming together in good order. Do you have pics of the bay before engine install, Id like to see the mount point and mounts if you can show me as well.

That is an 06A block right?

yep, 2.slow 06a block, AEG. and AEB head. mock-up

and Brady:

using a divided inlet turbo with this type of manifold generally is good for 3-500 rpm earlier spool, by keeping it more efficient. i put this up a couple pages back... but here it is again.

out on the Interwebz wrote:[/quote]

A twin scroll turbine housing uses dual side by side passages into the housing. When coupled with a pulse converter manifold that separates exhaust pulses as many crank degrees in the firing order as possible, a twin scroll or divided housing works to reduce lag, decrease exhaust manifold backpressure on the top end, reduce the potential for reversion, and increase fuel economy. The twin scroll is based off the same reasoning a tri-Y header uses: keep spent exhaust gases out of an adjacent cylinder drawing in fresh air. At high rpm on a turbo car, exhaust backpressure is usually significantly higher than atmospheric pressure, and often higher than intake manifold pressure as well. A divider between each of the two volutes allows the cylinders to expel the exhaust gases without it interfering with the fresh air for combustion. Since there are two openings, each a smaller overall volume than a single scroll design, the exhaust velocity of each pulse can be maintained. This also spins the impeller more easily because lag is a function of the scroll area. A single turbine housing opening isn't as efficient since cylinders on the exhaust stroke of the 4 stroke cycle contaminate the cylinders that are on overlap with exhaust gas. A conventional turbine housing is not as effective in using exhaust pulse energy to help spin the turbine up to speed as it does not exploit the energy contained in the pulses as well.[/quote]