Are rotors synchronised?
 

The 13B REW has 2 rotors. Are these synchronised so that they are doing the same things at the same time or is there a timing difference between them so that, for example the pulses into the exhaust manifold occur at different times (and, if so, what is the timing difference in terms of rotor rotation)?

I ask this as all the available exhaust manifolds I see for 13B REWs in RX8s all have a runner for each port and do not combine them before the turbo. Here, I assume that, whatever the answer, the exhaust manifolds on RX7s are so short that combining into a single runner is impractical.

Subscribed. Good question.

no. they are not synchronized. if you look at the 13B eccentric shaft, you will see that there are 2 different lobes. they are responsible for rotor phasing. they are 180º apart, which gives you the 6 working chambers.

i may be lacking a bit on the technical side for the second part of your question, but here are my thoughts. the exhaust pulses on a rotary are ridiculously high energy (heat promotes velocity), much more so than reciprocating engines. my guess is combining them that close to the ports would cause back-pressure issues and represent a huge waste of energy that could go into driving a turbine.

Thank you

Like nearly everything, this is not rotary-specific. See "DIVIDED MANIFOLD" at this link:
http://www.turbobygarrett.com/turbob...Tech%20102.pdf

diabolical1, thank you for your clear explanation.

Evil Aviator, thank you for the link. The other parts of that series look good too.

Out of interest, the 2 photos show the original 13B REW carbon steel exhaust manifold made by a professional builder that was on my car when I bought her. The main photo shows the general arrangement of the bastardized 2" runners from an existing manifold joined into a single 3" tube to the turbo flange with a wastegate port on the bottom; the 3" tube is reinforced by strips of steel welded to it. The second photo is a view through the wastegate port showing how the ends of the 2" runners jut out into the flow, spall left behind and the quality of the welding.

considering that i can't count welding among any of the talents i possess, my only comment will be this: that manifold was probably just a case of bolting a turbo he already had or got in a "deal" (that probably had no business on the engine in the first place) to the engine.