Add your comments
Please keep your comments relevant to this blog entry. Email addresses are never displayed, but they are required to confirm your comments.
When you enter your name and email address, you'll be sent a link to confirm your comment, and a password. To leave another comment, just use that password.
To create a live link, simply type the URL (including http://) or email address and we will make it a live link for you. You can put up to 3 URLs in your comments. Line breaks and paragraphs are automatically converted — no need to use <p> or <br> tags.
Please note that gratuitous links to your site are viewed as spam and may result in removed comments.
BREAKING: GM and Chrysler talking about merger
Spy Shots: Nissan 370Z again, with interior shots
2010 Mazda3 unveiled ahead of LA Auto Show
Spy Shots: Nissan 370Z caught undisguised
GM on Corvette ZR1 cancellation rumor: "Not true."
Knight Rider: The Liveblog -- Season 1, Episode 3
In the Autoblog Garage: 2009 Mazda RX-8 R3, return of the "hummer"
In the Autoblog Garage: 2008 Chevy Corvette Z06
Autoline on Autoblog with John McElroy
Paris 2008: Le Day 1 Wrapup
Reader Comments for
Subscribe to this thread2012 Mazda RX-9: Winding Road adds fuel to the fire
(Page 1 of 1)
why not the LS2LS7? @ Dec 31st 2007 2:35PM
Still reads like fanboy stuff. This fanboy is taking their favorite car and just dreaming of stuff to be tacked onto it, making sure to include all the latest buzzword items (like variable geometry turbo, two of them no less!).
I'm a bit shocked it doesn't have a dual-clutch sequential gearbox mentioned in there.
Anyway, the 2nd gen RX-7 had a twin-scroll turbo, which accomplishes the same thing as a variable geometry turbo, which is to extract maximum power from the lower-flow gases at low revs and small throttle openings.
It'd be nice to see Mazda make another turbo Wankel, even though they claim the side-port Renesis isn't particularly well suited to one.
Pouya @ Dec 31st 2007 7:38PM
Actually twin-scroll turbos and variable geometry turbos (e.g., variable area turbine nozzle) turbos work completely differently and do not exactly accomplish the same thing. For one, twin-scroll turbos do not accomplish much in comparison to non-twin scroll turbos top end, whereas VGTs accomplish a lot with its variable turbine a/r. The only thing VGT and twin-scroll turbos have in common is that they tend to perform better than conventional turbos low end, but even then there are some conventional turbos, such as the Garrett GT Ballistic Series, that outperform twin-scroll turbos.
Variable geometry turbos are designed to allow the effective aspect ratio (A/R Ratio) of the turbo to be altered as conditions change for better performance. For example, at lower rpms the a/r is less for a lower boost threshold, less lag, better response. At higher rpms the a/r ratio changes to a greater ratio so that the turbo doesn't choke at higher engine speeds, exhaust manifold pressures are decreased, and ultimately power output is increased as a result.
Twin scroll turbos work differently by requiring a divided exhaust manifold to separate the rotors or cylinders whose cycles interfere with one another to best utilize the engine's exhaust pulse energy. For example, on a four-cylinder engine with firing order 1-3-4-2, cylinder #1 is ending its expansion stroke and opening its exhaust valve while cylinder #2 still has its exhaust valve open (cylinder #2 is in its overlap period). In an undivided exhaust manifold, this pressure pulse from cylinder #1's exhaust blowdown event is much more likely to contaminate cylinder #2 with high pressure exhaust gas. Not only does this hurt cylinder #2's ability to breathe properly, but this pulse energy would have been better utilized in the turbine. The proper grouping for this engine is to keep complementary cylinders grouped together-- #1 and #4 are complementary; as are cylinders #2 and #3. Because of the better utilization of the exhaust pulse energy, the turbine's performance is improved and boost increases more quickly.
Pouya @ Dec 31st 2007 7:45PM
Winding Road makes horrible predictions, an Rx-series car with a V8?? Mazda will allows put a rotary engine in an Rx-series car, because RX stands for Rotary Experimental, and there is too much pride, history, and tradition to abandon the rotary in an Rx-series car. If they wanted to make a sports car with a V8, they would create a new model name. In addition, Mazda currently doesn't make a V8, and I doubt they would make a brand new V8 for such a sports car. If anything, they would borrow from the Ford parts bin, but in general, all of it sounds very very unlikely. . .so unlikely I wonder why anyone would even mention it.