kevin@voder.UUCP (The Last Bugfighter) (03/30/85)
*** The piston engine goes boeing...boeing...boeing... *** > I am considering buying a Mazda Rx7 (for various reasons) and I am > looking for the answers to some specific questions and peoples general > impressions. > > Is there anyway to get an Rx7 GSL-SE WITHOUT all the luxury features? No. The GSL is the luxury model and comes with everything! > What is the current state of Mazda's (the world's) rotary engine > technology? Mazda's rotary engine used to have seal problem (that > could be fixed by countersinking some bolts, or so I was told). Are > there still similar problems? Countersinking some bolts? Don't let that guy work on your car! The problem was inadequate water jacket seals. In a recipocating piston engine the cylinder has a cool intake charge sucked in, then compression and ignition, then hot exhaust is blown out, then another fresh intake and so on. This helps to stabilize temperatures within the cylinder. But in a wankel you have one large chamber with a rotating piston, thus the different portions of the stroke occur in different 'chambers' which are totaly isolated from one another and rotate around the eccentric shaft. This means that the area of the chamber where the intake is sucked in is always relativly cool compared to the other side of the engine where ignition takes place. This area of the housing between the inner wall and the water jacket (where the sparkplugs are) is thin compared to the rest of the engine and is sealed by a large O-ring around the perimeter of the engine. In pre `73 motors this O- ring could fail causing coolant to leak into the engine causing puffs of smoke in the exhaust, hard starting, overheating, loss of power and fuel economy. The cure is a rather simple teflon strip inserted along side the O-ring in the area of the compustion/ignition/power side of the engine, all new motors have this. Does this quarentee that the engine will now never fail? Of course not, it depends entirely on how you treat your engine and rotaries, due to their high revving nature, tend to get more abuse than your average commuter vehicle. > Are there fixes (I am willing to have mods made on a new car)? If you have an older model there's all sorts of stuff you can do to the engine to make it 'bullet proof', but you usually do that kind of stuff when you're building a high horsepower motor. Mods on a new motor? Unless you're racing it or don't give a damn about warrenties, NO! Remember that Mazda has a 50,000 mile/3 year warrenty on their engine. > Of what importance is the 'performance-tuned rear suspension'? I feel this is mostly advertising hype. All it means is that the rear suspension is more responsive and better handeling than that of a standard or previous models of the Rx-7. > What are the advantages/disadvantages of a fuel injected rotary > engine (vs. a 2-stage, 4-barrel carb)? The same advantage as to any engine. More precise metering of the fuel resulting in better economy, lower emisions, or more horsepower. > Finally, what are peoples general impressions of the Rx7 (and Mazda). As a high-performance motor the rotary is great. It's quite, high-revving, responsive and fun to drive. Reliability? My father's Rx-2 ( a pre-`73 motor) needed a rebuild at 67,000. My Rx-4, which I used to rally and generaly drove like a maniac, needed a rebuild at 97,000. My rotary pick-up, which has almost 80,000 miles (some by a previous owner) is going strong with no complaints. A friend's `74 Rx-4 wagon has over 120,000 with no major work other than the clutch and syncros at about 50,000. These cars are old too, there's been ten years of developement since then. Experience with my own cars and other's both piston and rotary have shown them to be well-built, reliable autos. You might be interested to know that Mazda will completely re-design the Rx-7 for 1986, although it will remain simular to current models in style. There are turbo Rx-7s in Japan but Mazda has said several times they will not sell the turbo in the U.S. (don't trust us I guess). They have been working on a stratified rotary and there is a rumor it will be one of the new engines as well as the (pant-pant) supercharged engine they have been developing. Another possibility is an increase in cubic inches. This will kick the Rx-7 higher into the hyper-buck range (which is still lower than the mega-buck range) and another rumor is that Mazda is working on a new car that will fill-in the low price gap the Rx-7 originaly held. --- Kevin Thompson {ucbvax,ihnp4!nsc}!voder!kevin "It's sort of a threat, you see. I've never been very good at them myself but I'm told they can be very effective."