Wheeler Dealers Mazda RX7
Discussion
I couldnt see another thread on this so wondered what people thought about the work they did to the Mazda last night?
The motor sounded sweet and during the usual test drive Mike said it felt smooth and powerful with no problems yet we had Edd doing a compression test on the car. It wasnt suffering from low oil pressure or smoke etc so it seemed overkill to do the test. Not sure whether it the right course of action before an RX7 remap (perhaps) but youd think if its running right you vacuum the inside and get it out of the door and make the sale which is usually the main point of the show. They do seem to do some unnecessary jobs on cars.
Interesting that Edd reckoned the common belief these rotary engines are only a 1.3 is wrong and that they are more like 4 litres so on that basis the 295bhp they got on the rolling road doesnt seem quite so great afterall.
Love the shape of these RX7s though and it was a nice car but I dont think I would have gone for fading snakeskin decals or the spoiler print. the wheels were kind of about my limit and to see them being dipped into the printed film was quite an eyeopener.....tbh it looked nice as standard.
Cant believe though the guy selling wanted 6k, sold it for 5k to Mike (old out yarand) then after Edd fitted a new rad and intercooler and remapping it he bought it back for twice the money if what was shown is to be believed even allowing for some entertainment value slack in the facts !
The motor sounded sweet and during the usual test drive Mike said it felt smooth and powerful with no problems yet we had Edd doing a compression test on the car. It wasnt suffering from low oil pressure or smoke etc so it seemed overkill to do the test. Not sure whether it the right course of action before an RX7 remap (perhaps) but youd think if its running right you vacuum the inside and get it out of the door and make the sale which is usually the main point of the show. They do seem to do some unnecessary jobs on cars.
Interesting that Edd reckoned the common belief these rotary engines are only a 1.3 is wrong and that they are more like 4 litres so on that basis the 295bhp they got on the rolling road doesnt seem quite so great afterall.
Love the shape of these RX7s though and it was a nice car but I dont think I would have gone for fading snakeskin decals or the spoiler print. the wheels were kind of about my limit and to see them being dipped into the printed film was quite an eyeopener.....tbh it looked nice as standard.
Cant believe though the guy selling wanted 6k, sold it for 5k to Mike (old out yarand) then after Edd fitted a new rad and intercooler and remapping it he bought it back for twice the money if what was shown is to be believed even allowing for some entertainment value slack in the facts !
Eh, not so much. Ed was referring to an old argument against the displacement of a rotary engine, and one that has been defeated many times over. The basic premise is that because each rotor housing has three chambers, each of which holds half of the engine's total displacement, then you need to multiply that number by 6 (3 chambers x 2 rotor housings) to get the engine's true displacement, which would be about 4 liters.
Uh, no. The problem with that argument is that for each revolution of the e-shaft (this is what the crankshaft is called in the rotary world) you get one and only one firing of the compressed displacement of ONE chamber, not 3. Therefore only the one chamber per rotor housing is involved in calculating the overall displacement. This decision was made by an international committee long before a rotary engine ever saw the light of day in any production capacity. So Ed, if you wanna make that argument, take it to the committee and they'll disprove you along with all of the other folk who have made the same argument over the years. Rotary enthusiasts such as myself don't care one way or another, we just go by what the committee decided oh-so-many years ago.
Funny too in this episode (which was ok in general, just didn't like Ed's assessment) was the frequency with which they referred to the engine as being the "wankel engine." Hah, that's a laugh. wankel detested the engine as we know it today, feeling that it wasn't a true rotary engine. And in the strictest sense, he was correct. His actual design was far more complex and requires no less than 12 state diagrams to explain properly. The problem with his design in the real world was/is that there is no way you can mate a transmission to it. Therefore change had to come and when it did, wankel loathed the end result. So to call it the "wankel engine" is a bit of a lark really. We in the rotary community simply refer to the engine as a rotary.
But I digress.
Anyway.
Uh, no. The problem with that argument is that for each revolution of the e-shaft (this is what the crankshaft is called in the rotary world) you get one and only one firing of the compressed displacement of ONE chamber, not 3. Therefore only the one chamber per rotor housing is involved in calculating the overall displacement. This decision was made by an international committee long before a rotary engine ever saw the light of day in any production capacity. So Ed, if you wanna make that argument, take it to the committee and they'll disprove you along with all of the other folk who have made the same argument over the years. Rotary enthusiasts such as myself don't care one way or another, we just go by what the committee decided oh-so-many years ago.
Funny too in this episode (which was ok in general, just didn't like Ed's assessment) was the frequency with which they referred to the engine as being the "wankel engine." Hah, that's a laugh. wankel detested the engine as we know it today, feeling that it wasn't a true rotary engine. And in the strictest sense, he was correct. His actual design was far more complex and requires no less than 12 state diagrams to explain properly. The problem with his design in the real world was/is that there is no way you can mate a transmission to it. Therefore change had to come and when it did, wankel loathed the end result. So to call it the "wankel engine" is a bit of a lark really. We in the rotary community simply refer to the engine as a rotary.
But I digress.
Anyway.
Cfnteabag said:
doogz said:
This is a rotary engine:
I thought that was a radial engine?It has pistons that go up and down, no?
I see now, rotary in this instance is used to describe the motion of the crankcase, not the pistons.
Edited by FeelingLucky on Thursday 3rd April 17:47
doogz said:
This is a rotary engine:
Uh, no. That is a radial engine. I've flown a couple myself as an avid pilot. Good fun!There have been several experimental (small) aircraft that have been retrofitted with a rotary engine however.
But they're different beasts. Don't confuse the two.
otolith said:
The nominal displacement is a silly thing to care about. What matters is - how big is it? How heavy is it? How powerful is it?
Yeah I concur. This is what is important. And in this sense a rotary engine kicks the ass of any piston engine of similar size and displacement. A rotary is smaller, lighter and more powerful. But that too is a bit of a theoretical argument. In a way at least.The real problem of the rotary isn't horsepower, it's torque. Quite frankly that's where the rotary falls a bit short of the mark. Low end torque just isn't what the rotary does well, period. And then when you combine that with heat sensitivity, average-to-poor fuel economy and a comparable lack of a support structure ... well it's little wonder that the rotary went the way it did.
It's a shame too because most of the issues that folk have with it are more myth than reality. But "perception is reality" and that will trumph truth most of the time. That's good for rotary enthusiasts though, 'cause it keeps the resale price lower - hah!
For a few years now Mazda has been promising to come out with a new version of the RX7, but hasn't done so yet. Hopefully they will have solved some of these issues, we'll see if it ever comes to fruition.
Personally I'm keeping fingers crossed, though it is a tough mountain to climb based on what we know today.
But I digress. Again.
Thanks
The torque issue can be fixed with turbocharging, although to be honest - and I accept it's a bit marmite - I loved the power delivery of the naturally aspirated Renesis in my RX-8. More or less constant torque over a very wide rev range. I'd love something like that in a properly light car.
av8or1 said:
Uh, no. That is a radial engine. I've flown a couple myself as an avid pilot. Good fun!
Uh, no. That is a rotary engine, and I very much doubt you have flown a plane with one, unless you happen to have access to working WW1 era planes.av8or1 said:
But they're different beasts. Don't confuse the two.
Like the people that confuse wankel engines with rotary engines...otolith said:
The torque issue can be fixed with turbocharging, although to be honest - and I accept it's a bit marmite - I loved the power delivery of the naturally aspirated Renesis in my RX-8. More or less constant torque over a very wide rev range. I'd love something like that in a properly light car.
I had an RX-7 many years ago, a Mk1 (I think) and the engine was an absolute jewel.I absolutely loved the car, superb benign handling and as nimble as you like. I would urge anybody who has not sampled the delights of a rotary to do so before it's too late and they're legislated off the road.
Back in the 80s it was pretty unusual for a car to rev out to 8500 rpm or so, but to do so with complete smoothness Mazda deemed it necessary to fit it with a warning buzzer to let you know. It's power delivery really was that good.
The engine is so small and mounted so far back, it really could be considered mid-engined, or front-mid after all the engine was completely within the wheelbase.
ToothbrushMan said:
The motor sounded sweet and during the usual test drive Mike said it felt smooth and powerful with no problems yet we had Edd doing a compression test on the car. It wasnt suffering from low oil pressure or smoke etc so it seemed overkill to do the test.
I didn't see it. Perhaps the compression check was for the sake of making interesting TV? If it serves as a heads up to those considering an RX-8 to get a compression check it's a good thing in my opinion. I think it's pretty standard TV to embellish or do things the wrong way around or labour tiny points to fill the time slot the programmes are commissioned for. I only lasted 30 minutes into the first of the Top Gear Burma special. If it was as good as the Miami to New Orleans one I missed out, but the first 30 minutes of seen it before, formulaic nonsense was enough for me.
Thanks for the previous posts about what they're like to drive.
The guy who sold then bought the car back made a cute move there buying the car back at the end….getting his car performance increased, improved cooling, wheels painted (albeit bloody awful), some dodgy graphics (again beauty is in the eye of the beholder) all for £4.5K.
Doesn't seem like a bad deal to me as labour for all that would have been close to that figure I think
Doesn't seem like a bad deal to me as labour for all that would have been close to that figure I think
The guy who sold then bought the car back made a cute move there buying the car back at the end….getting his car performance increased, improved cooling, wheels painted (albeit bloody awful), some dodgy graphics (again beauty is in the eye of the beholder) all for £4.5K.
Doesn't seem like a bad deal to me as labour for all that would have been close to that figure I think
Doesn't seem like a bad deal to me as labour for all that would have been close to that figure I think
carinaman said:
I didn't see it. Perhaps the compression check was for the sake of making interesting TV? If it serves as a heads up to those considering an RX-8 to get a compression check it's a good thing in my opinion.
I saw it and I agree.They showed the compression test because it's done differently on the wankel engine and because it's a pretty good idea to test a prospective purchase given the problems.
I didn't like the graphics and wheels but the rest of the car was good.
stevel123 said:
The guy who sold then bought the car back made a cute move there buying the car back at the end….getting his car performance increased, improved cooling, wheels painted (albeit bloody awful), some dodgy graphics (again beauty is in the eye of the beholder) all for £4.5K.
Doesn't seem like a bad deal to me as labour for all that would have been close to that figure I think
Do you think?Doesn't seem like a bad deal to me as labour for all that would have been close to that figure I think
The only work Ed did was the intercooler, radiator, batter relocation etc. The labour for the remap, graphics and wheels were all paid for as part of the overall price for the job.
I reckon garage rates for Ed's work would have come to less than a grand.
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