Twins vs future competition

[regal]

One of my craziest thoughts is the Twins becoming very popular filling the hole in the market that was once owned by small RWD pickups. I always thought the majority of buyers of little Chevy S10's and Ford Rangers were like me grew up driving RWD and couldn't afford a rwd car so they bought the little trucks. Most people who bought thos trucks didn't use them as trucks.

Its kind of an off the wall thought but if the twins could tap into that lost market the sales would be sky's the limit.

[ZDan]

Originally Posted by fatoni

was the cog of the 240 really all that low?

S13 c.g. should be quite low. I don't know exactly how low, but I'd bet it is in the ~18-20" range.

Originally Posted by zephyr69

But the Miata does not have a lower cog than an FRS, even in stock form.

The NA Miata does have a lower c.g., ~17". NC might be higher than the twins', but not by much.

50/50 weight distribution is NOT the best for ALL cars, that is a common misconception.

Totally agree that 50/50 is not "perfect" or "ideal" weight distribution. 50/50 on a fwd car would be a disaster! For a rwd car with serious power/weight, you want more rearward distribution than this. At the FR-S/BRZ's 200hp/2750 lb., 54/46 isn't a problem. Start adding power and it will become more of a problem.
If they'd wanted better (more rearward) weight distribution for the twins, they would have had to either ditch the +2 (losing sales with more limited utility) or extend the front wheels forward, which would have made it feel less nimble and added weight. In stock form, these compromises don't really hurt handling performance.

Body roll is one of the indicators for cog, although it is affected being the suspension of the car.

Body roll is not really a good indicator of c.g. height. Suspension stiffness and geometry are HUGE players here, much more so than +/-5% c.g. height.

why would Toyota base the FRS weight distribution on how many people are in the cabin?

Because that makes the figures easier to stomach for people who wanted it closer to 50/50.

I don't even know what to say to that... So do they predict how much the passenger might weigh too? Give extra weight to the back on the Scion FRS in comparison to the Toyota 86 because Americans on average weigh more than Japanese people?

Here it is:
53/47 is the weight distribution estimate they gave, *with 2 occupants* and presumably a full tank of fuel. Hell, it could be that the 2 occupants are in the back! Also note the marketing spin about how being front-biased achieves a "pure sense of steering". Utter b.s.!

Actual measured weight distribution has been 55/45 without a driver, 54/46 with.
Here's Motor Trend's 55/45 measurement:
http://www.motortrend.com/roadtests/...t/viewall.html

Again, this isn't that big a deal in stock form, with stock power. But for an FR car, more rearward than this *would* be subjectively and objectively better.

We all love the Miata, it is an amazing car, even till this day. But the FRS has it beat in almost all conditions. The FRS is basically the closest thing to a modern day Miata.

The Mazda MX-5 Miata *is* the modern day Miata! I'd like to hear why you think the FRS is more of a "modern day Miata". The FR-S is a bigger, heavier, fixed-roof 2+2 with a bit more power. It is the modern day S13 240SX. Which is fantastic as far as I'm concerned!

The FR-S has the Miata "beat" because it has superior power/weight. On the same token, countless other cars (Genesis coupes, Mustang, Camaro, etc.) have the FR-S "beat".

Should be noted that the stock Miata has *never* been about "beating" other cars. It has been all about pure unadulterated open-top lightweight rwd roadster fun

[regal]

Originally Posted by ZDan

The Mazda MX-5 Miata *is* the modern day Miata! I'd like to hear why you think the FRS is more of a "modern day Miata". The FR-S is a bigger, heavier, fixed-roof 2+2 with a bit more power. It is the modern day S13 240SX. Which is fantastic as far as I'm concerned!

The FR-S has the Miata "beat" because it has superior power/weight. On the same token, countless other cars (Genesis coupes, Mustang, Camaro, etc.) have the FR-S "beat".

Should be noted that the stock Miata has *never* been about "beating" other cars. It has been all about pure unadulterated open-top lightweight rwd roadster fun

Exactly why I bought the FR-S over similarity is spot on S13. As far as FR-S having better power/weight than a Miata, basically a wash, the difference isn't even worth mentioning. I think the less body roll , stiffer chassis, lower cog does add up to help the FR-S in not needing a super stiff suspension and that's where it outperforms the Miata as a daily driver.

[serialk11r]

Originally Posted by Be-Are-Zee

This - the new rotary will not be lacking. They already have the 16b pushing 300 hp non FI on a 1.6L. That's insanely small lightweight engine with huge output...now to just solve the mpg issue.

That 1.6 is 3.2 liters in normal engine speak, expect crap fuel economy no matter what magic they pull. The seal friction on a rotary makes up for its lack of friction elsewhere.

[R3d]

Originally Posted by ZDan

Should be noted that the stock Miata has *never* been about "beating" other cars. It has been all about pure unadulterated open-top lightweight rwd roadster fun

All very valid arguments but ill say this, on a track a Miata turbo is seriously annoying if your trying to pass it XD!

[ZDan]

Originally Posted by regal

Exactly why I bought the FR-S over similarity is spot on S13. As far as FR-S having better power/weight than a Miata, basically a wash, the difference isn't even worth mentioning.

~14.5 lb/hp for the FR-S, ~15.7 lb/hp for the MX-5. Not huge, but definitely worth mentioning, and not a wash as far as performance is concerned.

I think the less body roll , stiffer chassis, lower cog does add up to help the FR-S in not needing a super stiff suspension and that's where it outperforms the Miata as a daily driver.

The MX-5's 10% weight advantage more than offsets any FR-S c.g. advantage (which is 5% *max*, probably more like 2%).
The NC chassis is a lot stiffer than previous Miata iterations, but probably not as stiff as the fixed-roof twins'. But then again the twins have to be 10% stiffer just to have the same stiffness/weight as the MX-5, so again the weight disadvantage negates at least some of the stiffness advantage.

The FR-S/BRZ does seem to have stiffer suspension settings relative to weight, which is "better" as far as I'm concerned. But for a daily driver usage, the Miata's softer suspension is probably subjectively "better" for a lot of people who are less interested in autoX or road course performance.

[ZDan]

Originally Posted by serialk11r

That 1.6 is 3.2 liters in normal engine speak,

A 1.6 rotary displaces 1.6 liters per crank rev.
If you ask me, it would make more sense to call a "2.0 liter" 4-stroke piston engine a 1.0 liter (it only displaces that much every crank rev) than than to call a 1.6 liter rotary a "3.2 liter".

expect crap fuel economy no matter what magic they pull. The seal friction on a rotary makes up for its lack of friction elsewhere.

I believe it's the heat loss due to the broad rotor faces that kills the rotary's efficiency, much more so than frictional losses from the seals. They generate a LOT more heat for a given power level, so more fuel is wasted to heat in the cooling system and heat out the exhaust.

[DarkSunrise]

Originally Posted by ZDan

The MX-5's 10% weight advantage more than offsets any FR-S c.g. advantage (which is 5% *max*, probably more like 2%).

You actually nailed it on the head the first try. The Twins' CGH advantage over the NC Miata is 5%.

GTI: 22.0"
JCW Mini: 21.0"
Mustang GT: 21.0"
Evo X MR: 20.5"
370Z: 20.0"
350Z: 19.3"
NC Miata: 19.0"
S2000: 18.7"
FR-S: 18.1"
Cayman R: 18.0"
LFA: 17.8"
NB Miata: 17.7"
C5 Corvette: 17.7"
360 Modena: 17.6"
911 GT3: 17.4"

[serialk11r]

Originally Posted by ZDan

A 1.6 rotary displaces 1.6 liters per crank rev.
If you ask me, it would make more sense to call a "2.0 liter" 4-stroke piston engine a 1.0 liter (it only displaces that much every crank rev) than than to call a 1.6 liter rotary a "3.2 liter".



I believe it's the heat loss due to the broad rotor faces that kills the rotary's efficiency, much more so than frictional losses from the seals. They generate a LOT more heat for a given power level, so more fuel is wasted to heat in the cooling system and heat out the exhaust.

Right but what I was getting at was that despite the rotary appearing to have less moving parts, less reciprocating forces, less things sliding against each other per unit air breathed, the efficiency scales with load similarly to normal piston engines, suggesting that they don't really save much friction per unit displacement, and a 3.2 liter engine typically consumes quite a lot of fuel doing nothing since it's quite large.

The broad rotor face is a problem at lower rpm, and at higher rpm the long chamber makes ignition a challenge, along with the fact that recessed spark plugs suck. The physical limit to compression ratio is also something like 11 which sucks. The 26b race engine had 3 spark plugs so it actually was somewhat fuel efficient, but only above 5000rpm lol (that's comparative, it's efficiency just drops less than piston engines since they suffer from high reciprocating forces, pumping and friction the faster you spin them)

The proposed 16x has a slightly better surface area to volume, rumored laser ignition to improve that aspect even more (this helps on all engines though, would be nice to see across the board), direct injection to help a bit with the fuel sticking to the walls problem.

[Be-Are-Zee]

The inefficiency of the rotary actually had a lot to do with the ignition cycle itself. This is why a new laser technology was being researched instead of traditional spark plugs.

[Be-Are-Zee]

The real world mpg of the rotary was interesting. In my experience with three of them my mpg very rarely varied. I could go 55 or 100 mph and still get about 20 mpg. It made driving it hard an easy decision!

[regal]

Originally Posted by ZDan

~14.5 lb/hp for the FR-S, ~15.7 lb/hp for the MX-5. Not huge, but definitely worth mentioning, and not a wash as far as performance is concerned.



The MX-5's 10% weight advantage more than offsets any FR-S c.g. advantage (which is 5% *max*, probably more like 2%).
The NC chassis is a lot stiffer than previous Miata iterations, but probably not as stiff as the fixed-roof twins'. But then again the twins have to be 10% stiffer just to have the same stiffness/weight as the MX-5, so again the weight disadvantage negates at least some of the stiffness advantage.

The FR-S/BRZ does seem to have stiffer suspension settings relative to weight, which is "better" as far as I'm concerned. But for a daily driver usage, the Miata's softer suspension is probably subjectively "better" for a lot of people who are less interested in autoX or road course performance.

Good points, but whatever Toyobaru did to the chassis it just works. It feels like a classic Gran Touring car but 500 lbs lighter. I mean which car would you rather drive 85mph on the interstate for a 10 hour road trip? There is no comparison, yet the Twins still compete well with the Miata through the turns, that's what makes this car so special.

Another thing that is sort of amazing is how you can have a car that handles this nice and not have to clinch going over RR tracks.

There is just something this chassis has that no other car I can think of has, maybe its the not the low cog, the low slung boxer placement, but just the overall chassis stiffness in this weight class due to the modern engineering. Its definitely an improvement on the S13/S14 and better than an E30 BMW or 944 Porsche. The car reminds me of an old '85 6 series BMW I once owned more than anything else I've driven since. And I don't see any new competition since the car is such a multi-tasker.

The things chassis engineers can due with CAD these day has benefited our Toyobaru's.

[DarkSunrise]

Originally Posted by regal

Good points, but whatever Toyobaru did to the chassis it just works. It feels like a classic Gran Touring car but 500 lbs lighter. I mean which car would you rather drive 85mph on the interstate for a 10 hour road trip? There is no comparison, yet the Twins still compete well with the Miata through the turns, that's what makes this car so special.

Another thing that is sort of amazing is how you can have a car that handles this nice and not have to clinch going over RR tracks.

There is just something this chassis has that no other car I can think of has, maybe its the not the low cog, the low slung boxer placement, but just the overall chassis stiffness in this weight class due to the modern engineering. Its definitely an improvement on the S13/S14 and better than an E30 BMW or 944 Porsche. The car reminds me of an old '85 6 series BMW I once owned more than anything else I've driven since. And I don't see any new competition since the car is such a multi-tasker.

The things chassis engineers can due with CAD these day has benefited our Toyobaru's.

All those qualities you're describing are what you'd expect to see from a car with a low CG. You don't need as much roll stiffness because you have less load transfer with a lower CG. If there's any upside to all of the hassle of dealing with the FA20 boxer, it's the low CG achieved by mounting it low in the 86 chassis.

[WolfpackS2k]

Originally Posted by DarkSunrise

All those qualities you're describing are what you'd expect to see from a car with a low CG. You don't need as much roll stiffness because you have less load transfer with a lower CG. If there's any upside to all of the hassle of dealing with the FA20 boxer, it's the low CG achieved by mounting it low in the 86 chassis.

ding ding ding! This guy gets it.:happy0180: