FR-S vs. 370z, end all be all of discussions

[fatoni]

Originally Posted by DarkSunrise

My view is both are important, neither less so than the other. Take an NC Miata for example. Lowering the car 0.5-1" shouldn't cause any major issues with suspension travel, especially with shortened bumpstops and stiffer spring rates and damping. But with only 4.6" of ground clearance to start with on the chassis, lowering the car that much would drop the minimum ground clearance to 3.6-4.1" total. That is really starting to push the limits on a street driven car, at least for me.



Agree with this. It's fun seeing 300+ whp 86s, but it's relatively unknown how well the chassis deals with that much power. As a general rule, it's better to buy a car that was designed to handle the amount of power you're aiming for (although the 370z might not be the best example for that either, with its brake fade and oil temp issues at the track stock).

a couple tenths of an inch doesnt really seem to be a make or break feature on a car for me. what i would like to see is the frs polar moment and how much tire you can fit in the wheel well. those are two departments that make a miata hard to beat

Originally Posted by switchlanez

As with any car, you have to upgrade brakes and tires when you increase power and maybe implement some chassis stiffening. But that's a helluva lot easier than re-engineering the chassis. The engineers intended for this to be a tinkerer's car so they built it to handle more power.

Chris Harris states the Z is an 8/10ths car meaning it starts to feel squirmy (vague steering feel, etc.) at higher speeds. The Z already cannot handle its own stock power.

you dont need to reengineer a chassis. we dont even know that the frs has a better chassis than the z do we? its 2012, im pretty sure every chassis is able to cope with power but things like suspension, diffs, tires, brakes and drivetrain are all going to need upgrades and that is expensive.

[DarkSunrise]

Originally Posted by fatoni

a couple tenths of an inch doesnt really seem to be a make or break feature on a car for me. what i would like to see is the frs polar moment and how much tire you can fit in the wheel well. those are two departments that make a miata hard to beat

It adds up to more than an inch on net. For example:

If you buy an FR-S and want to reduce CG down to 17.5", then you lower the car 0.6", reduce suspension travel by 0.6", and end up with a minimum ground clearance of 4.3". Everything looks fine here.

But if you buy an NC Miata and want to reduce CG to 17.5", then you'd have to lower the car 1.5", reduce suspension travel by 1.5", and end up with a minimum ground clearance of 3.1". Not as good here.

The difference is about 1.2", and that's a notable advantage in my mind for the FR-S if you're planning on tracking it.

Polar moment of inertia measurements haven't been released on the FR-S so we'll have to wait to see on those, but both have similar wheelbase to length ratios and neither has a ton of weight hanging outside the axles. I think it'll be close.

Don't get me wrong, the Miata is a great choice for tracking as well, but I think the FR-S has a couple of advantages on its end (and actually the most notable one for me is one we haven't touched on yet, the fixed roof).

[fatoni]

Originally Posted by DarkSunrise

It adds up to more than an inch on net. For example:

If you buy an FR-S and want to reduce CG down to 17.5", then you lower the car 0.6", reduce suspension travel by 0.6", and end up with a minimum ground clearance of 4.3". Everything looks fine here.

But if you buy an NC Miata and want to reduce CG to 17.5", then you'd have to lower the car 1.5", reduce suspension travel by 1.5", and end up with a minimum ground clearance of 3.1". Not as good here.

The difference is about 1.2", and that's a notable advantage in my mind for the FR-S if you're planning on tracking it.

Polar moment of inertia measurements haven't been released on the FR-S so we'll have to wait to see on those, but both have similar wheelbase to length ratios and neither has a ton of weight hanging outside the axles. I think it'll be close.

Don't get me wrong, the Miata is a great choice for tracking as well, but I think the FR-S has a couple of advantages on its end (and actually the most notable one for me is one we haven't touched on yet, the fixed roof).

the roof is why i spend more time on this forum than on the others. i have never heard of anybody with a certain cog as a goal. even if i did, i would imagine it would be much harder for the frs to gain the f:r balance than for the miata to be driveable with a comparable cog. all that aside, we still dont know that the frs has less weight above 18.1 than the miata. so despite having a better cog, it still may be at a handling disadvantage in this theoretical world we are arguing in. but still, the roof...

[Embarrassed]

Originally Posted by DarkSunrise

It adds up to more than an inch on net. For example:

If you buy an FR-S and want to reduce CG down to 17.5", then you lower the car 0.6", reduce suspension travel by 0.6", and end up with a minimum ground clearance of 4.3". Everything looks fine here.

eh.. maybe. How much travel did you start with? 5"? How much was in bump? Half? Keep in mind that reduces travel in compression only. since you seem to like numbers. THIS is where that foumula you were using comes in handy. Remember the 80% of the weight on the outside wheels? That needs to be accomodated by the springs. Go find the spring rates and figure out how far it deflects with that increases in load. You'll find that the stock car pretty much corners on the bumpstops and decreasing travel by 20% will make that situation much worse.

Originally Posted by DarkSunrise

The difference is about 1.2", and that's a notable advantage in my mind

Still working on that. But I assure you, just about anything you can achieve with a lower cg is easier to achieve some other way, and usually the other way is much, much more effective.

Originally Posted by DarkSunrise

Polar moment of inertia measurements haven't been released on the FR-S so we'll have to wait to see on those, but both have similar wheelbase to length ratios and neither has a ton of weight hanging outside the axles. I think it'll be close.

Polar moments. Another one of those hard to change, not terribly important things.

O

[SUB-FT86]

I like how everybody says the Z is so heavy yet when Porsche comes out with the 911 weighing around the same weight nobody says nothing bad about Porsche with the same amount of weight.

[brewksy]

Originally Posted by fatoni

the roof is why i spend more time on this forum than on the others. i have never heard of anybody with a certain cog as a goal. even if i did, i would imagine it would be much harder for the frs to gain the f:r balance than for the miata to be driveable with a comparable cog. all that aside, we still dont know that the frs has less weight above 18.1 than the miata. so despite having a better cog, it still may be at a handling disadvantage in this theoretical world we are arguing in. but still, the roof...

Just because people don't look to closely at COG doesn't mean that it isn't a much more important metric than f/r ratio, hp/weight figures, etc. Of those metrics, the COG tells a much better picture of a car's ability to transfer weight. COG, suspension effectiveness, and weight seem to be the most important to me.

[fatoni]

Originally Posted by brewksy

Just because people don't look to closely at COG doesn't mean that it isn't a much more important metric than f/r ratio, hp/weight figures, etc. Of those metrics, the COG tells a much better picture of a car's ability to transfer weight. COG, suspension effectiveness, and weight seem to be the most important to me.

well then by all means slap some raceland coilovers on that bad boy, slam it, and have the best handling frs you can have

[Lonewolf]

My cat's breath smells like catfood...

[brewksy]

Originally Posted by fatoni

well then by all means slap some raceland coilovers on that bad boy, slam it, and have the best handling frs you can have

Way to take it to the next level. Or, throw a heavy suitcase in the back of your FRS to make it have a better F:R weight ratio and have a FRS that handles like a Miata.

[sho220]

Originally Posted by brewksy

throw a heavy suitcase in the back of your FRS

Or a dead hooker...

[fatoni]

Originally Posted by brewksy

Way to take it to the next level. Or, throw a heavy suitcase in the back of your FRS to make it have a better F:R weight ratio and have a FRS that handles like a Miata.

yeah i probably shouldnt have said it like that. sorry. the issue here is that you said cog is way more important than these other things which i dont agree with. not agreeing with that doesnt mean i think all these front:rear ratio is way more important that cog. overall weight among other things is something i would say is way more important though which you seemed to have a problem with

[brewksy]

Originally Posted by fatoni

yeah i probably shouldnt have said it like that. sorry. the issue here is that you said cog is way more important than these other things which i dont agree with. not agreeing with that doesnt mean i think all these front:rear ratio is way more important that cog. overall weight among other things is something i would say is way more important though which you seemed to have a problem with

Huh? Reread my post over again?

I said COG should be more important than hp/weight, not weight. My only problem is we look at F:R ratios as the ultimate determinant of balance when by itself it says almost nothing about a car's ability to transition weight quickly. Then we'll look at COG differences of 2 inches and think "meh, that doesn't matter much..."

[brewksy]

Originally Posted by sho220

Or a dead hooker...

I believe, with the seats folded down, this is easily a 2-dead-hooker trunk.

[Embarrassed]

Originally Posted by brewksy

I said COG should be more important than hp/weight, not weight.

Your call. I think it's silly, but it's your call.

Originally Posted by brewksy

My only problem is we look at F:R ratios as the ultimate determinant of balance when by itself it says almost nothing about a car's ability to transition weight quickly.

F:R isn't the best, but until they start giving us things like spring rates, effective bar rates, installed motion ratio curves, frame and bushing stiffness measurements, it's the best we got. That, and when it comes right down to it, there are some pretty fundemental reasons why it actually says A LOT about what a car should handle like at the limit. It also says lot about how it will handling combined loading (braking+cornering)

Originally Posted by brewksy

Then we'll look at COG differences of 2 inches and think "meh, that doesn't matter much..."

...the COG tells a much better picture of a car's ability to transfer weight

That's becuase the CG has compartively little effect on how or how fast weight transfers. Dropping CG height by 10% will only get you a 10-15% response improvement in repsonse time - an amount that can be barely felt by even pretty competant drivers. By comparison, I've measured 300% improvements by changing damping, and up to 700% changing springs, dampers and tires.

When it comes right down to it, CG tells you almost nothing about how a car transfers weight. IT'S BEING USED BY TOYOTA AS A MARKETING GIMMICK. Nothing more.

O