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Discussion Starter #1 (Edited)
Power to weight ratio is a simple way to guage a vehicles potential performance. Off course, actual abilities are affected by a number of things including gear ratios, torque and horsepower curves, tire type and size, etc.
Here is how the Solstice stacks up against some former and current vehicles of mine and a few others thrown in for the fun of it. The smaller number the better. (All are published figures or where not available are estimated)

2006 Pontiac Solstice 177HP - 2900lbs = 16.38

1979 Mustang Cobra 5.0V8 135HP - 3200lbs= 23.70
1885 300ZX Turbo 3.0V6 195hp - 3000lbs= 15.39
1990 Corvette Z51 5.7V8 250hp - 3500lbs= 14
2000 Chevy Race Truck 428v8 700hp - 4800lbs= 6.85
2003 Harley VRod 1.1V2 115hp - 595lbs = 5.17
2004 GMS Siearra Z71 5.3HOV8 300hp - 5500lbs= 18.33


others: (base models)

2005 Maxda Miata MX5 142hp - 2447lbs= 17.23
2005 BMWZ4 184hp- 2998lbs= 16.29
2005 HondaS2000 240hp- 2835lbs= 11.81
 

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The Solstice should be right in there with other fun-to-drive vehicles but won't provide world class bragging rights or require a world-class income to own and operate. For many of us, it is just right out of the box. For others it is a tolerable compromise. And for a few others it is underpowered.

A 240 HP S/C Solstice like the Concept would = 11.9 lb/HP

I think the S/C Solstice will be around 210 HP or = 13.6 lb/HP

Obviously I want 240 HP. Obviously I only want to pay for 177HP. So far my wallet is winning. Obviously I hope the production Force-Induction engine is 240HP (guilt by association and all that).

The Solstice is going to be a very fun car, and one that will make you smile every time you walk away from it, glancing over your shoulder to bask in its gorgeous looks just one more time.

These are the good old days! :blueangel
 

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Discussion Starter #3
Within a year or two we will probably see a line of Soltice models similar to that offered by Mazda with the Miata. Those of us that grew up with British roadsters appreciate the simple and low cost performance fun of those cars and, I for one, believe that the Sol harkens back to those cars.

But, if I were to suggest to Pontiac a high end performance version it would be a DOHC all aluminum V6, rear transaxle, 6-speed, fuel bladers molded into the frame rails (to make more trunk space) and a dry sump oil system to lower the engine and center of gravity. That would bring its HP/LB rating to around the 10 to 12 range but the price over 30k.

But for me, the '06 production model is just what I am looking for.
 

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I don't want them to improve on the '06 until I am ready to buy a new one after the '06 has seen the end if its life. ;)
 

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PAS22 said:
1885 300ZX Turbo 3.0V6 195hp - 3000lbs= 15.39
Whew! That's an awful lot of power for 1885.

That there car won the Civil War single handedly it did!
 

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Discussion Starter #6
Oh for spell check on threads! Thanks for noticing, 'spose I should go back and edit the original thread. Can you imagine a carraige pulled by a stampede (or is it stampeed) of horses?
 

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Down here in Texas there's a guy that will build you a Super Seven clone that has a S2000 drive train. Weighs just 1200 pounds w/AC and side curtains! 1200#/240HP=5.0!!! 0 to 60 unbelivable. 0 to 120 no way.. aero brick wall.
 

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DreamerDave said:
Down here in Texas there's a guy that will build you a Super Seven clone that has a S2000 drive train. Weighs just 1200 pounds w/AC and side curtains! 1200#/240HP=5.0!!! 0 to 60 unbelivable. 0 to 120 no way.. aero brick wall.
I've seen that S7 clone - never got a chance to drive one, but I've wondered about one... They go like a scalded cat!!!
 

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Fortimir said:
Whew! That's an awful lot of power for 1885.

That there car won the Civil War single handedly it did!
A little late for the civil war. Hope you DO graduate if the sol is your grad present.

1885 had to be Studebaker Conestoga. They had been in business a long time by then. 'Head 'em up. Move 'em out. Rawhide!
 

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Fortimir said:
Whew! That's an awful lot of power for 1885.

That there car won the Civil War single handedly it did!
Thats real quick too, considering it was equipped with a cannon and machine guns uploaded and imported from the Terminator
 

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Aero brick wall?? Really? I guess with the open wheels it makes it tougher, as the S2000 can reach 155mph I would think a lighter S7 would go the same or faster.
 

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Open wheels really hurt drag coefficient. A LOT.

DreamerDave, are you talking about this one? http://www.wcmultralite.com/

It's tiny, and I can't find it anywhere, but I remember hearing that the drag coefficient was over 1.0 for the thing (mostly 'cause of the really wide, open wheels).

I think the Honda S2000 only goes about 150 MPH, which is in line with a car that size with a drag coefficient of around 0.45 - which is a typical drag coefficient for a short roadster along the lines of the Miata, Honda, and the Solstice.

Frontal area (size), drag coefficient, and power are the only determinants for max speed - mass has a neglible effect for top speed except in the increasing of parasitic drag (like from the loaded tires, or bearings, for example). Even peak torque doesn't matter.

Don't wanna bore anyone, but there's some simple ways to figure out top speed or if you know the size, power and top speed you can back calculate to find the coefficient of drag.
 

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solsticeman said:
Frontal area (size), drag coefficient, and power are the only determinants for max speed - mass has a neglible effect for top speed except in the increasing of parasitic drag (like from the loaded tires, or bearings, for example). Even peak torque doesn't matter.

Don't wanna bore anyone, but there's some simple ways to figure out top speed or if you know the size, power and top speed you can back calculate to find the coefficient of drag.
What about gearing? Wouldn't gearing come into play? I'm not talking about the rev limiter in top gear, but the idea that some cars are geared so that they'll hit the limiter in the "high" gear before they reach max speed, but not be able to overcome drag before they reach their peak power in overdrive.
 

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Discussion Starter #14
I threw by V-rod in for comparison since its dry weight hp/lb is comparable to many super cars and racers. Of course, add a rider and full tank of fuel/oil to this bike and your adding another 200lbs or so. Changes the ratio to 6.91. If you want to hit an aero brick wall try pushing a bike to 120 without a windshield! Hang on tight!
 

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2KWK4U said:
What about gearing? Wouldn't gearing come into play? I'm not talking about the rev limiter in top gear, but the idea that some cars are geared so that they'll hit the limiter in the "high" gear before they reach max speed, but not be able to overcome drag before they reach their peak power in overdrive.
Yep, I stand corrected (or revised). Let me restate:

Frontal area (size), drag coefficient, and power are the only determinants for max speed, provided the engine is properly geared to hit peak power at or near intended max speed.

I guess I was oversimplifying. Obviously, if you gear it so 5th gear is way overdrive and there's a big hole between 4th and 5th, the power getting through may be insufficient when you've run out of 4th and need to be accelerating in 5th, for example.

Perhaps I could even restate it to:

Frontal area (size), drag coefficient, and power are the only determinants for max capable speed. Gearing cannot make a car go faster than this speed, only slower.

Does that make sense?

There's a great aerodynamics section in Milliken & Milliken's Race Car Vehicle Dynamics.
 

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Discussion Starter #18
So if we assume that the drag co of a Solstice is around .45 and its HP 177, than what would its top end be, theoretically that is? Back in my racing days we used to have a formula for calculating the effect of rear end gear ratio on top end, but don't ask me now what the h--- is it. I do recall taller ratios for short twisty (read slower) tracks and smaller numerically for longer, faster ones. Do we know what rear end gears are going to be offered for the Solstice?
 

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Power is less a factor than the others in top theoretical speed. Power will determine how quickly top end is achieved. Example: a 'funny car' and a 'land speed record car', each with 1000 hp. One does the 1/4 mile in 6 seconds flat or less, the other takes 6 miles to reach top speed. Gearing makes the difference. The car mags used to calculate top end based on final drive ratio and engine rpm. This of course assumed a vacuum.

In other words, you have to have enough power to overcome drag, rolling resistance, internal resistance, inertia; but once you overcome those, the power required to maintain a speed falls off, ergo overdrive.

Also at play in motional fluid dynamics is lift at speed and its effect on vehicle control and drag. That's why the adjustable wings and downforce sucker fans which are no longer allowed as first conceived - too much advantage. Interesting to wonder if anyone tried magnetic force to keep the vehicle glued to the track, other than Lionel.
 

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achieftain said:
Power is less a factor than the others in top theoretical speed. Power will determine how quickly top end is achieved. Example: a 'funny car' and a 'land speed record car', each with 1000 hp. One does the 1/4 mile in 6 seconds flat or less, the other takes 6 miles to reach top speed. Gearing makes the difference. The car mags used to calculate top end based on final drive ratio and engine rpm. This of course assumed a vacuum.

...

Also at play in motional fluid dynamics is lift at speed and its effect on vehicle control and drag. That's why the adjustable wings and downforce sucker fans which are no longer allowed as first conceived - too much advantage. Interesting to wonder if anyone tried magnetic force to keep the vehicle glued to the track, other than Lionel.
Achieftain, understand, please do not take this personally, but you're not quite accurate.

Theroetical top speed (gearing removed from the equation) is primarily a function of Size, Cd, and Power. Gearing can only take away from this theroetical top speed. For most cars, the chassis parasitic losses can be estimated at about 15 HP at the wheels (bit more like 18 for sticky tires or heavier vehicles, 10-12 or so for lighter cars, but this works well for ballpark). The rest of the required power is to overcome aerodynamic drag, pure and simple.

The adjustable wings (on the Chaparral in '68) were banned because of the advantage - downforce when you needed it AND and air brake, reduced drag when you didn't need it (like on a straight). The other significant modification that got banned not because of competitive advantage but because of safety due to several "copycat installations" that failed, was the rear aero wing attached directly to the axle (as opposed to connected to the body), so downforces went only into the tires and did not compress the springs...

There is a chapter in "Race Car Vehicle Dynamics" all about the Chaparrals and the neat stuff they did (like the Chaparral Sucker, which got up to 1.7 g's on a skidpad).
 
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