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Discussion Starter #1 (Edited)
Ok Guys and Gals if you remember back in Janurary I was talking about changing the gear ratio in our trany's and getting ready to build my car to be the first Saturn Sky to go 200MPH.
http://www.skyroadster.com/forums/f2/has-anybody-tried-changing-gears-transmission-49578/

Well its time to start.
Now that I've bought a new Lysholm/Whipple 1.6 supercharger its time to start the build thread.
Yes I am still working in Texas going back and forth so it will start slow but hoping to have everything done within the next 6-7 months. Other then DDM Dave helping with some motor and trany work its all my labor and money going into the project. Its not like, here Dave take my 10K and do what you can, type of thing. I do all my own work. I wanted to start with the T56 trany but now that I got the new S/C I'll start with that first. Here's some pictures of the new unit. I am not going to take it apart because its brand new but here are some pictures of how the twin screws are made. :thumbs:
 

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This is just nuts!! This'll be a cool thread for sure. I'm thinking at 200 mph, our fiberglass fenders might disintegrate!! Be sure to keep us all posted Ricky.
 

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Discussion Starter #6
Well first I'm going to run it at the Texas Mile

Where will you drive it 200 MPH?

-GT
Probably in Houston or maybe Beeville TX first to see where I sit then go from there. Hennessey always manages to find a unfinished road or something to run on so we'll see but need to run the mile first.
When I went in March and will again in Oct the Lamborghini Aventadors were running 178-186 in the mile. Now those cars weigh 3465 lbs (lbs more then a sky) sure they have HP but the torque is considerably lower then the HP at 511lbs and their drag coefficient is .33 compared to our stock little cars at .42, Camaro- 37, Mustang -36 and the 2017 Corvette Stingray at a ridiculously low .29! I almost find it hard to believe that a Mustang with its huge front end as a lower frontal drag area then a Sky so I think the .42 is a little high but what ever.
It will be a fun project I think. :thumbs:
 

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Discussion Starter #7
Haha thanks Gabes

This is just nuts!! This'll be a cool thread for sure. I'm thinking at 200 mph, our fiberglass fenders might disintegrate!! Be sure to keep us all posted Ricky.
you may be right on the fendors but at the mile they tape over everything that they even think will come off. I have plenty of 200mph tape if I need it :)
 

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Discussion Starter #8
Thanks Bert

I think that would be the least of his problems.

Ricky, good luck, I'll be watching. I think you'll get close but I'm not sure about 200. I hope you prove me wrong.

Bert


:cheers:
Stay warm up there and I'll keep you posted. :thumbs:
 

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Discussion Starter #9
Nope the 1.6 is just one step in motor mods to get me close to 450HP/375WHP

That's not going to get you to 200mph.
I will need at least 425 but would like 450HP. Then the sloped back window hard top, close out under body panels and a 6 speed transmission. The rest will come as the runs proceed. Without a wind tunnel to run it in you have to start some where.
 

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I will need at least 425 but would like 450HP. Then the sloped back window hard top, close out under body panels and a 6 speed transmission. The rest will come as the runs proceed. Without a wind tunnel to run it in you have to start some where.
I'm a bike guy and just getting to understand cars but my two cents is this - I believe that the vehicle at the outset needed to be designed to handle the forces that this will entail. I don't think u can just take a car u happen to have and just add a bunch of power that it was not designed for to get there. I have seen videos of cars built for 200 and was shocked at the road and structural impacts. This was on a straightaway runway measured in miles. Tires can/will rip themselves to pieces with the heat. I wish u the best but I would not be the driver on a $25,000 car when only a hand full of cars in the world can do this this and they we're express built. To be honest I'm not do sure I'd do what they say it can do as is - IMHO.
 

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Keep in mind drag isn't just resolved longitudinally. There are down vectors (aka down force) and up vectors (aka lift). Cars that are "designed" to go 200mph typically go through a lot engineering to manage the drag vectors...and airflow in general. Cars that haven't been designed to go 200mph can be an aero crap shoots. If all that extra drag is converted to down force....probably OK. Up force...that can be bad. Very bad.
 

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At that speed any little but of a bump can turn the car into a sail and flip it up and over. If u have ever watched hydroplane racing u know what I mean. U don't want to try even slightly airborne at that speed. Nothing good happens then. This is an engineering probl not a power problem.
 

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I will need at least 425 but would like 450HP. Then the sloped back window hard top, close out under body panels and a 6 speed transmission. The rest will come as the runs proceed. Without a wind tunnel to run it in you have to start some where.
The hennessey c7 corvette that did 200mph had 700hp, it weighs 350lbs more than a sky but has a 0.29 drag coefficient compared to 0.42 for the sky.
 

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When I went in March and will again in Oct the Lamborghini Aventadors were running 178-186 in the mile. Now those cars weigh 3465 lbs (lbs more then a sky) sure they have HP but the torque is considerably lower then the HP at 511lbs and their drag coefficient is .33 compared to our stock little cars at .42, Camaro- 37, Mustang -36 and the 2017 Corvette Stingray at a ridiculously low .29! I almost find it hard to believe that a Mustang with its huge front end as a lower frontal drag area then a Sky so I think the .42 is a little high but what ever.
It will be a fun project I think. :thumbs:
First, let me start by saying I always wish people the best of luck when it comes to these kinds of things. I've done a similar build trying to push an RC car past 100 mph. You'll find the closer you get to your number, the more work you have to do for every mph you improve.

Remember that drag coefficient isn't calculated by just the front profile of the vehicle hitting the air but also how the air moves over and past the vehicle. The largest two issues with the Sky and it's drag coefficient are the material of the convertible top and the abrupt drop off of that top at the back window. The way the air moves over this area of the car will generate a lot of parasitic drag as the barrier layer of air moving across the car disengages with the surface of the car and creates turbulence behind our rear window. Which is why the following post is going to be a necessity:

Then the sloped back window hard top, close out under body panels and a 6 speed transmission. The rest will come as the runs proceed. Without a wind tunnel to run it in you have to start some where.
Note that the hard top will change the drag coefficient of the car tremendously and now you're into a whole new ballgame. The only way to know what the quantitive aerodynamic change is will be to get the car in a wind tunnel.

As for your underbody panels, you should see if you can get in touch with someone that understands the way air moves under a car. It would be beneficial to do something with the underbody to reduce air pressure and "suck" the car down to the ground when it comes to higher speeds. As others have mentioned, if too much air gets under the car and increases air pressure there the car may have the propensity to become a plane. That's bad.
 

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Discussion Starter #16
I really wanted to stick with the S/C

supercharger is the wrong choice. IAT will go to the moon.
Granted a big turbo would make more but I like the 'off the line responce' of a S/C. lbs/HP= how quick you get from point A to B but as far as top speed the weight really has very little effect. Its all about HP and drag that= top speed. :)
 

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When I went in March and will again in Oct the Lamborghini Aventadors were running 178-186 in the mile. Now those cars weigh 3465 lbs (lbs more then a sky) sure they have HP but the torque is considerably lower then the HP at 511lbs and their drag coefficient is .33 compared to our stock little cars at .42, Camaro- 37, Mustang -36 and the 2017 Corvette Stingray at a ridiculously low .29! I almost find it hard to believe that a Mustang with its huge front end as a lower frontal drag area then a Sky so I think the .42 is a little high but what ever.
It will be a fun project I think. :thumbs:
You really are a caft dunt.

The stock C7 Corvette with a Cd of .29 and 460 bhp tops out at 185 mph, but with a Kappa with a Cd of .45 and the same power, you figure you can do 200?

Here is a post from the other site:

I've known the frontal area and CdA since my original post. The frontal area is 21.1 ft^2. That's almost the same as the much bigger Corvette. The Solstice's CdA is 9.5. For comparison purposes, here are some CdA's followed by the pounds of force exerted on the car @ 70 and 150 MPH (assuming each car could hit 150):

Nissan 350Z: 5.8 CdA, 77 pounds @ 70 MPH, 353 pounds @ 150 MPH
C6 Corvette: 6.16 CdA, 82 pounds @ 70 MPH, 375 pounds @ 150 MPH
Porsche 911: 6.8 CdA, 90 pounds @ 70 MPH, 413 pounds @ 150 MPH
Dodge Viper: 7.7 CdA, 102 pounds @ 70 MPH, 468 pounds @ 150 MPH
Scion xB: 7.7 CdA, 102 pounds @ 70 MPH, 468 pounds @ 150 MPH
Miata: 8.01 CdA, 106 pounds @ 70 MPH, 487 pounds @ 150 MPH
Honda S2000: 9.08 CdA, 120 pounds @ 70 MPH, 552 pounds @ 150 MPH
Solstice: 9.5 CdA, 126 pounds @ 70 MPH, 578 pounds @ 150 MPH
New Beetle: 9.6 CdA, 127pounds @ 70 MPH, 584 pounds @ 150 MPH
Chrysler T&C Minivan: 10.9 CdA, 144 pounds @ 70 MPH, 663 pounds @ 150 MPH
Cadillac Escalade: 12.89 CdA, 171 pounds @ 70 MPH, 784 pounds @ 150 MPH

The Solstice is running about 5050 RPM in fifth gear at its top speed of 142 MPH. At that speed, there is 518 pounds of force pushing back against the car due to wind resistance. Factoring in the drivetrain loss, gear ratio, axle ratio, and tire size, that's about how much force the engine can deliver to the ground at that speed, so that explains the top speed on the car. If the car had a drag coefficient of .35 (which is still kinda poor by today's standards) instead of .45, I calculate it could hit about 160.

This might be an interesting thread for you.


pickups and even a Scion more aerodynamic than Solstice! - Pontiac Solstice Forum
 

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I reached 156 MPH in my Sky yesterday when the road was open. I believe it had more to give, but the noise at that speed is incredible, and the look from the lady (who had her hands over her ears) was an indicator that enough was enough.

Given the amount of noise at that speed, and the difference in noise from 130 to 156 MPH, I couldn't imagine going another 44 MPH faster than that. As it is I am worried I will rip the roof right off!

We were driving in Bayern, and I did manage to average 121 MPH over a 60 mile stretch, which I was quite pleased by. Where I live it is typically nothing but a major traffic jam so it is quite an experience to get to make such excellent time. :cheers:
 
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