200+ MPH in a C900?

[Adrian Thompson]

Wow, what an amazing thread, I’ve never seen it before. A couple of things, top speed it only limited by drag and power. Weight and torque have nothing to do with it, both of them only affect how long it takes to get to a speed, not what that speed is.

In its most basic form Power = Force x Speed. Force it the drag, which includes aero drag, rolling resistance, mechanical losses etc.

What you would have to is first pick you speed. Then work how much power it takes to go that speed and design an engine that can make that power. Once you’ve got that power, find out what the rpm of your engine is at that peak power and choose your gearing to hit your intended speed at the correct rpm. ‘Simple’ really.

Drag is the bitch though. Drag increases with the square of speed. So if it takes X hp to do 100 mph it will take 8X to do 200 mph. Also it’s not the drag Coefficient or Cd of a car, it’s the CdA which is drag coefficient x frontal area. Obviously if you have two perfect bricks, but one is 2” across and the other is 2’ across the bigger one will create more drag even though they have the same drag coefficient. The other issue is spoilers while helping stability do so at a massive cost of drag. I think you’d be better trying to create a rear diffuser using under body cladding to keep the rear end stable at speed.

There are various online calculators, but using this one http://www.wallaceracing.com/Calculate% ... 0Speed.php I ran some numbers. For some stupid reason it asks for weight, but you can put in 1lb or 10,000lb’s and it gives the same answer because as I said above, weight only affects acceleration, not top speed.
C900 Frontal area. 66.5”W x 56.25” H = 3740ⁿ2” ≈ 26ⁿ2’, take off the sides and area under the car, plus lower it a bit and let’s be generous and call it 24ⁿ2’
The magic internet says the Classic 900 had a Cd of around .34. Let’s assume we remove the mirrors, wipers, smooth out everything we can and tape up all the seams and call it .32.
Say the target speed is 200mph
Per the calculator the required power at 50mph = 7hp
Per the calculator the required power at 100mph = 35hp
Per the calculator the required power at 150mph = 177hp
Per the calculator the required power at 200mph = 420hp

I’ve heard talks from various people who have been to the salt flats, one the guy who did 208mph in an XR4Ti and a team who did 217mph or something in an Alfa Spider. Team members of both are Ford Engineers so I’ve bumped into them. Salt drag is massive, so is the altitude. In reality I think the Merkur needed 600-700hp and the Alfa had well over 400hp, but in a much much smaller car with a lot of streamlining done unlike the Merkur that had stock bodywork for the class.

I think your F prepared car would be the ideal basis with all the work you’ve done on the body, possibly without the rear spoiler, but it would be a great starting point as is on narrow wheels. When you get it running why not take it to an East Coast Timing association even just to see what it will do even in NA form? The ECTA seem to be running the Ohio Mile in Wilmington Ohio which according to the amazing googly-moogly-maps is only………oh eek, it’s 500 miles from you. Why do you live so far away? Bummer, it’s only 260 miles for me.

Well if you do go I’m sure you can meet the safety regs:

To go to 135 MPH:
Speed rated tires
Three point seat belts
Long Sleeve shirt/jacket
Long Pants
Snell SA2005 or SA2010 full-face helmet with face shield ( Car Helmet )
135 to 150MPH:
Five point safety harness SFI 16.1 or 16.5 (no more than 5 years old) Belts must be installed per manufactures instructions. If vehicle has a high back factory style seat, the belts MUST go thru the back.
Four Point Roll Bar (Open cockpit cars must have a six point roll bar) with SFI 45.1 Padding ( Soft padding is NOT SFI rated )
Speed rated tires
Hood Hold Downs
Kill Switch
Electric fuel pumps require an inertial kill switch to disable pump
Arm restraints OR door net

[Crazyswede]

several things people never seem to factor in when they arrive on the salt include:

1. Altitude...its a lot higher than sea level
2. Heat...its usually a pretty warm place.
3. traction on the salt.
You could arrive with a 1000 hp monster and actually reach a point where you have plenty of power on demand but not enough traction to exceed your drag.

[Adrian Thompson]

several things people never seem to factor in when they arrive on the salt include:

1. Altitude...its a lot higher than sea level
2. Heat...its usually a pretty warm place.
3. traction on the salt.
You could arrive with a 1000 hp monster and actually reach a point where you have plenty of power on demand but not enough traction to exceed your drag.

Agreed, that's why this needed over 700hp to do 200mph

And this needed well over 400hp to do 217mph

The Ohio Mile while not having the prestige, length or history of Bonneville is a far more realistic place to go too. Heck, the up to 135mph class is looking mighty tempting all of a sudden!

[SwedeSport]

It is probably more likely that I will have an opportunity to enter one of my existing cars in a speed trial type event. I highly doubt that I'll ever get around to building a car specific to the 200 mph goal.

The fastest I have ever been in a car was about 165. That was in a Porsche 911 Twin Turbo. I did once manage to get my 9-5 Aero to break 140 mph on the PA Turnpike before my girlfriend started freaking out.

[Adrian Thompson]

As I say, enter the FP car in the Ohio mile for fun.

Fastest I've ever been on the street was an indicated 150mph in my Supercharged Mustang, but that was 20 years ago when I was young and stupid. I'll bet with speedo error and tire growth it was more like 140 real mph though. I did cross an international boarder doing 130mph. That's the speed limiter on my Vovlo C30. We picked it up in Sweden, drove down to Denmark then later to Germany, the NEtherlands after going to the Ring, then via ferry to the UK before it was shipped back here. With the European open boarder policy you no longer need to stop for passport control, it was almost midnight when we crossed into Germany. Kinda fun, the kids thought it was cool going into a different country at that speed :)

[Crazyswede]

There was someone in a NG900 running around hp in the 400's that did 174 recently at the Texas Mile: http://jalopnik.com/insane-1996-saab-90 ... -472901153

[SwedeSport]

Looks like the only "aero mods" were removal of side mirrors, and wipers.

[Crazyswede]

Looks like the only "aero mods" were removal of side mirrors, and wipers.

An ng900 is a lot smoother than a c900. Also much more robust transmission.

[ric]

This thread was kind of just a pipe dream.

I don't know if it will ever happen, but it sure inspires some interesting ideas of how to make it so.

Yes, but it would be quite fun!
I understand the minor problem of building a car like that.
My car has been standing under a cover for over 2 years so I can´t realy tell anyone to hurry up.
Maybe someone will build a car for this with the help of our superior knowledge