Autobahn?

[Amanda]

Can anyone give me a list of all the differences between a regular classic and an Autobahn classic Aurora? Are there any external differences? How can one tell its Autobahn with out cranking it past 115mph? I know for example with the Mark VIII's you can tell and LSC from a non-LSC by the color of the grill. What are the distinguishing features of the autobahn package.

[JimW]

Most Autoban equipped Auroras require V rated tires, stock Michelin Energy MXV4+ from the factory (gawd I hated those things...but anyway). Thats the only external giveaway.

You need to look under the spare cover lid at your RPO codes. Search for QQX. If that Aurora doesnt have it...move on...

You want that 3.71 gearing, 140mph limiter and good V rated tires

[erw38]

The one's I know of are the listing of "V" rated tires on the inside of the door. I think the is an option code too of QQX. I know I had it but have seemed to misplace it.

I am sure of the V rated tires. As far as the RPO code, that is from memory and I flunked out of school.

You have been warned.

I think the tranny gear ratios are different too.

Dammit Jim, you beat me to it!

[Amanda]

so that's it huh? just a couple of code give aways? It's going to be pretty tough tracking one down then I suppose.

[erw38]

Jim, what's that gear ratio mean to me???

Higher speed with lower RPM?

[zimaad]

it means that the input shaft turns 3.71 times for every 1 turn of the output shaft. So, you jump into the higher horsepower/torque bands of the engine quicker but tend to run out of gearing and lose top speed (assuming you have the torque to get there anyways). Computationally, it's the ratio of the number of teeth of the driven gear divided by the number of teeth on the driving gear (in a reduced form obviously).

In a nutshell, higher ratio gives you more pop off the line and lower ratios give you less pop off the line but higher top speed (assuming you have the torque to pull you to the gearing limits and don't have a speed limiter).

[JimW]

High gear ratio = HIGH RPM...its revs really high pulling those 4000lbs faster then expected!

You will notice when accelerating hard how quickly that tach hits 6000 RPM

*edit* btw zimaad knows his stuff....!!

[erw38]

apparently so!

[zimaad]

good to know I'm good for something after spending 7 years in college to get my BS and MS in Mech Engineering.....to end up deciding to be a dentist !!!!

[erw38]

What if the patient needs a root canal? At least they will know that you are qualified to draw up the blueprints!

[zimaad]

Well.... they have another name for blueprints for root canals...X-rays.

[dred98]

I'm not sure how this works - a couple of people have explained it to me, but the Autobahn is quicker off the line and also has a higher top speed.
The higher top speed (140 mph) is a function of the speed limiter and apparently because of the V rated tires.
I always used to think that if you got quicker acceleration you got a lower top speed, but it doesn't work that way with an Aurora.
Those Oldsmobile people really knew their stuff !!

[zimaad]

The autobahn is quicker b/c of it's gearing and has a faster top speed b/c it doesn't have a speed limiter. The Aurora is a fuel cutoff I think, but many cars have rev limiters. The V-rated tires don't really do anything for speed except they are rated to withstand the radial and contact/friction forces generated by the higher wheel speeds. I'd be interested to see what a std aurora classic could do for top speed without the speed limiter. I wonder where the torque falls off so that it can't accelerate any more.

[erw38]

At least you know the technical terms

[dred98]

The autobahn has a speed limiter at 140 mph - although I haven't tested it yet . .

[hdewees]

My '95 topped out at 137 MPH - but our state (Minnesota) uses 10% Ethenol which can make a big difference. I think it would be faster without the corn -

[Amanda]

I think it's aggravating the only way to distinguish between the autobahn and others is in the codes...

[JimW]

I kinda like it...its a sleeper thing.

You don't know what you have until you do some exploring

[Aurora40]

dred98 said:

I'm not sure how this works - a couple of people have explained it to me, but the Autobahn is quicker off the line and also has a higher top speed.
The higher top speed (140 mph) is a function of the speed limiter and apparently because of the V rated tires.
I always used to think that if you got quicker acceleration you got a lower top speed, but it doesn't work that way with an Aurora.
Those Oldsmobile people really knew their stuff !!

In this case, top speed is soley determined by a governor. The governor is set based on the tires, not in any way by the gearing. The V-rated tires, with a lot of weight, can apparently handle about 139mph sustained. One thing to remember is the Aurora puts lots of weight on the front tires, and the pressures were not that high (30psi). A V-rated tire can't just go 145 no matter what, it depends on load and pressure in it. If you plan to run top speed, you should really adjust the tire pressure to be safe. The 2001+ has H-rated tires, but a limiter of about 136, only 3mph shy of the V-rated Classic (the 2001 is a lighter car for one).

Anyway, on a car that is not governor limited, it can then be rev limited, or drag limited. Rev limiting means the car can't go any faster because the engine is at redline in the top gear. Another gear or a higher redline would mean it could go faster. Drag limited means the car has hit a wall where the drag is equal to the power the engine is making.

On a rev limited car, the lower 3.48:1 axle of the non-autobahn would likely raise the top speed. However the Aurora is definitely not rev limited.

The Aurora is drag limited, so the 3.71:1 axle ratio is probably the best for top speed. The reason being, is that say the 3.48:1 hits the wall at 150mph. The engine is probably turning, what, about 4800 rpm at that speed? And at 4800 rpm, it maybe makes like 220hp? These are totally out of my head, not real numbers (though hopefully reasonable). If you went to the 3.71:1 axle, then at the same speed, the engine is turning ~5100 rpm. At this higher rpm, the engine is making more like 235hp (peak is at 5600 rpm), so it will have more power to keep accelerating. So it might hit the wall at like 155-160mph instead of the 150 of the non-autobahn.

Does that make sense? If 150mph means 220hp worth of drag, then it will stop the non-autobahn car at 150 (the drag on the cars is the same since there were no aero mods on the autobahn car). The autobahn car is hit with 220hhp worth of drag too, but it has about 15hp left to keep accelerating, albeit slowly. As the speed creeps up, so does the drag until maybe 160mph where the drag is like 240hp worth and the engine is making 240hp...

Of course, it's all irrelevant because the Aurora, no matter what trim, is electronically limited because of the tires... ;D

[JimW]

I guess DHP or Intense needs to design us a chip now!

Which btw Intense is doing for the GXP (4.6L NS)

[dubya]

hdewees - do all mn gas stations use 10% ethanol? i never new that, man that sucks. i know you need 2x as much ethanol as gas to get the same effect, so we get 95% the fuel economy, and probably 95% the performance too, which is 12.5 hp. the HP im not sure about, but i know it gives less mileage.

i gotta know were i can score some all gas!!! cheese country? lol

[dubya]

MN people check this out

www.motorbyte.com/norton/ethanol-free.htm

its a list of all MN stations that dont use ethanol in there gas

not laid out very well, but you should eventually find one by your house

more economy and performance glad i saw this, oh, btw its 8% when the do it i guess, so ive been at 96% of potential...

[JimW]

Maybe its time for that toulene mix...lol, get the gas back up to..oh I dunno...98 octane ;D

[RADEoN]

does that stuff actually work?

[JimW]

Yes, if mixed properly you can create race grade gasoline from lesser grade octane gasoline. Care must be taken.

I have a link somewhere

[RADEoN]

get searching