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-   -   How stable a 330ci at 170mhp (landspeed racing) (http://forum.e46fanatics.com/showthread.php?t=765918)

schulmann 05-20-2010 01:47 PM

How stable a 330ci at 170mhp (landspeed racing)
 
In my area we have the opportunity to participate in a landspeed race. I have 330ci 5sp with an AA supercharger kit. I have the impression that I could hit 170mph. The track is 2.3 mi long with an acceleration zone 1.4mi and a deceleration zone of 0.9mi. The track is an airport runway in concret. Joins are very smooth.

I was wondering if my engine would hold up 15-20 seconds at 6500rpm.

But I am esptially concerned regarding the high speed stability. How a 330ci behaves at this speed ?

///Flash 05-20-2010 01:53 PM

your tires are going to blow

ChasCan 05-20-2010 01:55 PM

You can probably expect the car to be very stable at hi speed, especially with stock suspension. I have had my 330xi up to 140 mph & felt very comfortable. I just ran out of road. And yes, Your engine will hold up. Just ck your oil level b4 the attempt. Chas

BruceWayne 05-20-2010 01:56 PM

It depends on your suspension set up, I had KW V2s on my 330ci it was comfortable at 130 but I never had the governor taken off. My M3 with KW V2s is comfortable at 150 and at 130 it is more comfortable than the 330

jcns 05-20-2010 02:02 PM

I am not sure the stock gearing will get you to 170mph.
Check oil and coolant. Your engine should hold up if maitenance has been kept up.
Make sure you have the correct rated tires for those speeds.
If you could add a M3 spoiler, that'll help stability.
Check tire pressures all around before the run. That'll help with speed and stability.

BMWstudent 05-20-2010 02:08 PM

If it were me, I would go over every bit of my suspension first. I've been 130 in a car, but not even close to 170. Since things change exponentially with increased speed, saying a car is okay at 130 doesn't exactly mean it will be okay at 170.

Look at everything tie rods, control arm bushings, ball joints, tire pressure, everything. There is a very real reason why not every car is able to go that fast, (1) they don't have the mechanics to go that fast/stay stable/stop, or (2) they aren't well enough maintained. I would think that your car fits the bill for the first part, but make sure you're up to snuff on the second. It would really friggin suck to get wobble at 170... I can only imagine the amoung of ground you could cover with just a few degress of error.

What tires are you going to use? Are you having your wheels balanced for higher speeds? Hitting resonence at 160mph would be terrible for your lugs and hubs .

my $.02

edit: when i say exponential, I mean it. the equation of kenetic energy is 1/2(mass)(velocity)^2 ... you have about 58% more energy at 170mph than at 130.

Rayce185 05-20-2010 02:13 PM

My car starts feeling shaky at 100+ mph, but I stripped out the entire rear of the car :eek:

firefirefire90 05-20-2010 02:16 PM

I would check over your suspension beforehand, otherwise I think you'd be fine

firefirefire90 05-20-2010 02:16 PM

Quote:

Originally Posted by Rayce185 (Post 11771125)
My car starts feeling shaky at 100+ mph, but I stripped out the entire rear of the car :eek:

that shouldn't make much difference :rofl:

FIX YOUR RTABS RAY

mvrk10256 05-20-2010 02:17 PM

how is your gearing going to let you do that? what kind of diff do yoiu have? 6 speed?

check over your suspension, and get z rated tires. and check your brakes as well, new fluid is a must. I have done 140 i9n my car. and it is super stable. but i am lowered, with wide sticky rubber. but the car was stable. i just ran out of redline.

n2Bimmer 05-20-2010 02:35 PM

First make sure your tires will handle that speed, Then make sure you balance the tires, Best to have a Road force balance. Then make sure your control arms and bushings are good, Make sure everything is tight, Check oil, coolant. Be safe good luck, Carry a fire extinguisher just in case.

jcns 05-20-2010 02:37 PM

Quote:

Originally Posted by Rayce185 (Post 11771125)
My car starts feeling shaky at 100+ mph, but I stripped out the entire rear of the car :eek:

funny you should mention that.
topgear stripped out a Renault (I believe) of several hundred lbs. After all that weigh saving exercise, the car was slower around the track because now the car was out of balance.

rEid46_323 05-20-2010 02:46 PM

watch out for the MONEY SHIFT!!

mvrk10256 05-20-2010 02:50 PM

Quote:

Originally Posted by rEid46_323 (Post 11771248)
watch out for the MONEY SHIFT!!

how would he money shift in a straight line accelerating? in theory he should never have to downshift hard. but rather use the engine to brake by going one gear at a time.... :confused: :facepalm:

Rayce185 05-20-2010 03:00 PM

Quote:

Originally Posted by jcns (Post 11771220)
funny you should mention that.
topgear stripped out a Renault (I believe) of several hundred lbs. After all that weigh saving exercise, the car was slower around the track because now the car was out of balance.

No washer fluid or HVAC in the front either ;)

I just need to get my car's suspension inspected and rebalanced.

xixixi 05-20-2010 05:04 PM

i've had my xi up to 167 via tomtom loads of mods no shaking no unstable feeling 3.07 diff... on the highway. You're on a run way grow some balls :rofl: i constantly run my car well over 140 on the highway not issues.

PEI330Ci 05-20-2010 05:35 PM

I've hit 166mph with a stock suspension and it scared me. (On a rough surfaced straight line) You should be fine on a smooth surface, but you probably don't have enough power to see 170 in only 1.4 miles.

Have fun.

FTWeisse 05-20-2010 09:11 PM

Raceland.

330I6SPD 05-20-2010 09:19 PM

Quote:

Originally Posted by ///Flash (Post 11771042)
your tires are going to blow

HOW SO?? If OP has unpatched, unabused, Y rated tires, he is good to go AT LEAST 186 mph with no tire issues!

vaio76109 05-20-2010 10:40 PM

Quote:

Originally Posted by mvrk10256 (Post 11771264)
how would he money shift in a straight line accelerating? in theory he should never have to downshift hard.

Money shifts can happen while accelerating too...

And LOL at this thread.


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