I can't remember where credit is due but a few years back a respected member posted calculations of the potential top speed of a stock 4.6 and one that has the Dinan supercharger.

As you can see it takes a bunch more horsepower to increase top speed even a few mph. The X5 has a lot of frontal area so it doesn't take a huge amount of speed before it just can't make a hole in the air. The calculations do not consider a head or tail wind, hills or valleys, road friction, temp, yada yada yada. Other than conditions maybe like an all downhill road and a 40 mph tail wind these speeds would not be achievable in the real world.

Thank you bcredliner:thumbup:

I was aware the 46is addition HP was not going to make a huge difference in top speed. The additional power would make it get there quicker though.

Just can't understand BMWs thinking, putting a speed limiter on the 4.6, when it's top speed is not much higher then the 4.4 Sport/V tire equipped X.

Worth noting, the high speed run was done during the 90day powertrain warranty period, highest it's been post-warranty is around 135mph (ALWAYS without passengers). Knowing how the X handles at those speeds made it comfortable to take 4 passengers to around 120 mph (on the Sebring 12hr track). Been around that track 100s of times with the ZR1 Vette, Vipers & E46 330 perf pkg.

Post was informational only, not directed to anyone.

Math is not a strength of mine and the formula to calculate the top speed is not there. However, other than 290hp to 340hp and aerodynamic differences, the 4.4 has 3.64 gears and 18 inch tires and the 4.6 has 3.91 ratio and 20s. Assuming everything but the difference in gear ratios is a wash and the 290HP can still push a hole in the wind it would be possible for the 4.4 to have a higher top speed than the 4.6. The difference being that the gear ratio in the 4.6 would cause the 4.6 to reach redline at a lower speed.

My guesses are that the 4.6 was capable of crossing a maximum speed threshold that BMW allowed at that time and the 4.4 could not, or, that low profile fat 20in tires were not available at the time in the required speed rating.

I have thought about running the Texas Mile event that has been on an airplane runway as it is about as safe as it can get. When I looked at the associated costs and requirements of multiple runs at limited speeds before you can go for broke coupled wth increasing safety requirements as speed limitation increases, it more than offsets my interest. May be some here that would be interested https://www.youtube.com/watch?v=yS1NU6xjTSY and then again maybe not.

my garage told me i have a slow leak fluid on both transmission and power steering ... will i get a warning message when level gonna be low ?

hi Guys.

1.What is the normal RPM on idle 3.0i 2001? Mine is pretty low. About 550... or something. I can feel a little vibration on my steering wheel. When I add little more gas vibration is gone.

2. Can I swap my 2001 radio for 2005 radio if I have DSP installed? I haVe BMW BUSINESS CD - NO AUX unfortunately.

Any thoughts? Thanks.

Nope just lots of noise from the power steering pump and transmission damage as each one gets really low on the right fluids. Repair now before there is a LARGE $$ repairs/replacement.

Leaking trans: Trans service and a maltronic (sp?) seal replacement where the wiring comes into to the trans. Cheap and easy DIY see articles above
PS Fluids: Usually lines to and from the reservoir. Easy DIY also.

sounds like a basic tune up is needed. plugs/air filter/maybe some valve cleaning

or could be a vacuum leak

1. Thanks... I have just found out that there is a rattle noise coming somewhere from the engine when the engine is hot. Only when idling.
Only when hot - starting in the morning the problem is non-existent.

If I add gas it disappears around 1000rpm. I must admit I'm worried. I don't think it is disa :/ Any sugestions?

2. I want to replace my Y2000 business CD RADIO with Y2005. I have a dsp soundsystem. Can I replace only the radio and not mid to get aux?
Thanks.

Might help if you record the sound and post it on youtube and provide the link.