[m3onrails]

I've hit the top speed in my M3 (electronically limited) back when I first got it and was young and stupid, and I also lived in the Midwest where there were straight flat empty roads that went for miles. Now that I've moved back to the NYC area, there are no safe roads to be able to travel those types of speeds, and I can't remember the last time I had it over 110. Top speed is just not all that exciting to me, and I would much rather enjoy the handling of this beast at lower speeds. Not to mention it probably wouldn't be that high of a speed anymore with my 3.46

[englishtom1596q]

I've hit 150 in my car when it was bone stock under the hood. i don't believe its tuned and rear end is the same. car didn't have much left in the way of RPM but it was still pulling well. must say my car felt absolutely planted compared to other cars I've taken to those speeds. no high speed wobbles or jumping around, should imagine it would be even more stable now I'm on coil overs.

But again now getting caught isn't work it. Id rather blast around a track

[englishtom1596q]

Originally Posted by bremms

No way. Drag limit is about 150max. 170 Takes a lot of HP not 210WHP. Well over 300WHP. 170?? you are dreaming. I would like to see some real top speed tests.
On the autobahn the Euro cars get to a real 160.

170? Maybe a modded Euro motor,but even then. US spec stock car? Not going to happen.

Maybe I'm wrong, maybe the E36 is a lot more slippery than I think. 170 is is serious power territory.
I want to see verified numbers.

no way is drag limit 150. my car was still pulling hard at 150. if i had another gear and an s50 intake i guarantee it'd get to around 170. you may be surprised but BMW does give some thought to aerodynamics.

[enderw88]

Originally Posted by englishtom1596q

no way is drag limit 150. my car was still pulling hard at 150. if i had another gear and an s50 intake i guarantee it'd get to around 170. you may be surprised but BMW does give some thought to aerodynamics.

Remember, power required goes up with speed CUBED. That extra twenty MPH is a LONG way away.

(170/150)^3=1.45

So, 45% more power to get from 150 to 170...do you really think it was pulling that hard at 150?

[jafo1701]

I buried the needle 3 or 4 years back after I first did the M50 mani and shark injector. Takes a while to get there and I'm more worried about hitting deer, which we have a lot of. Not worth it imo. I've done some aero mods with a front splitter and rep LTW wing so probably couldn't do it again if I tried, which I won't unless I'm on some sort of close course. I started doing HPDEs last year and it's much more fun to drive around a track and take corners then doing a straight line speed run. Max speed I've hit around a track is 120.

[white out]

140mph speedo indicated.

Nick

[M3n00b]

0.5mph, over speedbumps.

[desertdriver]

Enderw88 is right about the power requirement if you assume that the drag coefficient does not change.

170 is no joke.

For reference, what is the top speed of a Ferrari F40? About 200 mph, right?

Well, that car has 471 hp and weighs 2400 lbs.

Let's calculate the drag limit of a stock 1995 E36 M3. Bear with me.

% density of air at sea level and 20 C

rho=1.2041; % kg/m^3

% conversion factors

ft_m=3.2808399;
hp_kW=1.34102209;
mph_m_s=1/0.44704;

% 1995 BMW M3

da=6.77; % drag area in Cd*ft^2
pwr=240; % hp, stock, at the crank

% convert drag area to SI

da_m=da/ft_m^2;
pwr_kW=pwr/hp_kW;

v_m_s=(2*1000*pwr_kW/(da_m*rho))^(1/3);

v_mph=v_m_s*mph_m_s;

And there you have it: 174.25 mph.

This assumes that all of the power of the engine is going to resist aerodynamic drag and nothing else. It also assumes that the drag area of 6.77 Cd*ft^2 is correct, and that the drag area does not change with speed (which is not true).

Now, what if auxiliary and mechanical power losses are only 10% of power at the crank, you ask?

Then we're down to 168.23 mph. Aux & mech losses of 15% bring top speed down to 165.06 mph. 20% --> 161.76 mph.

Hmmm . . . what is the general relation between hp at the crank and RWHP? With 200 RWHP we get a top speed of 163.97 mph.

To achieve 200 mph requires (according to our model) 363 RWHP, but this doesn't seem accurate anymore (see Ferrari stats above). As you go faster beyond a certain point the drag coefficient increases, demanding more power at the wheels.

[devilbones]

Originally Posted by desertdriver

Enderw88 is right about the power requirement if you assume that the drag coefficient does not change.

170 is no joke.

For reference, what is the top speed of a Ferrari F40? About 200 mph, right?

Well, that car has 471 hp and weighs 2400 lbs.

Let's calculate the drag limit of a stock 1995 E36 M3. Bear with me.

% density of air at sea level and 20 C

rho=1.2041; % kg/m^3

% conversion factors

ft_m=3.2808399;
hp_kW=1.34102209;
mph_m_s=1/0.44704;

% 1995 BMW M3

da=6.77; % drag area in Cd*ft^2
pwr=240; % hp, stock, at the crank

% convert drag area to SI

da_m=da/ft_m^2;
pwr_kW=pwr/hp_kW;

v_m_s=(2*1000*pwr_kW/(da_m*rho))^(1/3);

v_mph=v_m_s*mph_m_s;

And there you have it: 174.25 mph.

This assumes that all of the power of the engine is going to resist aerodynamic drag and nothing else. It also assumes that the drag area of 6.77 Cd*ft^2 is correct, and that the drag area does not change with speed (which is not true).

Now, what if auxiliary and mechanical power losses are only 10% of power at the crank, you ask?

Then we're down to 168.23 mph. Aux & mech losses of 15% bring top speed down to 165.06 mph. 20% --> 161.76 mph.

Hmmm . . . what is the general relation between hp at the crank and RWHP? With 200 RWHP we get a top speed of 163.97 mph.

To achieve 200 mph requires (according to our model) 363 RWHP, but this doesn't seem accurate anymore (see Ferrari stats above). As you go faster beyond a certain point the drag coefficient increases, demanding more power at the wheels.

I just came in to post this. Great minds think alike.

[Bimmerman325i]

Matlab to the rescue!

Sorta hate the fact I can spot .m code.