186 mph (300 km/h) two-way average top speed

[Mac Attack]

[MENTION=12723]greenberet[/MENTION]

Hope you're doing well Andreas! Any new aero developments on your car?

I'm finally working on my aero mods, and you're threads have been very helpful. Thank you.

You've commented on how stable you thought yours handled at 300 km/hr, and I've noticed that the "rake" or angle of our relatively flat underbody with the road plays a big role with that (in addition to alignment and tires obviously).

From what I understand, you were using '02+ wheels with OEM-sized tires and Bilstein shocks. I remember, however, that you had custom grooves cut into your Bilsteins for a different ride height. Do you have an estimate on what the underbody angle was please? I'm just curious to compare it with my high-speed observations. It appears as if about 2 degrees down in the front is a nice balance of lift, drag, and weight balance (oversteer/understeer).

For reference, my target alignment settings for a low car are:
Front toe = 0
Front camber = -1.5 degrees
Rear toe in total = 0.36 degrees (4 mm) <--- I have noncompliance rear bushings but like this setting for threshold braking stability in the rear and when I'm trailbraking
Rear camber = -2 degrees

Thanks!

 

[Lude_2_NSX]

Meanwhile, in California, we just passed a law that makes any aftermarket exhaust illegal. And you can't spend more than 30 seconds over 70 MPH without getting stuck behind a Prius in the #1 lane.

 

[CB72]

I personaly don't like to drive at this kind of speed.
The fastest I went with my NSX was when I followed at Maserati at an indicated 290 km/h.
It can be extremely dangerous as the following video shows...
https://www.youtube.com/watch?v=Jvk2hSIJd9A

 

[Hass]

Wow that's insane, I hit 105 once in the nsx.

CB72 did those people survive?

 

[The King]

Wow that's insane, I hit 105 once in the nsx.

CB72 did those people survive?

Not likely. I'm surprised there was anything left of the camera.

 

[Bram]

True, the camera may be the only thing that survived that shunt.......Shit happen fast at that speed, a little bump, like what happen here will send you flying. Luckily, no one else was involved.

Bram

 

[Miner]

Speed and conditions. I was in Montana just after the 55 MPH speed limit was removed and was driving my Legend coupe. The state didn’t post speeds for curves, they only removed the speed limit signs.

 

[docjohn]

my best was 158 long course at pocono...windows down.....with short gears and R R%P.....I heard scotty saying the engine could give no more captain...

 

[Hass]

Speed and conditions. I was in Montana just after the 55 MPH speed limit was removed and was driving my Legend coupe. The state didn’t post speeds for curves, they only removed the speed limit signs.

Fastest ive ever gone was 125 in my Legend Sedan in 2002.

 

[Miner]

Fastest ive ever gone was 125 in my Legend Sedan in 2002.

That was about the speed I was doing on the interstate there, wide open road, clear vision and most importantly, smooth, straight road. Looking back, it was less stressful than 65 on the I-15 on my daily commute.

 

[Mac Attack]

I don't exceed posted speed limits by more than 5-10 MPH, but my NSX always feels too light in the front end above 60 MPH. This is at the factory recommended rake, where the visible front tire/fender gap is bigger than the rear. 90% of the NSX's I see online have an equal front/rear gap, or the front gap is less. That makes a difference in aero and handling.

I hit 140 MPH in the quarter mile, and that's the quickest I've been in my NSX.

 

[greenberet]

Dear Dave,

Yes, I'm doing well but I haven't made any more aero mods to my NSX yet.

The rear Bilstein dampers on my NSX have some custom grooves about 1/4" (if I remember correctly) lower than the stock lower grooves. Like that, the gap between the top of my OEM 2002-2005 wheels and tires and the rear fenders is still a bit larger than the gap in the front, but it's close enough that it doesn't bother me aesthetically. Like that, the underbody doesn't have much of a downward rake at all. It's probably close to 0. A -2° rake to the underbody like you mentioned would surely be better for lift and drag but I just don't like how it looks with my wheels and tires.

The alignment settings I use are 0 front toe, stock front camber, just enough caster so that my front wheels don't rub on the frame rails at full lock (that's still within the stock range), the same rear toe as the OEM settings on my BMW 7 series (not a lot), as little rear camber as possible given my ride height and toe settings (so a touch more rear camber than stock), and most importantly all the settings are exactly the same left and right.

Aero mods I'm thinking about:

• having all the air that passes through the radiator exit under the front centerline of the car, like what VW did with the XL1, and as little as possible getting into the front wheel wells. That would require a cutout in my NSX's front undertray plus I'd add some shrouding under the hood to guide the air.
• perhaps modifying the front wheel well liners so that the air that has passed through the a/c heat exchangers isn't just dumped out in front of the wheels but instead is blown out along the leading edges of the wheelhouses like the "air curtains" manufacturers are incorporating into more and more cars these days.
• putting an undertray under the passenger compartment as well, even though that area isn't particularly rough anyhow
• having the rear undertray begin its upsweep right after rear beam rod A, which would require custom catalytic converters that don't hang as low as stock and a new muffler that tucks up closer to the trunk.
• All of those mods would be pretty much invisible and I'm thinking about one that would be visible but could be mounted temporarily: custom 3D printed sub boundary layer vortex generators over the rear glass. It would be interesting to empirically test how small vortex generators could be and where they would have to be mounted to get rid of the separation bubble over the rear window and trunk.

 

[CB72]

Wow that's insane, I hit 105 once in the nsx.

CB72 did those people survive?

Apparently yes, according to the comments on YouTube!
In fact they managed to get out of the car before the fire started.
The car came from a rental company.
It all happened in Hungary not even on the german highways...

 

[The King]

They should have went out and bought a lottery ticket after walking away from that! Didn't realize it caught fire, looked really messed up. Hope they bought the extra rental insurance.

 

[Hapa88]

Meanwhile, in California, we just passed a law that makes any aftermarket exhaust illegal.

That's not true. Aftermarket exhausts are still legal in California (just not louder than 95 dB(A)). :surprise:

And you can't spend more than 30 seconds over 70 MPH without getting stuck behind a Prius in the #1 lane.

This is true, however. :redface:

 

[hondasash]

Interesting thread from a German perspective.Indeed the left lane is for overtaking slower cars on the right lane. Anyhow if you are not able to overtake due to trafic / slow car, you should use the right lane - this is called "right lane drive instruction".Unfortunately many of the drivers do not care for that and therefore you have to really take care when driving fast on the left lane.the good thing in Germany is that overtaking is NOT allowed from the right lane - when I am in the US for business reasons I always struggle with that.It is much more dangerous if you could be overtaken from right AND left side.Anyhow sometimes driving fast makes really fun - on my "standard NSX route" during a rollout I alway have a portion driving 140 mph plus.

If I'm not mistaken the slower traffic is not allowed in the laft lane. Someone please correct me if I'm wrong {it won't be the 1st time} but I swear I heard it on the discovery channel.

 

[1BADNSX]

Wow, my hands were sweating watching the video. I am curious if you have a dyno curve for your car and could post it. Is my memory correct, the Euro cars still have the same 5th gear as the U.S. cars?,

 

[hondasash]

140 mph is only 225 kilometers per hour so that is "easily" acchievable with the nsx

 

[nis350]

loud exhausts (over 95dB) have always been illegal, the only change is that there is a fine now in addition to the correction.

Meanwhile, in California, we just passed a law that makes any aftermarket exhaust illegal.

 

[greenberet]

I am curious if you have a dyno curve for your car and could post it. Is my memory correct, the Euro cars still have the same 5th gear as the U.S. cars?

I think I uploaded a dyno chart to my gallery here on NSX Prime years ago so that it would remain available over time but it's not in my gallery anymore and several other pictures seem to have disappeared as well. In any case, the measurements indicated that my engine produces peak horsepower at about 7500 rpm and from there up to 8000 rpm the power stays flat. Various dynos have measured various absolute levels of power. I've seen sub-300 crank hp up to 400 wheel hp with the engine in the same state of tune.

I think you're right that the Euro 5th gear is the same as the US 5th gear but my car is a US car anyhow. I bought my USDM Acura with its long second year when I was living in the States.

 

[davidf]

WOW, 10 years later and this thread is still active. Pretty cool!!!!!

 

[Honcho]

my best was 158 long course at pocono...windows down.....with short gears and R R%P.....I heard scotty saying the engine could give no more captain...

John, was that with the Comptech IEM 3.0 or your 3.2L?

 

[docjohn]

Iem