Top speed run

[Smeesmasher]

I was wondering what is the fastest top speeds any of you guys have run with a boosted e23, e28, or e24. I would be interested to hear what setups you are running also.

[Kyle in NO]

I'm sure 160 is possible with the proper gearing, maybe more. Does it really matter?

[Smeesmasher]

I'm sure 160 is too. I've been in a N/A e28 that went a little over 150. I'm just curious more than anything. I really want to know if someone has recorded going over 200.

[Jeremy]

I really want to know if someone has recorded going over 200.

With the aerodynamics on the e28 that's unlikely. I hit nearly 150mph with 10psi non-intercooled and 3.46 gears. It was still pulling hard, it definitely would have gone over 160. There isn't much reason to go a whole lot faster than that IMHO, even on an autobahn.

[Jelmer538i]

I've done a little over 300km/h (187,5mph) in my brothers E28 S38 turbo but thats pretty scary in a E28. He has 3.07 gears and a 0.81 6th gear.

[Smeesmasher]

What do you estimate the power level to be during that run? Im sure any of the chassis would require serious aerodynamic and suspension modifications to attempt it, but I can't help to wonder if anyone has attempted it or done it.

[turbodan]

Fifth gear was just getting started at 140 in my 528. Judging by the rate of acceleration at that speed I would guess it could have cleared 180. In the five years or so I was driving it I never felt like that was something worth doing though.

[T_C_D]

I am astonished that Jelmer saw 180+. I didn't think the car would stay on the ground at that speed. I am sure my car would accelerate until the car took off so I avoid speeds above 140mph.

[Jelmer538i]

The upright windscreen provides enough downforce.....

[stuartinmn]

I read a post on another board recently where some guy claimed he'd driven a basically stock e30 323i at over 300km/hr on the Autobahn.

[ovide]

My 540d does 265km/h (166mph) flat out, it would run faster but it's limited by the diff ratio of 2.65 and the lower RPM band of a diesel.
It weighs 1700KG (3750lbs) giving it a very solid feel, even at that speed.

[Shadow]

My rear tread separated at 130, just sort burst on the way home from work.
it wasn't crazy.

Maybe short bursts to 160 but trying to max out 5th gear it's some stuff to think about if the tire actually did blow.
or somebody got out in front of you. I have an e30 so the suspension and brakes are real shit compared to the e28.
Going from 160 down to 50 rear quick acouple times overheated my brakes and had no braking power left.
It felt as if the pads turned into chalk board erasers dipped in grease.

It's now what you were asking for but I know you guys do that shit on the freeway so just make sure you have some aftermarket brakes and high speed rated tires or fill them up to like 40-45psi when trying to do 180 or whatever.

[T_C_D]

high speed rated tires or fill them up to like 40-45psi when trying to do 180 or whatever.

High speed runs heat up the air inside the tires and raise pressures so over inflating to start with is a really bad idea.

[Jeremy]

high speed rated tires or fill them up to like 40-45psi when trying to do 180 or whatever.

High speed runs heat up the air inside the tires and raise pressures so over inflating to start with is a really bad idea.

IIRC, in the owner's manual of the e28 BMW does advise adding some pressure to the tires if "sustained high speed driving" (or some similar wording) is anticipated. Not 45psi high, but I don't remember what the exact number was.

[wkohler]

The tire sticker on the B7 Turbo suggests higher pressures for speeds over 240 kph. Not by much but they are higher.

[T_C_D]

The tire sticker on the B7 Turbo suggests higher pressures for speeds over 240 kph. Not by much but they are higher.

I wonder if tire pressures recommended for 1980s rubber is still relevant?

[Shadow]

For high loads, tires need more pressure.
High speeds are like high loads.
I got high speed rated tires it's like max pressure 58psi.
The H rated tires were like max 45psi makes sense I think.


+13psi for full load vs half.

[Jeremy]

The tire sticker on the B7 Turbo suggests higher pressures for speeds over 240 kph. Not by much but they are higher.

I wonder if tire pressures recommended for 1980s rubber is still relevant?

The rubber flexes less with slightly more pressure and thus generates slightly less heat. It's still relevant. As Chris said though, the recommended bump in pressure wasn't much. It was less than 5psi cold. I think it was something like 2-3psi.

People "air up" their tires slightly for autoX and track days too. Same basic concept.

[wkohler]

I ran about 46 for autocrossing. You have to keep the pressures up to keep the tire from rolling off the bead among other things. The guys with r-comps run lower pressures to try to get heat in the tires. I remember a December event where the street tire guys were pulling faster raw times.

[Bill in MN]

Mine would do a consistent 170. That was with a pretty strong motor, effective aero on both ends, race slicks and weighing 2500lb. It had a 3:07 at the time and was set up for running the long course at BIR. NA it will now do about 145 with a 3:73 and I've no delusions it's much faster than that. A brick is still a brick. Going fast in a straight line is all well and good. Try throwing it into a turn at 150 and see how long your undies stay clean

[leadphut]

hopefully no one is relying on the oem speedos for accurate information.