Dave has questions about the E39 530 and its potential as a drag racing car

[SilverStreak]

Howdy All! So this is das' new home, huh??? :D

Ok, what gears and rear does the newer 530 have??? Is it the Torsen LSD like the Z3 3.0 in my car???

[Dark Helmet]

I have no clue dave... but I'm going to exercise my mod priviledges and make this its own post since you are waaaaay the F off topic.... we were in the middle of pron adn you bring up something technical!

oi vey!

[SilverStreak]

Well, sorry, I like :boobies as much as the next guy, but my thoughts would be a 530 with my mods, a sleeper 4 door.

The object would be to out muscle the M5. What does the 530 weigh in comparison to the M5???

And someone get back to me on the gears question, and if it's the Torsen LSD that was OEM in the Z3 3.0.....????

[Dark Helmet]

OK... stock gearing, not so good, 2.93, BUT find a totalled automatic and pirate the gears (3.46)

not sure re: the diff, the cars do have 'automatic differential braking" though so I doubt it has anything like an LSD.

but I suspect that ONE of the M cars uses the same ring-pinion setup as teh 530 (one of the M3s, or the M5) and those would make nice M-diff donors as well. or call quaiffe, or if it is the same gearset as the /7 3.0i, then use that diff. I do not really know where to look for that info, but I'd start with whoever you got the 3.0i info from.

I still think Suzanne needs a blown 530! :D :D :D :D

and bren needs a blown 528! :D (or maybe just a 540iT??? either way lotsa grins!)

[Dark Helmet]

or we could call rukman.....

[SilverStreak]

Well, at that point, I'd just go Quaife with 3.46's for some nice oomph. That, plus my mods.... hmm...

Also, what's the weight of the 530? What's the weight of the M5?

[Dark Helmet]

3494-4024= 530lbs

IF the M5 makes 395 at the crank, then it has 10.187 lbs/hp
IF the 530 makes ~360 at the crank, then it has 9.7 lbs/hp...
do a little extra work to it and push the 3.0 to 400 (little more boost, headers, racing cats, small diet), and you have 8.5 lbs/hp.


DAMN..... and dave, the 530 trans is the same as your Z3, so use the same ratios for your trap-speed calculations.

I think you can get WAY the F into the 12s!

[SilverStreak]

So the 530 weighs about 3500 lbs, and the M5 weighs about 4000 lbs? Is that what you're telling me?

And you want less lbs per hp, not more lbs per hp.

Figure my car has about 365 bhp. I could simply do headers for another 15-20 hp, if I wanted more...

M5, 396 hp, 4024 lbs = 10.16 lb/hp
530 s/c'ed like my Z3, 365 hp, 3494 lbs = 9.57 lb/hp

Lower # is better, so it would beat an M5 on power to weight ratio.

Throw in some 3.46 gears for better launches.

Most cars gain about 150-200 lbs over their curb weights with options, fluids, etc. So figure ~3700 lbs with the s/c.

Drop the spare tire and jack (30 lbs), both rear seats (80 lbs), front passenger seat (60 lbs), 1/4 tank gas max (80 lbs) you're at 3450 lbs, add in my 210 lb frame, 3660 lbs race weight.

Throw on those headers for the extra 15-20 hp for say, an even 380 hp at the crank.

I'd guestimate, a 3660 lb car with 380 bhp, with the Quaife LSD w/3.46 gears, and my drag radials on the back to be about:

Mid 12's with traps near 108-110 mph....

[SilverStreak]

Now THAT would be a SLEEPER!!! :evil2

[Dark Helmet]

heehee... :evil2:

[SilverStreak]

With traps of only 110 mph max, I bet I could get away with 3.73's, maybe 3.91's....

[Dark Helmet]

I'd suggest looking at the 3.73s.... the 3.91s would just KILL the car on street tires.

[SilverStreak]

I'll have to play with my calculator later, if the 530 has the same trans ratios and tire sizes as me, I have a chart from all these gear calculations from before, but the 108-110 mph trap speeds buys me some room for lower gears versus my 115-116 mph traps on the Z3....

[Dark Helmet]

3.73:1 gives you 109 even at 6500 in 4th... using an estimated 25.66124" diameter for the DRs...

[SilverStreak]

Perfect, thanks for the calcs, das! Maybe I should go with 3.64's just to be safe...??

[SilverStreak]

Or simply stick with the 3.46's so it'll work in 4th on street tires too...??? hmmmm....

[Dark Helmet]

or use the 3.91s and plan on getting into 5th?

If you are going to swap gears anyway, go as deep as you can, so if you want some "margin" use the 3.64s, otherwise, 3.73 or 3.91

the other thing to do would be to do the engine and get it to the track to get a feel for the traps and then pick the gears, it would take longer to get everything "dialed in" but would give you some piecde of mind on the selection.

[SilverStreak]

Actually, that's exactly what I'd do, run it stock, get a feel for the traps and then do the gears. But I wonder how it would launch with my mods and no LSD back there???

And going to 5th requires 1 more shift in the 1/4 mile, costing me a tenth or two or three.... (unless I can always shift like Spider-Man :D ) and the 4-5 shift is like the 2-3, meaning it's the tougher of the shifts, positioning-wise.

Going from 2.93's to 3.46's alone would make a nice difference... maybe 3.64's.... Does BMW have a ratio in the 3.5x range for gears??

[Dark Helmet]

not that i have ever seen.... go for the 3.64s.

and you also might have some trouble getting those big-boy slicks on the back....

[SilverStreak]

Actually to play it safe, 3.46's might be just fine, plus I can use the Torsen LSD if need be for savings. And what's the largest size tire the 5er comes with stock on the rear? I assume the M5 has larger wheel-wells?

My DR's are mounted on my OEM 17x8.5" rear wheel set, and are only a tad taller than the 245/40-17's....

What size rear tires come on the 530's Sport Package?

[Dark Helmet]

welllll... the 540 uses an 255/40 on a 17x9... so you should not have a problem going to 255/45 or so with the DRs...

[SilverStreak]

If 17x9's fit back there, I'll be ok with 275/40-17's back there. And the DRs would only be mounted up for the track, not everyday...

[Dark Helmet]

my only concern would be with the width of the DRs... but I know you can also fit 285/35-18s under a 540 or M5... so maybe its not such a big deal...

[SilverStreak]

Should be ok... :evil2

If 285/35-18's fit, 275/40-17's will...

[SilverStreak]

Matter of fact, I could get new wheels for the Z3, and just put the OEM Z3 wheels on the 530, save some money on the 530, and keep the wheels that come on it for winter driving....

[Dark Helmet]

it comes with type-42s..... you will NOT use those for winter driving! :D :D D :D :D

(if you HAVE to, sell them to me for the touring! :D)

[SilverStreak]

Type 42's?? The ones in your avatar? I've seen the 540i's with my wheels....

[Dark Helmet]

yes, the V8 comes with the radial style wheels, but the 3 liter has a lame ass base wheel and the sport package include the 42s....

so unless you are gonna drop 55k+ another 13k on a stage 2 blower and 2 or 3 grand on the cage...... you will have the 42s

(keyboard is hosed agan....oi!

[SilverStreak]

I would keep the options somewhat limited for weight and all, and have to think about the sport package, softer suspension is better for launching....

[Dark Helmet]

yes, but too soft makes it a liability with that much power attached to it. I know the suspension on Bren's touring would be a disaster with 350hp. the sport-package 525 we drove had enough grip for at least twice the stock 184hp.

[SilverStreak]

hmmm... i'll have to drive both to see....