top speed

[Danny]

S50, shut it down right around 135/140

[318isfc3s]

Eh, I'm not to sure whats going on. I've been saving for the MM 2.1 turbo m42, so hopefully this fall/ early winter when I pick it up that will solve my speed issues... And to whom asked if I was tracking the car, no not really. I've been to a few scca track runs but I have no plans on making this a track car. I'm just in the process of re building it to my spec.
I don't know how to add photos but if one of you will be so kind as to inform me how I'll post some pics of my progress with the car from stock to now. Until I get my recaro interior in it's been pretty even between cosmetic and mechanical work that I've done so far. I do have my drivers side recaro in though and the passenger side just got in from Germany. The rear will be reupholstered to match the front seats.

[mlytle64]

and have 17s with 225/45s.

there is part of your problem. tires are too big a diameter for the little engine to push. those are an inch taller than stock. that has a significant negative effect on your final gearing, not to mention they are heavier and higher drag. slower acceleration and lower top speed. bigger is not always better.

[Adrian_Visser]

E30s are not very aerodynamic. Try lowering the car and adding a functional splitter?

Actually e30's have a pretty decent CoD, he'll it's better than a Corvette of the same vintage.

[Hey_You]

there is part of your problem. tires are too big a diameter for the little engine to push. those are an inch taller than stock. that has a significant negative effect on your final gearing, not to mention they are heavier and higher drag. slower acceleration and lower top speed. bigger is not always better.

True! You are probably going faster than 110mph, but your wheel/tire setup will read it slower than what you are really going.
My car at the moment tops out at as fast as I can push it. But when it ran, I made it to 100mph once, with a good downgrade, a good LONG downgrade.

[Simon S]

Just to chime in..
Last weekend – mostly to say I crested ‘the ton’ mark – I wound out my healthy m42 car (stock tire size/4.10LSD/91octMarkD/COP/4pintle/SuperSprint) on a short stretch. It zipped right up to an indicated 110mph – then I backed off though..

Definitely felt like it would have made it up to an indicated ~125 with more road..

[Wanganstyle]

stock 87 eta, 115mph or so on gps tracking glympse. very long downhill with wind assist.

325iT BPU (all bolt ons, chipped, final drive changed) about 125-130mph during wangan/fwy pulls, had a little left to go but not that much more.

17" tires on a M42 car would most likely add rotational heft due to tire upsize and weight increase. also frontal drag area, smaller narrow rims are better for wangan if stable. always need more hp and torque for pushing the top end :)

[318isfc3s]

the rims I have are actually lighter than the stock bbs 15s that came on my car... And as far as the height difference its maybe a quarter inch taller with the set up I am running. As far as the mph difference, before with stock rims and tires the gauge according to gps and the road side radar was four mph low. With my 17s I am now reading 1 mph low.

I pushed it again the other night on the way to work and hit 115, although I had a nice 30+ mph tail wind. I just need more power to get what I am looking for... Soon as I am done with this job here in Iowa I will be heading to Missouri to pick up my motor.

[Wanganstyle]

the rims I have are actually lighter than the stock bbs 15s that came on my car... And as far as the height difference its maybe a quarter inch taller with the set up I am running. As far as the mph difference, before with stock rims and tires the gauge according to gps and the road side radar was four mph low. With my 17s I am now reading 1 mph low.

I pushed it again the other night on the way to work and hit 115, although I had a nice 30+ mph tail wind. I just need more power to get what I am looking for... Soon as I am done with this job here in Iowa I will be heading to Missouri to pick up my motor.

rims+ tires lighter or just rims? did you weigh them both in ready to go on car form?

Bigger size tires/low profile tend to weigh more than smaller/higher profile ones

rolling Diameters in inches - makes a big difference on overall final drive gearing:

215/45/17: 24.62"
215/40/17: 23.77"

stock:

195/60/14: 23.21
195/65/14: 23.98

between 60 series and 65 series on stock 14" wheels I can feel a noted gearing/weight change.


Also, the width matters, Cross section is a big deal for wangan aero- wider the tire the more air you are pushing.

215mm tire vs stock 195mm - there is an aero difference with the width.


you never pay attention to the speedo when calculating higher speeds; only GPS verified is valid!!!

my fc3s was GREAT on top speed :)

[camshaftgsxr]

me and a buddy managed 110 in my eta... down hill with a tail wind

[E30SPDFRK]

135 sitting at redline in 5th in my stock m42 with 16" BBS boat anchors

[mlytle64]

rims+ tires lighter or just rims? did you weigh them both in ready to go on car form?

Bigger size tires/low profile tend to weigh more than smaller/higher profile ones

rolling Diameters in inches - makes a big difference on overall final drive gearing:

215/45/17: 24.62"
215/40/17: 23.77"

stock:

195/60/14: 23.21
195/65/14: 23.98

between 60 series and 65 series on stock 14" wheels I can feel a noted gearing/weight change.


Also, the width matters, Cross section is a big deal for wangan aero- wider the tire the more air you are pushing.

215mm tire vs stock 195mm - there is an aero difference with the width.


you never pay attention to the speedo when calculating higher speeds; only GPS verified is valid!!!

my fc3s was GREAT on top speed :)

and his tires are even taller.....225/45 17. full inch taller than stock. slow....

[trackjunkie21]

I guess I had a good running m42, Hit 115 on a slight incline.

[Jafxod]

Thats beat, ive done 145 in my m50 car and it wanted to keep going

[Gubernaculum]

Wheel/tire weight, just like vehicle weight, has nothing to do with top speed, other than the time it takes to get there.
Diameter, like they said, explains your "problem". Use a GPS to figure out how far off your speedo is, and keep in mind that the diameter change effectively changes your gearing as well.