550 vs 575 max speed.

Hi,

i was wondering why the 575 was so much faster than the 550 on top speed.
Hence a few questions :

1. Do you know for both cars the 0-200 kmh, 0-300 kmh times (useless for the post but fun to know) ?
2. Do you know for both cars if the gearing has been changed (g'box or diff) ?
3. Do you know if the rev-limiter is higher on the 575, or if the tires are bigger ?

I could hardly understand if neither 2. nor 3. apply how it could be faster, since everybody says the max speed of the 550 is limited by the revs, not by HP.

 

Don't know if this actually answers any of your questions, But in this clip they compare the differences between a 575 and a 550. And it's a nice clip anyway

http://www.carenthusiast.com/video/ferrari_575m2002.asf

 

Don't know the answer to 1. but gearing is identical as is rev limit according to the owners manual.

 

So how could it be quicker ?

At same rpm, with same gearing, you can't go faster/slower depending on power. it makes no sense.

 

Is the circumference of the 575 tyres longer than those of the 550? If the gearing is the same and the rev limit is the same then the only way the 575 could be quicker would be that for every given rev it is going just a fraction further.

 

Tyre sizes are identical. This one has me baffled too. The rev limit on the cars is not sufficient to reach their quoted top speeds.

 

Why do you say that? The 550 is said to do 199 mph, and the 575 is said to do 201 mph correct? I know Car and Driver drove a 550 to like 198 mph when they broke some record in 1998 I think....

 

2mph is a big difference?

I think that 2mph comes from the new front fascia which (I think) is much smoother and sleeker...

 

It could come from a good tail wind too. Those numbers only count on paper anyway. Someone could own either one of those cars for DECADES and I bet they would either never see that top speed or have spent less then 3 seconds there during their entire ownership. For 99.99999999999% of us, ever seeing that top speed is like going to Mars.

 

the 575 has a bump in HP and a tiny bumb in torque because of the 2.5L upgrade in the engine

98 550:

Type: V12
Displacement: 5474 cc
Horsepower: 485 bhp @ 7000 rpm
Torque: 419 lb-ft @ 5000 rpm
Redline: 7700 rpm


575 M:


Type: V12
Displacement: 5748 cc
Horsepower: 515 bhp @ 7250 rpm
Torque: 434 lb-ft @ 5250 rpm
Redline: 7750 rpm

 

In your experience on your car what is the actual top speed? I know all about Ferrari speedometers so my comment takes that into account but I know of a couple of circumstances of stock US spec 550's showing an indicated 200 MPH.

Also I am well aware of Ferrari's exagerated claims of many performance specifications so my following remark takes that into account as well but the information came from a trusted (to me) employee of the Ferrari company.
The place the 550 was run by the factory to establish an official top speed was not a long enough straight to get the car to it's absolute top speed but they were able to see 199 so they called it there.

Also I have, lets just call it significant reason to believe that the car used for the world endurance record was not quite stock.

 

there is only one way to solve this

TO THE MULSANNE STRAIGHT

 

Brian
I have posted on this before. Max revs is 7250 even though rev limit is 7500, but ECU drops one bank at 7250 as a "soft limiter" The car does NOT rev to 7700 rpm under acceleration. This comes straight out of the workshop manual and has been confirmed by my authorised dealer.
It is not phyically possible for the car to achieve the quoted top speed without additional revs, sure this could be achieved by an ECU tweak, but not in a standard car as fas as I am aware, unless there is a sensor that allows the car to rev higher when 6th gear is selected, which I doubt.
I am sure that people have seen 320kmh on their speedos, but realistically it would only be about 305kmh.
Mathematically the car has a 306.5kmh (191.26mph) top speed at 7250rpm based on a 331mm rolling radius (18" wheel 35 profile 295 wide tyre). The factory manual quotes 320mm under load, which is only 295.57kmh, this however, doesn't allow for any tyre "growth" at high speeds.

Update:
I just went downstairs to the car park, I have a 315/30 on my car right now and the measured radius was 315mm. I will measure the standard wheels and tyres in an hour, when I have the track wheels swapped off the car and confirm the true measurement, which is critical to this speed calculation.

 

I just measured standard wheels off the car, the radius is 330mm. Confirmation that with a standard rev limit, neither the 550 nor 575 is capable of reaching the quoted maximum speed, unless there is a system for changing the rev limit in 6th gear.

 

I discussed it with the dealer some time ago, and he mentionned around 305 kmh.
What i don't get is that while everybody agrees to say the top speed of the 550 was overrated, everybody says (or rather nobody discusses the fact...) that the 575 can reach the 325 kmh it is told to do.

Maybe that's an option as you say stephen that in 6th gear there is no rev limiter, but i doubt it, since it's probably built in to protect the engine in some way.
I see quite frequently ~280 kmh on the speedo, but acceleration slows down, and when you know it's *VERY* illegal to drive at these speeds, you don't want to spend too much time, esp. when you see in the distance trucks overtaking or you have some corner to take (it's not a video game and this speed for sure kills...). Anyway, i hope i can solve this issue one day, but then again i would need some precise way of measure.

 

You can just use a handheld GPS for this.

 

Thanks, thats what I wanted to know. 191 MPH with the standard Ferrari speedo error could easily come to 200 indicated.

 

I've run my 550 to 7600 rpm in every gear but 6th. I don't know what it does in first since I don't have enough time to look before I have to shift. The engine hits the rev limiter fairly hard.

At very high speed the centrifugal forces on the spinning tire cause the tire diameter to actually "grow" a small amount. The amount of growth depends on the type of tire. Also, different tires have a different degree of slippage against the road (another small effect that accounts for small differences in top speed). Keep in mind that if a tire grows by 5% (that's probably too large a number) a top speed of 190 mph would become 200 mph (provided the engine has enough power to reach this speed). In any case, Motor Trend did a top speed test on a 1999 550 at 194.5 mph.

 

Yes and my tacho shows 7700rpm before the engine cut out occurs, fact is thought that it actually only 7250rpm, the tacho is being a bit optimistic.
Maybe tyre growth is a factor, but I tend to believe that the cars provided to the journo's for these tests aren't exactly standard.

 

Heck, I have not even gotten close to the top end. 150 mph

Only drive 12 cylinders

 

Tire size on 550 is 18". Tire size on 575 can be 18 or 19. Perhaps test was done with 19" tires?

 

Today I took my car for a quick spin with a friends hand held GPS to check my speedo for accuracy.
The speedo in fact reads 10% optimistically. ie at an indicated 160kmh, the car was actually travelling at 145kmh.
This was a consistent error from 60kmh to 200kmh, so will assume that the same inaccuracy exists from 200-300kmh.
What this means in plain english is that when a 550 speedo shows 320kmh (199mph), you are actually travelling at 290kmh (180mph).
I think this finally explains how the car has a quoted top speed which is higher than theoretically possible, given the previous discussion of rev limit and gearing.

 

Every cars speedo will vary a little.....and quoted top speeds are not from the speedo...but from radar or GPS...

I can't remember teh year, but I think either Car and Driver or Road and Track mag did a top speed run/ record for attained speed a few years back in a 550....they got it to like 194 mph if I remember right.....

 

What's the point if 99% of the Ferrari owners here (or anywhere) will never try to find out?

 

it sure is comforting to know that its possible, isnt it?