5th gear redline MPH

Fifth at redline in my Alfa (1960 vintage) is about 133, however there is no sixth. - George

 

in 5th gear at 7.800 rpm is 205 mph in the LM, that's when the high rpm caution light comes on.
Roland
F40LM

 

in a stock F40 at 7000rpm, almost 180
Roland
F40LM
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Easy enough to figure out go out on the hoghway and..no, not redline it in 5th!

Just note the speed at a given RPM, say 60 mph at 2000 rpm, or whatever it is, then multiply that speed by redline speed and divide it by 2000 rpm. Or just divide the speed by the rpm to get a mph per rpm number then multiply by redlin rpm. Same thing.

To get a more accurate answer, note the speed at several engine speeds 1500, 2000, 2500, 3000, whatever, up to the speed limit, and average the results.

I'm an enginerd, can you tell?

 

You lost me at multiply....

 

I'm lost too, but you sound smarter than me so I'll go for it. Thanks
Roland
F40LM

 

Dubai Vol ...Your answer will come out a bit close as your are assuming the same ratio (or slope if u want to go the math way) but it is not an exact proportional rule if you look at the power/RPM chart you'll see is not linear for most cars also you have to adjust for air resistance, front area coefficient , blah blah but it gives an idea ;-)

A while ago I was actually trying to come up with a formula to compute the peak power only with those parms since it is easy read RPM/speeed/etc via the OBD and log it.

Cheers

 

What I find interesting Roland is that at 7000 RPM, 180MPH and about 18 or so lbs. manifold pressure the motor is obviously working pretty hard and the H2O temp is down around 160.

Supports what Dave and I have always said about overcooling.

 

We're not computing power, just speed, and gears are linear. If you go 60 mph at 2000 rpm, 4000 rpm will make you go 120 mph and 6000 rpm will be 180 mph.

So the REALLY easy way to find speed at redline in 5th is to go half of redline rpm, note your speed, and then double that speed.

Beer's on me! Grolsch anyone?
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What do you guys say about over cooling?
My F40 runs really cold on the street. Even if we are doing some high rpm 2nd and 3rd gear canyon runs it sits at 160. I would think that it wouldn't like the high rpm, low speed, but that is not the case. Too much cooling or well engineered?

 

Max boost is 20psi and will shut down after that, my temp on the street F40 goes close to 200 on water and 220 oil.The LM as the same boost but water temp is around 180 and oil around 200. Cooling, cooling!!!
Roland
F40LM

 

There were problems with those since new that had all of FNA and Spa stumped for a little while. Except when in slow or stopped traffic many of them run just cool enough that the engine management system thinks it is not being warmed up and would cut out before full boost was reached. When they were first delivered to dealers it was quite cold in this area and we could get enough heat in the car for it to accept full boost before the overboost light went on the motor cut fuel. Ferrari had a couple of us around the country running test after test after test and reporting to them and Spa our findings. After spending lots of man hours on it Ferrari finally had a US version car and a cold day on their hands and determined it was within normal limits. There is a lot of variation to it and many cars did not have the problem. I still experience it once in a while, going slow everything is hot and working great, get up to freeway speeds and it cools down enough on a cool day that some cars cut out well before full RPM or boost is reached.

 

Not to be a smart a$$ or anything, but wouldn't a proper 180 degree thermostat solve a lot of the overcooling problems? Just a question.

Darrell.

 

Not as fast as Ferrari claims per the recent lawsuit file by an owner who couldn't get the car do go as fast as Ferrari advertised that it would go...

 

Opening and closing temps are 2 different things. The do have 180 or 185 t-stats but they close at lower temps.


Don't want to go any further off topic. It was discussed at GREAT length in the past. A search should turn it up.

 

this is a good one for Dave Helms at Scuderia Rampage.
Roland
F40LM

 

Most of the thermostats that I've used in the past begin opening at the stated temp, then fully open about 20 degrees later. Your right, closing doesn't always match-up. The experience I've had in the past with sports cars and hot rods , I just try 5 degree increments until I get it where it should be. I've had times where the car ran better with a thermostat waaay off from where I thought it should be. Funny how cars can make you rethink what you learned in the past.

Darrell.

 

With all due respect to dubai, i do not think it is linear at all. Wind resistance will interfere a lot the faster you go. Didn't ferrari post in an owners manual the max speed in gears?

I would like to know the max speed of a stradale in 2nd gear at redline? As i have driven one there and could not look at the speedo either during a tight maneuver.

 

It is linear. The motor turns at a speed that turn the gears that turn the wheels. The only variable in this is the ratio of the gear that is being used to turn the wheels. For each turn of the crankshaft, the rear wheels turn a certain number of times that gives a speed based on the circumference of the tire.

However the resistance of the air becomes a factor when the motor does not have the horsepower required to push the car through the resistance that has to be overcome from the air. In this scenario, the car would not reach the max RPM because of not having the power to overcome this resistance and at that point you would be at maximum speed for the car.

 

Only if the wind resistance causes the wheels to spin!
I think you may be confusing "what speed is the red line in 5th" with "how fast will it go"

 

Thanks guys for correcting me i was thinking about drag limited vs. gear limited and got HP mixed up in my head.

How about this, since it is my understanding at least on my car that in the torque converter there is not a direct mechanical connection between torque tube and the tranny gears instead the tranny fluid makes the parts spin wouldn't some energy be lost in the form of heat and not directly transferred to forward movement? Throw me a bone here.

How about top speed in 2nd??

 

You are right that a torque converter would prevent a direct relationship with gears and would slip more under load, unless it is the type that locks up. There actually can be a very slight variation in the RPM/wheel revolutioin calculation because the tires become ever so slightly taller at high speeds. Drag racers use this fact to in effect vary their gear ratio somewhat as the car gains speed

Looking at the speedo to determine speed in a Ferrari is never accurate anyway. They all read high at least 5%. You need an independent measure of true speed like radar or GPS. Many Ferrari owners manuals will give you the mph or kph per 1K RPM in each gear and you can use that to calculate the real speed very close. For instance, 3X8's are all pretty close to 20 mph per 1K in 5th, so 3K RPM is close to 60mph. If your speedo reads higher (I have seen some say 70-75) you get an idea how much your speedo is off.

DAve

 

Well I haven't even sat in one, let alone drive one... but assuming 8500 rpm redline and 186 mph top speed, my math says
1st - 48 mph
2nd - 73 mph
3rd - 98 mph
4th - 124 mph
5th - 153 mph
6th - 186 mph

The gear ratios are as follows
Final - 4.44
1st - 3.29
2nd - 2.16
3rd - 1.61
4th - 1.27
5th - 1.03
6th - 0.85

Granted this doesn't take in all the details, like wind resistance etc, so as the title says take with a grain of salt.

Joe