Serious Question
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You are currently reading a thread in /o/ - Auto
Hi people,
I was thinking of a thing, want to hear your opinion.
Is the top speed that a car can reach an indicator of the status of the engine?
Let me give you some details.
Let's say that a car, for example, is rated at 130 mph top speed by it's manufacturer, brand new.
So, if someone buy an used car, properly serviced and in very nice conditions, warm up the engine and do a full speed run, and the car reaches and/or exceede the rated top speed (given by GPS, not the on board speedo), can someone say that the car still produces the horsepower it has?
In my understanding, given a car aero coefficient and drivetrain, then it's the horsepower that makes the full speed.
Am I wrong?
Thanks.
Some cars, if made brand new today, would be able to even exceed that due to the better road standard and much better tires we have today
But yes, I don't see anything wrong with the idea, and if a car reaches the same speed it did back in the day today then it will have the same amount of horsies
>>13885132
yeah sorry, I did state the example of the 130 mph but the following sentence didn't use the example.
Just forget the 130 mph thing.
no one else to contribute in this?
>>13885117
alternatively for $60 you could get a dyno run.
>>13887528
yeah, that's a direct measurement, ok with that.
I was trying to discuss about that as a "rule of thumb" of some sort.
>>13887532
should be roughly accurate, yes
There could be wear on the springs, the cable could be loose or buckled, the pointer might not line up correctly, etc, so unless you've checked all of this when purchasing the car, you won't know for sure that your test is accurate.
Honestly who's going to be able to check a speedo mechanism when they're buying a second hand car?
Lincoln Mark 8 could go 181 mph with a speed limit removed, bonneville salt flat wheels, and the mirrors taken off.
Its speedometer goes 140. Which it can exceed completely stock.
>>13885117
Sort of, it depends though. A lot of high end cars have electronic top speed limiters and some (highly uncommon in street cars) are top speed limited by gearing. If this is the case the horsepower the engine makes may still be enough to reach the original top speed.
>>13885117
Top Speed is more credit to the trans & diff gears.
Like I have a SR S13 that's mildly built & due to gearing I top out at around 175mph, but I'm banging limiter at that speed due to aggressive gearing with the power I have.
Meanwhile a older 4th gen fbody with a T56 has the gearing to top out at 260mph, but not enough power to get there, (also other factors like drag/wind resistance, traction, & space to do that) So will usually only top out at around 170mph off stock power.
Measuring Horsepower is probably a better bet for measuring engine health, or if you wanted you could try and see how long it could hold top speed before failure, but that would be a pretty destructive test that would leave you with some pointless end results
>Sources<
http://www.automobile-catalog.com/car/1997/1505600/chevrolet_camaro_z28.html
http://www.automobile-catalog.com/car/1993/2178935/nissan_silvia_ks_5-speed.html (Have a 4.08 LSD in mine, so slightly higher top speed)
