ok i was talking with a guy (an engineer none-the-less) about a week ago about cars... anyways i brought up wishing i had gotten lower gears for my car... but how i liked the high top end which is why i kept the 2:73's...

to which he responded "actually, believe it or not, lower gears ADD to your top speed"

i called for obvious reasons (never do that with an engineer)

he said basically, that higher gears (2:73's) will theroetically go faster top end wise... he said they would run out of power to fight the drag of the vehicle at a certain speed (example) 140mph... where as if the car was up on the dyno... it could go (example) 180mph.... the lower gears would harness the acceleration power of the engine to push the car thru the drag farther before it ran out of muscle.... (example) 150mph with say 3:73's.... he said... the only instance where higher gears would go faster, in real life... is if the other gears are so low (he said 4:56's and up) that they simply whind the engine up to its limit before reaching that point where it can't fight accerlation vs. drag....




that really got me wonderin...

what do you guys think? i mean... he IS an engineer...?

 

he knows exactly what hes talking about.


scroll down to the bottom of this page http://web.camaross.com/forums/showt...hreadid=153995

this topic is going on right now.

 

Yeah he is right. Sorry

 

He's absolutely right..... But in real life (like he said) you would never get your car up to 180 mph... But on the dyno you would. Once your vehicle gets up to a certain actual speed on the road the drag of the body will limit how fast you can go no matter what gears you use. Law's of Physics man....

BTW: I don't claim to be an expert so don't bash me if my explanation is unclear or a little off...

 

thats what i thought.... i figured he was right after he explained it to me... but i just always believed higher gears = higher top end... i had trouble adjusting



so anyone good at physics? tell us how fast a lt1 formula would go, stock with 2:73's, 3:23's, 3:73's, 4:10's and 4:56's....

please? im really interested

 

160 is not a problem with 4.10s and you get there alot quicker. and if you had a cam that would pull up to 6300 rpms 170 wouldnt be a problem i wouldnt think.

 

I think you're still missing the point..... No matter what gears you use... There's still the same top speed for each car on the road. Now if you mean on the dyno thats different.

Also the same engine and car can go faster by reducing the drag on the body. If you could make the F-body longer and more sleek, a little narrower, with skinnier tires. Lower to the ground you would be able to get a higher top speed out of it.

 

no, you missed the point... each set of gears changes the point at which the engine can no longer fight the resistance of drag...

the only difference is the way of thinking is the opposite....

the lower the gears = the higher the top end UNTIL the gears get slow low that you redline the last gear BEFORE you get to the point where you could have still pulled thru the air drag


the top speed will still change between each different gear ratio

 

I can't really explain it, but hopefully someone else can. If I am wrong then I truely am sorry.

 

thank you someone understands this other than me.

 

im learnin as im talkin...


how'm i doen?

 

just fine.

 

Exactly..you cannot tell me a 4.10 A4 will get to the same top speed as a 2.73 A4...not happening.

 

Think about it this way...start at a really short gear ratio, say 4.88. Your top speed will be limited by your max rpms in top gear. Now, as you go to progressively taller gear ratios, you will reach a point where you can no longer reach max rpms in top gear. At this point aerodynamic drag becomes the limiting factor in top speed. As you contnue to change ratios, you will reach a point where you reach top speed with the rpms at the point where the engine makes its peak hp. This point is your highest possible top speed. From this point, if you continue to taller gear ratios, you will be lowering your rpms and therefore hp in relation to drag so you will lower your top speed.