How far do engine rpms really drop after an upshift?

[383LT1]

How far do engine rpms really drop after an upshift on an automatic car? For example if one is shifting from 1st (3.06) at 6000 rpm to 2nd (1.62), the rpms if there was a direct mechanical link would drop to just under 3200 rpm (6000 x 1.62/3.06 = 3176 rpm). But there are two reasons why this rpm drop is not fully realized on an automatic car.

Reason #1: During a shift execution, the speedo needle climbs and by the time 2nd gear is fully engaged, the rpm drop is a bit less than calculated because the vehicle continued to accelerate during the shift. Let's neglect this as I have a question about Reason #2.

Reason #2: Torque convertors not in lockup mode, particularly high slip/drag racing oriented unit, greatly reduces the rpm drop.

My question does anybody have any example cases of rpm drop on an upshift and can also quote the gear ratios so I can see how much a torque convertor limits the theoretical/direct link rpm drop on an upshift?

 

[WE4]

all depends on..

Stall speed of converter
That will determine rpm drop and then the gear ratio split can be figured .
But the converter will dictate that.

Bruce
WE4
PTS XTREME

 

[chris718]

383 lt1.this is a very good question one of the best ive seen here in a while.now providing you have a trans that will shift all gears (meaning 1st to 2nd and 2nd to third)at the same rpm at wide open throttle you can simplify things and remove the converter from the equation.now you gotta get your hands on that well known auto math handbook and itll be a piece of cake .im sorry i dont have the information in my head but i understand the question completely and its 1.30 am here.

 

[Chuck Leeper]

NO converter "input"??

Chris said:
"you can simplify things and remove the converter from the equation.now you gotta get your hands on that well known auto math handbook and itll be a piece of cake ".

???????????????

 

[chris718]

if each shift is at the same rpm at wot than the amount of coupling will be the same at that rpm.any torque ratio changes will be directly factored from the planetary gears back not the convertor.if the trans drops 2000 rpms from 1 to 2 than the shift point number in rpms and the gear ratio numbers can be used in a formula to ABSOLUTELY STATE what the 2/3 and 3/4 shift recovery rpms will be if the wot shift points are all at the same rpm.the book is called auto math and contains this information it is sold all over the place.383lt1 thanks for lighting the fire because i am going to really research this and give you all the results shortly.if we were talking 400 i could tell you specifics but i am not ready to post it for the 700 in question w/out looking it up.

 

[ulose2av6]

there is a car show in wildwood just thought you like to know.

 

[chris718]

im packing my bags now and telling my wife i have to go see a sick relative with something highly contagious so she cant go.