LS1 T56 Diff Gear RPM's

[Zhac]

Hey guys, just wanting to know what RPM people's 6 speed LS1's sit at on 100 km/h in 6th...

Mine sits at around 1600-1700 rpm. This is with the stock 235/45/17 VT SS wheels.

The reason im asking is when I bought my VT SS off the previous owner, I got a receipt that states the diff was rebuilt and had 3.9.1 diff gears put in at the same time for around $1200. I have always thought it has 3.9's in it (very punchy compared to a few LS1's I have driven), but I was talking to a mate at work, and he is saying the T56 in 6th at 100 will sit at 1600 rpm with the stock diff gears. I always thought it was more like 1200-1250 rpm with the 3.08 diff ratio. I know it will depend on wheel/rim sizes aswell but surely someone has a similar setup to me and knows what there rpm's at 100km/h is and what diff gears they have.

Put my mind at ease and tell me I wasn't ripped off ? Thanks fellas!

 

[_R_J_K_]

Manual LS1 will have 3.46 gears to start with instead of 3.07 that came with the LS1 auto (304 and V6 have the 3.08, regardless of trans).

Can't really answer your question, but looking at your GPS speed vs. the speed on your dash might yield some info if the speedo was never recalibrated.

Probably get a better response by asking in the VT section.

 

[Bigfella237]

According to my calculator, with a "MM6" trans code (0.50:1 sixth gear) and your tyres...

Tyre Size = 235/45R17
Tyre Diameter = 643.3mm (25.33")
Circumference = 2021mm (79.57")
Tyre Revolutions = 494 per km (796 per mile)
Sixth Gear Ratio = 0.50:1
Diff Ratio 2.60:1 = 1070 engine RPM @ 100km/h
Diff Ratio 2.78:1 = 1144 engine RPM @ 100km/h
Diff Ratio 3.08:1 = 1268 engine RPM @ 100km/h
Diff Ratio 3.36:1 = 1383 engine RPM @ 100km/h
Diff Ratio 3.46:1 = 1424 engine RPM @ 100km/h
Diff Ratio 3.55:1 = 1461 engine RPM @ 100km/h
Diff Ratio 3.70:1 = 1523 engine RPM @ 100km/h
Diff Ratio 3.90:1 = 1606 engine RPM @ 100km/h
Diff Ratio 4.11:1 = 1692 engine RPM @ 100km/h

...seems to me you have a 3.90:1 diff ratio.

Andrew

 

[blackve76]

Hey guys, just wanting to know what RPM people's 6 speed LS1's sit at on 100 km/h in 6th...

Mine sits at around 1600-1700 rpm. This is with the stock 235/45/17 VT SS wheels.

The reason im asking is when I bought my VT SS off the previous owner, I got a receipt that states the diff was rebuilt and had 3.9.1 diff gears put in at the same time for around $1200. I have always thought it has 3.9's in it (very punchy compared to a few LS1's I have driven), but I was talking to a mate at work, and he is saying the T56 in 6th at 100 will sit at 1600 rpm with the stock diff gears. I always thought it was more like 1200-1250 rpm with the 3.08 diff ratio. I know it will depend on wheel/rim sizes aswell but surely someone has a similar setup to me and knows what there rpm's at 100km/h is and what diff gears they have.

Put my mind at ease and tell me I wasn't ripped off ? Thanks fellas!

i think mine was sitting around 1700rpm at 100km/h with 3.9s

 

[Zhac]

Thanks for all the responses... puts my mind at ease haha. I thought 1600-1700 rpm seemed high for stock diff gears at 100km/h. Everyone seems to complain how useless 6th is but mine seems fine in 6th doing 100+.