100km/h in 1st ??? - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

Rhubarb · 09-07-2002, 05:00

I was wondering what sort of performance increase I'll notice in general driving conditions when I upgrade my VT std 6 to an XR6 std I6 (Turbo not within budget unfortunately).

Recent Commodores have always felt quicker off the mark than the Falcons because of the higher 1st gear ratio, despite the performance edge of the Falcon engine.

A few basic calculations suggests the torque x 1st gear x diff ratio (ie standing start performance) will only be about 8% better than the VT. However, the 1st gear ratio combined with new 6000 rpm rev limit suggests the new falcon XR6 could do nearly 100km/h (93.9) in 1st gear, as opposed to the commodores 70km/h or thereabouts.

Is this right or have I screwed this up somehow ?

PS I have assumed an XR6 diff ratio of 3.45 and a 1st gear 2.39 on the new XR6 182 Auto.

T3man · 09-07-2002, 05:10

With the assumptions you have made ie 6000RPM, 3.45 diff and 2.39 first gear the max speed in first would be about 85kph

Rhubarb · 09-07-2002, 05:18

what about the comparison to the VT ?

Will it be about 8% better or will the bigger wheels on the Falcon (17 v 15) actually make it worse ???

YOOT · 09-07-2002, 05:28

My ED does 79-81 in 1st depending on the conditions. This is the point where I pass all 6 cyl commodores and change in 2nd and keep passing them...

T3man · 09-07-2002, 05:37

Don't really care much about comparisons with a VT. Who really cares??

But to answer your Q regarding 17" v 15" wheels - well, simply put there will be bugger all difference either way, as the change in tyre profile results in same overall rolling circumference.

IE - a 15" wheel with a 65% profile tyre = a 17" wheel with a 45% profile tyre.

FORDV8 · 09-07-2002, 05:43

Hrmm.... The 15" on the vt used 65 profile? I thought it was 55?
For some reason my gut feeling is that the 17" will make more of a difference than you think.... Correct me if im wrong.

T3man · 09-07-2002, 05:51

You're corrected......LOL

FORDV8 · 09-07-2002, 05:59

:btonge:

Zomwit · 09-07-2002, 06:54

In terms of 1st gear speed its like almost as if were back in the days of the 3 speed EA Faclon. My LTD has the worst gearbox/diff combo for quick acceleration (2.77 diff/3 speed auto) but i've had it to about 85-90km/h in first. But a 3.45 diff with 6000rpm redline would kick arse if it could do the same speed in first, assuming the torque curve hasn't moved further up the rev range.