RPM for 80 mph? T350/Tam

[Waitey]

What's yours? There seems to be a bit of variation between mine an my friends ones!

[Targarama]

One of you will have different final drive ratios if in 5th gear. 3.46 (std on most cars) 3.73 (usually combined with CR gearing option from factory) or 3.91 (aftermarket). Mine is a few hundred rpm higher with the 3.91.

[steveT350C]

As close to exactly 3000 rpm, although no idea of diff.

[TVR_owner]

steveT350C said:

As close to exactly 3000 rpm, although no idea of diff.

3.46.

[steveT350C]

TVR_owner said:

steveT350C said:

As close to exactly 3000 rpm, although no idea of diff.

3.46.

Thank you!

What would different diffs do?

[TVR_owner]

steveT350C said:

Thank you!

What would different diffs do?

3.73 76 mph
3.91 72 mph

(ish)

[steveT350C]

TVR_owner said:

steveT350C said:

Thank you!

What would different diffs do?

3.73 76 mph
3.91 72 mph

(ish)

Ah! I am leaning something here. So what are the advantages of these two diffs over my standard one?

[Ant.]

Mine is around 3100rpm @ 80.

[T66ORA]

Taken from another thread a while back, here are all the differant combos.


Speed/Gear Ratios (assume change up at 7500 rpm, and 255/35/18 rear tyres)

CR Box 3.46 diff 3.73 diff 3.91 diff
1st-2.43 66 mph 61 mph 58 mph
2nd-1.56 103 mph 96 mph 91 mph
3rd-1.24 130 mph 120 mph 115 mph
4th-1.00 161 mph 149 mph 142 mph
5th-0.8 201 mph 187 mph 178 mph


Std Box 3.46 diff 3.73 diff 3.91 diff
1st-2.95 54 mph 51 mph 49mph
2nd-1.95 82 mph 77 mph 74mph
3rd-1.34 120 mph 113 mph 108mph
4th-1.00 161 mph 150 mph 145mph
5th-0.8 201 mph 187 mph 181mph

[Waitey]

Mine is around 3300, so I must have a reasonably short diff in there.

[Targarama]

Waitey said:

Mine is around 3300, so I must have a reasonably short diff in there.

If you do it will feel punchier in every day driving compared to a std diff ratio. Only comparable with another 3.6L engined T car of course.

[TVR_owner]

Waitey said:

Mine is around 3300, so I must have a reasonably short diff in there.

3.73.

[Waitey]

No wonder it feels a bit quicker than my old T350!

[Geoff Ashcroft]

Swapped my 3.46 for a 3.73 this winter, and it's a massive difference with acceleration. 80mph now happens at about 3250rpm instead of 3000rpm. The while car feels keener.

[Sevenman]

My Tamora is around 3000 rpm at 80, and I quite fancy longer gearing rather than shorter. But I have yet to take it on the track, and that might change my mind.

[sanquin]

I'm interested in getting a 3.91 diff. Can someone give acost estimate perhaps?

[Targarama]

sanquin said:

I'm interested in getting a 3.91 diff. Can someone give acost estimate perhaps?

£1100 fitted.

[Don1]

I have an invoice from Str8-Six for a c/r box and a 3.7 diff (plus labour and two exhaust hangers) at £2694. Well worth it, and the cheapest I found supplying and fitting.

[Targarama]

Don1 said:

I have an invoice from Str8-Six for a c/r box and a 3.7 diff (plus labour and two exhaust hangers) at £2694. Well worth it, and the cheapest I found supplying and fitting.

Sounds steep. What does a C/R box cost? Its only a T5 with different gearing.

I got my diff changed at Topcats around 4 years ago. Great guys and service.

[TVR_owner]

Targarama said:

Sounds steep. What does a C/R box cost? Its only a T5 with different gearing.

I got my diff changed at Topcats around 4 years ago. Great guys and service.

Sounds aboud right actually Targ.

6 years ago 750 for a diff and 1250 for the box mods + labour etc.