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Best Final Drive For 1275 Fast Road Spec Spi


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#1 MarkC123

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Posted 17 May 2020 - 05:57 PM

Hi all,

 

I am having an engine built off a Spi core engine from scratch.

 

To give a brief idea of spec - 1310 with a stage 4 super sport head off Keith Calver as well as his recommended BP255 Piper Injection Cam and some upgraded standard ratio rockers. It will have a centre oil pick up with a 4 pin diff as well as a lightened flywheel and heavy duty clutch. I am also running 6x10 os4 Turbos. Suspension and brakes overhauled recently also. 

 

I am looking for a nippy fast road car which will be primarily doing shorter distances on flatter / windier roads as well as some city driving. However I wouldn't mind having the ability to do some longer distances from time to time.  

 

I was recommended a 3.1 FD but after doing some reading many have found 3.44 to be the better so I am unsure. Wondering this is the case? 

 

Thanks in advance. 


Edited by MarkC123, 17 May 2020 - 06:36 PM.


#2 Steve220

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Posted 17 May 2020 - 06:02 PM

Either a 3.2 or 3.44. However be prepared that the shorter you go, though louder it will be on the motoway.



#3 alex-95

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Posted 17 May 2020 - 06:06 PM

I'd recommend a  3.2, with a similar spec engine to yours, great acceleration still and not too bad on long journeys.



#4 Cooperman

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Posted 17 May 2020 - 09:09 PM

I love the 3.44:1. It is the ratio fitted to the original Cooper 'S' 1275 and is ideal for twisty roads.

It gives, in round figures, 16.5 mph per 1000 rpm in top gear with excellent acceleration through the gears. 4000 rpm is about 70 mph in top, and that's fine.



#5 and90cooper

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Posted 26 May 2020 - 06:41 PM

I had a big power 1380 that had a 3.1 but also a close ratio box-it was a nightmare to drive round town as first and second were very long gears.
I’d be inclined to go for 3.44 -as Cooperman said,70mph at 4000rpm is tolerable.




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