12 replies to this topic

[Rtw3lions]

Hi going to have my 1275 bored out to 1340 just wondered do I have to go from 9 head studs to 11
Thanks mick.

[KernowCooper]

No mate you dont have to, can you not bore out to a lesser cc? 1340 is the final rebore to the block and offset bores, it wont give more than a couple of bhp more then a 193/1310/1330, and you get to keep your engine longer and a bigger surface area between the bores so kinder on the headgasket.

[Kam]

Boring out to 1293cc or 1310cc is considered the better option if you want the best all rounder, actually 1293cc out the two 

 

Still takes maintenance as its still an engine but in the long run the better option for a daily driver

 

Don't be fooled by the cc, its the setup and tuning that makes the difference 

[Cooperman]

You are probably going to go to 1330 as 1340 is almost impossible to achieve without a special offset-ground crank.

+0.060" gives 1330 cc.

For a road engine just go to the next size up and preserve the block for later rebuilding. There is really no difference in terms of power.

A 9-stud head is fine unless you want to run very high compression ratios, like over about 11:1. The 'S' had 11-studs, well 10 studs & a bolt actually, to allow for homologation for developments for racing and rallying where very high compressions would be used.

[Rtw3lions]

Thanks guys was gonna try 1380 but judging by your comments I'll stick to 1330

Edited by Rtw3lions, 22 April 2014 - 11:50 AM.

[Cooperman]

1330 cc is the largest you can go and not have to offset bore the block (expensive!). Also, at 1330 cc, when the next re-build is due the standard sleeves will fit easily and at no great expense, so that you can go back to 1275.

In fact, the very best thing unless you are wanting the absolute bit of torque & power, is to always go the next size up. That way you preserve the increasingly rare and expensive block without losing anywhere.

If more power is the aim, more can be achieved with a really well flowed head at a higher C.R. a good cam like the Kent 266 and best induction & exhaust system.

[Rtw3lions]

Yeah I will take your advise so that it will preserve the block, being new to this thought bigger is better but tuning head and carbs and exhaust seems to be the way. Just want to have a bit of fun.

[Dusky]

Add some 'go faster stripes' for an extra 2 bhp

[Rtw3lions]

Great ill cover in stripes

[sonikk4]

And paint the engine red that's worth 10 bhp!!!  I have gone the 1293 route which leaves me plenty of scope for later rebores. Take Coopermans advice, he's been doing this for a very long time and is the Yoda of all things Mini.

[Cooperman]

One of the nicest engines I ever built was a 1293 (that's +0.020" overbore) with 21253 pistons, an MG Metro cam, a lightly gas flowed head, CR of 10.2:1, 1990 Cooper exhaust manifold with RC40 twin box silencing system. HIF44 carb, slightly lightened flywheel and a cleaned up alloy inlet manifold. I fitted an Aldon Yellow dizzy and a 3.4:1 FDR in a standard gearbox.

It had about 84 bhp at 5700 rpm and was very smooth and splendid to drive. Ideal for a good road car. 

[Rtw3lions]

How do you go about gas flowing a head?

[Cooperman]

Buy Vizard's 'bible' - Tuning the A-Series Engine. It goes into great detail about how to de-shroud the valves and smooth out the chambers and inlet throats. It is not as difficult as it sounds to get a fair improvement, although a full-on race head is a lot more difficult.