10 replies to this topic

[DiscoDarren]

I bought myself a little project to keep me busy over winter, namely a 1993 sprite.  Its only my 3rd mini and It's the first 1275 engined one i've had. Was just wondering what's different between mine and a cooper or cooper s  of the same year (engine/tuning wise).  Any help will be gratefully received, i'm sure your all alot more knowledgeable than me.  

[Noah]

Sprite engined 1275 ie 12A2BG03 numbered engines have a 9.4:1 CR, a softer cam, a HIF38, and a 3.1 FD. There are lots of other differences which I can list but don't really link to engine performance as as such. 

Cooper eninges of the same Era would actually be a fuel injected car. 9.75:1 CR (iirc), a higher lift cam, and a 3.2FD. Other than that they were fairly similar. 

 

From factory the 12A2BG03 engines are said to produce something around the 50-55bhp mark. 

With coopers stated to make more towards the 60 mark. Not alot of difference really. 

[DiscoDarren]

Sprite engined 1275 ie 12A2BG03 numbered engines have a 9.4:1 CR, a softer cam, a HIF38, and a 3.1 FD. There are lots of other differences which I can list but don't really link to engine performance as as such. 

Cooper eninges of the same Era would actually be a fuel injected car. 9.75:1 CR (iirc), a higher lift cam, and a 3.2FD. Other than that they were fairly similar. 

 

From factory the 12A2BG03 engines are said to produce something around the 50-55bhp mark. 

With coopers stated to make more towards the 60 mark. Not alot of difference really. 

Thanks for that speedy question answered Noah. I guess i'd be able to get that extra bit of performance without breaking the bank and without the hassel of changing final drive etc.  Probably i should concentrate on getting her back on the road before i worry how fast she will go...its good to dream tho

[Noah]

 

Sprite engined 1275 ie 12A2BG03 numbered engines have a 9.4:1 CR, a softer cam, a HIF38, and a 3.1 FD. There are lots of other differences which I can list but don't really link to engine performance as as such. 

Cooper eninges of the same Era would actually be a fuel injected car. 9.75:1 CR (iirc), a higher lift cam, and a 3.2FD. Other than that they were fairly similar. 

 

From factory the 12A2BG03 engines are said to produce something around the 50-55bhp mark. 

With coopers stated to make more towards the 60 mark. Not alot of difference really. 

Thanks for that speedy question answered Noah. I guess i'd be able to get that extra bit of performance without breaking the bank and without the hassel of changing final drive etc.  Probably i should concentrate on getting her back on the road before i worry how fast she will go...its good to dream tho

 

 

Being a Mini 35 owner (also uses the 12A2BG03 engine), I too have gone for the route of getting the best out of it. - an MG metro head has bigger valves and bigger ports than the standard head, I picked up mine for £90, i've had it skimmed by 10 thou, which has raised the compression ration to around that of the 'Coopers'. 

I've also got a HIF44 instead of the the 38, the 38 being the modern replacement for the HS4, a carb that in single form was used for 998s. Again you can pickup a good HIF44 anywhere from £50-£100. I paid £50 and got myself a rebuild kit for it. 

And then the usual things, a Cooper freeflow manifold will provide a better torque curve than an LCB, considering I don't drive around on the red line 24/7 thats what I've gone for, with the rest of a the system being a standard bore (1.75") maniflow side exit optimising the flow and power output, massive exhausts often loose you power. 

The 3.1FD is OK. My car will be used to drive from Essex to what is essentially Hertfordshire, so I'd rather not have a 3.44, I'll sacrifice my ears not bleeding on the motorway for slightly less acceleration. 

 

 

[postma]

I'm currently restoring a Sprite of 1992 with the following specs:

Engine number: 12A2BG04 254974               A+ engine low compression 9.4:1

 

Gear box: Wide ratio with pot joints Final drive 9.4CR 2.76  (French only spec.)

 

Could someone explain the difference of my  final drive 2.76 compaired to the regular 3.1 or 3.2.

I bought the car here in France, but have not driven it yet on the road, so cannot make any compairison with my previous Mini's.

 

Thanks,

 

Peter

[DiscoDarren]

 

Being a Mini 35 owner (also uses the 12A2BG03 engine), I too have gone for the route of getting the best out of it. - an MG metro head has bigger valves and bigger ports than the standard head, I picked up mine for £90, i've had it skimmed by 10 thou, which has raised the compression ration to around that of the 'Coopers'. 

I've also got a HIF44 instead of the the 38, the 38 being the modern replacement for the HS4, a carb that in single form was used for 998s. Again you can pickup a good HIF44 anywhere from £50-£100. I paid £50 and got myself a rebuild kit for it. 

And then the usual things, a Cooper freeflow manifold will provide a better torque curve than an LCB, considering I don't drive around on the red line 24/7 thats what I've gone for, with the rest of a the system being a standard bore (1.75") maniflow side exit optimising the flow and power output, massive exhausts often loose you power. 

The 3.1FD is OK. My car will be used to drive from Essex to what is essentially Hertfordshire, so I'd rather not have a 3.44, I'll sacrifice my ears not bleeding on the motorway for slightly less acceleration. 

 

 

Sounds a pretty good route to go and relatively cheap too.  Have you any idea what you've gained power wise and how does it compare to a satge 1 or 2 kit.??  Would a stage 2 kit take our sprites performance past that of a standard cooper??

 

Also still getting my head around these modern carbs when i had my first mini we used to talk of swopping  an 1 1/2 inch SU for  a 1 3/4 inch ..... i take it that the HIF38 is 38mm (1.5") and the 44 is (1.75") in old money

[Mrpeanut]

^^^ yes, a hif44 is a modern 1.75 and a 38 a 1.5

A freeflow with an rc40 exhaust or similar, plus up rated inlet, air filter and needle to suit is a stage 1 kit. The diffrence to the norm is that a freeflow is suggested rather than your standard lcb. Personally I agree raft a freeflow is better in mildly tuned 1275's. An easier and better fit, plus a little more low down.

A better flowing head will help a lot too but you'll be restricted by your cam as to what you'll ultimately squeeze from it.

In your position I'd fit the freeflow, rc40 inlet etc and take it it to rolling road. Then when funds permit stick on a large valve mg metro head, or better still a large valve ported head (stage 3). Thereafter its a new cam.

I did it that way in my carb cooper and noticed a significant improvement at each stage.

[Noah]

I'm currently restoring a Sprite of 1992 with the following specs:

Engine number: 12A2BG04 254974               A+ engine low compression 9.4:1

 

Gear box: Wide ratio with pot joints Final drive 9.4CR 2.76  (French only spec.)

 

Could someone explain the difference of my  final drive 2.76 compaired to the regular 3.1 or 3.2.

I bought the car here in France, but have not driven it yet on the road, so cannot make any compairison with my previous Mini's.

 

Thanks,

 

Peter

 

12A2BG04 is a similar engine but as your notes say it has a 2.76FD.  

The 2.76FD is the same as fitted to the Multi-Point Injection cars, great on motorways, not so great for acceleration. AR gave the 2.76FD to the french sprites, I presume testing it's capabilities motorway wise (as you have a lot of motorways!), for when they launched the MPI a few years later. 

[Noah]

Sounds a pretty good route to go and relatively cheap too.  Have you any idea what you've gained power wise and how does it compare to a satge 1 or 2 kit.??  Would a stage 2 kit take our sprites performance past that of a standard cooper??

 

Also still getting my head around these modern carbs when i had my first mini we used to talk of swopping  an 1 1/2 inch SU for  a 1 3/4 inch ..... i take it that the HIF38 is 38mm (1.5") and the 44 is (1.75") in old money

 

Yep a 38 is an 1.5" and a 44 is 1.75". 

I couldn't tell you as it's not been on a rolling road, it's not even back on a fixed road yet! - But ACDodd showed me some figures a while back of a 12A2BG03 Engine with a home made ported head, with slightly bigger than MG metro valves and clearly massive ports, and you know HIF44, stage 1 kit etc. was making more than some of 1380cc cars he tested that day. Clearly that is just an anomaly, but I can't see any reason why it shouldn't make equal if not more than the Coopers from factory did, at the flywheel. 

Other than that as Mr Peanuts said, your only limiting factor is a the cam. Once it's back and on the road I plan to take the engine out next year and fit a Mini Spares Evolution 001 camshaft and a X-Pin diff. Being 17 I goes with the territory that I 'drive it like I stole it'. 

[Mrpeanut]

Sounds a pretty good route to go and relatively cheap too.  Have you any idea what you've gained power wise and how does it compare to a satge 1 or 2 kit.??  Would a stage 2 kit take our sprites performance past that of a standard cooper??
 
Also still getting my head around these modern carbs when i had my first mini we used to talk of swopping  an 1 1/2 inch SU for  a 1 3/4 inch ..... i take it that the HIF38 is 38mm (1.5") and the 44 is (1.75") in old money
 

Yep a 38 is an 1.5" and a 44 is 1.75". 

I couldn't tell you as it's not been on a rolling road, it's not even back on a fixed road yet! - But ACDodd showed me some figures a while back of a 12A2BG03 Engine with a home made ported head, with slightly bigger than MG metro valves and clearly massive ports, and you know HIF44, stage 1 kit etc. was making more than some of 1380cc cars he tested that day. Clearly that is just an anomaly, but I can't see any reason why it shouldn't make equal if not more than the Coopers from factory did, at the flywheel. 

Other than that as Mr Peanuts said, your only limiting factor is a the cam. Once it's back and on the road I plan to take the engine out next year and fit a Mini Spares Evolution 001 camshaft and a X-Pin diff. Being 17 I goes with the territory that I 'drive it like I stole it'. 

I'm not sure that there's much difference between a sprite and a mainstream carb cooper. The carb is different but they're both lowish compression and the cooper hasn't got a great cam (unlike the rsp which had an mg metro cam). It also has a stock, small valve, 12G940 head.

A stage 1 kit alone should take the sprite past the factory 61bhp of the carb cooper. An hif44 and decent head will take it much higher. Mine (with that set up and stock cam) gives 78.4 at the fly. There's a rebuilt 1330 going in soon with an evo1 cam - should make a difference!

[DiscoDarren]

 

Sounds a pretty good route to go and relatively cheap too.  Have you any idea what you've gained power wise and how does it compare to a satge 1 or 2 kit.??  Would a stage 2 kit take our sprites performance past that of a standard cooper??

 

Also still getting my head around these modern carbs when i had my first mini we used to talk of swopping  an 1 1/2 inch SU for  a 1 3/4 inch ..... i take it that the HIF38 is 38mm (1.5") and the 44 is (1.75") in old money

 

Yep a 38 is an 1.5" and a 44 is 1.75". 

I couldn't tell you as it's not been on a rolling road, it's not even back on a fixed road yet! - But ACDodd showed me some figures a while back of a 12A2BG03 Engine with a home made ported head, with slightly bigger than MG metro valves and clearly massive ports, and you know HIF44, stage 1 kit etc. was making more than some of 1380cc cars he tested that day. Clearly that is just an anomaly, but I can't see any reason why it shouldn't make equal if not more than the Coopers from factory did, at the flywheel. 

Other than that as Mr Peanuts said, your only limiting factor is a the cam. Once it's back and on the road I plan to take the engine out next year and fit a Mini Spares Evolution 001 camshaft and a X-Pin diff. Being 17 I goes with the territory that I 'drive it like I stole it'. 

 

Thats how i drove my first mini when i was 17 (and every other car since), and if i'm honest, probably why i've bought this one....so i can re-live my youth. Brilliant choice for a first car tho noah, think it makes you a better driver in the long run.

 

Can't wait to get started on my new project.  Hoping to get the rear subframe off in the next couple of days.  Need to get her roadworthy before i start on the engine

 

Mrpeanut  - like the sound of your 1330, i'm sure it will make a big difference.  Thanks once again everyone for your good advise, i keep seeing pound signs flashing before my eyes as i think of all the repairs and mods i'd like to do.