17 replies to this topic

[NIMini1275]

Hi guys,
I’m fairly new to the mini scene and here so hello.

I am looking for advice on my SPI 1275
I have stripped my engine down to rectify the 2nd gear synchro issue. This has turned into further mod ideas, so here is my plans so far.

Bore block to 1330
Piper 270 camshaft - bought
Larger valve metro head - bought
Lightened flywheel, balanced crank
Vernier duplex timing kit
Lcb manifold - bought

Will all this be a waste of time on SPI set up, I have been told by several people that a carb is the only way to release true potential.

I am not looking to brake any HP records, just want a nippy, nice to drive mini. Before engine removal car was sluggish.

If I convert to carb, I will have to spend several hundred pounds on carb,mani, and rewire to suit.

Any feedback appreciated.

[sonikk4]

Hi and welcome to TMF.

 

Personally i would go to 1293, keeps plenty of rebores in the tank. As for the head, its a starting point but to release more power look at getting it ported and gas flowed.

 

Make sure the manifold is the right diameter and of course the rest of the exhaust system, no point strangling the engine.

 

As for the carb, if you go that route then a Hif44 suitably needled so a rolling road will be needed. Decent dizzy curved for the engine spec.

 

Uprated oil pump etc etc.

 

I'm no expert on engines but you can certainly build a decent grunty engine on this sort of spec.

[Wazzah]

I have an spi also so lets assume we have the best of all the mini configurations. We could argue that carbies are a backward step or just a step back in time. You are on the right track with lightening the engine internals. If you lighten the crank, rods, pistons and flywheel by 10kg total the car sees that as a 120 kg lightening overall in first gear and 80 kg in second. This is due to the torque multiplication of the driven gear x the final drive. This is huge. This is free torque. Back to the injection bit. Lets trust the standard ECU and all its sensors to get us 85 hp. Head mods, 1.4 - 1.5 ratio rockers, LCB and K&N filter should see that easily. SC programmable ECU could see another 5-10 hp. a bigger of the shelf bosch injector and a rolling road tune could release another 5hp. I am at he start of this trek and have ordered a SC super sport head with big exhaust valves and there delta 400 ECU. Got the rockers fitted already. Just finished suspension and brakes going light and adjustable. Mostly KAD stuff. Head goes on next week. 5 speed gearbox ordered and illl throw in a SW-5 and light crank, rods, pistons and lifters once split. Electric fan and electric water pump will all help with torque multiplication and parasitic loses. I'm building a hillclimb car that will be good everywhere.

[brivinci]

Yep, 85bhp is about all the ECU can handle. I would agree that a 1293 is a better idea just in case you need a rebuild down the road. The heads on these is where all the power lies. Simply replacing it with a properly ported big valve head will give you the most significant bump. The rest of the bits just add to the experience really...but are needed. A proper head, cam, lifters, correct exhaust, and a simply K&N drop is will get you just about everything the Rover ECU can offer. Timing is the cam correctly with that vernier set is a great idea so you are ahead of the game there.

 

Weight reductions to the rotating mass is like adding HP. Depending on what you plan to do with the car, swapping the diff is another way to get instant acceleration improvements. Personally, I think the SPi cars were fitted with the best final drive for everyday Mini motoring but going down to a 3.44 is said to really "wake these up". I was thinking about going this route but backed out in the end...which was the right move for me personally. I have driven my Mini 8 hours straight on US highways (can be seemingly endless, straight and flat) and was happy I kept it. 

[rich_959]

I'm in a similar boat, trying to make a decision about the final drive on my MPI after light mods. Cam, head, lightened flywheel etc. I know I'd get much better performance going down to a 3.2 or 3.44 or but I may occasionally do some long runs, even a road trip to France - so I know I should really stick with the long legged mpi final drive. I also think it will give me the best 'like-for-like' comparison of how much difference the engine mods have made. I'm going to 10" wheels too, so I'm hoping that also helps performance/acceleration a bit (compared to the heavy sportpack wheels it used to have).

[Wiggy]

I bought my MPi with the JC package and standard final drive. I quite liked the long final drive, but it was a pain to drive slowly. Pretty dead below 3k too. Always had to drop to 1st gear.

I then had the box rebuilt and changed the final drive to 3.1 or 3.2. I can't remember. That certainly perked her up, but the lack of low down torque was still annoying.

So then I added the Kent 274 Cam. Wow, what a difference that made! So much more low down torque, so much nicer to drive. And she'll still cruise down the Motorway at 70mph+ at about 3500rpm.

[rich_959]

I bought my MPi with the JC package and standard final drive. I quite liked the long final drive, but it was a pain to drive slowly. Pretty dead below 3k too. Always had to drop to 1st gear.

I then had the box rebuilt and changed the final drive to 3.1 or 3.2. I can't remember. That certainly perked her up, but the lack of low down torque was still annoying.

So then I added the Kent 274 Cam. Wow, what a difference that made! So much more low down torque, so much nicer to drive. And she'll still cruise down the Motorway at 70mph+ at about 3500rpm.

 

I've gone for the Swiftune SW5-07 and duplex timing kit, plus the head work and an MED flywheel. X Pin diff, maniflow manifold and system, and a K&N element.  So I think I'll stick with my leggy final drive and see how it goes. Maybe get my road trip done, then consider changing it at a later date if it needs it.

 

I had two different standard MPI's back in the day, and never gave the final drive any thought (but I had nothing to compare it to except my 998cc). I'd quite like to drive a standard MPI with a 3.1 or 3.2, just to see the difference. 

[neal]

Hi guys,
I’m fairly new to the mini scene and here so hello.

I am looking for advice on my SPI 1275
I have stripped my engine down to rectify the 2nd gear synchro issue. This has turned into further mod ideas, so here is my plans so far.

Bore block to 1330
Piper 270 camshaft - bought
Larger valve metro head - bought
Lightened flywheel, balanced crank
Vernier duplex timing kit
Lcb manifold - bought

Will all this be a waste of time on SPI set up, I have been told by several people that a carb is the only way to release true potential.

I am not looking to brake any HP records, just want a nippy, nice to drive mini. Before engine removal car was sluggish.

If I convert to carb, I will have to spend several hundred pounds on carb,mani, and rewire to suit.

Any feedback appreciated.

I helped a friend of mine who has a '94 Cooper SPI with 85,000 miles on the clock (the standard bores were in good shape and the original cross hatching of the honing was still noticeable) and put a ported and gas flowed head with 10,25:1 compression ratio. We also fitted a set of 1.5 roller rockers, a 1.5" maniflow exhaust system with a LCB and replaced the air filter with a K&N item. After changing the oil, filter, leads and plugs and some fresh fuel in as well as checking the wheel alignment and tyre pressures we took it to SMMC for a rolling road test, after the second run after a little fettling it made 75BHP at the wheels at 5950rpm. Colin commented that this was a really good figure for a vehicle with the standard ECU and had seen many 1380's deliver less. On the motorway in 4th gear at a whisker over 3800rpm the car sits at 70mph, when you plant your foot down the car just keeps pulling and pulling. The car has bags of torque in the back roads and returns great fuel economy if driven steady. My friends wife has a standard SPI car (similar mileage) with no mods whatsoever and comparing the two is very noticeable throughout the rev range, making these simple mods well worth while. Before you go spending more money on carbs etc, try your proposed spec with a good cylinder head as you may well be really happy with the results and can fit carbs when funds are healthier, but I would consider a X-pin diff though.

Edited by neal, 16 March 2019 - 09:59 PM.

[rich_959]

 

Hi guys,
I’m fairly new to the mini scene and here so hello.

I am looking for advice on my SPI 1275
I have stripped my engine down to rectify the 2nd gear synchro issue. This has turned into further mod ideas, so here is my plans so far.

Bore block to 1330
Piper 270 camshaft - bought
Larger valve metro head - bought
Lightened flywheel, balanced crank
Vernier duplex timing kit
Lcb manifold - bought

Will all this be a waste of time on SPI set up, I have been told by several people that a carb is the only way to release true potential.

I am not looking to brake any HP records, just want a nippy, nice to drive mini. Before engine removal car was sluggish.

If I convert to carb, I will have to spend several hundred pounds on carb,mani, and rewire to suit.

Any feedback appreciated.

I helped a friend of mine who has a '94 Cooper SPI with 85,000 miles on the clock (the standard bores were in good shape and the original cross hatching of the honing was still noticeable) and put a ported and gas flowed head with 10,25:1 compression ratio. We also fitted a set of 1.5 roller rockers, a 1.5" maniflow exhaust system with a LCB and replaced the air filter with a K&N item. After changing the oil, filter, leads and plugs and some fresh fuel in as well as checking the wheel alignment and tyre pressures we took it to SMMC for a rolling road test, after the second run after a little fettling it made 75BHP at the wheels at 5950rpm. Phil commented that this was a really good figure for a vehicle with the standard ECU and had seen many 1380's deliver less. On the motorway in 4th gear at a whisker over 3800rpm the car sits at 70mph, when you plant your foot down the car just keeps pulling and pulling. The car has bags of torque in the back roads and returns great fuel economy if driven steady. My friends wife has a standard SPI car (similar mileage) with no mods whatsoever and comparing the two is very noticeable throughout the rev range, making these simple mods well worth while. Before you go spending more money on carbs etc, try your proposed spec with a good cylinder head as you may well be really happy with the results and can fit carbs when funds are healthier, but I would consider a X-pin diff though.

 

 

Very interesting that Neal. The 75bhp was definitely at the wheels? Standard cam?

 

I'd be mega-pleased with similar results for my mpi with similar planned mods (but also a SW5-07 cam).

[minimadman1]

Hi Rich
Yes the 94 Cooper is mine, and actually Neal was playing it down a bit, it was nearer 80 BHP at the wheels and yes it’s a standard cam. It would probibly be an extra 5 BHP if I changed the cam I’m guessing.

[neal]

Hi Rich
Yes the 94 Cooper is mine, and actually Neal was playing it down a bit, it was nearer 80 BHP at the wheels and yes it’s a standard cam. It would probibly be an extra 5 BHP if I changed the cam I’m guessing.

No mate, defo made 75 at the wheels, Colin said it would be well into the 80's at the engine. Either way that thing goes for a high mileage standard bore/cam for very little cost.

Edited by neal, 16 March 2019 - 10:00 PM.

[rich_959]

Amazing results chaps. 

 

Neil, thanks for the PM.

[Bobbins]

 

Hi guys,
I’m fairly new to the mini scene and here so hello.

I am looking for advice on my SPI 1275
I have stripped my engine down to rectify the 2nd gear synchro issue. This has turned into further mod ideas, so here is my plans so far.

Bore block to 1330
Piper 270 camshaft - bought
Larger valve metro head - bought
Lightened flywheel, balanced crank
Vernier duplex timing kit
Lcb manifold - bought

Will all this be a waste of time on SPI set up, I have been told by several people that a carb is the only way to release true potential.

I am not looking to brake any HP records, just want a nippy, nice to drive mini. Before engine removal car was sluggish.

If I convert to carb, I will have to spend several hundred pounds on carb,mani, and rewire to suit.

Any feedback appreciated.

I helped a friend of mine who has a '94 Cooper SPI with 85,000 miles on the clock (the standard bores were in good shape and the original cross hatching of the honing was still noticeable) and put a ported and gas flowed head with 10,25:1 compression ratio. We also fitted a set of 1.5 roller rockers, a 1.5" maniflow exhaust system with a LCB and replaced the air filter with a K&N item. After changing the oil, filter, leads and plugs and some fresh fuel in as well as checking the wheel alignment and tyre pressures we took it to SMMC for a rolling road test, after the second run after a little fettling it made 75BHP at the wheels at 5950rpm. Phil commented that this was a really good figure for a vehicle with the standard ECU and had seen many 1380's deliver less. On the motorway in 4th gear at a whisker over 3800rpm the car sits at 70mph, when you plant your foot down the car just keeps pulling and pulling. The car has bags of torque in the back roads and returns great fuel economy if driven steady. My friends wife has a standard SPI car (similar mileage) with no mods whatsoever and comparing the two is very noticeable throughout the rev range, making these simple mods well worth while. Before you go spending more money on carbs etc, try your proposed spec with a good cylinder head as you may well be really happy with the results and can fit carbs when funds are healthier, but I would consider a X-pin diff though.

 

 

Who did you use for the porting of the head?

[R658UYC]

Hi guys,
I’m fairly new to the mini scene and here so hello.

I am looking for advice on my SPI 1275
I have stripped my engine down to rectify the 2nd gear synchro issue. This has turned into further mod ideas, so here is my plans so far.

Bore block to 1330
Piper 270 camshaft - bought
Larger valve metro head - bought
Lightened flywheel, balanced crank
Vernier duplex timing kit
Lcb manifold - bought

Will all this be a waste of time on SPI set up, I have been told by several people that a carb is the only way to release true potential.

I am not looking to brake any HP records, just want a nippy, nice to drive mini. Before engine removal car was sluggish.

If I convert to carb, I will have to spend several hundred pounds on carb,mani, and rewire to suit.

Any feedback appreciated.

[R658UYC]

Hi guys, update on this.

Bore block to 1330 - not done just had bores rehoned and pistons cleaned up
Piper 270 camshaft - fitted but ran very rough, took engine out again and checked timing...it was out 4 degrees or so but decided now against putting this back in so have bought SW5 cam which I’m waiting on
Larger valve metro head - going to do a mild port at exhaust ports to match gasket to free up airflow
Lightened flywheel, balanced crank - didn’t do
Vernier duplex timing kit - purchased will be fitting next week
Lcb manifold - fouled water line on inlet so didn’t use, I have a straight through stainless from bottom of manifold which I will use between MOTs for fun