What issues that i should look when tuning A+ series?
Discussion
I'd go +60 (1330) get a strong gearbox (close ratio) and SC Drops, a decent light flywheel and S Size valves, run a Avonbar Ph2 cam and bung a supercharger on it running a 2.9FD. Either that or a 276 Kent cam.
The catch 22 with tuned A Series engines is that in order to maximise a long cam, you need high CR's and high revs, hence the thing beats itself to death. I have a mate who runs a silly 1380 with 296 cam, lightened fangly spangly bells and whistles, dog box, etc, etc on his road car, the engine cost £2K and the box about £2.5K, my estimate is that it will shit itself in about 1/10 of the time mine does.
The latest mini world has a standard sportspack cooper running 9psi and it develops 138hp at the flywheel. Even if you knock 20hp off for pub bragging, that's pretty good.
The name of the game is to get as much area under your power curve as possible, not pull it into a silly spike. Superchargers do this. Having said a 1275 with 1.5 SU's and a 649 cam is beyond most peoples balls.
The catch 22 with tuned A Series engines is that in order to maximise a long cam, you need high CR's and high revs, hence the thing beats itself to death. I have a mate who runs a silly 1380 with 296 cam, lightened fangly spangly bells and whistles, dog box, etc, etc on his road car, the engine cost £2K and the box about £2.5K, my estimate is that it will shit itself in about 1/10 of the time mine does.
The latest mini world has a standard sportspack cooper running 9psi and it develops 138hp at the flywheel. Even if you knock 20hp off for pub bragging, that's pretty good.
The name of the game is to get as much area under your power curve as possible, not pull it into a silly spike. Superchargers do this. Having said a 1275 with 1.5 SU's and a 649 cam is beyond most peoples balls.
The usual trade-offs when you're tuning a motor for power... if you want N/A and high power then you ultimately will need high revs. The A series can put out good power - competitive racing series like the Miglias see to that - but reliability at high revs means you'll need crank / rods and secure the bearings (only 3 bearing engine). Breathing at very high revs will require plenty of work on the head, if you're rich then there are 16v head options.
I'd agree with LM on this re: forced induction and I'd also prefer supercharging, assuming the whole shooting match can be kept adequately cool. I may be mistaken but I can't see room for both a small blower and an intercooler in the Mini engine bay. At least with supercharging you can keep the rev limit standard if you wish, and some of the inadequacies of the head flow are worked around with forced induction.
There are PHers here with both high-output N/A A series minis (some with special 16v heads though) and those with forced induction. General consensus appears to be that the gearbox becomes a problem pretty rapido.
So, to summarise, plumb in a monster bottle of laughing gas, and replace the engine and gearbox from a breaker's every week or so
I'd agree with LM on this re: forced induction and I'd also prefer supercharging, assuming the whole shooting match can be kept adequately cool. I may be mistaken but I can't see room for both a small blower and an intercooler in the Mini engine bay. At least with supercharging you can keep the rev limit standard if you wish, and some of the inadequacies of the head flow are worked around with forced induction.
There are PHers here with both high-output N/A A series minis (some with special 16v heads though) and those with forced induction. General consensus appears to be that the gearbox becomes a problem pretty rapido.
So, to summarise, plumb in a monster bottle of laughing gas, and replace the engine and gearbox from a breaker's every week or so
That's all so true.
Supercharging is really effective as a way to great performance.
The gearbox/transmission is the weak-link and there is no easy way to overcome this. Even a s/c c/r box will break eventually at high outputs, especially with the huge increase in torque from a 'blower'. The problem with the s/c c/r box is that 1st gear is then very high and there can be a need to run a much lower diff ratio, thus cutting effective easy cruising speed. Remember, the s/c c/r ratios were originally developed for the competion Cooper 'S' in the 60's.
Insurance can be a problen with a supercharged car, or so I understand.
Maybe the problem with how far to tune and still retain some reliability is the stuff printed by the Mini Mags which extoll the advantages of really hot cams, 1380cc bores, high power outputs, but don't mention the short in-service life of such units.
My 1310 cc rally engine with its 286 cam, twin 1.5's, 11.1:1 c.r, lightened, etc, unit gets stripped and rebuilt every 6 rallies to kep it going, but my biggest problems are always with the drive line, and that's with a cross-pin diff, s/c c/r gears & s/c drops.
My advice is not to look at what modifications are available, but to define what you want the car to do on a day-to-day basis, then talk to an expert (or 2) to evolve a specification to suit your application. If you want to drive to work in the traffic every day, but don't want to be changing the clutch plate every month and strippoing the entire uniot out every 6 months, then keep the spec fairly mild. I've just built a nice road engine, A-Plus, at 1330 cc (+0.060"
with Hepolite 21253 pistons, Kent 266 cam, MG Metro head (35.6 mm inlets and 30.5 mm exhausts) gas flowed with a 10.5:1 c.r, 1.75 carb. The inlet manifold has been cleaned out and polished a bit, the cam timed in accurately, the block accurately 'decked' and everything carefully assembled. The gearbox has been fitted with Mk 1 Cooper 'S' gear ratios (slightly closer than A-Plus) and a cross pindiff with a 3.44:1 ratio. It goes very well with about 88 bhp at the flywheel. It's very tractable and the acceleration is good. All-in-all not an expensive build and it will last a long time as a road car and for insurance purposes it is really still 'standard'.
Just one thing, keep away from the old 649 cam on any road car. Modern cam profiles are just so much better.
Mini Spares do a Mk 1 Cooper 'S' gear set, but to fit to an A-Plus box needs a new layshaft.
Supercharging is really effective as a way to great performance.
The gearbox/transmission is the weak-link and there is no easy way to overcome this. Even a s/c c/r box will break eventually at high outputs, especially with the huge increase in torque from a 'blower'. The problem with the s/c c/r box is that 1st gear is then very high and there can be a need to run a much lower diff ratio, thus cutting effective easy cruising speed. Remember, the s/c c/r ratios were originally developed for the competion Cooper 'S' in the 60's.
Insurance can be a problen with a supercharged car, or so I understand.
Maybe the problem with how far to tune and still retain some reliability is the stuff printed by the Mini Mags which extoll the advantages of really hot cams, 1380cc bores, high power outputs, but don't mention the short in-service life of such units.
My 1310 cc rally engine with its 286 cam, twin 1.5's, 11.1:1 c.r, lightened, etc, unit gets stripped and rebuilt every 6 rallies to kep it going, but my biggest problems are always with the drive line, and that's with a cross-pin diff, s/c c/r gears & s/c drops.
My advice is not to look at what modifications are available, but to define what you want the car to do on a day-to-day basis, then talk to an expert (or 2) to evolve a specification to suit your application. If you want to drive to work in the traffic every day, but don't want to be changing the clutch plate every month and strippoing the entire uniot out every 6 months, then keep the spec fairly mild. I've just built a nice road engine, A-Plus, at 1330 cc (+0.060"
with Hepolite 21253 pistons, Kent 266 cam, MG Metro head (35.6 mm inlets and 30.5 mm exhausts) gas flowed with a 10.5:1 c.r, 1.75 carb. The inlet manifold has been cleaned out and polished a bit, the cam timed in accurately, the block accurately 'decked' and everything carefully assembled. The gearbox has been fitted with Mk 1 Cooper 'S' gear ratios (slightly closer than A-Plus) and a cross pindiff with a 3.44:1 ratio. It goes very well with about 88 bhp at the flywheel. It's very tractable and the acceleration is good. All-in-all not an expensive build and it will last a long time as a road car and for insurance purposes it is really still 'standard'. Just one thing, keep away from the old 649 cam on any road car. Modern cam profiles are just so much better.
Mini Spares do a Mk 1 Cooper 'S' gear set, but to fit to an A-Plus box needs a new layshaft.
100% With Cooperman on this. Building a unit for a friend at the Moment for day to day use. 1293cc - MG Metro Cam - MG Sized valves with cleaned up head and manifold. HIF 44 SU Carb LCB/RC40. Might even stretch to some 1.5 ratio rockers dependent on budget. This is going onto a rebuilt standard box with a 3.44 final drive. The plan is for about 80 bhp which is enough to make any Mini rattle along quite nicely.
1380's give good torque but even with offset boring they just don't last. Gearboxes don't last if you start putting more than 90lb ft through them.
1380's give good torque but even with offset boring they just don't last. Gearboxes don't last if you start putting more than 90lb ft through them.
That's a nice spec.
I always thought that the 1.5 offset roller rockers would be a significant item, but when I tested a set on my Cooper 'S' I only gained a couple of BHP (almost not measureable) whilst I definately lost a bit of bottom-end torque, so I removed them. That is with a really well modified combustion chamber with de-masking of valves taken as far as possible. Maybe they only work really well at over 6400 rpm, which was where we max'ed out on the rollers. They are not strictly allowed under historic race/rally regs anyway and I don't want to use the 1.5:1 without the rollers as they put so much side load on the valve stems and the valve guides then wear even quicker than normal. For a rally car, 6400 is quite enough, although I have seen 7000 on tarmac and even 6700 in top (100 mph)on gravel (exciting!). That's with a 3.9 diff and 10" wheels.
I always thought that the 1.5 offset roller rockers would be a significant item, but when I tested a set on my Cooper 'S' I only gained a couple of BHP (almost not measureable) whilst I definately lost a bit of bottom-end torque, so I removed them. That is with a really well modified combustion chamber with de-masking of valves taken as far as possible. Maybe they only work really well at over 6400 rpm, which was where we max'ed out on the rollers. They are not strictly allowed under historic race/rally regs anyway and I don't want to use the 1.5:1 without the rollers as they put so much side load on the valve stems and the valve guides then wear even quicker than normal. For a rally car, 6400 is quite enough, although I have seen 7000 on tarmac and even 6700 in top (100 mph)on gravel (exciting!). That's with a 3.9 diff and 10" wheels.
1.5 ratio Rockers work well without destroying bottom end on short duration cams. My Road Mini is a 1275 mini with a well modified MG Metro sized valve head, on a standard A+ cam, 9.4 to 1 comp ratio that gave 64bhp at the wheels on Ralph Saunders roling road at Brize Norton and a table top flat torque curve.
The head and rcckers went on at 20K miles and the car/engine is now showing 104K miles, so relaibility is pretty good, no excessive oil use getting down the guides (no smoke on overun).
The head and rcckers went on at 20K miles and the car/engine is now showing 104K miles, so relaibility is pretty good, no excessive oil use getting down the guides (no smoke on overun).
That does sound a nice set-up for a road car. How often do you change the oil and what oil do you use?
Until the cross-pin diff came along, the diff pins seemed to be one of the worst reliability items on the big engined cars. It's funny, but I don't remember having the same diff pin problems with Coopers in the 60's. Maybe the pins were better, or the heat treatment was superior quality then.
Talking cams, I put a 649 into a 1071 'S'with 1.5 rockers a few years ago and after about 5000 miles one of the lobes went due to failure of the case hardning. By then the car was in California with my best buddy, so I had a trip out to help him rebuild it - with a Kent 286. Lovely engine the 1071 in rally tune, unlike the 970 which is, IMHO, horrible in any state of tune - all revs and no go! I had one in an historic rally car a few years ago, a 1000 cc class contender. It had a 286 plus all the other bits and pushed out just under 90 bhp at the flywheel at about 6600 rpm. B****r all torque anywhere, nothing below about 4500, rev right round to 8000, but no real useable power. When a 1000cc Imp on Twin 40's blew it away on a tarmac stage event my son, who was driving it, was really upset. We sold it and the current owner uses it competitively and loves it. Me, I'll choose a 1275 anytime.
Until the cross-pin diff came along, the diff pins seemed to be one of the worst reliability items on the big engined cars. It's funny, but I don't remember having the same diff pin problems with Coopers in the 60's. Maybe the pins were better, or the heat treatment was superior quality then.
Talking cams, I put a 649 into a 1071 'S'with 1.5 rockers a few years ago and after about 5000 miles one of the lobes went due to failure of the case hardning. By then the car was in California with my best buddy, so I had a trip out to help him rebuild it - with a Kent 286. Lovely engine the 1071 in rally tune, unlike the 970 which is, IMHO, horrible in any state of tune - all revs and no go! I had one in an historic rally car a few years ago, a 1000 cc class contender. It had a 286 plus all the other bits and pushed out just under 90 bhp at the flywheel at about 6600 rpm. B****r all torque anywhere, nothing below about 4500, rev right round to 8000, but no real useable power. When a 1000cc Imp on Twin 40's blew it away on a tarmac stage event my son, who was driving it, was really upset. We sold it and the current owner uses it competitively and loves it. Me, I'll choose a 1275 anytime.
Unipart Silver Semi Synthetic 10w/40 with regular changes at 6K including a decent GFE part No. Unipart Filter. Can't get it any longer now Rover have gone Bust.
I race on Valvoline VR1 Racing Fully Synthetic 5w/50 and that has proved very good - Competition Diff pins don't show distress. As Valvoline 10w/40 semi sythetic isn't too expensive I'll probably move onto that next.
>> Edited by fwdracer on Monday 7th November 16:23
I race on Valvoline VR1 Racing Fully Synthetic 5w/50 and that has proved very good - Competition Diff pins don't show distress. As Valvoline 10w/40 semi sythetic isn't too expensive I'll probably move onto that next.
>> Edited by fwdracer on Monday 7th November 16:23
For rallying I always use either Valvoline Racing 20/50 or Morris Olis 'Multivis' 15/50.
I change it after every event.
Diff pins: The current competition ones from Mini Spares are, apparently, very good, but now the X-pin is available that seems the perfect solution. I 'friction-welded' a planet wheel to a x-pin diff pin on one event, the pin sheared and we did the reamining 350 miles of the event with the snapped pin rotating in the steel housing. We won the event, but to get the 'S' output shaft out of the x-pin housing I had to turn the housing in a lathe and use a parting-off tool! To friction weld the planet wheel to the pin was not easy, but I managed it nevertheless!
I change it after every event.
Diff pins: The current competition ones from Mini Spares are, apparently, very good, but now the X-pin is available that seems the perfect solution. I 'friction-welded' a planet wheel to a x-pin diff pin on one event, the pin sheared and we did the reamining 350 miles of the event with the snapped pin rotating in the steel housing. We won the event, but to get the 'S' output shaft out of the x-pin housing I had to turn the housing in a lathe and use a parting-off tool! To friction weld the planet wheel to the pin was not easy, but I managed it nevertheless!
As most people have said, the gearbox is the problem area. I had a '99 sportspack twinpoint a few years ago & I got MED to do the engine work on it. I had a 1293 road/race bottom end, fully lightened & balanced, stage 3 head,1.5 Roller rockers, maniflow 3-2-1 into a de-cat into a playmini smallbore, & a K&N filter in a modified air filter housing with direct cold air feed & a crushed fuel pressure spring.
This was a few years ago now & it produced 89bhp & 125 Lb ft of torque on West Tunings Rolling Road.
I had a 2.9:1 TranX cross pin diff in it & it used to bloody fly (125mph GPS verified on the L2B) but it would eat gearboxes.
Sadly, after the 4th layshaft, I neither had the time nor inclination to keep it, so I traded it for a 306 Gti-6. Oh how I miss it. T430 BPX where are you?
>> Edited by gwaredd on Thursday 10th November 16:35
This was a few years ago now & it produced 89bhp & 125 Lb ft of torque on West Tunings Rolling Road.
I had a 2.9:1 TranX cross pin diff in it & it used to bloody fly (125mph GPS verified on the L2B) but it would eat gearboxes.
Sadly, after the 4th layshaft, I neither had the time nor inclination to keep it, so I traded it for a 306 Gti-6. Oh how I miss it. T430 BPX where are you?
>> Edited by gwaredd on Thursday 10th November 16:35
i have to agree with coopermans comments on diff pins, i've had mini's (or mini based cars) for over 20 years, my dad navigated in a cooper's' in the 60's/early 70's, his mates have raced, rallied or just built fast road going mini's since i can remember, ever since i've been driving i've known someone with a tuned up mini, me included, but it only seems fairly recently that diff pins have been a problem.
it only seems to have come about since the last 10 years of mini production, where general standards seem to have dropped, i mean look at how bad the later mini's rust compared with earlier ones.
it only seems to have come about since the last 10 years of mini production, where general standards seem to have dropped, i mean look at how bad the later mini's rust compared with earlier ones.
You could look at the Ford/Mini conversions which come up, they are usually bought for their SC gearboxes and sold on, about £300 gets you one, bung a zetec engine on it and off you go. Occasionally you see mini box/coventry climax conversions come up but they are a bit pricey but all alloy and are good engines. All period stuff though.
I look at these £15000 engine builds on a mini and the RWD bike engined jobs and think "Why?" it might be a better idea to get a Caterham or something with a decent chassis. I love minis but they are pretty naff really, I don't think it's worth spending megabucks on them. The cheapest route to massive power is with a blower and gives a nice engine response/life as well. If you're competing, fair enough but for a fast road car, a silly cam makes it impossible to drive, I had a Morris Minor with a sprint cam in it and it was virtually impossible to drive less than racing speeds, it hardly ran below about 3000 and surprisingly, the engine lives on in my ex-A35 still!!!!
BMW mini blowers are about £100 on ebay and if you've got a strong gearbox, not really much needs to be done to a standard 1275 to make it work, just carve a head and when the thing shits itself, go down the scrapper and get another 1275 engine for £50
I look at these £15000 engine builds on a mini and the RWD bike engined jobs and think "Why?" it might be a better idea to get a Caterham or something with a decent chassis. I love minis but they are pretty naff really, I don't think it's worth spending megabucks on them. The cheapest route to massive power is with a blower and gives a nice engine response/life as well. If you're competing, fair enough but for a fast road car, a silly cam makes it impossible to drive, I had a Morris Minor with a sprint cam in it and it was virtually impossible to drive less than racing speeds, it hardly ran below about 3000 and surprisingly, the engine lives on in my ex-A35 still!!!!
BMW mini blowers are about £100 on ebay and if you've got a strong gearbox, not really much needs to be done to a standard 1275 to make it work, just carve a head and when the thing shits itself, go down the scrapper and get another 1275 engine for £50
I think its more a case of why not, rather than why.
I've been in one of those bike engined conversions and they are very very impressive, and for what they cost, about the same as my cylinder head, they are extremely good value. Theres a road legal one doing 11 second quarters at the mo, how many 5 porters do you see doing that and still be able to drive to the shops.
I've been in one of those bike engined conversions and they are very very impressive, and for what they cost, about the same as my cylinder head, they are extremely good value. Theres a road legal one doing 11 second quarters at the mo, how many 5 porters do you see doing that and still be able to drive to the shops.
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