Twin HS6 on Custom Manifold and Special filters 4 big engine
Discussion
I have a 91 Cooper S Conversion (last year of the carbs). Great car with the 3.44 diff and the Cooper head mods and all the rest that goes with it.
I get Vmax to service and tune it. Recently it had been running crap at the bottom end Stuart Gurr tells me this is the bushes of the twin 1.25" Su' being worn and seeping air in at idle to say 3k revs.
Got this priced up at Minispeed (bot the smaller carbs needed doing at £65 pound each!), then remembered I had some 1.75" one from a TR4 Racer I had (that I had since gone to twin 2" and then twin Webber 50's!), so had these looked at and only one needed rebushing - thought though sod it - let try them. So then spent 2 months getting a manifold from Maniflow (really for racers) and modding it a bit for the road car (brackets and vaccum take off's) - small ram pipes, really tasty Ramair filter kit with no back plate holes (they do not make in this size - so cut all this), finally got back on the car and with needle that were in it seemed fine all through the rev range to 6 but wary of canning in high revs for long and needed setting up and might be lean at the top end.
Finally got Stuart to setup and found were lean at the top (piston belting!) so needles modded, but now a bit lumpy at the bottom end. Goes like a mad thing past 3k! 88bhp at 6k and 92 ft/lbs on the 3.44 diff!
But think they are really for a bigger engined car (that will get the best out of them - just drawing to much ari low down I think for a 1275).
***If there is anyone out there that fancies these - I'll have to add all the bits up and will do in next week or so. Wish I had cash to do a 1380 or bigger to make them work but think I want a later longer final drive MPI that Stuart can Supercharger - So likely get the Cooper S sold when back to std carbs, pity Mega car - Sad day- but to much on. I will be taking the bit set off after Goodwood LSMOC trackday (wednesday) and going back to the 1.25 (have to rebush them after all this!) - few bhp less but alot more driveable.
Will be great at Goodwood though!
I get Vmax to service and tune it. Recently it had been running crap at the bottom end Stuart Gurr tells me this is the bushes of the twin 1.25" Su' being worn and seeping air in at idle to say 3k revs.
Got this priced up at Minispeed (bot the smaller carbs needed doing at £65 pound each!), then remembered I had some 1.75" one from a TR4 Racer I had (that I had since gone to twin 2" and then twin Webber 50's!), so had these looked at and only one needed rebushing - thought though sod it - let try them. So then spent 2 months getting a manifold from Maniflow (really for racers) and modding it a bit for the road car (brackets and vaccum take off's) - small ram pipes, really tasty Ramair filter kit with no back plate holes (they do not make in this size - so cut all this), finally got back on the car and with needle that were in it seemed fine all through the rev range to 6 but wary of canning in high revs for long and needed setting up and might be lean at the top end.
Finally got Stuart to setup and found were lean at the top (piston belting!) so needles modded, but now a bit lumpy at the bottom end. Goes like a mad thing past 3k! 88bhp at 6k and 92 ft/lbs on the 3.44 diff!
But think they are really for a bigger engined car (that will get the best out of them - just drawing to much ari low down I think for a 1275).
***If there is anyone out there that fancies these - I'll have to add all the bits up and will do in next week or so. Wish I had cash to do a 1380 or bigger to make them work but think I want a later longer final drive MPI that Stuart can Supercharger - So likely get the Cooper S sold when back to std carbs, pity Mega car - Sad day- but to much on. I will be taking the bit set off after Goodwood LSMOC trackday (wednesday) and going back to the 1.25 (have to rebush them after all this!) - few bhp less but alot more driveable.
Will be great at Goodwood though!
Wildfire said:
Jon I can get hold of a 1380 engine, sadly one piston is holed but otherwise in good nick. The bores are ok. Very cheap if you want to match you carbs.
Tempting honestly, but I have been told it has to go. Basically it is to loud. Toys out of pram about it - trying to pacify with a low ratio MPi (that will be slow) but later can get Vmax to blow it. That way quite and evenentually fast as well - saw on down there last week with big 48 tyres all one colour - immaculate - 150bhp Late car the ful works. Some art dealers - Absolutely AWSEOME. love machine said:
Have you considered belting up your own Bini charger?
I've written an article about it on the interweb somewhere. There is a better way to skin a cat.
Where? I've written an article about it on the interweb somewhere. There is a better way to skin a cat.
Think a bit late for me know - in the mind set to get one like that Red Beast (missed that edition - see the custom crap in this months one!). Seems to not be running too bad low dwon today - stuart think he can sort it - think I might get some For Sales signs on it for the Goodwood Track Day tomorrow.
I'll do one better, I'll bung it here. I'm not a big advocate of suck through, in my opinion you can have fun with things exploding. The M45 has quite a heating effect as well, so you're going to need a lower CR than you would anyway, either that or less advance. Since metro turbo carbs are blow through, you can see where I'm going here. From what I gather Stu is an incredible craftsman and a brilliant engineer and I'm sure he produces the best results for that configuration, I disagree that it's the best way. It is a challenge to mount up, if you hold a bini charger next to the engine, it's massive!!!! I think the way to go on the A series is running the lest boost, the highest CR and the most advance. Blow through is the best way of doing this, blowing through an intercooler. They do break gearboxes though.
Here goes........
Bini Supercharger Conversion.
As I am bored, I will put my views down and then you lot can see what you reckon.
Blower.
The blower as fitted to the Bini is an Eaton/Magnuson 4th generation blower. These guys are at the forefront of rootes blower technology and their series 4 is about as good as Rootes blowers get. Sadly that is about 60%(max) Adiabatic Efficiency (Eaton). Comparing poorly to a Screw Blower or Turbo at about 80% (Haynes). Which means when you load it excessively, the unit re-circulates excess air and heats the charge excessively. So, for 12 PSI, the temperature rise is 80 deg C (over ambient). This tails off exponentially and is about 60 at 10, etc, etc. So, the only thing that Bini blowers have got going for them is that they are very cheap. The intake housing is a bad shape and inconveniently large, the unit is gigantic, when placed next to the A Series, it is pretty mind boggling. But for a low boost unit to just augment an engine with already good characteristics, it does it a treat. Which is why the unit figures in low boost applications. It may be practical to use an intercooler to cool the charge slightly, but a boost increase will be non-linear and so the returns don?t justify the means. However, it will allow a higher compression ratio to be used, which will reveal as much power as possible. This looks like being achieved in the biggest possible capacity running as little residual boost as possible, but getting the most air through the intake and out of the car exhaust. This has to be done with particular attention to gas flow, as much as any high performance engine although the characteristics are peculiar to a supercharged engine.
Configurations.
There are only 2 serious options available to the supercharger conversion chap. The Shorrock style ?Above the inlet manifold? is the best idea. The easiest to belt up, is probably the best space for it but there is no way in God?s earth (I can see) it would be possible to pipe up for a intercooler (Without a big bonnet bulge). As the engine is a small capacity job (for the blower) and I am trying to get as much out of it as possible, I will consider the alternative. Having it sited at the front, where the alternator would go, but a bit higher up. Before you think otherwise, there is insufficient space (with the pipe work/mounts/oil filter, to mount it with the rotors stacked (ie:- Vertical) so the unit must be mounted ?sunny side up? blowing downwards into a fabricated collector. You know if you have it the right place as the unit will foul the slam panel near the bonnet catch, it will be necessary to tip the engine back a tad on special mounts. Once this is achieved, it must be belted up and mounted (which is a lot more tricky than it looks) then it can be piped into a suitable intercooler (Rover TD looks like my favourite choice, although the ?Bar and Pipe? design is not the most efficient) then blown through a conventional metro turbo set up. The difference is that a conventional exhaust manifold will be required.
Cam/Head/breathing stuff.
This is where I talk bollox but it makes sense to me. What is the go for N/A engines, isn?t the same for Turbo engines and again different to supercharged engines.
As the Vizard book says (I had to quote that), increasing the cam duration allows the engine to behave in a form relative to it?s N/A cousins. Whilst this is true and I hear a 276 is great and ultimately a 286 is expected to give great results, I think this is largely bollox. Whilst it might work the inherent differences must mean that the cam for a N/A engine has insufficient exhaust duration. So, this chokes it up a bit and might sod up the low RPM running. Besides, I?m not investing in a steel bottom end, so I am not going to rev its nuts off anyway. So, the point is at low RPM, the overlap will allow blow by and kill potential power, just as the converse will choke the cam off with not a bit of overlap. Bypassing a load of complicated maths bollox, about an extra 15deg on the exhaust is a good idea, going to 20 with more wild cams. So, not wanting to go for a special grind, I looked at the Avonbar Ph2 cam, which has the added exhaust duration and lift. (Off the top of my head, it is pretty much a 266 with added exhaust duration of about 15deg).
So, having a look further at the figures for the cam, I see that the exhaust has really high lift, which is a good thing as well. I am now going to go on about the bit of valve choice. Since dP between the inlet and chamber is going to be a lot more than N/A, it follows that the inlet can flow less, as it doesn?t need to, hence less lift, less important inlet valve sizes but the contrary for the exhaust. It will be producing loads of exhaust gas (Try a 2.0 N/A Engine) and so needs big flow. It doesn?t need any more overlap to start interfering with the bottom end, so a bigger valve is more important than a greater rocker ratio.
Roughly, 1.3->1.5 rockers ups area for flow by about 15% more.
Going from a 29mm->32mm exhaust valve adds about 10% more area for flow and acts 10% quicker whilst leaving the overlap untouched. 1.5 rockers increase the significance of the present overlap. Maybe a good idea, but I think not. Obviously, the exhaust system will have to flow for the bigger capacity and I personally would choose a big bore LCB as well as a 2? system.
So, looking at the head. From a load of bollox and personal hunching, I have decided that 12PSI intercooled, with a 8:1 CR should allow me a sensible margin with 98 RON fuel. That is with a 1380, offset bored, as the extra capacity should release much more useful ?work? than an overblown 1293. This appears to be a good move from what I have read elsewhere. Regarding the rev limit of about 6500, it may be possible to gain more power by stroking to 84mm (1430cc) as the lever action should free up a significant amount of torque.
The problem is, how to get the chamber out to the right size. Looking at my casting, and a few others I have, I think that squish matching a head to a piston, with a circular chamber milled out to about 28-30cc, radius being the most important thing. The required gap would then be filled with a matched ?Decompression Spacer? gasket, of the required thickness to drop the compression ratio. To 8:1 (I think the area required is about 15cc after 4cc taken off for 2 gaskets). The exhaust ports would be enlarged and the bosses cut back ?enough? and the exhaust ports controlled vortex bollox eliminated and the thing totally matched.
There is very little to read about supercharging an A Series, cam choice, etc. The shit above is entirely fabricated by me, outlines what I believe to be the right way of getting the most out of the set up. It might make a useful read for someone planning to do a conversion by themselves. However, it is a lot more difficult than it looks. Much more and a kit would be pretty much a good idea.
But, that would be too easy.
Cleaned up and ready to be put back together now (as above)
Stu (off to the pub)
Here goes........
Bini Supercharger Conversion.
As I am bored, I will put my views down and then you lot can see what you reckon.
Blower.
The blower as fitted to the Bini is an Eaton/Magnuson 4th generation blower. These guys are at the forefront of rootes blower technology and their series 4 is about as good as Rootes blowers get. Sadly that is about 60%(max) Adiabatic Efficiency (Eaton). Comparing poorly to a Screw Blower or Turbo at about 80% (Haynes). Which means when you load it excessively, the unit re-circulates excess air and heats the charge excessively. So, for 12 PSI, the temperature rise is 80 deg C (over ambient). This tails off exponentially and is about 60 at 10, etc, etc. So, the only thing that Bini blowers have got going for them is that they are very cheap. The intake housing is a bad shape and inconveniently large, the unit is gigantic, when placed next to the A Series, it is pretty mind boggling. But for a low boost unit to just augment an engine with already good characteristics, it does it a treat. Which is why the unit figures in low boost applications. It may be practical to use an intercooler to cool the charge slightly, but a boost increase will be non-linear and so the returns don?t justify the means. However, it will allow a higher compression ratio to be used, which will reveal as much power as possible. This looks like being achieved in the biggest possible capacity running as little residual boost as possible, but getting the most air through the intake and out of the car exhaust. This has to be done with particular attention to gas flow, as much as any high performance engine although the characteristics are peculiar to a supercharged engine.
Configurations.
There are only 2 serious options available to the supercharger conversion chap. The Shorrock style ?Above the inlet manifold? is the best idea. The easiest to belt up, is probably the best space for it but there is no way in God?s earth (I can see) it would be possible to pipe up for a intercooler (Without a big bonnet bulge). As the engine is a small capacity job (for the blower) and I am trying to get as much out of it as possible, I will consider the alternative. Having it sited at the front, where the alternator would go, but a bit higher up. Before you think otherwise, there is insufficient space (with the pipe work/mounts/oil filter, to mount it with the rotors stacked (ie:- Vertical) so the unit must be mounted ?sunny side up? blowing downwards into a fabricated collector. You know if you have it the right place as the unit will foul the slam panel near the bonnet catch, it will be necessary to tip the engine back a tad on special mounts. Once this is achieved, it must be belted up and mounted (which is a lot more tricky than it looks) then it can be piped into a suitable intercooler (Rover TD looks like my favourite choice, although the ?Bar and Pipe? design is not the most efficient) then blown through a conventional metro turbo set up. The difference is that a conventional exhaust manifold will be required.
Cam/Head/breathing stuff.
This is where I talk bollox but it makes sense to me. What is the go for N/A engines, isn?t the same for Turbo engines and again different to supercharged engines.
As the Vizard book says (I had to quote that), increasing the cam duration allows the engine to behave in a form relative to it?s N/A cousins. Whilst this is true and I hear a 276 is great and ultimately a 286 is expected to give great results, I think this is largely bollox. Whilst it might work the inherent differences must mean that the cam for a N/A engine has insufficient exhaust duration. So, this chokes it up a bit and might sod up the low RPM running. Besides, I?m not investing in a steel bottom end, so I am not going to rev its nuts off anyway. So, the point is at low RPM, the overlap will allow blow by and kill potential power, just as the converse will choke the cam off with not a bit of overlap. Bypassing a load of complicated maths bollox, about an extra 15deg on the exhaust is a good idea, going to 20 with more wild cams. So, not wanting to go for a special grind, I looked at the Avonbar Ph2 cam, which has the added exhaust duration and lift. (Off the top of my head, it is pretty much a 266 with added exhaust duration of about 15deg).
So, having a look further at the figures for the cam, I see that the exhaust has really high lift, which is a good thing as well. I am now going to go on about the bit of valve choice. Since dP between the inlet and chamber is going to be a lot more than N/A, it follows that the inlet can flow less, as it doesn?t need to, hence less lift, less important inlet valve sizes but the contrary for the exhaust. It will be producing loads of exhaust gas (Try a 2.0 N/A Engine) and so needs big flow. It doesn?t need any more overlap to start interfering with the bottom end, so a bigger valve is more important than a greater rocker ratio.
Roughly, 1.3->1.5 rockers ups area for flow by about 15% more.
Going from a 29mm->32mm exhaust valve adds about 10% more area for flow and acts 10% quicker whilst leaving the overlap untouched. 1.5 rockers increase the significance of the present overlap. Maybe a good idea, but I think not. Obviously, the exhaust system will have to flow for the bigger capacity and I personally would choose a big bore LCB as well as a 2? system.
So, looking at the head. From a load of bollox and personal hunching, I have decided that 12PSI intercooled, with a 8:1 CR should allow me a sensible margin with 98 RON fuel. That is with a 1380, offset bored, as the extra capacity should release much more useful ?work? than an overblown 1293. This appears to be a good move from what I have read elsewhere. Regarding the rev limit of about 6500, it may be possible to gain more power by stroking to 84mm (1430cc) as the lever action should free up a significant amount of torque.
The problem is, how to get the chamber out to the right size. Looking at my casting, and a few others I have, I think that squish matching a head to a piston, with a circular chamber milled out to about 28-30cc, radius being the most important thing. The required gap would then be filled with a matched ?Decompression Spacer? gasket, of the required thickness to drop the compression ratio. To 8:1 (I think the area required is about 15cc after 4cc taken off for 2 gaskets). The exhaust ports would be enlarged and the bosses cut back ?enough? and the exhaust ports controlled vortex bollox eliminated and the thing totally matched.
There is very little to read about supercharging an A Series, cam choice, etc. The shit above is entirely fabricated by me, outlines what I believe to be the right way of getting the most out of the set up. It might make a useful read for someone planning to do a conversion by themselves. However, it is a lot more difficult than it looks. Much more and a kit would be pretty much a good idea.
But, that would be too easy.
Cleaned up and ready to be put back together now (as above)
Stu (off to the pub)
So Stu - a lover or a hater orf the Vmax kit?
Well you can't hate it - it works Damned well. Having just been in two at Goodwood and Stuart Wright NUTS Turbo thing (a whole different ball game and not really pracical for the road).
The two Vmax one I had a go in were a 1275 one on a 1.75 SU that made about 135bhp and a 1380 with cam that made 160bhp! Both bloody fantastic - and LOADS of torque - like having a tuned 2litre engine up front just like having a huge big hand pushing you along from behind.
The larger engined one had a heater just down steam of the carb to avoid carb icing - which apparently the other one did suffer from a bit.
They are great on std or tweeked bottom end but all have a larger valved head.
Trouble is they are reasonable cash for the carb carb but really start to get expensive for the full MPI Emerald converted ones (Awesome one in Vmax with 150bhp) - late Cooper all one colour on nice after market deep dish black wheels and tasty interior.
Well you can't hate it - it works Damned well. Having just been in two at Goodwood and Stuart Wright NUTS Turbo thing (a whole different ball game and not really pracical for the road).
The two Vmax one I had a go in were a 1275 one on a 1.75 SU that made about 135bhp and a 1380 with cam that made 160bhp! Both bloody fantastic - and LOADS of torque - like having a tuned 2litre engine up front just like having a huge big hand pushing you along from behind.
The larger engined one had a heater just down steam of the carb to avoid carb icing - which apparently the other one did suffer from a bit.
They are great on std or tweeked bottom end but all have a larger valved head.
Trouble is they are reasonable cash for the carb carb but really start to get expensive for the full MPI Emerald converted ones (Awesome one in Vmax with 150bhp) - late Cooper all one colour on nice after market deep dish black wheels and tasty interior.
my tuppance.
the shorrocks kits are a waste of time and money. they where designed to work on 850s not 1300ccs and are always worn out bits of crap when ever they turn up for sale. a few years ago a mate of mine had a big thing for them (before the new s released a flood of cheap chargers) he spent a fortune and a lot of effort building a supercharged 850 which, for a 850 went about as well as a standard 1275. the kit behaved ok, but used to smoke really bad (i.e red arrows!) on start up. we ended up making a full set of tools to strip the charger and had to buy a few to make one good one. we reconned a few for people but after a few just gave up as the rotors where usually beyond repair. we sold all the crap we had left on eaby (with a honest description!) for silly money, so someone somewhere conned a load of people with shagged old chargers!
the bm ones are a better option and if i where to do one it would be with the single injector like the later vmax ones. i know a few people running su.s on them and they are a little problematic.
the shorrocks kits are a waste of time and money. they where designed to work on 850s not 1300ccs and are always worn out bits of crap when ever they turn up for sale. a few years ago a mate of mine had a big thing for them (before the new s released a flood of cheap chargers) he spent a fortune and a lot of effort building a supercharged 850 which, for a 850 went about as well as a standard 1275. the kit behaved ok, but used to smoke really bad (i.e red arrows!) on start up. we ended up making a full set of tools to strip the charger and had to buy a few to make one good one. we reconned a few for people but after a few just gave up as the rotors where usually beyond repair. we sold all the crap we had left on eaby (with a honest description!) for silly money, so someone somewhere conned a load of people with shagged old chargers!
the bm ones are a better option and if i where to do one it would be with the single injector like the later vmax ones. i know a few people running su.s on them and they are a little problematic.
guru_1071 said:
my tuppance.
the shorrocks kits are a waste of time and money. they where designed to work on 850s not 1300ccs and are always worn out bits of crap when ever they turn up for sale. a few years ago a mate of mine had a big thing for them (before the new s released a flood of cheap chargers) he spent a fortune and a lot of effort building a supercharged 850 which, for a 850 went about as well as a standard 1275. the kit behaved ok, but used to smoke really bad (i.e red arrows!) on start up. we ended up making a full set of tools to strip the charger and had to buy a few to make one good one. we reconned a few for people but after a few just gave up as the rotors where usually beyond repair. we sold all the crap we had left on eaby (with a honest description!) for silly money, so someone somewhere conned a load of people with shagged old chargers!
the bm ones are a better option and if i where to do one it would be with the single injector like the later vmax ones. i know a few people running su.s on them and they are a little problematic.
the shorrocks kits are a waste of time and money. they where designed to work on 850s not 1300ccs and are always worn out bits of crap when ever they turn up for sale. a few years ago a mate of mine had a big thing for them (before the new s released a flood of cheap chargers) he spent a fortune and a lot of effort building a supercharged 850 which, for a 850 went about as well as a standard 1275. the kit behaved ok, but used to smoke really bad (i.e red arrows!) on start up. we ended up making a full set of tools to strip the charger and had to buy a few to make one good one. we reconned a few for people but after a few just gave up as the rotors where usually beyond repair. we sold all the crap we had left on eaby (with a honest description!) for silly money, so someone somewhere conned a load of people with shagged old chargers!
the bm ones are a better option and if i where to do one it would be with the single injector like the later vmax ones. i know a few people running su.s on them and they are a little problematic.
One of my mates ex-girlfriends dad worked at Abingdon doing development work. It sounded like serious playtime and they had an 850 mini fitted with an aircraft cabin blower in the passenger footwell, I think it was in the region of 100hp at the wheels, the engines used to last about a week. Not sure how they did it but I think they used short rods or the wrong pistons or something. It was a case of giving it about 25psi with about a 7:1 CR. I can't remember the exact details of the other stuff but they had something like a rear engined V8 spitfire. It sounds like they spent a lot of time making scrapheap challenge style stuff.
guru_1071 said:
the shorrocks blower was a cabin pressure blower for a 1950's jet plane and i think (from memory) would blow 12 psi, this is one of the reasons they are so crap. any more psi needs bigger and smaller pulleys which just overspeeds them.
They are more efficient than even a Bini blower though. I don't think they recirculate that much, you can get modern vanes for them which make them even more efficient. I would see about getting an autorotor or something similar. But a bini charger and intercooler do pretty much the same thing.
the main problem we found with the shorrocks was worn vanes, it was impossibe to revane them due to the way they where made, as one vane acts upon its opposite, also the main cylinder body would wear as well, so fitting a differant 'pack' of vanes in a worn cylinder was a waste of time.
we did try surface grinding the tips of the vanes, and remaking them with other materials, but the main problem was always the wear in the bodies.
this proved impossible to fix, though i guess with expensive liners and what not it could be got round, with some special tools and presses. we always found a better charger to use!
our other problem was that every charger bought as 'perfect' would always have been stripped by some fool, so all the threads where stripped and normally the innards had been taken to bits using punches and hammers!
we did try surface grinding the tips of the vanes, and remaking them with other materials, but the main problem was always the wear in the bodies.
this proved impossible to fix, though i guess with expensive liners and what not it could be got round, with some special tools and presses. we always found a better charger to use!
our other problem was that every charger bought as 'perfect' would always have been stripped by some fool, so all the threads where stripped and normally the innards had been taken to bits using punches and hammers!
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