Found this today in amongst other car magazines and 131 roadtests etc which I forgot I had.  Its a photo copy of a three page report on lampredi and his work with superchargers and test cars fitted with them which are mainly 131 sports. Also mentions a 285bhp supercharged 131 they tested. I dont know if anyone is aware of this article ?  its dated July 1980. Sorry about the pictures but I dont have a scanner.

                         with turbochargers winning universal acclaim
                its nice to know that not everyone is so strongly commited to
                juggling exhaust gases. Roger bell reports on how an eminent
                         italian engineer is finding a different answer

                                      BLOWER JOB, FIAT-STYLE

Was this hearsay? Here was the great man himself - designer of the 4.5 litre grand prix V12 Ferrari that finally trounced the all-conquering 1.5 litre blown type 159 Alfa Romeos in the early '50s - advocating superchargers. It had been Aurelio Lampredi's conviction that a normally aspirated engine could beat a blown one (at least under the equivalancy formula of the day) that led to a rift with his predecessor and mentor at Ferrari, the legendary Gioacchino Colombo. Who returned to the vanquished Alfa camp from whence he had come.
Now thirty years on and in the twilight of a distinquished career with Ferrari and Fiat, Lampredi sees the good old fashioned supercharger as the answer to many of our problems " Turbocharging" he is declaring with characteristic latin flamboyance, has its place. Its the right way to go for diesels, sports cars and racing. The Lancia montecarlo turbo proves the point.
But for road cars, and especially modest family saloons. I believe positive displacement superchargers can do a better, cheaper job.
It would all be a little hard to swallow, this sudden love affair with the the belt-driven compressor, this thinly veiled sideswipe at the fashionable turbo, were Lampredi not to back up his theories with a couple of demonstration cars, 131 mirafiori's fitted with Abarth's new superchargers, that rams home his message, not to say the fuel.
Under Lampredi's direction, Abarth have done all the design and development work on what Fiat emphasise is at this stage just a research programme. The roots compressor is in concept familiar enough, with two geared together cast iron lobes running in a figure of eight light alloy chamber, drawing air from one side and forcing it out through ports on the other. It is neatly interposed between block and carburettor and driven by a toothed belt from a crankshaft pulley. A special pump provides engine oil lubrication. It is the application of new technology to an age old idea that has in part rekindled Lampredi's enthusiasm for the supercharger: modern toothed belts don't fly apart like the old vee-section ones and advances in die-casting techniques, oil seals and lobe profiles have led to a cheaper, more efficient unit.
But there's more to it than that, Lampredi contends that the secret of a successful blown road car is a constant low pressure boost not the sudden relatively high pressure one of an exhaust driven turbocharger- a centrifugal compressor, of coarse the delivery of which is proportional to the square of its speed. Even when tuned to give a relatively strong blow at low and medium revs and waste through a valve the excessive pressure generated at high speeds, Lampredi contends that the turbo is an unsatisfactory and inefficient way of increasing output of a small production engine. There remains too the problem of throttle lag while the turbo is spun to its normal and phenominally high (100,000rpm or so) operating speed as well as the efficiency sapping exhaust back pressure.
There are no such drawbacks with the roots supercharger, the output of which is directly proportional to its speed, Abarth's blower is actually geared down by a 0.85 reduction ratio to turn at less than crankshaft speed (in the past its been usual to spin even a roots blower to two or three times as fast as the engine) At such modest revolutions the boost remains more or less constant, says Lampredi, at a lowly 0.40-0.45 bar, from 1500rpm to the engine's normal operating limit of around 6000rpm. So theres no sudden surge as the supercharger comes on song: its already singing modestly and progressively boosting output throughout the rev range. Running on lowered compression ratio to avoid detonation and consequent destructive thermal loads (remember the melted valves and piston crowns of those supercharged conversions of the 60's ?)
Output of the guineapig  2.0 litre engine has been lifted from 115 to 138bhp, after deducting the 5-6bhp absorbed by the compressor. Torque is up even more-to around the 155lb/ft mark if it really has increased by 25% as Lampredi claims. And it was torque rather than power he was after, for good acceleration rather than a high maximum speed is up from 112mph to 119mph.
At steady speeds, Fiat allege that this 2.0 litre is just as economical as the normally aspirated one, although pressumably the supercharged car will gobble up more fuel when it's gunned through the gears.
Comparative acceleration tests are based on timed improvements over measured distances rather than to a specific speed from rest, so a gain of 4.4 sec over 2000 metres may not mean much. Rough speedometer readings suggest that by the normal yard stick, the 0-60mph time is down from around 10.5 sec to about 9 sec, and thats quick-Saab Turbo quick. Far more significant improvements are claimed for top gear.
Lampredi relates the performance-but not the fuel consumption-of the blown 2.0 litre to that of a normally aspirated 2.7 litre. Encouraged by the 2.0 litre results, Abarth have also fitted exactly the same supercharger, this time with a 0.80 reduction gear, to a twin cam 1300. Result almost the same power and torque curves of a normal 2.0 litre but, on the bench, a significant reduction in specific fuel consumption, especially on a light throttle when there's an excess of air rammed into the combustion chambers, just as important for some markets, the emission on toxic hydrocarbons, carbon monoxide and nitrous oxides are cut to well below the legislative limit (it isn't clear whose) with out recoarse to catalytic burners.
For our test drive, Fiat had laid out one of the most torturous and imtimidating barrier-bound circuits imaginable on their huge La Mandria proving grounds which dips and meanders its way through picture book forest slopes near Turin. The blown 1300 I tried first felt more like an ordinary 1600 than a normal 2.0 litre, a point Lampredi later conceded, although it seems there is little to choose between the two through the gears. Apart from an idling chatter from the supercharger (too much clearance "we can eliminate that"). There was absolutely nothing about the response or performance of the car to indicate that it was not normally aspirated. No compressor whine, no sudden surge, not even enough poke in second to spin the wheels on the acute ascending hairpins where an unblown 2.0 litre, the yard stick car, would squeal its tyres all too easily.
It is the blown 2000 that best supports Lampredi's belief in the supercharger, if not vicious, its performance is strong throughout the range: however low the revs, flooring the throttle gives instant clean, vigourous acceleration. Pickup in fifth, normally a bit flat, is impressively lively without the gearing- 19.1mph/1000rpm- being changed. On full boost Saab's Turbo would certainly outsurge the Fiat but not before the blown 131 had lugged itself several lengths clear on shear gutsy flexibility. On the road, there would probably be little in it, although the Fiat's better low speed urge might well give it the edge on roadability.
A win for the supercharger then ? Well, it's early days yet. There's no doubt that Lampredi has put theory effectively into practice. but at what cost ? His contension that a supercharged engine could be 20percent cheaper than a comparable turbo seemed to be qualified with several 'if's and buts' , and greeted with a certain amount of scepticism. Even allowing for modern manufacturing techniques and a simple bolt-on installation, Abarth's Roots blower is a massive piece of machinary compared with the tiny turbo, weighing over 32lb. True, it does not require any exotic materials or fancy plumbing, and the belts and pulleys required to drive it can't add all that much to the cost. But 20percent cheaper ? There's also some development work needed, which Abarth readily accept, to eliminate the disquieting idle chatter, not to mention the high-speed whine like that of a blower Bentley, present on all the well-worn 2.0 litre prototypes.
Fiat will not be drawn about production plans, but it seems unlikely that they would have publicised this breakaway line of development without some tangiable end product in mind. Lampredi agrees that we're on the threshold of a revolution on ram feeding: its the simplest and cheapest way to get respectable outputs from small, clean, economical engines, but how to blow them ? is the turbo really the right answer ? By showing that there is a viable alternative with certain clearcut advantages, the Abarth team have, if nothing else, thrown the issue in to the debating chamber. What's more , they mean to persevere. Plans to run a supercharged Lancia Monte Carlo at Le Mans, alongside the much more powerful 1.4 litre turbos, had not been finalised when this was written, but the 2.0 litre blown competition engine on test at La Mandria in a 'silhouette' 131 racer, will make aformidable rally weapon. With kugelfisher fuel injection, it develops 285bhp as well as massive low-speed torque, using the same road-car blower running at 1.125 times engine speed.
Perhaps of even greater significance , though, was a smaller display supercharger-albeit still a large and hefty chunk of machinary-designed for engines of less than 1300cc. The Strada, it seems, is next in line for a blow job.


                                                     DATED:   JULY 1980


                              

Thank you David, it?s interesting reading.

I want to collect some knowledge before i start another project with an Argenta VX engine.