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Jets and turbo props take the cabin pressure off the turbine engine. Turbocharged piston engines take it off the turbo, I think. So not sure.
Andrew
 

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The unique GTASA timing cover mounts the hydraulic pressure pump which in turn drive the blower units. The oil pressure and return lines are the hose plumbing visible around the outside.
 

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All I can say is "Why?" ... were they trying to cheat around a non supercharger rule?

Otherwise just chuck a belt driven roots supercharger on the side. Job done and all the weight down low ... This appears to be another example of Alfa Romeo deliberately finding the most overly complex solution to a simple problem, lol
Pete
This too contributes a little to the "charm" of everything that was invented according to criteria that at the time might have seemed solutions that, perhaps, could have had developments in competitions or at industrial production level. Although they actually had a nice fantasy ...:)
 
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Question on the turbines. Did Alfa make them from scratch or were they repurposed from some existing use?
Andrew
Here is the GTA SA story:
Alfa Romeo GTA SA
The rarest and least known of all the GTAs was the SA (supercharged) version, presented at the third competition car show in Turin in March 1967 and then re-presented at the Geneva Motor Show that year. The acronym SA was an acronym for Sovra Alimentata, and indicated the presence of the two centrifugal coaxial compressors fixed to the sides of the carburetor group, which fed the two double-body Weber 45 DCOEs, typical of the GTA, by means of a watertight collection box. The car was designed for group 5, which in the permissive interpretation of the FIA rules, left the possibility of massive processing on the production models. This concept, exploited at the time by the English and German tuners, which often changed the lazy family sedans into real racing cars for the tracks, prompted Alfa Romeo to join the GTA (already crowned queen of the European Tourist Challenge Championship), its sister push with forced feeding. The engines with the compressor were already in the DNA of the Casa del Portello, and the memory of Alfetta 158 and 159 indicated the choice of the turbocharged engine to increase power as a natural solution. The paternity of the project at the Experience Center was of the engineer Gianpaolo Garcea, and the lack of enthusiasm with which Carlo Chiti accepted the idea is known, but as a good commander on the battlefield, he set to work to translate it into a useful weapon. In truth, the project was obsolete right from the start, and the idea of dramatically increasing the power of the small aggregate and putting it in a position to compete with Ford or Porsche "monsters" was destined to be short-lived from the start. However, GTA SA passed like a meteor, leaving a long trail of unanswered questions, mysteries, and uncertain data, which are still the object of curiosity for historians and simple enthusiasts. Very little is known about GTA SA, starting from the number of assembled units, the geometry and origin of the engine, its stay on the tracks and its fate after retiring from competitions. The SA represents perhaps the rarest and most mysterious object in the entire history of the Giulia 105 racing cars. Already during the winter of 1966, the "strange" GTA was noticed on the Balocco track, where Dorino Zeccoli was trying to extract the secrets of its wild nature and decipher the oddities of character, which only years later he would describe as "a tragedy, the car on which a driver of today would certainly not have set foot”. Told by Zeccoli, the driver who more than any other knew the secrets of the Alfa Romeo cars, this judgment takes on even greater weight. According to Zeccoli, the GTA SA was an unpredictable car, difficult to drive, delicate and fragile, but also full of charm, and in some situations, it became the winning opponent. GTA SA hid its secrets well and from the outside nothing, not even the initials, betrayed the difference from the other GTAs. Only the well-trained eye could notice the rear wheel studs placed to accommodate the larger Dunlop 65SC-5.50 M. racing tires. Looking for the differences, one could have noticed only a pressure gauge on the dashboard and until the opening of the engine compartment, the appearance of the SA remained unchanged compared to the other racing GTAs. Instead, once the bonnet was raised, the differences jumped out. The already restricted space of the engine compartment of the GTA was drastically reduced with the "additions" to the carburetor side containing complex structure of the compressors and the watertight box that fed the engine of the GTA SA. As already mentioned, the place of the air box of the air intake of the racing GTA was replaced by the watertight box, with at the ends two turbines of FIAT aeronautical origin (cabin blowers) of small diameter (7 cm). Schematically, the operation of the supercharging system followed a simple logic. A piston pump, located on the suction side of the engine, driven by a chain from the engine, sent oil at high pressure (80 kg / cm2) into two coaxial turbines with two centrifugal compressors that rotated at a maximum speed of 95,000 revolutions per minute. The compressors sucked in the air from the outside and sent it compressed into the fuel supply box of the carburetors, forming the mixture that, through the inlet ducts and the intake valves, reached the cylinders, and this air-petrol mixture was not only " aspirated "by the pistons but also compressed by the compressors. This resulted in a significant improvement in volumetric efficiency. With a high number of revolutions, the turbines created a pressure of 0.6-0.7 bar, which pushed the mixture into the mouths of the usual Weber 45 DCOE 14, which in turn put it compressed at 16.8 bar into the combustion chambers, generating a power of 220-240 hp. This tremendous engine thrust in theory had to be available immediately and in a linear way, since the feeding pump was connected directly to the crankshaft to avoid the classic "gap" of the turbines. The jump in power, however, occurred only (and often unpredictably) from around 3000RPM up to 7500 RPM. To remedy the immediate problems, such as the very high temperature of the oil that moved the pump and the danger of detonations, caused by the small inevitable leaks, an additional radiator was installed to cool the oil, with the appropriate creation of a system of water injection in the ducts to the combustion chambers, to avoid possible fires during operation. Nonetheless, the SA proved to be unreliable and prone to catch fire easily. The other flaw was its behavior, which Zeccoli described as "unpredictable power surge, which came suddenly and without warning, making the SA difficult to steer when cornering or in maneuvering situations". Up to 3000 rpm the engine was suffering and below the performance of “normal” GTA, but when switched to supercharging, it proved to be a beast of enormous power, capable of downgrading concurrency cars. At the time, in the absence of the "wastegate" valve, the compressors were difficult to manage, and the SA, otherwise identical to its GTA sister but with a good 70 HP less, was unable to exploit the braking power of the engine, and in any case showed poor stability in sudden braking. What was certainly not lacking, beyond 3000 rpm, was the enormous torque, which pushed the 780 kg of the SA with incredible ease in every gear ratio at lightning-fast accelerations. Another innovative element that appeared on the GTA SA was the transistor ignition, the true progenitor of future systems, which since 1968 replaced the classic Marelli S119 distributor. But the real Achilles' heel remained the easy overheating in conditions of medium and low speeds. Excessive heat dissipated better at higher speeds, aided by a good cooling system, but in circuits at low speeds and not very high rpm, engine overheating was the order of the day. Another problem consisted in the frightening consumption of petrol, which reached 32 liters per 100 kilometers in running regime, and penalized the SA in long races, forcing it to stop frequently for refueling. The torque that the SA developed sometimes caused easy rear slippage even in longer gears, and the more frequent use of the brakes in endurance races (given the poor performance of the engine braking effect), exposed the entire braking system to fading. But the real mystery in which the history of the Giulia GTA SA remains shrouded begins with its technical content, never completely revealed (or the data have been lost), so much so that over time two schools of thought have developed, which see the SA with different eyes. The majority of Italian authors, describing the engine of the SA, cite the bore and stroke values as 86x67.5 mm, consonant with the search for a super square engine, which perfectly corresponded to the research of a brilliant engineer such as Chiti was undoubtedly. Given the period of development of the SA engine which coincides with the absence of the 1300 engine, with which the SA would theoretically share the stroke of the piston, the crankshaft, the bearings, the connecting rods, and other mechanical components, some seek in the experimental engine developed for the F2 (86x68.5 mm), the base from which all the specific mechanical components have been transplanted. The cylinder head could only be the classic "double ignition", slightly adapted to the purpose; otherwise, the bulk of the changes concerned the base, where the oil pump that powered the compressors was housed. The shortened stroke and the larger bore were the logical way to reduce the speed of the stressed piston, and many are inclined to believe that this was the solution adopted, given that even the specialized magazines of the time highlighted this innovative technical side. But given that the compression ratio was significantly lowered (8.5: 1) and that it was not possible to adopt the classic pistons of the GTA, this opens the bore chapter, which really contains several unknowns. On an engine destined to run continuously even for the entire time of long race events, thinning the shell of the barrels to a thickness much lower than usual, with subsequent weakening of the housing of the same (significantly enlarged holes) meant exposing the base (the whole thruster) to a critical weakening, absolutely not able to perform the task of duration under a regime of high stress. Since they all agree that in the case of the GTA SA engines, only the separate barrels were always used, and that the single barrel (perhaps more robust and rigid) only appeared on the GT Am, the presence of detailed descriptions and many Precise data cited for an unlikely solution certainly remains a mystery. Perhaps, we must take into consideration the presence of two different variants of the same engine, already at the time. In favor of this thesis, the different origin (Portello and Settimo Milanese, with respective markings) of the various surviving engines can also be found. However, it seems that all the engines recently examined (and here we are at the second school of thought) are based on the classic geometry of the GTA, i.e. 78x82 mm, and this data speaks in favor of those who have long argued that the engine block was the traditional 10532.01.010.99 processed for GTA. Given the presence of the same values on the classic racing GTA, it is to be assumed that particular pistons were adopted, considering the lowering of the compression, which only approached the declared 10.5: 1 with the boost factor. In this case, things were simpler, and the use of the 10532.01.053.99 cylinder head, the sodium-cooled valves, and the rest of the GTA kit was logical and easy. The mystery of the number of engines assembled, however, has never been solved. No one can say with absolute certainty how many engines and how many cars have been assembled in the SA version. Opinions are fairly in agreement on the hypothesis that no more than twelve engines were produced for competitive use, while for the number of cars the estimate does not exceed ten GTAs in SA setup. Data that can be found regarding certain chassis numbers list the following cars, present in races between 1967 and 1970: AR 613015, AR 613016, AR 613056, AR 613069, AR 613470, AR 613929, AR 613919. Later 1969, almost all the GTA SAs were converted to the classic aspirated 1600 or 1300 version, with atmospheric pressure carburetors and the last certain appearance of a GTA SA dates back to March 8, 1970, when the GTA SA (AR 613069) driven by Christine Beckers finished second overall in the uphill race in Condroz. Shortly thereafter it was converted to an experimental version with the 1300 engine, but this changes little. GTA SA was already in the legend ...
 

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In regard to the bore/stroke dimensions of the GTASA, most likely was the traditional 78x82. Even the picture in Fusi's book of what is presumably an official factory photo, shows the distance above the water pump to the head as that of the normal dimension, as Alleggerita pointed out in a previous post. The larger mono-bore/shorter stroke version has no height distance in this area and is easily identified from the front.
 

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Discussion Starter · #108 ·
Question on the turbines. Did Alfa make them from scratch or were they repurposed from some existing use?
Andrew
Hi Andrew,

The turbines, attached to the airbox, were an adaptation from the aircraft industry application.
I'll check what I can find about them, concerning purchase and adaptation.

Ciao, Olaf
 

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Such a shame that this was not done properly. We could have ended up with a production supercharged 105 series road car :eek: ... but it needed a roots type supercharger. These engines with their power loosing piston tops almost need supercharging to fix that design flaw.

There should have been a special racing class for our conceptually 1930's designed engines, i.e. 1600cc Alfa Nord engine + supercharger = 1600cc normally asperated Ford, etc. engine :D

Love my Alfas but heck Ford and Cosworth produced some absolutely amazing and beautifully powerful engines
Pete
 

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In regard to the bore/stroke dimensions of the GTASA, most likely was the traditional 78x82. Even the picture in Fusi's book of what is presumably an official factory photo, shows the distance above the water pump to the head as that of the normal dimension, as Alleggerita pointed out in a previous post. The larger mono-bore/shorter stroke version has no height distance in this area and is easily identified from the front.
The only existing data on the bore and stroke of the SA engine were measured in Loris Paone's Turbo Motor workshop in Cesano Maderno, on three "surviving" engines, and correspond to the known values of the atmospheric aspirated GTAs, that is, 78x82 mm. However, to declare ignorant Fusi, Tabucchi and the others that in period indicated 86x67.5 mm as a value, is ridiculous. It was certainly not the people who did not know the subject. It should be noted that the measurement is only performed on three of the approximately 12 motors prepared for racing. For the other engines (majority) data do not exist. However, it is known that there have been constant changes on the SA (switching on the transistors for example) and also from the photos of the period it is visible that the engine was different from car to car (just note different oil pans). Everything could be changed because the engines were partly produced in Settimo and processed on site. The data discrepancy remains one of GTA SA's unsolved mysteries.
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To my knowledge the turbines were sourced quasi in-house from Alfa Romeo Avio (Aeronautical division).
This is what Teodoro Zeccoli told to Maurizio Tabucchi during interview in June 1991:
“…Questo gruppo occupava il posto della presa d’aria dinamica della GTA da corsa e il cassoncino era a chiusura stagna. Alle estremità erano montate due turbine di piccolo diametro già esistenti come regolatori di pressione delle cabine negli aerei militari. Erano prodotte dalla FIAT e sul motore della SA erano mosse dall’olio in pressione, alimentato dalla pompa situata a lato aspirazione, e collegata tramite la catena all’albero motore. Erano il cuore del sistema di alimentazione forzata…”
Translation:
"... This group took the place of the dynamic air intake of the racing GTA and the box was watertight. At the ends were mounted two small diameter turbines that already existed as cabin pressure regulators in military aircrafts. They were produced by FIAT and on the SA engine they were moved by pressurized oil, fed by the pump located on the suction side, and connected via the chain to the crankshaft. They were the heart of the forced feeding system ... "
And to precise, turbine in question came from FIAT G91Y military jet.

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Let's face it, they built 12 one off engines. It is possible they tried 12 variations before righting canning the, interesting to us now, waste of time.

It is the V16 BRM of saloon car racing. Both projects failed because the wrong supercharger was selected.

Pete
 

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My assertion that 78 x 82 was the most likely dimensions used dose not exclude the possibility that the short stroke version may have also been tried. All I am concluding is that so far, in all published pictures of GTASA engines, the block height corresponds to the normal dimension, not the short stroke version. I would think that they would have at least tested the short stroke version, but so far have never seen a photo an actual engine of this version.
 

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Discussion Starter · #115 · (Edited)
Let's face it, they built 12 one off engines. It is possible they tried 12 variations before righting canning the, interesting to us now, waste of time.

It is the V16 BRM of saloon car racing. Both projects failed because the wrong supercharger was selected.

Pete
The GTA-SA had some issues. I name a few that I know of.
Its fuel consumption was such that fuelstops would be more frequent in longer races, compared to other cars.
Degradation of the tires was higher. Smoking up the (rear) tires was easy as Rob Slotemaker shows in a test at Zandvoort with a GTA-SA. There is a film of the trainingday of the SRT team with their Hillman (?) showing Slotemaker doing some laps around the track in his typical style.
The GTA-SA had to compete in a different class (gruppo 5) than the GTA because of the homologation / number of cars built.

I suspect that these issues played a role in not pursueing the development of the 1600 GTA-SA and go for the smaller capacity GTA 1300 Junior and the larger capacity 1750 GTAm. I would categorize the 1900 GTA as a step in that direction.
Please feel free to add and correct!

Ciao, Olaf
 

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Discussion Starter · #116 ·
My assertion that 78 x 82 was the most likely dimensions used dose not exclude the possibility that the short stroke version may have also been tried. All I am concluding is that so far, in all published pictures of GTASA engines, the block height corresponds to the normal dimension, not the short stroke version. I would think that they would have at least tested the short stroke version, but so far have never seen a photo an actual engine of this version.
I would agree with the observations Vince made.
I'll check if I can find a reference to a short stroke GTA-SA in the list of experimental Autodelta engines that was published in "Alleggerita".

Ciao, Olaf
 

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I would agree with the observations Vince made.
I'll check if I can find a reference to a short stroke GTA.....

Ciao, Olaf
Olaf, certainly in Fusi's book the dimension listed for the GTASA is 86 x 67.5. However, on the accompanying page showing a picture of the engine it displays the normal block height, not the 67.5mm height. So there is still some discrepancy between figures and photos.
Below shows a picture of the stepped heights of the A/Delta monosleeves according to stroke used:
from rear tallest GTAm 84.5 x 88.5, center GTA1900 86 x 82, front short stroke GTA1600 86 x 67.5.
The external height of the block closely follows these steps, so it is usually possible to identify the approximate stroke
used from the outside.
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This supercharging system was developed in 1964 by the Alfa research centre, led by Filippo Surace. The intention was to increase the performance of the standard production 1600 four-cylinder engine by going back to Alfa's long tradition of supercharging, which dated back to the 1920s. Following the successful installation of some prototypes, the project was later abandoned for market reasons. It was later resumed in a higher performing version on the GTA-SA.

Initially it was designed, tested and installed in Giulia TI with two Webers by AR.

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The Giulia Sprint GTA - SA (Gran Turismo Alleggerita – Sovra Alimentata) was first introduced during the third Turin Sports Car Exhibition, in February 1967. Later it also went on show at the 37th edition of the Geneva Motor Show.

A wish to take part in Group 5 competitions in England, Belgium and France led Alfa Romeo to develop a higher performing version of the GTA at the beginning of 1967. Their chosen solution was to equip the 1600 twin shaft engine with 2 centrifugal compressors.


ENGINEERING

The starting point was the 1570 cc GTA engine. The displacement had however been obtained by reducing the stroke to 67.5 (subsequently the stroke of the GTA 1300 Junior engine). Upstream of the carburettors, an intake chamber was fitted acted on by two centrifugal compressors operated by the same number of hydraulic turbines. The oil was pressurised by an axial pump with six pump elements manufactured by Alfa Romeo, connected to the crankshaft by means of a chain. To promote cooling of the mixture in the combustion chamber and prevent knock, water was injected into the intake ducts (not a normal solution in racing). Water injection was common practice in aircraft engines during takeoff. In the Alfa engine, this took place near the compressor, because the vanes improved nebulisation.

The power achieved by the power unit was 220 HP at 7500 rpm (146 HP/litre), able to propel the car up to 240 Km/h. The car was notoriously difficult to drive, due to its abrupt and unpredictable power delivery.


CAREER

After a series of demanding trials at the Balocco and Monza tracks, it was raced within Group 5 in the 2000-2500 cc category, because its displacement of 1570 had to be multiplied by 1.4 according to the regulations as the engine was equipped with a compressor. A "new" displacement of 2198 cc was therefore achieved.

The racing career of the GTA – SA was plagued by registration problems due to its unusual mechanical configuration although the car achieved excellent racing results, beginning with an overall first position achieved by the German Dau at the Hockenheim 100 Mile race in 1968. The GTA – SA's final victory in Group 5 was an overall first place achieved by Carlier at the Masbourg Rally in Belgium on 31 May 1970.
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