Hi Olaf
Thank you for trawling thru the books - great work, and I am sure appreciated by many.
Richard
Thank you for trawling thru the books - great work, and I am sure appreciated by many.
Richard
Hello Borzacchini Jr,Nice work Olaf, and having your signature almost a guarantee of serous analyses and well done job. Small objections based on my memories and not book confrontations as I discus sometimes the topics on this forum with my “same age fuel tank” friends, (we were all GTA drivers once with different stories and luck, some without history and some EU champs, but forever in love in AR) and general impression is that this forum is high level board with “prime” articles. I simply don’t want to be a judge in topics where some of you are much better informed than me or my friends, but sometimes I (we) notice the facts different from my (our) records. So, take my objections as simply desire to improve this important and beautiful work that has contributed to the general story and memory of Alfa Romeo. As I understand that you can translate Italian, I am sending you a small portion of Domenico Chirico’s (chief engineer in AR in Massacesi era) text about “all Giulia’s heads” as you didn’t mention 3V variant ( it was tested in Autodelta in 1968, and tried in more than one engine), and that is my first objection. The other curious fact is statement that 1300 engine ”testa stretta” was proved in its 16V form in 1966. In my opinion, that data is a little bit too early, though “testa stretta” was experimented even on Giulietta engines (in 1959) and was not new as idea. But let us remember. In 1968, 16V engines were excluded by FIA regulation from Gr.5 and remained as a source for F2 only. Chiti has tried for GTA, a Heron flat head where chamber was incorporated in piston head, but that experiment was abandoned soon because of thermal troubles and enormous bore. In that situation first experiments with 45° degree head were tried to improve GTA’s competitivity, and after surprisingly good results that solution was transferred to 1750 GT Am block in 1970 and GTAJ 1300 block in 1971 changing only chambers form. From these facts supported also by Tabucchi, results that 1966 is too early, and first “testa stretta” was proved on GTA 1600 in “4 Ore del Jolly Club” in Monza, 24.03.1968. (I have to say that I never got the possibility to consult “Alleggerita” book , though I know very well that this is capital source in AR history). In that year (1968), according to Tabucchi, also nautical engines were developed (probably 16 V engines “banned” from Gr.5 too)Twin spark and single spark were tested whenever possible and only the limits of space avoid general use of TS on each model. Beside Autodelta and Angelini, also Conrero, Monzeglio and Balduzzi have contribuited to the development of original Busso’s concept of twin cam Giulia 105. Engine project to its perfect form. (Conrero and Angelini produced almost all engine parts on their own designs, and could be considerate as engine producers in every sense).
Here is Chirico's text:
“Uno studio Autodelta qualche anno prima aveva confrontato diverse teste del 2.0: quella di serie a 2 valvole e 1 candela, la testa stretta GT-Am a 2 valvole e 2 candele, una testa stretta a 4 valvole e 1 candela centrale:
Sopra 5000 giri la migliore era la testa stretta a 4 valvole ma sotto 5000 giri la migliore era la testa stretta GT-Am. Si decise quindi di approfondire il comportamento stradale di un motore a testa stretta, studiandone i transitori di accelerazione dai regimi bassi e medi. Ciò fu fatto assemblando un motore con una testa stretta costruita anni prima e giacente nei magazzini del reparto sperimentale: si riscontrò un'elevata p.m.e. e prestazioni nettamente migliori del motore "normale". Si progettarono quindi tre nuove teste strette: 2 valvole 2 candele, 3 valvole 2 candele, 4 valvole 1 candela (per un'altra candela non c'era posto se non modificando profondamente il disegno). Dopo le prime sperimentazioni fu abbandonata la testa a 4 valvole, perché quella a 2 e quella a 3 valvole avevano comunque prestazioni migliori dei motori della concorrenza ai bassi e medi regimi e quasi equivalenti agli alti. L'urgenza della delibera non consentì di completare le prove di affidabilità sulla testa a 3 valvole (si temevano deformazioni termiche dovute alla dissimetria del layout) e quindi si optò per il 2 valvole. La situazione aziendale non consentiva però gli investimenti necessari all'acquisizione di nuovi macchinari e perciò si decise di mantenere tutto quanto già esisteva nel bialbero sotto alla testa (basamento, albero a gomiti ecc.) e far realizzare le nuove teste (fusioni e lavorazioni meccaniche) all'esterno.”
Hello Sid,Hello Olaf,
Is there any information about the sovralimentato engines with the hydraulic superchargers? And which cars they went into?
Sid
To slow the piston speed the stroke was shortened to 67,5 mm, and bore majored to 86 mm. The same values on the later 1300 GTAJ engine and identical crankshaft, were the certain sign that 1300 engine was already in preparation in that times.
Hello Borzacchini, Alleggerita and members,Hi Alleggerita,
The same statements I have already heard from equally serious sources as you are. Also, your explanation about dubious benefits of shortened stroke in this charged version is logic to me. And to finish, if you have measured the bore, the doubts are cancelled. (I have never seen SA engine except on photos, and sincerely for me it was a mere experiment in GTA story). Remain the mystery why all the books repeat the same wrong data (probably they all have started from the first, erroneous source), and the fact is that I have also only repeated what I have found in Tabucchi’s book. Thanks for clearing.
I thought they were 1300 engine not 1600?The short-stroke GTA-SA engine is a myth perpetrated by Fusi and other Alfa history books. I was alerted to this by the late Angelo Chiapperini who told me that the bore and stroke measurements of the SA engine were identical to the standard GTA 1600. He had several SA engines in his shop at the time and I measured the bore on the one that was opened up at the time with a vernier caliper.
This makes sense engineeringwise in that a supercharged engine delivers torque low down and would not much benefit from lower piston speeds - unlike a short stroke 4-valve 1600.
Moreover, the monobloc engines always had some headgasket sealing issues which would have been worsened in a supercharged application - 1750GTam motors in historic racing continue to have them to this day, maybe more so because of the age of the material.
So, GTA-SA engines were 78mm bore with 82mm stroke.
One was out in a GTA in Australia and raced ...Olaf,
I asked earlier about the tipo 33 v8 being put into the gta for testing but nobody replied. Since you seem to have all the relevant records of the period do you know more about these cars since they were tested by Autodelta as i do not have any photos either of them?
It was a Tasman 33 motor, and was put into a GTAm - Vibn Sharp is 90% of the way through the restoration of that one back to a GTAm.One was out in a GTA in Australia and raced ...
Pete