Why the 1800 was a sweeter motor than the 2000

[carlo rossi]

Technically there are some very mathematical reasons why the 1750 always was said to be the sweeter more revy engine over the 2000 with 10hp more power
and after alot of research and direct application im happy to tell you my findings ( not saying its perfect but i will say it works)
fell free to switch topics if you dont like maths
the 1750 was the stroked version of the 1600 which went to a 88,5mm stroke ( quite long) and 80mm bore ( very undersquare) and without going to the detail of max piston speed
let it be said not ideal that is why the real monster nord engines have 1600 base motors cranks shorter stoke mono block cylinders of 86mm bores

the 1750 motor had carburettors borrowed of the sporty 1600 upjetted and up choked to 32mm from 30mm for the 1750 and some italian boffin decided to throw them onto the 2ltr with same jets and chokes as the 1750! the hot 1600 gta as also the 1300gta had 45 mm webers ?? so whats a 2000 doing with 40mm choked for a midly grumpy 1600? Thats right the 2000 carbys are slighty larger than a 1300 junior gtv PRIMARILY THE ISSUE.
the 2000 has a 4mm larger bore (84mm) and 4m larger inlet valve being 44mm over the 40mm 1750 yet had the same carburation
So first you have to jet the carburettors for a 2000 motor which means minimum 34mm chokes and jets to suit. idealy for road use the the choke should be 75-80% of the inlet valve diamete
also due to pollution problems they also reduced the cam from 10.1mm lift to 9.6mm for the 2000
you can see the picture here
again back to the books  the ideal street camshaft lift should be between 25% and 27% of the inlet valve diameter
the 1750 has a 40mm x 0,25 you get 10mm the euro 1800 cam lift is 10.1mm  ( 10.6mm goes very well)
the 2000 has 44mm valve x 0,25= 11mm lift
which is the cam lift (10.9) autodelta used for the production stock racing cars group1
and @27% thats 11.9mm ( funny thats the group2 camlift)

SO in essence to get a 2000 to have the same characteristics as a 1750
change the carb chokes to 34mm adjust jets
change the camshafts to 11 mm lift
and you have a beautiful 2000 motor not racy or lumpy just very sweet power they say should be 122hp at rear wheels 105 series @5800 to 6000rpm
and 110hp at rear for a transaxle or 160hp flywheel
up from 122hp flywheel yep 30% better
you have start playing the compression game to get another 5-7 hp going from 9:1 to 9.7:1 ratio

[bonno]

Hi Carlo
Good info on engine design and associated performance characteristics, let alone the additional performance gains for port and polished head, extractors and air intake enhancements.

[Paul Newby]

While I don't necessarily disagree with your findings, I think there are a few more details at play here.

Are we just talking about Alfetta 1.8 and 2.0 engines here? If we put camshafts to one side (more later) the major differences are bore size, inlet valve size and compression ratio, which you didn't discuss. The 1.8 had 9.5:1 compression whereas the 2000 had lower 9.0:1 compression, which would have to make a difference.

The 105 2000 engine and early Alfetta 1800 "S" engine had the famed 10548 high lift camshaft for 131hp and 122hp (DIN) respectively.

The later Alfetta 1.8 "X" engine was detuned with 10520 camshafts and 118hp (DIN) and the Alfetta 2.0 with the same camshaft had 120hp (DIN). I believe the 10548 camshaft was reintroduced with the "Nuovo" Alfetta range for 130hp (DIN). Of course the ADR27A emissions regulations from 1976 onwards) affected the response of these Nord engines and probably reduced the horsepower marginally too compared to European spec.

Having owned an early Alfetta 1.8 and a 105 2000 GTV, I agree that the 1.8 spins quicker (up to 7000rpm) and is sweeter. The 2000 105 engine has better mid-range torque but there isn't much point revving it past the 5700rpm redline.

[carlo rossi]

agree completely Paul I was only trying calculate how do you get a 2000
to feel the same as the 1974 1800
and I have to say the maths works 'and when you look at the difference 'its not hard to see why
so it will go from 120hp to 160 hp from standard if you car has the 105320 cams
or 130 to 160hp  if it started with the 10548 cam quite a difference
but the real difference is the free reving that the 1750(1800) had
the compression well for 5hp its alot of work but if you shave it I think not sure on this 0.9mm it takes it too 9.7
no need to change pistons
ps most heads have had a slight shave in the last 30 -40 years so they all should be 9.4 plus
but without touching the head
it is simple  happy and is quite easy to do
cams 2hrs
jets 30mins

this a head shave calculator i found
works for 2ltr not sure of the others I believe they are low compression US cars

http://www.alfabb.com/bb/forums/attachments/engine-repair-diagnostics-rebuilding/194155d1290796855-shave-my-head-head-milling-calculator-rev1.xls