Hi All
I am appealing to the forum wisdom on any info that might be out there on the impact on the torque by reducing the stroke.
Currently I am using a 67.2mms stroke crank from the 1350/1490c.f. Engine with 81.4mms pistons giving me 1399cc.
Now I have got to rebuild the engine I am investigating using something like the 87mm 16V pistons with a crank from the 1186 engine with a stroke 59mm. This will give me near as dammit 1400c with a drop in stroke of 8.2mm.
What I was wondering was has anyone built a 1600 using both techniques? What I mean is:
Option 1 - a 1700 crank with 1490 pistons
Or
option 2 - a 1490 crank with 1700 pistons
Theory says that keeping everything else the same the 1700 crank should give more torque and the 1490 crank should rev easier and produce more BHP. Can anyone confirm this and how big a difference in torque and BHP was found?
Any thoughts comments guidance much appreciated.
Rsfruitbat
1600 boxers
Re: 1600 boxers
Maybe try asking Gus at Alfatune?
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LooLooSud33Spider
- Posts: 1756
- Joined: Mon Dec 05, 2016 11:14 pm
- Location: Staffordshire
Re: 1600 boxers
Hi Ade
Tom And Bryan Shrubb will be your best bet as I know they’ve built several 1600s. I know Shrew had one aswell.
I’m actually considering a similar build myself. I’ve got a part built 1500 (bored +1 mm) and I’ve got loads of 1700 cranks so it wouldn’t be too much hassle to go that route. But I’ll be keeping it as an 8v with some Fast road cams
Lou
Tom And Bryan Shrubb will be your best bet as I know they’ve built several 1600s. I know Shrew had one aswell.
I’m actually considering a similar build myself. I’ve got a part built 1500 (bored +1 mm) and I’ve got loads of 1700 cranks so it wouldn’t be too much hassle to go that route. But I’ll be keeping it as an 8v with some Fast road cams
Lou
Alfasud Ti 1984
Alfa Spider 2.0 Ts 916
Alfa Spider 20v Turbo
Alfa Spider 2.0 Ts 916
Alfa Spider 20v Turbo
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rsfruitbat
- Posts: 774
- Joined: Tue Jan 28, 2014 7:54 am
Re: 1600 boxers
Hi all
Had a chat with Tom today.
I need to investigate a bit further before coming to any decisions.
Rsfruitbat
Had a chat with Tom today.
I need to investigate a bit further before coming to any decisions.
Rsfruitbat
Re: 1600 boxers
Hi, a practical question,
it will be easy for you or not (?) get longer conrods that can adapt to alfa 33 crankshaft?
Custom made conrods? AHM conrods? Or some from japan cars?
About travel vs bore,
I will be very interested in reading about you experimenting a super-square boxer,
this will remind me to history of Ing. Carlo Chiti in 1986-1990 working for Minardi and Subaru to design an engine with 12 "opposed cylinder" to be used in F1 ( "opposed cilinder" it is almost like a "boxer" engine but not exactly, a bit less balanced, infact I read it needed balancing countershafts resulting heavy and still not enough powerful for a winning F1 car of that period);
it was super-square configuration, 52,6 mm travel x 84mm bore, with heads with 5 valves ( 3 in + 2 out )
https://it.wikipedia.org/wiki/Subaru_1235
just, I have doubts that going very very far from a square engine, and despite the advantage of longer conrods,
engine could have an increase in total mechanical losses (thinking both about cylinder than about diameter of main bearings); any increase of RPM have a dramatic effect in mechanical losses; this will be not a problem if one is just searching for extreme power/result and not efficiency or durability, like F1 engines or motorbike engines, but using normal quality pieces, normal electronic, "normal" budget one can risk to get only the more mechanical losses and not the extremely high revving power?
Thinking on a limited budget, If I have to do a bet, I will imagine that your current configuration (already quite over-square engine) could be less difficult to pump-up than a more extreme one, but it is just a sensation, so think about what you will like to do, It will be brave and interesting if you try to realise it
About experimentation with different travel vs bore with Alfasud / Alfa 33 boxer engines,
if we consider also 8v boxers (not your situation, you want use the advantages of 16v heads )
I liked also:
>>> the history probably you already know of the Gordon Allen Alfasud in 1976 (1600cc but with 8v head), where you can read about different configurations travel vs bore he tried, this engine tuner pumped boxer engines (moderately, for street use, not to the level of a racing car) just a bit before alfa itself developed similar evolution (as it was already planned from start in the boxer project, but the tuner was able to anticipate commercial alfa plans in increasing only progressively alfasud engine power ):
https://www.motorsportmagazine.com/arch ... fasud-1600
>>> instead, talking of racing engines, I liked posts of this user (some more detailed posts about his engine are no more on-line. but below there is a link to a post there he put some infos and a couple of photos) that in the past (but I friend that contacted him says he is still actually doing similar development of alfa boxers) did a wonderfull work to improve 8v heads with brass sleves for tappets to get crazy revving and power for his race alfasud, also without the advantage of 16v heads ( 16v not only have an air section advantage, but also uses less heavy tappets and valves); he says he had to rebuild the gearbox after every single race, as from a 1600cc 8v alfa boxer he get 170-200 hp at 8500 rpm (and being able to go to 9000 rpm) with compression ratio 12,5:1 (custom pistons); he didn't need to go for a super-square configuration, he used the common over-square configuration 87mm pistons (as 1.7 boxer) and 1.5cc crankshaft;
https://www.alfabb.com/threads/alfa-sud ... pecs.6483/
>>> similar power figures (hp vs cc, with 1300, 1600 or 2000cc boxers) I have see where obtained from Autodelta in the past and also are currently obtained I have see in youtube videos from other people preparing for race Sprint or alfa 33 (not turbo);
but ok, 8v can be a different situation respect 16v, may be 16v (and a "small" 1400cc) could rev higher than this, super-square configuration will help keeping piston linear velocity within a target limit, but will not help limiting the speed for valve train and electronic, you will need quality pieces with design strong and light (and quality electronic and superior oil lubrification) that can afford 9000-9500 (?) rpm, if these rpm are eventually the ambitious target to get advantages from a super-square 16v configuration respect an over-square one, that maybe will have less demanding requirements and same power if you have to limit at a just a bit less rpm ?
It is just a doubt, I will like to read your ideas after you speak with some other people racing/tuning these engines
it will be easy for you or not (?) get longer conrods that can adapt to alfa 33 crankshaft?
Custom made conrods? AHM conrods? Or some from japan cars?
About travel vs bore,
I will be very interested in reading about you experimenting a super-square boxer,
this will remind me to history of Ing. Carlo Chiti in 1986-1990 working for Minardi and Subaru to design an engine with 12 "opposed cylinder" to be used in F1 ( "opposed cilinder" it is almost like a "boxer" engine but not exactly, a bit less balanced, infact I read it needed balancing countershafts resulting heavy and still not enough powerful for a winning F1 car of that period);
it was super-square configuration, 52,6 mm travel x 84mm bore, with heads with 5 valves ( 3 in + 2 out )
https://it.wikipedia.org/wiki/Subaru_1235
just, I have doubts that going very very far from a square engine, and despite the advantage of longer conrods,
engine could have an increase in total mechanical losses (thinking both about cylinder than about diameter of main bearings); any increase of RPM have a dramatic effect in mechanical losses; this will be not a problem if one is just searching for extreme power/result and not efficiency or durability, like F1 engines or motorbike engines, but using normal quality pieces, normal electronic, "normal" budget one can risk to get only the more mechanical losses and not the extremely high revving power?
Thinking on a limited budget, If I have to do a bet, I will imagine that your current configuration (already quite over-square engine) could be less difficult to pump-up than a more extreme one, but it is just a sensation, so think about what you will like to do, It will be brave and interesting if you try to realise it
About experimentation with different travel vs bore with Alfasud / Alfa 33 boxer engines,
if we consider also 8v boxers (not your situation, you want use the advantages of 16v heads )
I liked also:
>>> the history probably you already know of the Gordon Allen Alfasud in 1976 (1600cc but with 8v head), where you can read about different configurations travel vs bore he tried, this engine tuner pumped boxer engines (moderately, for street use, not to the level of a racing car) just a bit before alfa itself developed similar evolution (as it was already planned from start in the boxer project, but the tuner was able to anticipate commercial alfa plans in increasing only progressively alfasud engine power ):
https://www.motorsportmagazine.com/arch ... fasud-1600
>>> instead, talking of racing engines, I liked posts of this user (some more detailed posts about his engine are no more on-line. but below there is a link to a post there he put some infos and a couple of photos) that in the past (but I friend that contacted him says he is still actually doing similar development of alfa boxers) did a wonderfull work to improve 8v heads with brass sleves for tappets to get crazy revving and power for his race alfasud, also without the advantage of 16v heads ( 16v not only have an air section advantage, but also uses less heavy tappets and valves); he says he had to rebuild the gearbox after every single race, as from a 1600cc 8v alfa boxer he get 170-200 hp at 8500 rpm (and being able to go to 9000 rpm) with compression ratio 12,5:1 (custom pistons); he didn't need to go for a super-square configuration, he used the common over-square configuration 87mm pistons (as 1.7 boxer) and 1.5cc crankshaft;
https://www.alfabb.com/threads/alfa-sud ... pecs.6483/
>>> similar power figures (hp vs cc, with 1300, 1600 or 2000cc boxers) I have see where obtained from Autodelta in the past and also are currently obtained I have see in youtube videos from other people preparing for race Sprint or alfa 33 (not turbo);
but ok, 8v can be a different situation respect 16v, may be 16v (and a "small" 1400cc) could rev higher than this, super-square configuration will help keeping piston linear velocity within a target limit, but will not help limiting the speed for valve train and electronic, you will need quality pieces with design strong and light (and quality electronic and superior oil lubrification) that can afford 9000-9500 (?) rpm, if these rpm are eventually the ambitious target to get advantages from a super-square 16v configuration respect an over-square one, that maybe will have less demanding requirements and same power if you have to limit at a just a bit less rpm ?
It is just a doubt, I will like to read your ideas after you speak with some other people racing/tuning these engines
Re: 1600 boxers
I had a 1600 16V in my race car with 87 mm and 67,2 stroke. Engine runs on carbs and gave around 172 bhp.
it revs on the straight around 8500 rpm with the short gear box and reliability was quiet bad. In short: with the stock crank I was not able to keep this engine alive for more than 3 or 4 races..
But as long, it was alive, it was a lot of fun to rev it..
https://youtu.be/h1tLBza-d7I
Ali
it revs on the straight around 8500 rpm with the short gear box and reliability was quiet bad. In short: with the stock crank I was not able to keep this engine alive for more than 3 or 4 races..
But as long, it was alive, it was a lot of fun to rev it..
https://youtu.be/h1tLBza-d7I
Ali