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Re: 8 ports cylinder Head project
Posted: Thu Aug 24, 2023 5:49 pm
by BAD942B
surely there must be better cams around than one designed 50 odd years ago unless a Cosworth designed cam which will probably be as good as can be bought
Re: 8 ports cylinder Head project
Posted: Fri Aug 25, 2023 1:14 pm
by wantafaster1
BAD942B wrote: ↑Thu Aug 24, 2023 5:49 pm
surely there must be better cams around than one designed 50 odd years ago unless a Cosworth designed cam which will probably be as good as can be bought
Not really, they all have a certain time frame to operate in and all they do is keep juggling figures around within that window. It's fractions.
I know someone using BDA profiles in a BMW K series headed car for example and I'm sure kad probably do similar.
I personally have a favourite saying, they weren't stupid 50-60 years ago! Think about it, if every race camshaft that has appeared since a 649 was 2 or 3 hp better than each one before we'd be seeing astounding numbers but we don't.
On a YouTube channel I follow, the guy had an engine to do for a race car restoration, the owner was adamant he wanted it to be just like in period, no modern cam profile or other developments. On the Dyno it's 3 HP down and the guy himself says it's like the last 40 years have been a waste given the tricks and development it's taken.
Re: 8 ports cylinder Head project
Posted: Fri Aug 25, 2023 5:36 pm
by BAD942B
wantafaster1 wrote: ↑Fri Aug 25, 2023 1:14 pm
BAD942B wrote: ↑Thu Aug 24, 2023 5:49 pm
surely there must be better cams around than one designed 50 odd years ago unless a Cosworth designed cam which will probably be as good as can be bought
Not really, they all have a certain time frame to operate in and all they do is keep juggling figures around within that window. It's fractions.
I know someone using BDA profiles in a BMW K series headed car for example and I'm sure kad probably do similar.
I personally have a favourite saying, they weren't stupid 50-60 years ago! Think about it, if every race camshaft that has appeared since a 649 was 2 or 3 hp better than each one before we'd be seeing astounding numbers but we don't.
On a YouTube channel I follow, the guy had an engine to do for a race car restoration, the owner was adamant he wanted it to be just like in period, no modern cam profile or other developments. On the Dyno it's 3 HP down and the guy himself says it's like the last 40 years have been a waste given the tricks and development it's taken.
Thats why I mentioned Cosworth cams, light years ahead of the competition & some profiles are still super versatile now, I use them a lot
Re: 8 ports cylinder Head project
Posted: Sat Aug 26, 2023 9:42 am
by roger mcnab
hi
when i wasworking in sydney australia a mate was working in a small machine shop where a man used to bring a twin cam head he had cast for machining
every few weeks as money came available it was simular to a fiat 125 twin cam head when it was all finished the guy had to get cams made but the mate said they never heard any results or weather it was ever run but it was impressive to look at it had a slight hemi shape combustion chamber
interesting to know where it is
cheers roger mcnab
Re: 8 ports cylinder Head project
Posted: Mon Aug 28, 2023 10:32 pm
by BAD942B
BAD942B wrote: ↑Thu Aug 24, 2023 5:49 pm
surely there must be better cams around than one designed 50 odd years ago unless a Cosworth designed cam which will probably be as good as can be bought
the cam often used in a Cosworth MAE, an A6 in the last screenshot, with an A6+ in the 4th screenshot 'negating the need for high lift rockers' with a 649 for comparison which is what I have in my modified 1275 with 1.5 roller rockers which was like a pussycat and over 100bhp
Perhaps BMC should have used / got hold of an A6 & tried that, Duckworth was probably one of the best engineers this country ever had if not the best.
Vizard wasn't impressed with the Sprint & Super Sprint cams IIRC but I don't know the cam part numbers for comparison but think they are 595 & 598, looking at the figures they are similar to the A6
Re: 8 ports cylinder Head project
Posted: Mon Aug 28, 2023 10:56 pm
by BAD942B
wantafaster1 wrote: ↑Fri Aug 25, 2023 1:14 pm
BAD942B wrote: ↑Thu Aug 24, 2023 5:49 pm
surely there must be better cams around than one designed 50 odd years ago unless a Cosworth designed cam which will probably be as good as can be bought
Not really, they all have a certain time frame to operate in and all they do is keep juggling figures around within that window. It's fractions.
I know someone using BDA profiles in a BMW K series headed car for example and I'm sure kad probably do similar.
I personally have a favourite saying, they weren't stupid 50-60 years ago! Think about it, if every race camshaft that has appeared since a 649 was 2 or 3 hp better than each one before we'd be seeing astounding numbers but we don't.
On a YouTube channel I follow, the guy had an engine to do for a race car restoration, the owner was adamant he wanted it to be just like in period, no modern cam profile or other developments. On the Dyno it's 3 HP down and the guy himself says it's like the last 40 years have been a waste given the tricks and development it's taken.
the A6 is over 55 years old, a race BD4 from a Twink is a good rally cam when timed properly (not Cosworth timing !)
Re: 8 ports cylinder Head project
Posted: Tue Aug 29, 2023 9:07 pm
by BAD942B
Early versions of the MAE had to run around 49° ignition advance to get good HP in their oversquare cylinders as there was no squish so they (Cosworth) had to copy the BMC kidney shaped chamber in the head to add squish & achieve a better burn speed, they eventually achieved 115bhp per ltr or there abouts so that is what anyone should aim at with the down draught port on a CI 8 port head, using all the tricks developed in recent years from Touring cars, etc. Not unrealistic.
Re: 8 ports cylinder Head project
Posted: Tue Aug 29, 2023 11:56 pm
by baptiste
Interesting, more picture?
The ports are important for sure, but there are other elements such as the position of the spark plug, the shape of the chamber, work on the angle of the seats, and so on.
Re: 8 ports cylinder Head project
Posted: Wed Aug 30, 2023 8:23 am
by BAD942B
baptiste wrote: ↑Tue Aug 29, 2023 11:56 pm
Interesting, more picture?
The ports are important for sure, but there are other elements such as the position of the spark plug, the shape of the chamber, work on the angle of the seats, and so on.
the plugs on a Ford non crossflow & crossflow are opposite the inlet ports, one thing I noted on the KAD scan was the squish band near the plug might just snuff the flame out, I think its too large
Re: 8 ports cylinder Head project
Posted: Wed Aug 30, 2023 10:52 am
by MiNiKiN
BAD942B wrote: ↑Tue Aug 29, 2023 9:07 pm
Early versions of the MAE had to run around 49° ignition advance to get good HP in their oversquare cylinders as there was no squish so they (Cosworth) had to copy the BMC kidney shaped chamber in the head to add squish & achieve a better burn speed, they eventually achieved 115bhp per ltr or there abouts so that is what anyone should aim at with the down draught port on a CI 8 port head, using all the tricks developed in recent years from Touring cars, etc. Not unrealistic.
115 should be well within reach and nowadays probably even provide some "roadworthiness"
For comparison:
Mini 8-Port Weslake hllclimb engine with modern electr. fuel injection: 123 bhp / litre
1973 Ford BDH 1300 with mech. fuel injection: 146bhp / litre
Re: 8 ports cylinder Head project
Posted: Wed Aug 30, 2023 12:37 pm
by Costafortune
wantafaster1 wrote: ↑Fri Aug 25, 2023 1:14 pm
I personally have a favourite saying, they weren't stupid 50-60 years ago!
They weren't. They just didn't know as much as they do now.
In 1967 a 2 litre Triumph did about 90 bhp and 22 mpg.
In 1977 a Ford 2 litre did 100 bhp and 25 mpg.
In 2007 a 2 litre BMW four did 170 bhp and 40 mpg. That's an every day plodder, not a performance thing.
Ford BDA's are dinosaurs. The head designs etc are outdone today by a cooking Kia.
Re: 8 ports cylinder Head project
Posted: Wed Aug 30, 2023 1:09 pm
by wantafaster1
Costafortune wrote: ↑Wed Aug 30, 2023 12:37 pm
wantafaster1 wrote: ↑Fri Aug 25, 2023 1:14 pm
I personally have a favourite saying, they weren't stupid 50-60 years ago!
They weren't. They just didn't know as much as they do now.
In 1967 a 2 litre Triumph did about 90 bhp and 22 mpg.
In 1977 a Ford 2 litre did 100 bhp and 25 mpg.
In 2007 a 2 litre BMW four did 170 bhp and 40 mpg. That's an every day plodder, not a performance thing.
Ford BDA's are dinosaurs. The head designs etc are outdone today by a cooking Kia.
Well I wouldn't disagree, but I was talking about modern methods applied to classic engines.
Re: 8 ports cylinder Head project
Posted: Wed Aug 30, 2023 3:36 pm
by Exminiman
Suppose one question is how much of a contribution does engine management have to total power output - rather than just mechanical design such a chambers, ports and cams... ?
Some of the new mechanical designs will not work without EM - so is it a fair comparison ?
Re: 8 ports cylinder Head project
Posted: Wed Aug 30, 2023 5:11 pm
by Richspec
Engine management will not make any difference to total power output, you could set some webers and a dizzy to give the same bhp.
The huge difference is with full engine management you can get the power 'everywhere' as you can set the timing and fuelling to whatever the engine wants at whatever condition.
Driveability (and for some some) tuneability is where you win big.
Re: 8 ports cylinder Head project
Posted: Thu Aug 31, 2023 12:40 pm
by baptiste
I quite agree with your arguments,
However, in my opinion, comparing the maximum power of this or that design is rather complicated.
what is the rest of the engine configuration, valve size, injection system, camshaft, use, what rpm...
what were the measurement conditions, what power bench was used for what purpose?
electronic injection management gives the engine what it needs, when it needs it.
this way ,we may obtain better curves