43 replies to this topic

[Clip]

Thank you again everyone. I expected some response, but this has been incredible. Fascinating to read Issigonis’ comments. Such a shame that the British motor industry that was so innovative in so many areas and then somehow lost its way in the later years of the 20th century with quality and reliability issues. This even leaked into the Australian market with Leyland P76s leaving the factory minus rear shock absorbers! Even forgetting the mini, other marques like Triumph that produced that amazing 2000 sedan and Rover with its equally innovative P6  back in the early 60s, and even the humble landcrab, were truely unique vehicles that still deserve some love, and fortunately do still get some. 

[Mini Manannán]

What was the difference between those early Datsun 1200s and the A-series?  I'd always thought that initially they were the same engines?

[Spider]

This even leaked into the Australian market with Leyland P76s leaving the factory minus rear shock absorbers!

 

Part of the 'quality' issues in the early P76's was that the CAB was never laid out to run a big car like the P76 through it. At many work stations, they could open the doors far enough for access to the inside to get at 'stuff'. When production finally commenced, it was already running late (by about a year) which didn't help matters either. Very sad actually, as fundamentally, they were a very good car. As time went on, they did get a lot better.
 

[Ethel]

What was the difference between those early Datsun 1200s and the A-series?  I'd always thought that initially they were the same engines?

 

 

I think it was actually the B Series they licensed. It made  very similar Nissan H & J  Series, 5 porters. 

 

The Nissan A is much less similar 5 bearing crank, 7-8 ports. Biggest difference is the cam swapped sides so the pushrods only have the sparkplugs to avoid.

[Shooter63]

I'm going to stick up for the old runty pig iron 5 porter here, it was a decent performer from the 50s to the 70s and beyond really, if you look a the torque figures it produced it was very much on par with anything else about at the time, in bog standard form it had anywhere between 51LBFT and 62LBFT per litre which for a production engine is pretty spot on, with a mild bit of tuning it was possible to add substantially to that figure. When you look at race engine outputs people have extracted close to 80LBFT per litre which is non too shabby. Even if you slap on a 7/8 port head the torque figure doesn't improve that much. The much maligned 5 port set up isn't as bad as people make out. I am in the middle of a 16v conversion at the moment but have stopped simply because I can't get the torque figures to better a decently put together 5 porter, I know why 16v engines don't produce the torque and I know how to cure the problem but the cost jeez. If you have a couple of hours spare have a google about and note down the torque outputs of engines right up to the 90s you might just be a little bit surprised how well the old A series compares.

Shooter

[IronmanG]

I'm going to stick up for the old runty pig iron 5 porter here, it was a decent performer from the 50s to the 70s and beyond really, if you look a the torque figures it produced it was very much on par with anything else about at the time, in bog standard form it had anywhere between 51LBFT and 62LBFT per litre which for a production engine is pretty spot on, with a mild bit of tuning it was possible to add substantially to that figure. When you look at race engine outputs people have extracted close to 80LBFT per litre which is non too shabby. Even if you slap on a 7/8 port head the torque figure doesn't improve that much. The much maligned 5 port set up isn't as bad as people make out. I am in the middle of a 16v conversion at the moment but have stopped simply because I can't get the torque figures to better a decently put together 5 porter, I know why 16v engines don't produce the torque and I know how to cure the problem but the cost jeez. If you have a couple of hours spare have a google about and note down the torque outputs of engines right up to the 90s you might just be a little bit surprised how well the old A series compares.

Shooter

Yep totally agree. My 7 port has less torque than a 5 port all other things being equal

[imack]

I was under the impression that 8 ports were supposed to produce better torque than the 5 port.

[IronmanG]

I was under the impression that 8 ports were supposed to produce better torque than the 5 port.

I think the 8 ports are ok as the ports are small. The 7 ports are to big so air speed is too slow so its not until 5000rpm that the torque is level with a 5 port.
Pound for pound the 5 port has more torque until the higher rev range

[Ethel]

We can forget the criteria changes with time, not just the technology.

 

A Model T or original Austin 7 does look antiquated in our eyes, but not many more modern cars, including Minis, would be as useable on the narrow, unmetalled horse tracks of their era, or the quality of fuel.

[Spider]

7, 8 porters and adding more valves lets them rev higher and that's where they can produce higher HP outputs, not from making more torque, but by spinning faster.

 

I've said it before and I'll add it here again. Bill Applby and his crew, who did much of the design work on this engine really knew their stuff. It was certainly an 'apex' design at the time and that it was in fact so good it was able to remain in production up to 2000. I've done some detailed reverse engineering on some aspects of these engines and they never fail to impress.

 

Here's some light reading from the man himself;-

 

 

 

 

 

 

 

 

 

 

 

[Shooter63]

7, 8 porters and adding more valves lets them rev higher and that's where they can produce higher HP outputs, not from making more torque, but by spinning faster.

I've said it before and I'll add it here again. Bill Applby and his crew, who did much of the design work on this engine really knew their stuff. It was certainly an 'apex' design at the time and that it was in fact so good it was able to remain in production up to 2000. I've done some detailed reverse engineering on some aspects of these engines and they never fail to impress.

Here's some light reading from the man himself;-

 

 

Fantastic piece of info there Spider, where the hell do you keep finding this stuff, if BMC had upped the B.E.M.P they would have had an engine far ahead of the opposition, but I suppose when they were testing pump fuel wasn't much better than cold tea with a ground up sparkler in it.

Shooter

[KTS]

interesting points on the positioning of the oil pump ports, and that the crank damper was first fitted to prevent the timing gear breaking up rather than stop the crank breaking

[Shooter63]

I was under the impression that 8 ports were supposed to produce better torque than the 5 port.

I think the 8 ports are ok as the ports are small. The 7 ports are to big so air speed is too slow so its not until 5000rpm that the torque is level with a 5 port.
Pound for pound the 5 port has more torque until the higher rev range

I think its such a shame about the current 7 port head as the idea is an excellent way round producing great power, I believe the heads are cast in the USA by a company called Pierce? why the company that flogs them over here doesn't ask for the ports to be cast smaller seems a bit wierd, with the right size ports you would think a +10FTLB per litre would be on the cards. An enterprising type of guy could take a bare casting to the Chinese tell the to copy it but with port revisions, then harden it properly and be on a right winner, especially if you got a common plenum designed and cast up at the same time, as this would bring the supercharged crowd into play as well.

Shooter

[Spider]

Some of the after-market heads are only semi-finished, the idea being the end user can grind them to where and what they want. I can't recall off hand who's heads are offered this way, but last time I looked (a while back !), there was a few offerings of this type.

[IronmanG]

Some of the after-market heads are only semi-finished, the idea being the end user can grind them to where and what they want. I can't recall off hand who's heads are offered this way, but last time I looked (a while back !), there was a few offerings of this type.

A guy in Holland does them with bike carbs.
SC s way around the issue of port size is stick a 286 or 296 cam in it and rely on injection to get through the worst of it. Then when it starts coming on song at 3500 it hits hard and revs long.
Even if you ran a 256 there would be absolutely no torque below 3k ish which is where the port speed finally gets fast enough to start making it work properly.
I'm actually looking at either adding a turbo with low boost to just up it a bit, or go 1430. But that seems a bit extreme

Edited by IronmanG, 08 July 2023 - 01:06 PM.