Lambda on LCB with remote

[Charlynsane]

Hello Guys

Iit's time to tune my rallye engine,

I planned to install a PLX device AFR gauge



Where is the best place to weld the lambda boss? on the LCB Y? does someone has any pic?

Thank you

Charles

[InnoCooperExport]

I think Timmy201 on here fitted an AFR gauge on his car, maybe you can find it in his build thread on Our Cars & Projects.

Without the hindrance of experience the Y-piece seems like a sensible place to me as well, but I will gladly defer to anyone who has fitted one before.

[timmy201]

The user manual for the gauge normally tells you the recommended position. You need it to be sampling all cylinders, so it needs to be in the Y piece or further down stream.

I use mine only during tuning, and you can get a clamp that goes up the end of the exhaust tip

I have some photos here
http://mk1-forum.net/viewtopic.php?f=6&t=9224&start=210

[Charlynsane]

Hello Timmy

Do you have any pic of the lambda fitted ?

I assume you weld an adaptor on the LCB Y ?

Thank you Charles

[timmy201]

I use the tailpipe adapter, it works really well for testing - just not at idle. This is the same way 99% of dyno/rolling roads work too.

[CALIMKIIIS]

I installed an AEM air/fuel gauge in my mini van. Since I don't weld I used the stainless clamp AEM supplies as an alternative. Since the 1310 S motor is extensively modified, the unit is most helpful in dialing in the carbs and adjusting timing. Initially I found that the BF needles in the 1 1/2 SU'S were slightly lean and got better results after switching to BG's. With a new digital timing light I also found the existing timing was a bit too advanced as well. Subsequently I installed a CSI distributor from Swiftune and fiddling with fuel and timing was better able to interpret the results obtained by using the A/F gauge. More experimentation will be needed to achieve an optimum tune as I'm still learning this newer technology and how to apply it properly..The car is a remote shift S tranny and has been converted to L/H drive.
The gauge and be switched to Lambda, O2 and other versions of measurement that I barely understand and can be combined with various mapping software and crank triggers, etc. beyond my caring for now.
Pictures-

P1012971.JPG

P1012970.JPG

P1012968.JPG

dash mount, cable floor exit, sending unit clamp on exhaust, dash mounted gauge:

P4271819.JPG

[mk1]

They usually recommend that the lambda sensor is mounted at least 24" from the head outlet. Any closer & you can cook the sensor. I have lambda bosses on all my cars & usually mount the boss under the floor about 6" behind where the lcb would connect to the exhaust. I only use them for tuning though & remove the sensor plugging up the hole with a suitable plug when done.

While sticking the sensor up the tail pipe is certainly an option, it is worth bearing in mind that is there is even the smallest leak in any of the exhaust joins the Lambda sensor will read weak / lean.

Having this facility makes setting up carbs a 5 minute job. Ask AndyB

This is the one I use nowadays, I started off with a home made jobby though.

https://www.amazon.co.uk/Innovate-Motor ... 9752&psc=1

These are an absolutely invaluable tool!

[CALIMKIIIS]

I agree with how useful they can be for various aspects of tuning. I reckon the permanent installation can be more useful with the ability to monitor things on the road under various conditions. I would think it even more so for racing/rallying situations as well. It seems I've located the sensor in a similar position as you recommended, as when choosing a spot, there remains few alternative locations revealed whilst under the car with a remote shift. I'm still not up to speed as to the optimum A/F ratio for a road car as not everyone seems to agree. Seemingly something between 13/1 to 15/1 works well for maximum power. From my last attempt it's running 13ish but more time should help things develop. Whilst driving, it's interesting to watch the numbers rapidly change from idle to full throttle, I would think ideally that some consistency between the two extremes would be the goal. The other tuning issue on this particular car is getting the timing right as it's an original Cooper S motor with no timing marks on the front pulley/damper, well 1 for TDC but also no tab on the timing cover as with A+ engines. Even with the digital timing light where you can dial in the desired advance, on this car the only way is to use the marks on the flywheel as reference through the small hole in the flywheel housing. Of course this means you need three hands, one for the timing light, one for the small mirror over the housing aperture and another for the throttle control. One solution might be to buy an aftermarket damper with etched timing marks and fashion a pointer from a coat hanger or welding rod. Even then, difficult for seeing things through a non removable van grille, then there's choosing the best advance curve available with the CSI distributor as part of what will be an ongoing project..

[murty]

You also have to consider that on a siamese port cylinder head, the outer cylinders (1 & 4) run leaner compared to the inner cylinders (2 & 3).
So when the O2 sensor is measuring the average of all 4 cylinders, you have to run it a little richer compared to a conventional engine in order to not run the outer cylinders too lean. A conventional petrol engine would typically run a ratio of 14.7:1 at light throttle, and maximum power around 12.5:1 to 13:1. So a siamese port head would tune these numbers to be a little richer.

[CALIMKIIIS]

Interesting observation, I wasn't aware that that the design of the 5 port head made differences between the flow to outer and inner cylinders. Inlet manifold design can influence the bias between cylinders in some cases to a greater degree such as those designed for DCOE Weber carbs as the carb throat centerlines are farther apart than those on the head inlet ports. In David Vizard's book for example, it's shown that most all Weber manifolds tend to favor the outer cylinders. This is why racers went to creating split Weber manifolds so each barrel had a straight shot from carb to inlet port. Good to know that I may not be far off with the current A/F ratio around 13/1 for the time being, thanks! A recent addendum to my last post about ignition timing. As mentioned the problem with setting timing at the flywheel, not a problem when finding settings at idle, for stock engines that is. Making things more complicated is with highly tuned engines with anything from 'fast road', rally or race camshafts. With stock cams the idle is set at around 900 RPM or so. More radical cam profiles require a faster idle, fast enough that even at 1200 RPM idle, the distributor has advanced a bit past what would be an idle advance setting, therefore negating what would be a baseline beginning point to set timing, hence the problem, in my case running a Swiftune SW 10 cam. It's my understanding from much research that flat tappet cams don't 'like' low idle speeds as it can lead to premature cam wear. Yeah a lumpy cam equipped car may sound cool at low RPM idle but total engine rebuilds due to cam failure, not cool!

[timmy201]

I added a timing mark to the front pulley so that I could easily check the timing without having to go through the flywheel housing (especially as I have a heater right in the way)

A dialback timing light makes it easy to check the timing advance over the whole RPM window, not just at idle. All you need is the one TDC mark, and the dialback feature in the light means you can work out the advance.

[mk1]

I usually aim for between 9.5 & 1 lambda as opposed to a specific AFR.

I have never been interested in fitting one permanently, on some of my cars the gauge would look out of place & on my competition car I am FAR to busy to check what the AFR is during an event

Having one of these gauges IS NOT an alternative to either many hours of fine tuning or a good Dyno session! Either way after these you should have a decent fuel / air mixture across the range & an AFR meter can be easily used to make sure things don't wander too far off.

[murty]

The main reason for the difference in AFR between inner cylinders versus outer cylinders is the firing order of 1-3-4-2 (or re-ordered 2-1-3-4). Since the siamese ports are shared for cylinders 1 & 2, and for cylinders 3 & 4, the inner cylinders suck first, followed by the outer cylinders. Depending on camshaft selection, there is quite a bit of overlap between 1 & 2 (or 3 & 4) and there is port robbing between the two cylinders.

A good way to measure the difference is to put two bungs just before the final Y collector, making sure to place them far enough away from the exhaust ports as mentioned by Mark previously. That way you get to see the inner cylinders from the center branch, and the outer cylinders from the Y branch.

The only way around this is to use a 7-port or 8-port cylinder head, or wait for the Specialist Components direct injection 5-port head to come to fruition.

[cheesebadger]

For anyone interested, I found this a decent explanation of the port/charge robbing issue...
https://www.starchak.ca/efi/siamese.htm
Enjoy!

[murty]

Yes, that link is a great explanation of the problem.

[CALIMKIIIS]

Thanks to everyone for the education! In response to timmy201's post, since using the single mark on the flywheel (no brake servo in the way thankfully) and with using my newer timing light where I can set a desired advance,(not familiar with the term 'dial back') but perhaps the same type of unit I have, in any case, my damper has a single TDC mark, it seems I could make a pointer attached to a timing cover bolt and do the same as with using the flywheel mark, needing only 2 hands! Responding to mk1, I was thinking it would be useful during track testing sessions, of course, as one needs to be more mindful of RPM's, competitors and the like during a race, methinks. Yes I considered how such a gauge would look out of place on the dash of a vintage mini, not exactly 'period correct'. The alternative is the temporary one or going back to tuning by ear. Having one a show car means one might lose points at the next concour 'd elegance, can't have that! Few if any dyno shops around here, even then, if one were to pull up in a mini, most wouldn't even know what it is, much less anything about tuning one. Responding to murty and cheesebadger's posts, thank you for the explanation, I didn't consider the firing order as a factor but did consider the effect of the centre shared exhaust port and exhaust reversion pulses with high overlap cams might come into play. I do remember the Rimflow valve's anti-reversions design and that of one exhaust manifold maker that included a step near the port to partially remedy that issue but don't know if that situation would impact the more obvious firing order effect on the intake tract. I have 2 Gunson Colortune spark plug devices and have tested the differences between inner and outer and side by side cylinders at the same time but never noticed any differences, for what that's worth. Yes I have long considered going to a 7 port head with twin 40mm DCOEs. The original cast iron Danish one that later became the Mini Sport version seemed promising but for unknown reasons went out of production. Others produced aluminium versions but for some folks they were deemed problematic. Then there's the KAD and Specialised Components ones, lovely but beyond expensive for me. The Westlake design 8 port as from Mini Spares with 4 Amal carbs or 2 Webers would be an amazing set up on looks alone and importantly to me, period correct too. I'd love to send my motor over to Bill Richards for a full 8 port conversion but no room in the budget for that either, right now...

[timmy201]

I think the most important thing about the AFR/Lambda gauge is the initial setup and fine tuning. Nothing should change with the tune once it’s set up. Of course with any carburettor you have a compromise in tuning, and can’t get every part of the fuel use 100% correct

I get a bit paranoid if I leave the gauge in, and look at it too much while I’m driving. Perhaps if you had a turbo/supercharged car it might be worth keeping one all the time, but not for my basic road engine

[murty]

The shared exhaust port does not contribute to the problem since cylinders 2 & 3 are shared, and their firing order is 360 degrees apart.
It's mainly the shared intake ports that cause the issue since their firing order is only 180 degrees apart.

[CALIMKIIIS]

This discussion about the vagaries of the 5 port head jogged some memories about the subject, forcing me to go to my extensive mini library and open a book! Recalling now, I used to know all this stuff, just forgot about it over time. The intricacies involved were not lost on David Vizard many years ago which led to the development of the Scatter Pattern Cam! Not wanting to further derail this thread started by Charlyinsane, I hope he finds success in his endeavour to apply modern technology to an engine that when designed, the calculations thereof were likely made on a slide rule, not a computer. Hopefully he will report back about the experience and subsequent findings...

[Charlynsane]

Here we go guys!

The car will be ready for serious tuning