The V8 Owners Forum -

Just having a thought... I'm thinking of fitting a closed loop lambda system to my induction LPG rangie to improve economy... Is there any reason why I couldn't drill holes into the exhaust and weld a nut in place to screw the sensor into??? I'm undecided on this... I keep thinking yes/no/yes/no... Help me please!!!!

you can buy bungs to do exactly what you want so yes is not a problem

I thought I'd seen something like that... Thanks Marki.

Does anyone know if I could get away with 1 sensor at/after the y piece or would I need 2 due to the distance from the manifold? I think 1 at the y should be ok.

1 sensor should be fine, as both banks should be producing similar readings. I'll post a pic of a set of RV8 headers with sensor boss tonight.

Do you have a link to the system you are looking at fitting?

If the sensors are un heated, the further they are away from the ports the longer it will take them to warm up and start producing readings. I can't remember the nut I used but I just put one on each down pipe about 300mm away from the ports, but one sensor is beginning to die now so i'm just down to one now. That's on LPG, i'm wondering if the upper head lubricant had anything to do with it.

On my original LPG Lambda set up I fitted a boss (18mm) at the mating point of the V pipe, you must however use a heated lambda sensor in this location, unheated won't work as it is too far down the line, been there and done it .

I have just fitted a full double S stainless exhaust and manifolds and had to fit the LR spec heated Lambdas (12mm)

If you are stuck for a Lambda sensor my old one is available as I will never use it now. It was new when fitted and has only covered @20k miles

Innovate sell 12-channel lambda gear because they say :-

For example, an engine that shows 13.1 AFR at the collector might have cylinders anywhere from 11.1 to 15.1. A rich cylinder (11.5 AFR) is wasting fuel, losing horsepower, and fouling plugs, while a lean cylinder (15.5 AFR) is loosing horsepower, detonating, and dangerously close to damaging valve, pistons, and cylinders. In this example, after balancing the cylinders, the engine gained more torque, more efficiency, and will almost certainly last longer, and all the while the average stays at 13.1 AFR.

Makes you wonder whether even with one or two lambda sensors that you're getting the whole story?

Cheers,

Ian

Very few V8 fuel systems are capable of changing the mixture between individual cylinders so I don't really see the point of that. I don't even know if you can even change between cylinders using sequential injection so the only way I know for sure is if your using down drafts like IDF or whatever.

I suppose if you've got eight throttle bodies and eight lambda sensors and an ECU that can cope with the fuelling then you should get a 13.1 AFR for each cylinder.

Gotta be worth some extra BHP and MPG but loadsa dosh methinks!

Cheers,

Ian

Really interesting change of direction and thought... Although a bit irrelevant to me as it's only for the LPG and that is induction!!

Richard, just looking around and chewing the fat, but saw this on fleabay.
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... &rd=1&rd=1

Royston, sounds interesting... I may be interested... PM me with a price! Also, where did you get the boss from please if you can remember? Did you find it made a difference to the LPG running?

Thanks for the help guys!!

Hi LazyDocker.

The lads are right about the heated sensor issue - been a while since I even thought about the unheated ones! I've got heated ones in the downpipe after my left manifold on my Range Rover, and in the collector of my other car (a long way from the cyls). Both work fine.



This leads to what kind of sensor to get? A basic 3 or 4 wire sensor is cheapest and easiest, but not as useful for tuning. As posted above, there are controllers available from many manufacturers that can handle "wide band" sensors. These will give an accurate reading over a wide range of Air-Fuel ratios... which is useful if you want to tune for 13.5:1 instead of 14.7:1 (nb, these are petrol ratios, but you'll really be working with lambda values, say 0.95 or 1.0 when using LPG) That all said, a basic heated 3 or 4 wire sensor with that controller would be good to start with.

Cheers,
Rich

katanaman wrote:Very few V8 fuel systems are capable of changing the mixture between individual cylinders so I don't really see the point of that. I don't even know if you can even change between cylinders using sequential injection so the only way I know for sure is if your using down drafts like IDF or whatever.

There a few out there can do sequential per-cylinder fuel and ignition trim, but yeah, you'll be chasing 1% power increases at that point... unless something is very wrong. More useful as a warning than a performance gain, IMHO.

BTW, some folks (aircraft in particular) even run per-cylinder EGT and CHT as well!

I've had another thought on this idea...

Will running on petrol cause any problems with the sensor? It wont be connected to the ecu so thus wont be controlling the petrol so therefore it will be 'overfuelling' for the sensor.
Will this cause any major problems?

Also, can anyone tell me if this makes a noticable difference to the performance/economy on LPG compared to a basic setup please?

Running on unleaded petrol will be fine.