carburettor and lpg

Larosto · Post by **Larosto** » Sat Mar 31, 2007 9:35 pm

Hi,

I want to set the mixture of my two Zenith CD 175. Does anybody know which carburettor is for which cylinder? Or are both carburettors for all cylinders together?
What compression must the engine (copression ratio 8,13:1) have? After about 500 miles since rebuilding (new pistons, rings and boring) mine has about 8,1 bar on all cylinders. Is this enough?
Has anybody expirience in running a stage one with compression ratio 8,13:1 and CD 175 carburettors on lpg? What is gasconsumption about, and is power decreasing?
Iknow, again many questions, but perhaps someone knows the answer.

regards

Horst

Dante · Post by **Dante** » Tue Apr 17, 2007 1:05 pm

Larosto wrote:Hi,

I want to set the mixture of my two Zenith CD 175. Does anybody know which carburettor is for which cylinder? Or are both carburettors for all cylinders together?
What compression must the engine (copression ratio 8,13:1) have? After about 500 miles since rebuilding (new pistons, rings and boring) mine has about 8,1 bar on all cylinders. Is this enough?
Has anybody expirience in running a stage one with compression ratio 8,13:1 and CD 175 carburettors on lpg? What is gasconsumption about, and is power decreasing?
Iknow, again many questions, but perhaps someone knows the answer.

regards

Horst

I would have thought that you are looking for 10bars.

Regards, Dante

Raggylad · Post by **Raggylad** » Tue Apr 17, 2007 9:23 pm

Hi Horst,

I have now run my very early (1983 - so engine-wise not that different from Stage 1s) 110 V8 on LPG for just over 1000 miles. MPG is down from 15-16 on petrol to 12-13 on LPG - but here in UK the cost per litre is only about half that of petrol, so I'm quite happy with that.

No noticeable loss of power, even when towing a boat. Cold starting is a no-no; 1st thing in the morning after anything other than a warm night, I need to start on petrol. If I push it in marginal conditions for cold starting , I get a lot of backfiring (if it starts at all) until the engine has warmed up.

In the conversion, I also included an Aldon electronic ignition module in the distributor and a sports coil as you need a fatter spark for LPG. The engine runs (on both fuels) much more smoothly as a result.

Richard (Glencoyne) did the job for me and - all in all - I am very pleased with it.

Nick

Basil · Post by **Basil** » Fri Apr 20, 2007 3:24 pm

Raggylad wrote:Hi Horst,

I have now run my very early (1983 - so engine-wise not that different from Stage 1s) 110 V8 on LPG for just over 1000 miles. MPG is down from 15-16 on petrol to 12-13 on LPG - but here in UK the cost per litre is only about half that of petrol, so I'm quite happy with that.

No noticeable loss of power, even when towing a boat. Cold starting is a no-no; 1st thing in the morning after anything other than a warm night, I need to start on petrol. If I push it in marginal conditions for cold starting , I get a lot of backfiring (if it starts at all) until the engine has warmed up.

In the conversion, I also included an Aldon electronic ignition module in the distributor and a sports coil as you need a fatter spark for LPG. The engine runs (on both fuels) much more smoothly as a result.

Richard (Glencoyne) did the job for me and - all in all - I am very pleased with it.

Nick

Intresting that Nick, mine alway's start's from cold infact it never had a petrol tank for two year's, but i do have to prime the system twice or it won't fire, like you I don;'t notice any difference between petrol/lpg only at the pump

cheer's Baz

stirlsilver · Post by **stirlsilver** » Fri Apr 20, 2007 3:53 pm

If you go to a 12:1 compression ratio all your starting worries will dissappear. Starts easily when cold or warm. I chopped off the carbies and put on a throttle body with a mixer ring above it. Power is pretty much on par, however i'm sus on the efficiency of the intake manifold.

Just to show how I got around the problem:

And also in regard to which carbies feed which cylinders, they cross over. Each carburettor will feed two outter cylinders on one bank and the two inner cylinders on the other bank. However they are linked together by a small hole which allows the pressures in the intake manifolds to blance to a degree.

Raggylad · Post by **Raggylad** » Fri Apr 20, 2007 10:35 pm

Baz,

Thanks. Haven't tried priming twice and will give it a go. I can usually start her down to 0 degrees C (bit colder here, Stirl, than in Oz - unless you live on the top of Mt Koziusko !), but she then overfuels, stinks of gas & backfires on the overrun until the temp gauge shows some movement.

Mind you, what passes for cold down here in Dover compared to Elgin where I grew up does not compare; pathetic how 1/2" of snow cause the southern English to grind to a halt !

Nick

stirlsilver · Post by **stirlsilver** » Sat Apr 21, 2007 2:44 pm

Ah... I had forgotten about the cold bit... hmmm...

Basil · Post by **Basil** » Sun Apr 22, 2007 3:15 pm

Raggylad wrote:Baz,

Thanks. Haven't tried priming twice and will give it a go. I can usually start her down to 0 degrees C (bit colder here, Stirl, than in Oz - unless you live on the top of Mt Koziusko !), but she then overfuels, stinks of gas & backfires on the overrun until the temp gauge shows some movement.

Mind you, what passes for cold down here in Dover compared to Elgin where I grew up does not compare; pathetic how 1/2" of snow cause the southern English to grind to a halt !

Nick

I know what you mean about the snow Nick, just imagine what would happen if it snowed for a week!!!! they would have to declare a national emergency

Baz

jonnyboy · Post by **jonnyboy** » Sun Apr 22, 2007 4:14 pm

Mind you, what passes for cold down here in Dover compared to Elgin where I grew up does not compare; pathetic how 1/2" of snow cause the southern English to grind to a halt !

I know what you mean about the snow Nick, just imagine what would happen if it snowed for a week!!!! they would have to declare a national emergency

Not all us English folks start to panic over 1/2" of snow

I used to work in Elgin every Friday night and drove up there from Perth through all sorts of weather. Oh for Drumochter pass, 18" of snow and a transit van again

Raggylad · Post by **Raggylad** » Fri Apr 27, 2007 8:06 pm

Jon,

Sorry - grossly unfair generalisation. But if you had seen some of the p******s driving in Kent in winter you would be amazed; 5 1/2 hours from Dover to Maidstone, anyone ?!

The A9 experience, now that they have modernised it, is not what it once was. More danger of the Polis catching you speeding than anything else !

Nick

Raggylad · Post by **Raggylad** » Thu May 10, 2007 7:14 pm

Have just re-done the mpg calculations on LPG over the last 1000 miles. Much better than I thought - 17.54mpg !

Should mean that I would get about 20 off petrol, but use it so little that it is hard to work out accurately.

Nick

glencoyne · Post by **glencoyne** » Sat May 12, 2007 9:31 am

Dammit Nick, how come the conversion I did for you gives 17.5 mpg, but my own 110 V8 Hicap, using an almost identical setup, only does 11? Life is so unfair sometimes

Richard

Raggylad · Post by **Raggylad** » Sat May 12, 2007 9:08 pm

Richard,

Checked & re-checked my maths (not my strong suit !) and that's what it came out at over 1044 miles of mixed bag driving. Could be because I mostly start from cold on petrol and switch to gas after about a mile. It will start on gas when cold, but runs as though (were it petrol) it was way over-choked with a stench of unburned gas from the exhaust and some backfires on the overun. Warming up on petrol, I guess, might mean that very little gas is wasted ?

I suspect, also, that replacing the radiator (original 24 year old item) which has made the whole engine run cooler has helped as well - even if I am still atoning for all the coolant that missed the bucket and covered the drive !

Then again, you did say that you didn't have the time to look after your HiCap as well as you would like ? ...

Nick

mictho · Post by **mictho** » Tue Jun 12, 2007 9:09 pm

Hi Guys, I've got a 120Ltr tank in the back on my landy and I can do about 250-270 miles on that. I mostly do motorways, at 80-85mph. Sometimes a short sprint off the speedo....

So, I can get 110lrs in to the tank, which I believe is the equivalent of 24UK gallons (1 gallon = 4.545Ltrs?).

260/24=10mpg..........

I think if some environmentalist reads this I'm gonna have an arson attack soon!!!

I am trying to sort the bastard thing out though. My disty is shot, my coil is shot, my cables are shot and my engine isn't running at the right temperature. So, once I get those bits sorted I should get better mileage.

stirlsilver · Post by **stirlsilver** » Wed Jun 13, 2007 8:57 am

I've got a 180 litre gas tank on mine and I can do 900km on that... yep, good ole 20 litres per 100km. Thankfully gas is half the price of petrol!

Stage 1 V8

carburettor and lpg

carburettor and lpg

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