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fassi1
29-01-2014, 11:34 PM
Finally managed to purchase EGT kit which actually works.
Fitted in the downpipe just after rear flange. It is only for comparison petrol-lpg.
I only managed to test warm idle.
LPG lambda 1 (closed loop) - egt stable 240degC over 1 minute period
petrol lambda 1 (closed loop) - egt stable 240degC over 1 minute period

fassi1
30-01-2014, 10:17 AM
Low load 220rpm 5th gear stable throttle and speed
LPG lambda 1 (closed loop) - egt stable 440degC over 30sec period
petrol lambda 1 (closed loop) - egt stable 440degC over 30sec period

I'm very impressed with the response from the probe, it's instant almost as fast as afr gauge.

crazydriver81
30-01-2014, 11:49 AM
What gauge did you choose Chris? Brand and type please as I was looking into this too...

fassi1
30-01-2014, 11:58 AM
http://rspec.co.uk/performance-gauges/digital-dual-display-series/52mm-smoked-digital-exhaust-gas-temperature-gauge
I like the quality.

Davezj
30-01-2014, 12:56 PM
this is interesting stuff chris.

what are the temps like on WOT runs or is it difficult to read the gauge when doing this as it changes so quickly.

adaxo
30-01-2014, 01:12 PM
floor it! floor it!! FLOOR IT !!!

fassi1
30-01-2014, 01:58 PM
I didn't have time yet to test it on WOT.
Gauge is fitted temporarily just for the test purposes and it's in perfect location for keeping an eye on it.
So far haven't experienced lpg burning hotter.

Davezj
30-01-2014, 02:01 PM
this is looking very interesting.

fassi1
30-01-2014, 02:54 PM
Yes Dave it's very interesting. You can find a lot of opinions saying that lpg burns hotter
and most often it comes from those who never had any experience with it and never really tested it.
Some say it burns hotter but what do they actually mean?
5 10 50 or 100 degC hotter than petrol??? or maybe without any difference to the petrol???
Always wanted to do it.
I'll keep updating you with the results, they are gonna be true readings not made up numbers.

Davezj
30-01-2014, 03:16 PM
i am a big fan of LPG, i just never seem to be able to gather the money together and keep hold of it to get the conversion done.

adaxo
30-01-2014, 03:32 PM
Yes Dave it's very interesting. You can find a lot of opinions saying that lpg burns hotter
and most often it comes from those who never had any experience with it and never really tested it.
Some say it burns hotter but what do they actually mean?
5 10 50 or 100 degC hotter than petrol??? or maybe without any difference to the petrol???
Always wanted to do it.
I'll keep updating you with the results, they are gonna be true readings not made up numbers.

As I said to you via pm, LPG may burn slightly hotter in combustion chamber as its burn 'slower' than petrol hence flame/explosion in cylinder takes longer so maybe heating up cylinder heads a little bit more, but question is how little is little and how big (if any) temp difference is still acceptable? but I said it probably will be hard to see on probe fitted after spinning compressor as it will spread/take lots of heat away, imo. temp difference will be very (if any) small.

fassi1
30-01-2014, 04:00 PM
As I said to you via pm, LPG may burn slightly hotter in combustion chamber as its burn 'slower' than petrol hence flame/explosion in cylinder takes longer so maybe heating up cylinder heads a little bit more, but question is how little is little and how big (if any) temp difference is still acceptable? but I said it probably will be hard to see on probe fitted after spinning compressor as it will spread/take lots of heat away, imo. temp difference will be very (if any) small.
So you see Adam it's all speculation not real data.
We have to base our opinions on true data and egt is the right one.
So you suspecting that having post turbo 440deg on lpg and petrol the temperature in the combustion chamber is higher when running on lpg.
Give me the explanation for higher temp. loss on that distance for lpg?
You seriously trying to get me to get it fitted in the manifold and I will probably do it.

adaxo
30-01-2014, 04:13 PM
Hehe, no im not saying is deffo higher or lower, imo it COULD BE slight difference temp in combustion chamber not showing on your gauge, anyway so far so good temps show no difference.
Wonder if there will be difference if you deliberately set lpg to run leaner, I know its risky but most of guys running lean when they got cars converted without proper setting with afr sensor.

And yes, when you fit egt sensor where it should be and temps will not change regardless of fuel then you will shut many mounts saying it's hotter, incuding mine, forever :)

fassi1
02-02-2014, 05:43 PM
Managed to do few tests.

1.
0-110mph through the gearbox 1-5, the lowest AFR around 11.5 for both lpg and petrol
lpg - 640degC
petrol - 660degC

2.
50-110mph in 4th gear (doing 50mph in 4th foot all the way down untill 110mph)
lpg - 640degC
petrol - 640degC

3.
constant speed 80mph in 5th gear on perfectly flat motorway (mid load, closed loop for both with lambda 1)
lpg - 550degC
petrol - 550degC

adaxo
02-02-2014, 05:45 PM
What a result!!!, so you trying to say that petrol gives hotter AFRs?? nah :unbeleeva :)

fassi1
02-02-2014, 06:09 PM
I didn't say that petrol burns hotter, these are just the results I got.

Nick Mann
02-02-2014, 07:13 PM
In reality conditions become less than ideal. However, in ideal conditions, petrol flames burn at approx 2100 degrees C, propane burns at approx 2400 degrees C.

There are several instantly obvious less than ideal conditions.
LPG is not just propane, it usually has other flammable gasses in it too.
These flames are calculated at stoichiometric proportions, most heat is generated in an internal combustion engine when on WOT at which point the mixture is not in stoichiometric proportions.

Nick Mann
02-02-2014, 07:15 PM
Oh, also these flame temps are calculated at constant pressure. Obviously the pressure is changing massively in an engine.

There are probably very clever people out there that specialise in this kind of investigation and I'm not one of them!

Davezj
02-02-2014, 07:29 PM
some interesting results and probably unexpected buy most people.

fassi1
02-02-2014, 07:42 PM
Yeah there is a lot of parameters behind it. One of them is mixture temp entering the combastion chamber which can vary for petrol and lpg.
Depending on reducer's efficiency, rpm and load, lpg temp. meassured by temp. sensor fitted on vapour side can vary 70-20degC with the lowest at WOT when engine asks
for huge amounts of of it. There could be even lower lpg temps but they are not desired for 4th gen vapour injection.
Warmed up lpg expands what will definitely affect mixture's pressure and temp.
On the end of the day the parameter we should worry about is exhaust gasses temp and after all that I've seen so far there is nothing to worry about.
My thoughts.

P.S.
I'm gonna bring egt kit with me to Eurospec so interested can see it in real live.