Super unleaded, necessary?
Discussion
griffdude said:
It depends what fuel was in the tank when it was mapped I suppose.
I always use Shell VP/Tesco Super as that's what was in the tank when Jools mapped it.
Good point!I always use Shell VP/Tesco Super as that's what was in the tank when Jools mapped it.
Mine had super in when mapped.
If super makes no difference I could have the map tweaked to suit........
The reason for asking is that my car seems to average about 15mpg.
Now I'm not wringing my hands at the constant fill ups, (yet) but if is to no advantage, what's the point?
Not having any issues with mine on Shell 'regular'
I personally think it likes the V Power a little more, but at the time when Chilliman/dog/wizz was not producing the VP fast enough I was forced to try a tank of regular.
Still using it and so far so good.
ETA
If you are planning a track day though, then I would definitely go for the VP
I personally think it likes the V Power a little more, but at the time when Chilliman/dog/wizz was not producing the VP fast enough I was forced to try a tank of regular.
Still using it and so far so good.
ETA
If you are planning a track day though, then I would definitely go for the VP
When buying mine I was advised to put Super in every 2nd or 3rd tank full and looking at my history does't look like it's had a remap.
I don't notice any difference in performance,mpg or pops and bangs when running on Super and always think what was the point
After 23 visits to the pumps I have an average of 22 mpg on a standard 400 and drive it pretty sensibly and not often in standstill traffic.
Last weekend I drove down to London and back covering 270 miles both ways in the rain
so kept to a steady 65-75 with no hold ups and got my best average so far 27.5 using the regular unleaded. With that figure achieved I'm pretty confident that the engine and set up is all running well.
It is due a service in about 1,000 miles and will put my question to Dom if putting Super in has any benefits,because from my experience after 8 months of having this Chimaera I'm thinking what's the point.
I don't notice any difference in performance,mpg or pops and bangs when running on Super and always think what was the point
After 23 visits to the pumps I have an average of 22 mpg on a standard 400 and drive it pretty sensibly and not often in standstill traffic.
Last weekend I drove down to London and back covering 270 miles both ways in the rain
so kept to a steady 65-75 with no hold ups and got my best average so far 27.5 using the regular unleaded. With that figure achieved I'm pretty confident that the engine and set up is all running well.It is due a service in about 1,000 miles and will put my question to Dom if putting Super in has any benefits,because from my experience after 8 months of having this Chimaera I'm thinking what's the point.
Goaty Bill said:
Not having any issues with mine on Shell 'regular'
I personally think it likes the V Power a little more, but at the time when Chilliman/dog/wizz was not producing the VP fast enough I was forced to try a tank of regular.
Still using it and so far so good.
ETA
If you are planning a track day though, then I would definitely go for the VP
+1 re Super on the track. Rob told me I could run mine on cooking on the road, but to use super on the track. In fact I found it ran like a bag of mixed sized spanners on cooking, so tried some super and it sounded and pulled so much better. I try to use either V Power or Tescos 99, purely because it feels better.I personally think it likes the V Power a little more, but at the time when Chilliman/dog/wizz was not producing the VP fast enough I was forced to try a tank of regular.
Still using it and so far so good.
ETA
If you are planning a track day though, then I would definitely go for the VP
You do a reasonable amount of mileage, so long term you might benefit on the road from a well thought out "lean" map, a la Daz (and as Jools produced for him), with a rotary map switch close to hand. With such a torquey engine I would have thought you could laze along on such a map and make much better mpg? Perhaps chat to Jools? He's about 30 miles from me if you need an overnighter.
QBee said:
You do a reasonable amount of mileage, so long term you might benefit on the road from a well thought out "lean" map, a la Daz (and as Jools produced for him), with a rotary map switch close to hand. With such a torquey engine I would have thought you could laze along on such a map and make much better mpg? Perhaps chat to Jools? He's about 30 miles from me if you need an overnighter.
That is a plan and I'll take you up on the offer 
when I've arranged with Jools.BTW, mine runs perfectly on "0rdinaire" with no noticeable difference.
phazed said:
BTW, mine runs perfectly on "0rdinaire" with no noticeable difference.
I think (but someone will correct me for sure) that i remember being told that the ECU corrects for the octane rating of the fuel, which is why it will still run in all sorts of countries where the fuel isn't up to UK scratch. So the "how it runs" seems to be a car by car thing - a "suck it and swear" approach is needed. 
Daz would have heart failure!domV8 said:
I was under the impression that when the CR went up, at some threshold value you would have to run higher octane fuel to prevent knock/detonation/something - but have no idea what that threshold would be...???
Dom
That makes sense. Dom
The Honda S2000 has a CR of 11:1 and runs on super, IIRC
The Ferrari 430 has a CR of 11.3:1 and runs on super, (the Spider runs on Dom Perignon
) and the warning light apparently can come on if it's run on 95. I mention the Ferrari because the 0-60 time is about the same as our Chims.
My CR is 10:1 BTW, and seems to be fairly marginal on fuel type.
domV8 said:
I was under the impression that when the CR went up, at some threshold value you would have to run higher octane fuel to prevent knock/detonation/something - but have no idea what that threshold would be...???
Dom
True, and not true Dom
Logically, and all things being equal, it would be true; if you increased compression beyond the point that a lower octane worked, then increased octane would be needed.
There are numerous other factors that can affect this. Air fuel temperature entering the the combustion chambers, the shape of the pistons/chambers themselves, spark advance and associated advance curve of course, air/fuel ratio entering the chambers.
I am betting that some of our better PH theoreticians can come up with a handful of other factors that I have forgotten or left out.
The theoretical threshold would be more determined by the combustion chamber and piston top design.
For example, it was quite possible to run Big Block Chevys and Chrysler Hemis on 12:1 and even 13:1 compression ratios on fairly 'ordinary' petrol.
I doubt many people would try building a road going RV8 to those levels.
I took mine to Jools with high Octane ,he asked me if I use standard petrol , the answer was yes so he backed off the timing to suit .
I do have a lean map but I only see late 14`s so he has not gone mad for safety reasons . It could be leaned off more , I don`t think you would notice much difference in fuel economy .
The best thing about the three position switch is the "pops and bangs" it makes me chuckle
I`m not sure if it`s necessary to take the advance to the absolute max .
If you lean off areas on the ve map you will notice a power loss and drivability . The dot on the VE map has to travel through the same window in different gears and speeds so you can`t have your cake and eat it .
I wonder if modern cars have multiple ve maps to get over this .
I do have a lean map but I only see late 14`s so he has not gone mad for safety reasons . It could be leaned off more , I don`t think you would notice much difference in fuel economy .
The best thing about the three position switch is the "pops and bangs" it makes me chuckle
I`m not sure if it`s necessary to take the advance to the absolute max .
If you lean off areas on the ve map you will notice a power loss and drivability . The dot on the VE map has to travel through the same window in different gears and speeds so you can`t have your cake and eat it .
I wonder if modern cars have multiple ve maps to get over this .
Edited by SILICONEKID346HP on Friday 7th March 14:30
SILICONEKID346HP said:
I took mine to Jools with high Octane ,he asked me if I use standard petrol , the answer was yes so he backed off the timing to suit .
I do have a lean map but I only see late 14`s so he has not gone mad for safety reasons .
The best thing about the three position switch is the "pops and bangs" it makes me chuckle
Are your three maps all exclusively open loop or is there an element of closed loop in any of it?I do have a lean map but I only see late 14`s so he has not gone mad for safety reasons .
The best thing about the three position switch is the "pops and bangs" it makes me chuckle
QBee said:
domV8 said:
I was under the impression that when the CR went up, at some threshold value you would have to run higher octane fuel to prevent knock/detonation/something - but have no idea what that threshold would be...???
Dom
That makes sense. Dom
The Honda S2000 has a CR of 11:1 and runs on super, IIRC
The Ferrari 430 has a CR of 11.3:1 and runs on super, (the Spider runs on Dom Perignon
) and the warning light apparently can come on if it's run on 95. I mention the Ferrari because the 0-60 time is about the same as our Chims.
My CR is 10:1 BTW, and seems to be fairly marginal on fuel type.
I'm a knob with more money than sense so mostly use v-power - pretty sure it makes no difference.
ChimpOnGas said:
Are your three maps all exclusively open loop or is there an element of closed loop in any of it?
They all trim after fuel enrichment (engine temp) and a load more parameters .Two maps are full power so the same except the fuel over run tweaked for "pops and bangs" the lean one has been changed on very low throttle openings but can be tweaked a little more .
The ECU is self learning so it`s adjusting all the time from lambda feedback . It works very different to the megasquirt .
Once the cars as covered some miles I will be taking it to Jools so he can change the percentage of learning and permanently burn it .(Giving the lambda less control)
Jools can explain how it works ,its all a bit confusing.
When on the ECO map I can feel slight power loss ,obviously for micro seconds the dot is running through the lean area .
The car can happily travel at 25mph in fifth with no shunting ,snatching what so ever ,I`m not saying I need to do it but it just shows you how well its mapped .
What I do like about it is the lambda feedback from the Tech edge matches exactly to his far more expensive calibrated lambda on his rolling road ,this is telling me there are no voltage offsets and the techedge J21 is working has it should ,the problem with the Megasquirt was massive differences in the lambda reading which probably down to wiring issues .
Edited by SILICONEKID346HP on Friday 7th March 14:44
Edited by SILICONEKID346HP on Friday 7th March 14:47
Edited by SILICONEKID346HP on Friday 7th March 14:53
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