PHEV-ICE starting unexpectedly

[Hayzee]

Current cost delta between E5 and E10 appears to be around 4.5% so I can't see there being any current financial advantage in using E5 if the MPG loss with E10 is only 1.5%

[nlee]

1 hour ago, philip42h said:

Sorry Nigel - I need to challenge your nerdy calc. My understanding is that bioethanol has around 30% less energy than pure (100%) unleaded - so 70% of the energy.

Reworking your sum, E5 gives 98.5% of the energy of pure unleaded and E10 97.0% so a 1.5% reduction.

My source is: https://afdc.energy.gov/fuels/ethanol_fuel_basics.html

Do you have a better one? 😉

Apologies Philip, you are of course correct. I did the calc from memory and it is 33% less not 33% of the total. Bioethanol (E100) is 1.5 GGE (Gasoline Gallon Equivalent). In other words you would need 1.5x more volume units of ethanol for the same energy output of pure gasoline.

So to revise my earlier calculation E5 = 98.3% and E10 = 96.6%. So E10 is 98.3% of the efficiency of E5 or 1.7% less. Which makes 45 mpg on E5 equivalent to 44.2 mpg on E10. Still all just theory anyhow.

[philip42h]

41 minutes ago, Hayzee said:

Current cost delta between E5 and E10 appears to be around 4.5% so I can't see there being any current financial advantage in using E5 if the MPG loss with E10 is only 1.5%

There is absolutely no benefit in using E5 in terms running costs. My car is designed to run on E10 and so E10 it will get. The components used to build the engine are chosen to withstand both ethanol and petrol so there is no risk there, and the hygroscopicity phobia is just that - E10 fuel doesn't draw moisture out of the air. Fuel will go stale if left in the tank indefinitely but that is equally true of both E5 and E10.

2 hours ago, Nick72 said:

Will my car go faster with E5?

Well, yes! If you go a buy super unleaded E5 you'll get premium fuel with "all the additives" and a least 97 RON (99 RON at Tesco) so the management system will be able to rev your engine higher and extract every 'ounce' of the extra 1% - 2% energy in E5 fuel. That might well push our top speed from 112 mph to maybe 115 ... 🙂

[Cyker]

Ehh that's only true if the engine can take advantage of the higher octane level, which is rare for a normal car. If it's a high-compression petrol or turbo-charged car, then high octane fuel will often have a noticeable benefit, but otherwise it's just wasting money.

The TNGA hybrids and dynamic force engines are all designed to run on E10 so, at least in my experience, they don't seem to be affected at all.

Older engines that were designed to run on E5 or E0 will likely run a bit weird as they weren't designed to run on E10, even tho' they can.

 

TBH E10 should be mostly safe as long as it's cycled through regularly - Most modern fuel tanks are sealed which will greatly limits the water absorption (Also a good reason to fill the tank and not half-fill it!).

Where it's left to sit is where problems arise (Good example - My neighbour was telling me his lawnmower is wrecked because it's been sitting in the shed over winter full of E10 and apparently the carb's been badly corroded...)

[Nick72]

5 hours ago, philip42h said:

There is absolutely no benefit in using E5 in terms running costs. My car is designed to run on E10 and so E10 it will get. The components used to build the engine are chosen to withstand both ethanol and petrol so there is no risk there, and the hygroscopicity phobia is just that - E10 fuel doesn't draw moisture out of the air. Fuel will go stale if left in the tank indefinitely but that is equally true of both E5 and E10.

Well, yes! If you go a buy super unleaded E5 you'll get premium fuel with "all the additives" and a least 97 RON (99 RON at Tesco) so the management system will be able to rev your engine higher and extract every 'ounce' of the extra 1% - 2% energy in E5 fuel. That might well push our top speed from 112 mph to maybe 115 ... 🙂

Sold

[ernieb]

For those of us who have a PHEV and do not regularly use the ICE moving to E5 makes sense and that has been my motivation for paying the extra as the fuel is just sitting in the tank.  As I've indicated before I do regularly exercise the ICE to move the fuel and circulate the oil but for me the car is a keeper so I need to do the best I can to maximise it's life.

[Nick72]

4 hours ago, ernieb said:

For those of us who have a PHEV and do not regularly use the ICE moving to E5 makes sense and that has been my motivation for paying the extra as the fuel is just sitting in the tank.  As I've indicated before I do regularly exercise the ICE to move the fuel and circulate the oil but for me the car is a keeper so I need to do the best I can to maximise it's life.

Good point Ernie. May switch to E5. Hardly use the ICE. Only on the odd long distance business trip.

[Lawnmowerman]

I work 3 days per week where I cover about 60 miles so the ICE is used then. On a 4th day per week I will visit my daughter's - again about 60 miles so the ICE is used again.

About once a month I fill my tank (about 7 gallons or so). I don't think the fuel is in there long enough to create an issue (or justify E5) - and I am very sensitive about the fuel I use. I want this to be a keeper too (this is the 4th vehicle I have said this about 🤣).