silent running

For a number of reasons I'm toying with the idea of having my Power FC remapped for standard unleaded rather than V-Power which is what I use at present. Firstly my FMIC totally controls charge temps under any conditions. Secondly V-Power is now over a quid a litre and as petrol prices rise in general it's going to be super unleaded users who get the ****tiest end of the stick. Lastly, I am planning more driving on the continent and super unleaded varies in octane from 97 to 100 depending on country/brand - I need to be able to fill up anywhere, anytime and not worry about it.

Does anyone have experience of what kind of a performance and fuel economy variation a Power FC equipped Impreza will take when downgrading from V-Power to standard unleaded? Spec in brief is MY98/TD05-16G/440's/FMIC with K&N cone/ported up-pipe & headers/everything heat wrapped inlet and exhaust side/oil catch tank/7B plugs/Walbro pump/adjustable FPR(3.5 bar).

Cheers

scooby0809

iTrader: (11)

would be interested in the answer aswell for the same reasons!btt

silent running

Not just me then. TBH I'm not too bothered about my Scoob going slower than it does at the moment. Even at 0.8 bar which is my lowest current boost setting, it's plenty fast enough for UK roads, and if I need to put my foot down, I've every confidence that it won't overheat or do anything weird.

So I'm really wondering if lower octane fuel might actually give me worse fuel economy or using different makes of standard unleaded might do something odd to the engine. At the moment it has an uninterrupted diet of the finest road fuel money can buy, but will it still be ok if mapped for the normal stuff that I run my wife's Yaris on?

fireblade37

iTrader: (1)

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Same here, off to bobs next month for a map tweak and i was also considering swapping to a 97 ron.

Silent.. i have near enough the same spec as yourself apart from the fpr, is it worth putting one on, is there any benefit from doing so?

Cheers

silent running

Well I had the standard FPR on it when I fitted a VF35 with 440's. It was OK up to 1.4 bar and there was still a little headroom, but now I've fitted the TD05 and the bottom line is, it's a higher flowing turbo even though roughly the same size. I don't like running injector duties in the 90's so it was either swap for 550's or fit an adjustable regulator. I've got a good set of 440's in there that were tested as flowing 500cc at 3.5 bar, so I'll fit the SARD regulator later this month , then set it at 3.5 bar when it goes for the remap.

Welloilbeefhooked

iTrader: (3)

I'm looking at LPG through Tinley Tech to help fuel consumption.

Its about £900 for a kit that will run most scoobs. Can be set to switch back to petrol at a preset rpm, say 4k. Still need to find out if I can get it to boost switch which shouldnt be too difficult. I dont want LPG and boost!!

silent running

I'll be interested to see how you get on. LPG's still cheap, although of course if it ever gets popular, it'll come up to the same price as unleaded, just like diesel did.

Scott.T@PolarPerformance

I would set the Unleaded boost slightly lower i.e 1 bar instead of 1.2

You will then hit a different load scale on the map which you can adjust to be suitable for the regular unleaded.
This leaves the rows normally hit at 1.2bar and SUL untouched so you can switch in/out as petrol is changed.

silent running

So I have a 1.4 bar map on my Power FC at the moment but I'm running at 0.8 bar at present, pending a remap to suit my new TD05. So it would be possible to have the map at 1.4 bar expecting to run V-Power say for track work, and then a tamer map at 1.2 bar for normal unleaded. And never the twain shall meet...as long as I make sure I only use the 1.4 bar setting with a full tank of V-Power?

funkyspider

Wouldnt running a TD05 have a negative effect on ecconomy due to the later and more aggressive spool up than smaller turbo's. I always though turbo assisted engines tended to be pretty inefficient at lower revs if completely off boost, but at their most efficient when the turbo was providing a little assistance (obviously not when at full boost lol). I could be talking bollox however

Jolly Green Monster

iTrader: (4)

I do silly mileages in my car and run it on which ever fuel takes my fancy and tweak accordingly.. if you want to run anything over 1.2bar then you end up removing a reasonable chunk of timing for 95ron and the power reduction is very noticable, on my car anyway.. around 1.2bar it notices less so but probably 10~20bhp..
The play off between boost and timing is too heavy on the timing side.

I have been for a number of years running 1~1.2bar on 95ron and more boost than that on super unleaded, altering the 1~1.2bar part of the map to take the 95ron fuel.

Fuel economy is actually slightly better on super when trying to save fuel and drive sensibly. .

This is on a PowerFc.. If had it mapped in with two boost two fuels on an ecu that altered the timing itself like original ecu with ecutek or similar it would need resetting between to reset the advance multiplier..

Simon

dan83590

You could well be right. If you do some reseach the turbo was acutualy designed to save fuel. Power was a by-product. Sensible driving WILL help Economy. More boost = more fuel dependent on the map.. Anyone?

silent running

So I could keep the full strength map at 1.2 bar and above and have the timing pulled at 0.8-1.0 bar for economy mode, then simply set boost as necessary.

Jolly Green Monster

iTrader: (4)

Yes.. however.. you need the car to be running on 95ron to map it for the 95ron part of the map.. then another mapping session on the 99ron to do the higher boost.. or some guess work / checking needs to be carried out.

Simon

silent running

Spot on Simon, many thanks!

scooby0809

iTrader: (11)

thanks chaps! more food for thought!

silent running

Quick update. Just as a little experiment I ran my tank of V-Power halfway down then filled it up with 30 litres of standard Shell unleaded - a not insignificant saving of £2 on half a tank. People say 'what's £2', but I used to say what's a fiver when I used to smoke. It all adds up.

Anyway, on this half V-Power/half standard brew I've had not a sniff of knock at all, under my normal driving conditions and hot weather. I'll run this lot down and then fill up with a full tank of 95 octane and see what happens then.

Bear in mind this is at my minimum 0.8 bar setting that I am currently using everyday. Max boost is 1.4 on V-Power.

Jolly Green Monster

iTrader: (4)

Firstly do you know the powerfc detects knock? ie. you have seen a higher knock recorded when the car has detted before?

what type of driving have you done to ensure it is not detting?

You will need to do a couple of tanks to get pure 95

silent running

Yes it definitely does detect it when it happens. I've done normal cruising, stop-start traffic driving, hard runs through the gears so far. Still need to do a fast motorway cruise in 5th.

Welloilbeefhooked

iTrader: (3)

Simon, and others of course,

When you say map the 95ron part, do you mean just the on boost rows or do you mean everything from there back down to row 1 on the Apexi?

Just considering a 95ron @ 1bar /98ron @1.4 bar map.

Wayne.