SunnySideUp

I'm still trying my best to work out what the downside is of re-mapping for, say, 400 BHP?

It is claimed that the mpg on a motorway cruise will be much better than the standard map .... so, that's not a downside.

mpg drops drastically when all 400 horses are called upon .... that's obvious, and the owner accepts that cost ... so, that's not a downside either.

Something stops Subaru from mapping differently - what is it? It's not cost - a map costs the same as the next map ..... the 1's and 0's are just mixed up differently!

So, I ask myself .... what is the downside that Subaru chooses not to accept?

Jolly Green Monster

iTrader: (4)

tollerances on piston to block bore, piston ring bedding in - way the engine was run in, tollerances on fuel pump, tollerances on maf sensor, on injectors, on fuel pressure reg, on exhaust construction, different fuel to the original map they did etc etc everything has a tollerance which is a few items are on the extreme but still within the tollerances Subaru have decided are fine then the fuelling in the map will not be correct.. the ecu will be working to correct the fuelling.. using two lambda sensors to check the fuelling.. which oh have tollerances on..

Simon

SunnySideUp

This fuel pump tolerance ... what would that be?

If it is rated at 140lph ... are you saying it may actually be 135lph? If so, I accept that.

But Subaru know that 135lph is enough for the standard car at WOT ... we know most of the fuel is returned to the tank anyway ... so, how would a re-map help in this instance of tolerance deviation?

Jolly Green Monster

iTrader: (4)

politically correct to do an affordable 400bhp car?

emissions.. standard cats aren't that wonderful.. sportscat better, sound emissions too.. all the kind of things that the average owner isn't bothered about but subaru have all the red tape to get the cars through.

they don't do a custom map though.. to map and check every car would cost too much for them hence they just do a generic one and never check each car to see what AFR it is running and that it is not detting.

Simon

Jolly Green Monster

iTrader: (4)

yes everything will be manufactured and so many units checked for tollerance to the given spec (unless made in China lol) and they will have a % tollerance.

The relationship of flow and pressure is more complicated than it returns to tank..
easy example.. cruising in 5th and go WOT.. the boost goes from -0.2bar to +1bar therefore the fuel pressure which is static (not vaccum or boost) 3bar has to go from 2.8bar to 4bar in the time it takes the turbo to spool.. it is easy to see that a fuel pump with tollerance at the better extreme 145lph and one at 135lph (just using your example figures) will react faster and return the fuel pressure required quicker.

Simon

SunnySideUp

I'm very sure they would LOVE to do a 400 BHP, 40 mpg car!! Even if it drops to 10 mpg at WOT!

You say, "and never check each car to see what AFR it is running and that it is not detting" ..... that's very worrying - as what has been claimed in the previous pages is that the Subaru map is 'over-safe' .... you are saying that, in reality, it is actually un-safe!!

SunnySideUp

But the Fuel Regulator (sometimes called a pressure regulator) smooths out any variation in the fuel pump flow.

So no re-map can adjust for a tolerance on the fuel pump.

dynamix

iTrader: (3)

Tolerances and laws of average again.... sometimes all the tolerances conspire together against the owner - add that to a knock sensor that doesn't quite read as much knock as the average knock reads before acting upon it and you have a dead engine.

I think we have gone over the unsafe thing though. There are numerous examples that Paul posted earlier of ROM revisions that Subaru made to their code and the hatchback ROM is a very fresh example of it.

SunnySideUp

A car like that, thankfully, would be extremely rare .... every component at the worst possible tolerance value

Yes, it could happen, but I guess it would be 1 in a million - literally. And Subaru would pick that up under warranty quite quickly.

Jolly Green Monster

iTrader: (4)

40mpg is an unrealistic goal.

they do not check each individual car.. they hope their map covers all .. hence by setting the map up custom to that car all the tollerances and usually by this time modifications get taken into account you get more mpg and more power and torque.

Simon

dynamix

iTrader: (3)

Indeed.

A custom remap on that very same car - even if no extra power was sought would set it within that zero correction zone and would render it a safe (yet perky) performer.

Jolly Green Monster

iTrader: (4)

they would replace the engine several times under warrentee... lol

ignoring the extreme.. the slightly out tollerances on a few items would be caught by the subaru catch all overly safe map as it is very rich even on part throttle small amount of boost.. hence a custom map for that car would see better mpg and power and actually safer as it is possible to adjust the ecu to make the safety features it has on the ecu even safer.

Simon

SunnySideUp

As an aside, but on the same subject, I understand that Re-Maps have to be declared to your Insurance Company.

Of course, this would result in higher premiums and fewer companies offering cover. If not declared it would invalidate your cover. Could be bad news if you write off your car only for an investigation to discover that it had been re-mapped?

IainMilford

iTrader: (15)

just like any other mod, my insurance has come down again this year despite adding more mods, and is now half of what it was when I first had the car with 80 less bhp

MaDaSS

SSU - like most of us on here. All mods are declared. There is no way i would not declare owt. Can't afford not to. I might need it one day. Although I hope not

Cannon Fodder

iTrader: (100)

Isn't it funny how SSU changes the subject slightly when he cannot prove his arugment, after all that would be embarassing to admit that he was wrong wouldn't it?

If you insure with a specialist broker such as Keith Michaels (who I am with) then Gary Moulson will search out the best policy for you and your car, I would imagine that SSU insures his with SAGA.

IainMilford

iTrader: (15)

indeed, I dont really understand why SSU has gone down this route, only to continue slagging off remaps and mappers

like I said before

ZEN Performance

Pete,

Now you're going round in circles without the facts, or at least no more "facts" than Subaru are perfect etc. Since this thread is about improvements to MPG with mapping, do you have anything new to say? This thread is not limited to standard cars like yours, but here you are, so what have you got to say?

Does more fuel still equal more power?

IainMilford

iTrader: (15)

Bet the OP never envisaged the thread going off like this !

ZEN Performance

Nobody expects the Spanish Inquisition!

SunnySideUp

Yes, it does!!

If you say that you cannot get more power by pumping in more fuel you are going to look rather, well .... silly.

I assume that you admit that to get the extra power you must use more fuel? It has been confirmed that the mpg drops to the floor if the extra mapped power is used. If it isn't used then mpg 'may' improve ... but, then, why have the extra power?

Seems you may have painted yourself into a corner?

ZEN Performance

A corner really?

Depends on your definitely of fuel. If by fuel you mean the petrol consituent of the inlet charge, then simply adding more fuel doesn't guarantee you more power. As you have already written max power for N/A engines (and for arguements sake turbo engines on low boost) is around the 13:1 AFR or Lambda 0.88, then adding more fuel from lambda 1 will give more power.

But if we are at lambda 0.8 then adding fuel, richening the mix or whatever you want to call it, will result in less power.

You seem to have forgotton about the throttle in all of this.

71/200

iTrader: (2)

Wow, i think if Pete (SSU) actually went for a remap it would cost the mapper money not himself.

To replace the laptop after they have smashed it over his head!

I have to ask the OP, if MPG is a concern why buy a Subaru in the first place.

SunnySideUp

I'm awaiting my pm offering a complimentary re-map ..... to show me what can be achieved

SunnySideUp

And probably blow my engine up!!

ZEN Performance

Pete,

Instead of a complimentary remap, how about I offer to have you come and show me how it's done?

71/200

iTrader: (2)

LMFAO

dynamix

iTrader: (3)

Ok I'll play along.

I'll map it and if fuel consumption and power isn't better than before I will put it back to as it was. If it is better then pay for it

14N-FR

iTrader: (3)

Sunnysideup, are you quite an argumentative person or someone who likes conflict?

We have had at least two very experienced mappers explain the in's and out's of remaps and how they 'can' increase your MPG, use less fuel and be better for your engine, but you then go onto argue about how, if not declared to your insurance company would make your insurance void? Why?

If you dont like remaps, dont get one, avoid all thread's on forums with the word 'remap' and for god's sake stop 'trying' to find other ways to argue against professional mappers and listen to what they say to you.

You say you are an engineer? I find that hard to believe reading through your posts in this thread. An engineer is someone who can logically think and problem solve (or at least that's what has been drummed into me by my peers). You can do neither.

SimonD

I really don't see why everyone is so upset about this.
A Subaru map will give a massive margin for error/parts failure/wear and tear without the engine destroying itself. A re-map takes out some of that margin and trades it for performance. This is why Subaru can confidently offer a warranty. A warranty from a mapper would be worthless because it would be impossible to tell the exact cause of an engine failure. It would likely be a combination of various after-market parts, wear and tear and tighter margins from the map. It still amazes me when I hear people on here talking about re-mapping high mileage cars.
As far as I can see the only way a re-map could give better mpg is if the owner could drive at the same speed but with smaller throttle openings than before. This is unlikely and impossible to quantify…….not to mention plain stupid! If you’re worried about the cost of fuel, save yourself the cost of the map and drive slower .

I can understand the desire to get more power out of a second car as a hobby - in the full knowledge that things could go wrong - but to go down this route with a car you have to rely on to get to work, take the kids to school etc.. seems foolhardy to me.