HDI Remaps

I can grasp the concept of live mapping on a car that has got several mods going on eg induction kits , exhaust de-cats , bigger intercoolers etc etc. But mine is a stock 110-HDI untouched and unchavved. If potential sellers claim the mod is a strightforward 109 138bhp then I didn't think that there would be a heap of variables that could get in the middle of this. The only variables I envisage could be faulty anciliaries on the engine eg EGR valves , cats

What things would 'live' mapping do ? Ultra pinpoint injector timing?

The compression ratio on a NEW standard petrol engine can vary by quite a lot purely by manufacturing tolerances. On a TD I'm guessing they're no more accurate, in fact Ds are generally more agricultural in design. So as an estimation you're going to have a possible difference in compression ratio thats very noticable. I know of two new petrol cars, one with a compression reading of 170psi and one with 195. Thats a hefty difference, and makes a BIG difference to the timing allowed - the difference between smashed piston ringlands and not. With timing adjustment you need to adjust fueling to allow a complete burn for best power. now im no D expert so i wont claim to know the details of D timing but im told by a good tuning source that just introducing an intercooler to a previously un-cooled TD you have to adjust the fuel timing to prevent engine damage so its not as though they are more tolerant to adjustment than petrols.

This is part of the reason why the manufacturer doesnt just make the max power version straight out - increasing power reduces the allowable tolerance in manufacture - what appears to be an identical engine can have been created to much tighter tolerances specifically for the higher power output map.

Um, you wouldn't be thinking over 10 years ago would you? What's 'agricultural' about a HDI/TDI (heck, even an XUD) apart from the fact that they can run on red diesel?

cheers, clive

No, i wouldnt. It has improved but they still map them conservatively because an optimal map for each engine is too different for the opposite end of the scale. Agricultural is a phrase bandied around our lab, basically suggestive of tending towards lower tolerances and not exactly pretty but built tough enough to not care, not unlike a tractor :)

And they're basically tough, which is how I read it. Not like these fragile weany petrol engines... :)

This I can grasp. I just thought tols were much tighter these days due to CNC process and greater control on heat treatment / hardness etc.

I'm just thinking of the later version 2.0 HDI currently in the C4 etc. they are 138bhp std now and the only difference I knew was they are 16V, but didn't thik 16v had such a big effect on turbo'd cars.

I'll try and search for some rolling roads in the North West / West Yorkshire

Oooh it'll make a big difference, more valves means great chance to get air in and exhaust gasses out. It also makes it easier to manufacturer the engine to rev higher - the 2.2 16v diesel donk in the Saab revs to 5,000 rpm with a most un-diesel like gusto..

There's reckoned to be a decent one in the Humberside Bridge industrial area.

Yes, naturally they are better than 10 years ago but still there are differences and manufacturers tune for reliability across the range.

As DervMan says - 16v makes a very big difference, even in a turbo.

Theres two ways of looking at it - one is "they are more or less the same engine, I'll take the chance" and probably get away with it if you keep it for a year or two. The other way is realising they dont produce different power options for no reason - the base engine is not the same and it costs more to produce a higher power engine. They may have "invisible" additions like extra cooling galleries, different head work to allow more cooling or better air flow etc and you could push it too far.

If your're optimistic then find a load-in map and enjoy it (possibly with a little extra smoke) until it goes pop or you sell it. If youre a pessimist (like me, ive broken too many bits being optimistic!) then take a little more care. Bearing in mind if you smash a piston or two its a full engine rebuild, but being honest you're unlikely to get an

Sorry for sounding negative, i just hate seeing people screw things up without realising its not as simple as a console game powerup. That, i suppose, is the reason its bloody expensive for a live remap.

Whichever you do let us know how you get on, but dont be fooled by hype (about either side).

Also bear in mind that anyone loading a map in without a RR is giving you an un-proven service, they cant show you its more powerful and although it may feel it - its very easy to cheat the ass-dyno with a little midrange torque and actually not deliver what was promised. Also bear in mind that torque is what makes a fast car to drive, not power. (eg a honda vtec - you have to thrash it to death to make use of the power, if feels like a wet fish below 5.5k. I think its the new BMW

On Thu, 16 Nov 2006 18:38:47 -0000, I waved a wand and this message magically appears in front of DervMan:

Huh, detuned large petrol V6s last practically forever. It's why I love my 212k Audi cabriolet 2.6!

You didn't spot the smiley then?

Since I've been interested in cars, a well kept engine outlasts an uncared for engine, any type. The fuel or design is for the most part academic...

On Sat, 18 Nov 2006 18:21:10 -0000, I waved a wand and this message magically appears in front of DervMan:

I've cared for three of my previous cars. All expired at ~110k-~140k, and they were all four cylinder jobs. Current car is a V6 and has so far lasted much longer. Go figure.

Detuned = over-engineered or wasted capacity. BMW straight 6's last forever, but they are also heavy lumbering gutless beasts for their size. When you drag them up to a decent power output they last as long as a normal engine at the same hp/l. Claiming a detuned V6 is better than a straight 4 is like claiming a detuned 4 pot will last longer than a higly strung 3 cyl - blatently obvious. They key point being detuned. A detuned anything will last longer, but will use more fuel than an equivelently powered smaller engine so its wasteful. Seems most car bodies dont last longer than 100K anyway these days.

Completely irrelevant. The 4 cyl engines I've had have all lasted longer than that - 220K and not showing any signs of dying? It's nothing to do with the number of cylinders.

cheers, clive

On Sat, 18 Nov 2006 20:58:17 -0000, I waved a wand and this message magically appears in front of Clive George:

If what you say is true, it must be the manufacturer. What were the makes of these cars? My previous three cars were: Ford Fiesta MkI 1.1, Peugeot 106 1.1, Renault 1.8 16v Cabriolet 1.8.

The cylinders are irrelevant, it may be the quality of the oil, the use, or something else. If you do lots of motorway miles and stick to routine servicing it's possible that the lower powered machines were worked harder than a multicylinder machine.

Who knows. In America, some people dislike four cylinder engines after the first quarter million miles, would stick to a V6 or V8. Other people stick to the V8s, V10s and V12s at such mileage...

I disagree, there's no such thing as an over-engineered car engine. Wouldn't it be great if we could re-use the same engine in our first car as in our last car, just replace the body... :)

But it isn't, though - so much depends on the driving. Indeed really, the majority of engines have such reserves of power over ordinary driving that it's all wastage. If a car requires for arguments sake 40 bhp to cruise at

Not necessarily. Looking at some of the commercial vehicles, those with a

Under many circumstances but under some circumstances, the difference is tiny. Compare something like a BMW 523i and 528i and the difference in real world consumption is a gnat's willy favouring the 528i.

Where do you get that from? Conjecture?

Alex Buell ( snipped-for-privacy@munted.org.uk) gurgled happily, sounding much like they were saying :

Ah, there y'go. The key isn't the number of cylinders, it's how stressed the lump is.

An 1.1 - even shoving something small like a Fester or a 106 about - is working a damn sight harder for more of the time than something two and a half times the size and power.

On 19 Nov 2006 16:24:58 GMT, I waved a wand and this message magically appears in front of Adrian:

So what's the problem with the Renault? Mind you, it did go like s*it off shovel, but it was an expensive heap of s*it to maintain...