VinceW

Hi, Just a quick question, how much can you modify before a remap is needed on a hatch sti? I've seen big claims for power gains with the K&N Apollo induction kit.

The simplest things to do would be lower de-cat pipe, cat back exhaust and induction kit. Would this need a re-map? or what modifications can you make without having a re-map?

Is the induction kit a step too far and would you be ok without a re-map just running the lower de-cat pipe and cat back exhaust? Does the standard ECU map compensate for small alterations?

Cheers Vince

Splitpin

The short answer is not very much.

This is almost a self-fulfilling prophesy. If the claims you've seen are bullsh*t, then you probably don't need a remap. If the claims you've seen are true, then you almost certainly do and would be taking a big risk by not, at least, monitoring mixtures and combustion.

The reality of the situation here is this: The standard induction tract is very efficient at power levels a good margin above standard, and therefore as long as you are running the standard turbo you are unlikely to yield significant gains (much more than a small handful of horsepower) via an induction kit.

Therefore, if what you've heard is true and this K&N kit generates a "big" power hike, the likeliest method by which this is being achieved isn't due to an increase in induction efficiency, it is more likely to be as a consequence of skewing the response of the mass airflow sensor in quite a significant way, and, in practice, indirectly causing the increase by fooling the ECU into miscalculating the engine load and leaning the mixtures off (and probably running more timing advance).

If that is what is happening, it's a random, unpredictable effect, and probably not the sort of power hike you want to risk, especially given that the hatch STi engines (assuming you have a UK 2.5 car) already have a bit of a reputation for early expiration. A custom map will give you leaner mixtures and more advanced timing by design rather than by accident - and in a context where the mapper is checking on an ongoing basis that your engine isn't being pushed too far.

Yes, if you did all of the above. Someone else will be better qualified than I am to tell you whether you'd still need one if you did everything apart from the induction changes, but I'd imagine the answer would still be yes.

Erm, yes, and no. These ECUs do include a number of parameters that are regulated by closed loop feedback, but changing the induction tract isn't a "small alteration", it's a very big one.

The ECU cannot, for example "compensate" for the effects of an alteration in the mass airflow scaling caused as a result of fitting an induction kit, because, for obvious reasons, it has no way of knowing you've fitted one.

All you can do under those circumstances is hope that the amount of safety margin built into the factory tune is sufficient to keep you out of the red zone. The problem is that without the ability to monitor the consequences of what you're doing, you have no way of knowing whether the modification you just made is keeping the engine within a safe performance envelope or not.

Sure you can spend a four figure sum on a wideband AFR meter, knock monitor and a laptop to datalog it all, but then again you could spend less on having it mapped, and drive away with the confidence that the engine's running optimally and safely.

VinceW

Hi Splitpin, thanks for the reply. This is where I'm getting the information for the induction kit from

http://www.revolution247.com/filters-hatch-70715-0.html

Both the Typhoon kit and Apollo kit list big horsepower gains, strange if the standard induction route is not restrictive? Unless the car has been mapped for the induction kit (it does not state this for the Typhoon kit)? Maybe there is more to be gained by a remap even with the standard induction setup?

and

http://www.litchfieldimports.co.uk/U...mancepacks.asp

Litchfield get a big power increase by fitting their cold air induction kit, admittedly to a remapped car.

dynamix

iTrader: (3)

I have seen one car where the owner had fitted a K&N Apollo to a hatch and the inlet hose was cauing a vacuum in the inner wing and restricting flow to the extent that it wouldnt boost above 0.8 bar and less than that above 5000 where air consuumption was highest.

Needs remapping for anything that is likely to improve it. ie if it is a worthwhile mod - it needs a remap.

gisalook

iTrader: (1)

I put a K&N Apollo on my 06 sti and ran the cold air feed. It run foocking crap. To much air without a tweek to the map. So I diconected the air feed from the filter and left a small gap so the engine is only sucking what it needs rather than forcing it in. It runs ok but no power gains. Sounds better, not to noisey

Butty

iTrader: (2)

I hope you mean the air feed TO the filter

Fleetwood

I would also like to get a definitive answer to this question.

Just reading around, 'Theoretically' as I understand it the three key parameters that the ECU can NOT work around are:
1. Injector scaling table, so any work which affects the latency or flow of the injectors such as changing them to bigger ones (different fuel pressure?)
2. MAF Scaling table: Anything that changes the relationship between the volume of air and the speed of the air flowing past the MAF such as a wider intake by the MAF, CAI etc.
3. Wastegate duty table: Anything that substantially changes the relationship between the wastegate duty and boost at a given RPM like different turbo's (3 port boost control?)

But I guess the argument is that if you install a new exhaust system, although the ECU will probably cope, you will not get full value from your investement such as optimal spool and power without a remap?

Anyhow, would be interesting to get answers from the experienced guys on the forum.

rezaP1

Afaik, in general terms, if you change anything fuel,air,boost or exhaust related it would be very unwise not to map the car .... infact there are hardly any mods i can think of that are really worth doing without a remap

im sure splitpin will answer this much more technically than me though ....

Splitpin

Not like plenty of other folk couldn't have explained every bit as well.

Unfortunately, there isn't one. Especially when you try and provide one that works for all cars under all conditions. For example you can probably "get away" with something on one car that would kill the engine of the next, purely as a result of incidental issues.

Your general understanding's pretty much on the money. There's more to this than getting the full value for your investment. To use your own example, if you bolt on a new exhaust system that makes your turbo spool and respond to changes in throttle position a bit quicker than the boost control in the ECU can cope with, you end up with spiking, and the consequences of that can vary from benign to serious, depending on what you have, what sort of nick it's in, what other mods you have, what fuel you put in, etc. etc. etc.

Splitpin

No, not strange at all, especially reading the link. As I said earlier, the power gain is not coming from a "reduction in restriction", because there isn't enough restriction in the standard bits to get rid of to give you an honest 25 horsepower improvement.

The power gain is coming from altering the way air passes the airflow meter, leading it to underestimate the amount of air going into the engine, consequently leading to a miscalculation of the engine load, and resulting in the ECU leaning off the mixture and advancing the timing. The big giveaway is the disclaimer about not using them on a PPP/330S and having the mixtures checked. The seller obviously has an idea what's going on and is trying to protect himself from the possible negative consequences.

This isn't a "genuine" power increase caused by the induction kit being significantly better than the standard parts, it's basically "cheating". You could get a similar increase in power by cutting a hole in the flexible pipe connecting the MAF tube to the turbo intake and allowing a quantity of unmetered air into the engine. Not that I'm suggesting that you should actually allow unfiltered air in, but I'm trying to illustrate how the "power increase" is being achieved.

No, it won't have been. Let's assume for a minute that this induction kit does give an immediate 25bhp plug and play power increase. I suspect you would find that if an experienced mapper looked at the car, and did nothing other than rescaling the MAF lookup table to accurately reflect the new measurement characteristics, I would expect that 25bhp power increase to disappear pretty much completely. You may even find that the power output drops fractionally compared with its original figures.

There will be. You will get, to all intents and purposes, as much power from the standard induction bits, mapped optimally, as you will from bolting this thing on and then getting it mapped. Indeed if Duncan's experience of it is typical of every installation, you may well get more with the standard bits.

Their figures look a little confusing, seems as though there's a difference between the figures published on the webpage itself and those on the dyno chart.

The bottom line though is that their published increase is somewhere between 10 and 15bhp, with a cold air kit that is bespoke and better designed than the K&N thing, and also with an ECU that will be custom mapped for it. If they can only get 10-15 with their solution, which costs you £350 on top of/at the same time as their £1900 stage 1 performance pack, that puts the 25bhp claimed by the £150 K&N product into context, doesn't it?

VinceW

Hi Splitpin,

Thank you for the indepth reply. The Litchfield power graph shows about 340bhp and 365bhp (cold air kit) as far as I can see, which you are very correct in saying does not match the text of 340bhp and 355bhp, also very expensive at £330 + vat. Having said that the K&N typhoon kit supposedly has a R.R.P of £378.18. As the Apollo kit is cheaper it seems odd that it would deliver more power?

The K&N graph for the Apollo kit on the Revolution site (click on the picture) is even more confusing showing BHP of 200 and 225 and the correction seems to be different for both runs (what ever that is?)

It doesn't look like it's worth running to the extra cost of the induction kits. It would be interesting to hear from people who have fitted them to see if it made any difference in the real world.

VinceW

Just had a thought! Would the fuel pump need to be uprated after fitting the lower de-cat pipe & cat back exhaust with a remap running more boost to give approx 340bhp?

Cheers Vince

L.J.F

iTrader: (31)

If your car is still in the 3 year period then i would not bother touching it!