Just in case anyone wants to know (not sure with so many Scoobysport and similar followers), I have been driving for the past couple of days with the HKS induction kit, AFR (air-fuel ratio module, Hiper exhaust (all the way to the cat) and Iridium spark plugs installed on my STi V. Forget the sound - it is absolutely gorgoues and even more so forget the inhaling and exhaling of the induction kit - I think I WILL get used to it. Two things are the best part of the experience: a) changes in driveability and performance and b) games with the AFR adjustments.
Firstly, the car feels much better in picking up power, although the increase (?) in power and driveability makes you feel you are stationary while your speedo shows 85mph. Only the odometer and the clock tell you that you have done some distance in a given time element. Once above 2500rpm everything happens much quicker and swifter and I am pretty capable of making a distinction between acceleration and the exhaust noise!
Secondly, (and I have not forgotten David Power's warning in this direction!!), I experimented a little bit with the AFR settings from standard (fully bypass of the module) to medium rich. To cut the long story short, for someone like me who does not rev the engine over 6000rpm ( and very occasional 6500) the richer the mixture was the more difficult it seemed for the engine to pick up from the lower end of the rev band. This makes sense to an amateur technical mind like myself as I feel it is normal for the engine to need richer mixture as you push it harder and harder. In the end I left the AFR in just one position richer than the standard mixture simply to allow for much more air being pushed in as well for a considerably more free exit through the exhaust. All in all, it seems to have been a step worth while making.

If any of you out there may have the same or similar parts and have experience, it would be interesting if findings may be correlating. It will be even more interesting to take the car to PE one day and have the Phase 2 upgrade implemented and the ECU remapped to work at its best WITH the HKS part on the car. Let alone the fact to have DP experiment on his rolling road with various settings of the AFR module and appropriate mapping. So far so good, time will tell about the rest.

Thank you for reading!!

 

I would imagine that Power Engineering would remove the AFR before remapping the cars fuel and ignition, as the AFR would no longer serve any purpose.

 

Hopefully, the AFR will not be AS USEFUL (or necessary) as now, but it will never be completely obsolete as one sometimes has to drive a car in places where high-octane petrol may not always be available and richer mixture cannot do much harm. I will most certainly expect to have it maintained as an optional facility, although new mapping will simply become the 'bypass' (or 'standard) setting on the AFR.

 

The AFR is making the car richer than it should be running and will shorten the life of your cat.

The car itself already has an air flow meter and an O2 sensor so any changes to the exhaust and air filter side of things will not need any other adjustments as the car will do these itself.

As for increasing the richness of the mixture not causing any harm this is not the case as if the mixture is too rich then it can lead to washing of the bores which removes the oil from them and shortens the engine life and can lead to overheating problems but this does tend to be at extremes.

Darren

 

Darren,

Academically, your are absolutely correct, but your last sentence says it all. I am finding it a little bit strange (let alone unrealistic) to see most discussions elaborating very much 'on extremes" rather than real-life applications. Unless, of course, I am the only one not to drive the way it should be done, which, it seems, would cause all the theoretical problems.

As far as the AFR settings are concerned, my experiments almost totally support your views. The increase in richness of the standard setting and the one position higher where I have left it for the time being is only a marginal one and I had a pure subjective feeling it made the engine more responsive further down the band.

By the way, it is interesting to see that responses so far happen to far more interested in effects of the AFR module, rather than giving input I hoped to generate in my initial posting.

[This message has been edited by quattro (edited 03-09-1999).]

 

Thank you, David, for your continued concern and care. I am happy to be learning more about the engine's behaviour and will not enrich the mixture any further. All the experiments I described were conducted over a very short period of time (20 minutes) and equally short distances (10 miles in total). The engine was not revved over 5k at any point in time as I did not see a need to do so with the power and torque at disposal functioning so nicely.
I will also try to plan a visit to Uxbridge in due course as suggested.

best regards
q.

[This message has been edited by quattro (edited 04-09-1999).]

 

quattro
Having brought an induction kit from Pipercross only to be sent the wrong one I decided to get a refund and not wait for the correct version.I would be interested to know were you got the HKS kit from and how much.

 

Hi there

Originally TDI were the only source of HKS in the UK...

but HKS has now formed HKS Europe.... there are about 4 main reselllers now (TDI still the largest).

ABP is one of the other resellers....

I have got the number for HKS Europe.. Micheal (HKS Europe) is a sorted guy.. knows his stuff and really enthusiastic about his products.

J.

ps - All the resellers sell the kit for the same price... just their labour costs vary

[This message has been edited by firefox (edited 04-09-1999).]

 

Grant,

I am a Park Lane (UK) Ltd. client and they are one of the very few appointed agents for HKS products in the UK. Not to mention I still keep finding them very polite, professional and efficient. The cost of the Power Flow Induction Kit (I think this is +/- how it is called) is around £150+VAT and fitting (although you can fit it yourself easily). If you call them try to speak to Mr. Phil Suckling who will , I am confident, do his very utmost to assist you.

Finally one practical tip for you and all others who may have or want to install HKS induction kit on their Imprezas. In order to prevent a section of the filter 'mushroom' to rub against the remaining part of the original piece of black plastic induction element (which is now sticking out of the wing and not used any more), CAREFULLY cut a curved recess (with a sharp cutter knife) in the edge of the black plastic opening, but ONLY AS MUCH AS NEEDED for the HKS filter element to be free and not touch anything. This should only be a small area cut out and if you ever wanted to return the standard air filter box there will be more than enough of the opening area to slide into the entry hole of the filter box. Also, there are two hard rubber pipes (hoses?) of small and slightly larger diameter that used to be held by supports across the standard filter box. Once with HKS installed there is nothing to keep them fixed to anything, so a bit of creative imagination should be used. For the time being I detached two plastic holders from the standard filter box and attached them to the pipes where it matters so, at least, they are not touching anything, although still can move a bit.

Hope this helps. Let us know if and how it works.

regards
q.

 

Hi there,

In relation to the HKS induction kit.... have a look at Phil's Car (webmaster). He has the induction kit fitted. It uses stainless steel brackets (not the crappy ones supplied). The plastic doesnt need cutting, and the mushroom doesnt rub. The pipes are also held in place using the original plastic clip, that clips into a stainless steel L-shaped bracket which is bolted on using one of the bolts from the airflow sensor.

Cheers,

J.

 

It's always nice to see people know more than one would think. I am not sure what the word 'crappy' in this particular context means, but I looked again under my car's bonnet and there are no other but metal (not stainless steel) brackets which hold the inducton kit filter assembly in place. I am not sure how can it be that the mushroom does not rub as I described as the extension of the whole assembly towards the wing happens to be defined by the 'flange' which connects the induction kit to the air flow sensor body. Unless, different STIs have different layout.
Thanks for your input, firefox.

q.

 

Dont ya just love Sundays...

Crappy means rubbish/poor/****e/etc....

I designed the brackets myself... When I ordered the kit and it arrived, I found that the kit was actually for a 300ZX (HKS didnt produce a kit specifically for the Impreza). The mushroom and flange are identical and the brackets virtually fit. But I wasnt happy with them (there wasnt a bracket for the pipes). So I deisgned some out of stainless. These kept the mushroom off the plastic intake, off the inner wing, so that it is in free space. The bracket to hold the pipes is very simple and looks original. I also replaced the supplied steel nuts and bolts with stainless self lockers... I am fussy like that (has to be the best)

I think Phil might have a spare set of brackets I made.. I made a few sets.

Cheers,

J.

 

firefox

Yes, I love Sundays, and I would love to get a set of probably the very best brackets in the world for the HKS induction kit. So, be a good sport and see if and how that could be arranged. Perhaps you or Phil could email me off the bbs and we can arrange something convenient.
Like you, I am fussy and always want the very best (or more).

Thanks in advance and hope to hear from one of you with the brackets.

q.

 

One week later and a few more hundreds of miles...
Everything has been left as it was to begin with. AFR module settings have not been altered either. So, what is the news? The news is that the speedometer, rev counter and stopwatch clearly agree the car is running quicker and accelerating better. I add to that it has become extremely sensitive to throttle (which is much to my liking). Downsides? Funnily enough, and most liekly as a consequence of increased noise levels in dBs from the exhaust as well as the induction kit 'music', the subjective impression seems to be as if the car moves less easily into action and requires more work to get there. I know this is NOT the case, but, there you go. Also, it is either me getting used to the new conditions or the ECU may be learning different conditions of operation and as miles get done everything happens swifter and smoother (I did not reset the ECU!)
In a couple of weeks my STi will go to PE as they would like to establish minimum (lean) and maximum (rich) safe settings of the AFR module bearing in mind that my car always runs on RON98 and 1.25% of octane booster. It would be nice if my car's act could be balanced out to a degree which will keep me happy until the full upgrade for Phase II engine becomes available.

As always, constructive feedback and direct experience is more than welcome.

q.

[This message has been edited by quattro (edited 11-09-1999).]