Nick Read

I'm looking into a bit of basic tuning of my MY98 WRX wagon at the moment. Nothing too major and I'm not looking to break 300bhp or anything; I just want to optimise its performance and make sure it's putting out as much as possible in its current spec. It's a normal WRX engine which for the '98 year supposedly makes 260PS (around 255bhp?) - this is to be checked on a rolling road (Clive Atthowe Tuning in Norwich) next week, to make sure that the engine is in good order before going further with it, as it's done just over 100k.

Mods are an STi back box and panel filter, H&S decat centre section. It's always been run on Optimax petrol and Castrol RS 10W-60 oil. It pulls well and feels fairly strong and smooth in its delivery.

Assuming it gets a clean bill of health on the rollers, the options I'm looking at are:
1. Addition of a programmable 'baby board' and a full rolling road mapping session to optimise everything within safe limits. Quoted by Clive Atthowe Tuning at £700-£800
2. Replacement of factory ECU with an A'pexi Power FC and custom mapping as above. Price unknown
3. DIY increase in boost with an electronic controller e.g. GReddy Profec B Spec II - for around the £250 and I don't mind doing the plumbing work myself.

I haven't settled definitely on Clive Atthowe, I'm going to see how the rolling road diagnostic session goes first. But assuming that I go with them (and tbh, there's not a great many tuners who know Subarus, have a 4wd rolling road and the capability to map a Scooby around the Norfolk/Suffolk area!) what sounds the best option?

Above all I want my wagon to be quite discreet, and the full mapping session either with the 'baby board' or the Apexi Power FC (which I've not mentioned to them yet) would be better, as I'd rather not have gadgets like boost controllers in the cockpit but then full on mapping is twice as much money and I'm not looking to go beyond the limit of the existing turbo anyway. The key to it is I want the maximum performance with the minimum of physical mods.

opinions?

GC8

I wouldnt entertain a 'babyboard' whatever the f*ck it is. The A'Pexi is the best solution and it will cost £750 fitted and mapped by Andy Forrest. Also; itll save you £100+ on the cost of a Knocklink as it can be set to illuminate the CEL when det is detected. Clive doesnt really come close there does he?

A standard '98 'Wagon only makes 250PS out of the box though (240PS for the year before and the year after).....


Simon

Nick Read

Thanks for the reply. Well I thought a 'babyboard' was peculiar, but as I said, there aren't a lot of tuners out here on the Suffolk coast. Is Andy not in Scotland? How does that all work then?

Interesting you mention about the 'Knocklink'. It seems to be one of those things that's always mentioned but I can't for the life of me find anyone who sells one. But the thing that strikes me as odd is this: surely if a car has been mapped properly, there is absolutely no circumstance at all under which it would knock at all? Hot weather, high intake temps, low octane fuel...surely a decent ECU should just pull the timing and that will be an end of it. Obviously as it advances again to get as close to the 'knock limit' as possible it may detect a tiny amount of pinking at which point it should retard again. Surely there will never be enough detonation to register as important to the life of the engine. If the ECU is allowing that much knock before retarding, then it's a **** ECU, or a badly programmed aftermarket job?

I can see how it would be useful to be able to monitor detonation with a boost controller, where you're essentially just turning up the boost to see how much more power you can make before getting to the factory ECU's safe limits. In that situation, knowing if it's pinking before actually hearing it tells you when you've gone as far as you can. But surely a factory ECU or a fully remapped engine, done on the rollers using a 'babyboard' or a Power FC or whatever, should not EVER knock?

What do you think?

wrx.co.uk

Hi,

Is the car a 98 version 4 or version 5, it makes a big difference as the version 5's can be ECUTEK remapped saving you a few quid. As for the restriction on current power to 250 bhp, 5 door's are fitted with smaller turbo as standard.

Andy F is a superb remapper and alround great guy, but there are many other companies much closer to you.

Your comments on the knocklink are ok if the whole car is working correctly on the right fuel, what happens if there a sensor failure, or duff fuel (missing the octane booster).

knocklinks are available from Thor Racing, don't go to the other supplier....

Lee.

GC8

There are a whole host of possible causes for detonation, even after youve had a good aftermarket ECU mapped by an excellent mapper (MAF sensor failure, spoiled fuel, air leak, poor fuel supply.....). A Knocklink would probably be of at least as much use now though, while the cars running on the standard ECU which is set for much higher octane fuel than we can obtain.

The standard TD04 can pump enough air to produce 280BHP perhaps a shade more; if you have set your target a little higher then Andy Forrest has a TD04 hybrid thatll make 320+BHP while keeping the smaller turbos early spool up.


Simon

Nick Read

Errr....I think it's the earlier version. The older style bumper with three side segments rather than two. Clive Atthowe do the Ecutek but they said that my wagon was a little too old for it to be possible.

Is the 'smaller turbo' smaller than the UK models even? What is the boost limit and the most power it can make, roughly?

Yes from looking around on the forums, it's clear Andy F knows his stuff, just that it's not practical for me.

That certainly explains the Knocklink a bit better, and what you're saying makes sense, but having driven and tuned a number of different fast (and slow!) cars, both turbocharged and NA, there does seem to be a much greater tolerance for knock amongst Impreza owners! Most tuners/modders/enthusiasts/keen drivers are horrified by even the thought of their engines going into detonation, yet hunting through the forums, I get the feeling on here that it's kind of 'another day at the office' for Scoobies? I've read threads talking about their knocklinks lighting up on the wrong fuel, or on a hot day, or when the intercooler was knackered, or the fuel pump lost pressure, or whatever, and I'm thinking - "Hang on, if your knocklink is lighting up, you've already damaged your pistons; that's not right!"

Not that I'm saying that you shouldn't worry about knock, but for most cars it just doesn't seem to be an issue...

wrx.co.uk

I thought the TD04 was upgrade to a IHI VF something on a version 4?

GC8

Its certainly an issue for Impreza owners; the bearing surfaces on a horizontally opposed crankshaft are a lot narrower than on a conventional in-line one and many Imprezas have succumbed to 'knock'.

The turbo is of a similar size to the earlier WRX 'Wagons, later Classics and New Age cars, although they arent all the same. A little over 320BHP is the limit for a (hybrid) TD04; unless you are setting your sights higher Id stay with the smaller, quicker spooling TD04.


Simon

RoRu

If your going to go down the power fc route you could do alot worse than call Zen performance in Wellingborougha call Paul (Pavlo) is very well respected on the Subaru tunning scene and i'm sure he does the power fc fitted and mapped for the same sort of money.

www.zenperformance.co.uk

GC8

Pavlo does have a good reputation too, Ive always thought that Andy Forrest had a slight edge on price though, but I might be wrong. He's (Paul is) certainly a lot closer. Whoever you choose; Id suggest getting the FC Commander at the same time for an extra £80 or so

Simon

Pavlo £880
Andy.F £830

Nick Read

Thanks for all the replies. OK well Knocklink time it is then, cheers for the advice. SO now I need to know:
1. How do I find out if my WRX has a knock sensor already? Where would I find it?
2. If I need to get install a knock sensor myself, where's the best (and easiest) place to put it? Wouldn't the best solution be to have two separate sensors, one on the left hand block and one on the right?
3. What are the dimensions of the unit, width, height and depth?

I think I'm staying with the turbo it's got at the moment, my old motor (Clio 16v) had a T28/T3 hybrid and in comparison to that it spools up a lot earlier, with virtually no lag at all, but it does feel breathless once you get up into the higher rev ranges.

The other thing is this...it might sound stupid but no-one ever told me so I might as well ask - surely with all four pistons punching out sideways, the 'bottom' side of the cylinder bores (and one side of the piston rings) must get more worn than the 'top' after a while? Is there some secret of design to combat this, or is it just an accepted problem?

GC8

Thats because the turbo on your Renault didnt suit the application..... My point was, that if you propose to extract over 280Bhp from your car which isnt out of the way, then you will be beyond the pumping ability of the current TD04. In this circumstance many people here will advise you to upgrade to a TD05; I feel that the TD04 hybrid that Andy Forrest offers is a better solution.

With regards to Knocklink; as the PowerFC is the only real option for this car it wont be necessary, as it can be configured to illuminate the CEL if detonation is detected using the oem sensor.


Simon

Nick Read

Well with the greatest of respect - because I value your knowledge and willingness to share it - I know a fair bit about the ins and outs of the Renault F7-series engine, the restrictions that the engine bay place on it and how a full-house 240bhp turbo conversion works on one...0-100 in 11 seconds in my little FWD Clio would shame quite a few Scoobies that are designed from the ground up for that sort of power and have AWD to boot. :-) I'd say the T28/T3 hybrid suited the application as well as could be expected. All I'm saying is that it was a totally different type of drive from my WRX - from 4000 revs and on it would absolutely fly, pulling with the same urge all the way through to 7500. The Scoob is different. It feels a lot smoother and pulls well from 2500-3000 revs; it just seems that the show's over once you get up to 6000.

So as you say, Simon, what I may be after is a TD04 hybrid. 280 bhp with the physical setup as it is now and just a bit of remapping...that would be good. 300bhp would be a nice target, but what I'm getting at is I don't want to go crazy with this Scoob. I don't want to have to keep uprating everything to cope with the power. No FMIC, no cone filters, no huge injectors, no banks of gauges all over the place (although it is a little disconcerting not to have oil temp, oil pressure, boost pressure, charge temp and AFR which I used to have)

ANyway, let me just get this straight...Power FC is the best option bar none. It'll give me a knock warning using the existing knock sensor which I definitely already have? What is the CEL though? Also think about upgrading to a TD04 hybrid to comfortably exceed 280bhp, which I presume the Power FC can be remapped for when the time comes?

BTW what is the hybrid you're talking about - a TD04 turbine with an 05 compressor wheel? Cheers!

GC8

The CEL is the Check Engine Light in the binnacle, but I honestly dont know what the hybrid TD04 contains; thats a question better directed to Andy Forrest.

Nick Read

Aha! Yes that would make sense...I've just had a look on his website by the way and it really looks excellent, everything he's said on there is good common sense. I didn't realise he maps on the real road rather than the rolling road. Makes things a lot easier and more realistic I suppose.

What's your opinion on 'pocket money mods' such as an IC airflow splitter and tilting the IC forward to get better airflow. My current project is straightening every single bent fin on the IC. I do one row a day LOL

I've also managed to get hold of an STi waterspray IC shroud and the auto and manual switches. All I need now is a water bottle and pump and I'll have manual mode setup. Auto I'm working on.

wrxbouy

If you have the wagon just use your rear window washer pump. Not sure bout England but here in Aus lots of suby owners tend to upgrade then upgrade again with turbo's being the first option.
http://www.wrx.com.au/forum/viewtopic.php?t=23519
This is a link to a Ported vf34 minimal kms for about 400quid pulling close to 200kw at the treads. The power fc seems a well respected ecu, with lots of tuning potential, The gc8's loved a free flowing exhaust so maybe source a 3" turbo back option. Tilting the ic would be good but try sourcing an 02sti unit as they are bigger. no need to go fmic imho.

Nick Read

Some good ideas there. TBH I've only had my wagon a couple of weeks and I said to myself (and the wife) that I wouldn't mod it - and I've already started. Oops.

Anyway, I've not investigated the washer bottle thing yet. I know my rear washer doesn't work very well, but I think it's a blocked jet. Does the rear washer have its own bottle or does it run off the front bottle with a separate pump? I don't want to go any bigger on the exhaust than what I've already got...decatted centre and STi backbox. If I had to replace the front cat I'd want a 'sports' cat in there, not just an empty pipe.

Just out of interest, if you went to a slightly higher ouput turbo, say the TD04 hybrid or the VF34 you mention, could you control them with just an electronic boost controller and rely on the ECU to fuel properly? What's the factory boost limit on mine?

GC8

The issue is ignition rather than boost. You may well be able to fuel the increased charge but a 1998 JDM car was intended to run on higher octane fuel than is available to us; the ECU is notoriously bad at dealing with detonation and it simply doesnt have the range of adjustment required, even if it were up to the job. This is a problem when youre running enough boost for the standard 240PS/250PS and it will be magnified greatly if you increase the boost.

You mention that you have removed the centre cat; Im not sure about your MY JDM 'Wagon, but mine doesnt have a centre cat, only the one in the downpipe. What appears to be a cat is actually nothing more than a resonator.....


Simon

StanS

iTrader: (3)

YHPM
Stan

Nick Read

Very interesting. BTW Simon, thanks for all your feedback on this thread, it's good to hear from someone who's got something useful to say - after adminning (is that even a word?) and posting on Cliosport since its beginning, I can tell the wheat from the chaff so to speak.

I've got to say I wasn't overly happy about the boost controller idea, mainly because as you imply, it will control boost, but not ignition timing, so is a bit of a one-dimensional approach. Sounds like the best option is definitely a Power FC mapped by an expert like Andy with the det cans on.

As far as the centre section goes, I'm only going on what I've been told by the previous owner...that there is an H&S decatted centre section. whether there was a cat there before I don't know and I've not got round to jacking it up to have a proper look under there yet anyway.

I presume with a sports cat in the front pipe it would still just about pass the emissions?

BedHog

My MY02 Wagon had an up pipe cat, down pipe cat and a centre resonator. I removed the downpipe cat (leaving the up pipe one) and it passed it's first MOT no probs. I left the resonator as I was told there was no noticeable benefit in removing it (noise or power)

GC8

New Age cars do have an up-pipe cat; Classics only have a down-pipe cat and one in the centre section; or maybe not, depending on model.

Simon

GC8

I missed that Nick, sorry. My JDM 'Wagon only has the (standard) down-pipe cat and it sails through emissions. I'm thinking about removing it though as my V5 simply states: Impreza. Ive seen a number of Classics (saloons) that have had the down-pipe cat removed and they still pass the emissions test with the centre cat; you'd probably need to ensure that it was fully warmed up though.

Simon

Nick Read

Well funnily enough the cat thing has become more of an issue now, as coincidentally, it's started blowing somewhere on the downpipe under the heatshields. Well it's done over 100k so no surprises there, it's the last bit of the system that's not been replaced. So I'm sticking with my non-cat centre and STi backbox, therefore I need a new downpipe. I'm not happy about running with no cat at all - call me soft, but after all these years of decat exhausts and dodgy emissions all year round, the time has come to do my duty for the environment and run a 'sports' cat. So it's just a question of what works best and for what money. I've had a little look and it seems that H&S do a nice sports cat downpipe which isn't cheap. Miltek seem to do the same but I can't seem to find a price or whether they do it individually. Any advice?

GC8

Had you considered a de-cat down-pipe with a sports cat in the centre section? I read about a £200 one recently thatd fit the bill. It sounds like a win-win: youll benefit most from the de-cat (down-pipe) as youre having a new ECU and with the non-restrictive sports cat centre section you will still be running legally. I have no idea where to look for the sports cat though.....

Simon

Nick Read

I did think about that, but ruled it out, mainly cos I don't like paying twice for the same thing. I've already got a cat-less centre which should last a long time. While I'm going to have to replace the downpipe anyway, I might as well, leave the centre as it is, and cat the downpipe. Obviously, from a performance point of view, it would be better to have the cat as far downstream as possible, with a wide open downpipe. But from an emissions point of view, it's a lot better to have the cat right up close to the turbo where it will get up to temp a lot sooner.

As I'm not going for big big power at the moment I think I'll get away with it. Just really need anyone's experience of these sport cats - whether H&S, Miltek or as I've just found out, Graham Goode.