Floyd

iTrader: (9)

The majority of posts here describe how a new mod improves the performance, but there must be lots of people who have not had positive results from their purchases?

I think I read a post from Stephen Done(?) that described how he lost power from his latest mod. This was measured on a RR, as he sensibly monitors the gains each time he adds something new.

This can be a complicated subject due to some mods not working with others etc. There is also another subject of when mods, not only fail to improve performance, but cause bad running side effects (like not starting, poor running etc).

The Subaru Turbo engine is easier than some engines to extract more power, but I know that what seems to be a reasonable mod, may actually be detrimental.

So what mods didn't do it for you and why?

And what mods made your car a pain to drive when they should have been great?

F

john banks

PPP and DP both good. Induction kit perhaps small gain, but a lot of noise.

What I would say is that it is useful to know how much boost you are making with each mod. PPP in particular on my car seemed to be sensitive to overboosting, and more so after the downpipe. There is a fine line between shooting up to 20psi and then oscillating between there and 14psi, and shooting up to 17.5psi and holding 16.5psi - which is much the preferred option and I believe optimal at present. Or the other alternative of under-restricting it and only seeing peak/held of between 10-15psi. Had I not sorted out my boost control after DP fitting, I am convinced the car would have been slower if I just had it fitted and left the boost control as it was compared with just fitting PPP. See my very long Falkland DP thread for the boring details. I wanted to do PPP so I could avoid Lambda/Knock Links, boost gauges and the like, but for my car I have needed a boost gauge to sort it all out. Perhaps I've had more trouble than most, or perhaps I am a bit silly about these things worrying about whether I am 2psi down on boost - however, this is likely to represent over 20bhp - ie the sort of gains you would at best hope for from a DP, so I think it is worth getting right.

If you look on the dyno site, and see some of the variation in boost figures it is interesting to note examples where a DP was added to PPP - SunilP's car I think - curve 3, and then the boost was only 12psi. This could explain the disappointing curve?

[This message has been edited by john banks (edited 24 September 2001).]

StephenDone

Hi Floyd,

Depends how much money you have to spend. The PE Power Manifold is great if you want to spend that much. In hindsight, I wouldn't buy a replacement full exhaust unless I got the manifold too, since the exhaust on its own is just too damn loud for me.

Yes, I've got problems with my intake mods, and wouldn't recommend doing what I did there until I have worked out what is wrong. It's strange. I couldn't find a single dyno run on scoobynet that shows purely a change in induction components. I wonder whether others have this problem, but just don't know it - if you're always tanking round at above 3000RPM, it probably doesn't make much difference. If you're stuck on the motorway at 60-70mph (2000-3000RPM) for ages, it certainly does.

Cheers

Steve

[This message has been edited by StephenDone (edited 24 September 2001).]

Danny Fisher

Floyd, I ran the PE downpipe, then swapped to the SS downpipe. The ability to clear air was amazing. The SS pipe works so much better.

Dan

Floyd

iTrader: (9)

Danny

Did you change anything else or just the DP?

Floyd

iTrader: (9)

This is exactly the type of problems that can occur after modding. What can be infuriating is that you can't be sure where the problems started especially if several mods have been done at the same time.

Then you can spend lots of money changing stuff before biting the bullit and going to a dealer to fix it. You just know that they're going to have a sharp intake of breath and say "someones been messing around here", when the problem could be totally unrelated.

Theo, you should have replied here saying that you resonator removal killed your MAF!!!!

F

MorayMackenzie

It would appear that a certain company rebuilt my STI engine with cast rather than forged pistons... not good... engine eventually failed with snapped rod... coincidence? possibly. ho hum.

john banks

I suppose you have to decide what you are going to do based on how much extra you are looking for and how much hassle you are prepared to put up with getting it how you want it and then keeping it there. The modding can end up an end in itself.

Also you must consider how much possible engine life you are prepared to trade for increased power. PPP/DP/induction is as far as I am going to go on my UK car. But others go much further - like >50 lbft further in the knowledge that if their engine lets go it's a good excuse to start getting really expensive and doing the internals. I don't want to go there so I stay fairly conservative, but for the moment at least the car does not feel very conservative but an absolutely wild beast that needs some serious respect in the wet whereas before I could floor it just about whenever I dared as it had far more grip than power. This was good for me to learn with for a year. Now it is more of a handful and I am really growing to like it that way. Maybe when I put better tyres on I will want more power... but it's a completely different beast with only £2k or so spent on it.

PPP is a good way to go on a MY99/00 UK car IMHO for overall ease, excellent driveability and good resale value. But fit a boost gauge and watch it for a week or so and make sure it is doing what it is supposed to do, and do the same again if you then add a downpipe.

Floyd

iTrader: (9)

John

You are thinking along the same lines as me, just enhance the engine with reliable mods and keep it simple. Nothing too dramatic that your friendly dealer would disagree with, which should give a good increase and retain drivability/reliability.

The 'fly in the ointment' is that now I see people having trouble by changing simple things like the induction (diam. and length), DP/exhaust, different filters etc. Of course, I don't know what their driving styles are or servicing habits, which all play a part in reliability, but it still makes me nervous.

The conclusion, IMHO, is that to keep things problem free, you need to:

Do lots of homework before buying a mod, to get the right one for your needs.

Monitor any improvement and it's effects on fueling/temps etc.

Make sure the oil is changed regularly with top quality stuff.

Pay special attention to starting and shut- down.

Choose a good specialist with a known reputation, if you're not doing the mods yourself.

Generally, pamper the car more than when it was standard, because it is now working outside its designed parameters, which Subaru have spent millions to define.

I think that's everything unless I've missed something.

F