Tuning the 2.5i by Xtreme Racing Tuning (Tuner: West_Minist)

[HyRax]

Cheers mate - I'm an IT consultant, so "detailed" is my middle name.

Next service is due in 5,000K's time (75,000K's) and should be the J interval service which is normally done at 100,000K's (time is coming before kilometres on this car), so I will be getting pretty much everything changed then. I'll definitely be getting you to re-examine a new set of logs at that time to see if any further improvements can be made.

[west_minist]

[HyRax]

v3 ROM update

This was a very nice update. It was up to me to determine what Edward had changed in this ROM and one thing stuck out very quickly - the bottom-end is much stronger now. Fuel comes on very early and I attain quite high acceleration on very little throttle.

As a typical example, let's say you were high-geared and low rpm, eg: 4th gear at 2000rpm. On the stock ROM if you put your foot down flat to the floor, the tach very slowly starts to raise but the speedo doesn't really budge for another 3-5 seconds. Now I can put in less than 50% throttle and the car will pick up 5kph in about 2.5 seconds in 4th gear from 2000rpm. Useful in day to day traffic? Of course not, but it's a good indicator of how much more responsive the engine is at the bottom end.

In sensible gearing, the car picks up very quickly now. It's easy to hoon around and get to 100kph without even getting close to getting flat to the floor. of course power-runs will still require you to go flat-foot, but the majority of the power is delivered at the top of the pedal now, and I like it. Flat-footing it barely adds anything to the acceleration force you've already got.

1st is very strong now making it a doddle to get off the line as before, 2nd gear feels a bit stronger than it did in v2 and remains my favourite gear, but now that third is a lot stronger than before, I can easily take more corners in third without feeling like the car is about to lag and require a drop to second. The new bottom end allows the car to build up from low rpm quicker than before and get back into the meaty sweetspot of rpm nirvana. In a typical long left sweeper, the car just felt magical powering through it in third.

Where power used to come on at about 3,000rpm, getting meaty at 3,500-4,000rpm, the car now starts to come onto power at 2,600-2,700rpm and is in the sweetspot from 3,000rpm. The car powers onto 5,000rpm where it starts to lighten up a bit but it still gets to the redline pretty quickly.

One of the little differences I found in this release was the fact that I could actually feel myself being pushed back into the seat a bit for a change. Before you just more or less floated in your seat with a depressive force here and there, but now you can actively feel yourself being pushed back into the seat instead of it just being a comfortable, but laggy affair under the stock ROM.

In casual driving, 1st to 2nd gear changes were still a touch lurchy, but all other gears were fine. In hard accleration, all gears were silky smooth. In slow stop-start traffic, I found 1st gear still touchy, but more controllable and I did not need to rely on extra clutch action to control the extra throttle like before. As a side note here, when the car is cold, the car is lurchy in all gears, but once the car has warmed up, things are fine after that. I usually drive no harder than 3,000rpm for the first 10 minutes of driving to warm the car up anyway.

In high revs, gearing down actually felt and sounded more sympathetic to the car - it doesn't sound like it's simply revving its guts out anymore - it sounds much "cleaner" now, so now coming down from 3rd to 2nd is easier, but as I said before now I don't even need to take 2nd - third will climb back sufficiently now. Even letting the revs get down low enough that if you did take second, the traditional bogging down is near-eliminated because the car can quickly get itself back into power territory.

On the economy side, I've now racked up just over 200kms on this tank and the estimated distance-to-empty still only says 380kms! That's great considering how much hard driving I've done on this tank in a short time.

As you can see from the logs in Edward's post above me, compared to stock, he has manage to extract an extra 10kw of power and 15nm of torque overall. Remember that my car has had zero modifications of any sort in the engine department. It may not sound like much, but a 2.5 litre N/A engine, I think that's pretty good.

I was supposed to run the v3 ROM for a few days to see how the learning component of the car goes, but Edward has already sent me v4 already, so I've got that on the car and again will do more testing tonight, and presumably over the next couple of days. The v4 ROM now features some ignition changes so we'll see what difference that makes.

[tangcla]

Good feedback, most importantly (regardless of dyno readings) it's how the car drives afterwards. There's no graph that can show how much more responsiveneess and how the car 'feels' to drive.

[west_minist]

Stock


v3

[HyRax]

v4 ROM update

Not much to add here. The v4 ROM was basically a tidy-up of v3 with some changes to ignition to sort out some minor knock issues.

Accelerative power remained the same, but at high revs it felt somewhat more refined.

What stood out for me the most this time was normal daily driving in places that I have a distinct memory of what it was like to drive under the stock ROM. Case in point, a driveway exit on an upward incline to the main road. Normally I have to rev up and slip the clutch fairly quickly to get sufficient launch to tackle the start of the hill and beat oncoming traffic and this always resulted in a lurch, but with the v4 ROM I was quickly out of there with no effort, no lurching, and in fact I had to tap the brake as I got into my lane because I'd gotten out far quicker than I had mentally expected to. The whole experience of the car has just been so radically changed and I keep getting reminded of it everywhere I go.

Edward feels we are probably now at the limit of what we can do with the engine with 100% stock components until I get my oil and spark plugs changed and get some better quality fuel. Beyond that would be the need for physical mods to allow the car to breathe better to gain more power.

The next ROM is likely to be the final ROM for engine tuning and will have some final torque-related tweaks.

[teK--]

Is the improved pickup mostly due to more aggressive dbw mapping?

[west_minist]

Yes. Its the mixture of both DBW and engine tuning. Tuning soon finish. I will reset the dbw to stock for HyRax feedback. We are at v5 to determine if I can enhance more low end tq from 2700rpm now. Once that feed back is in, we will be happy to know that the 2.5i have some life in it.

[west_minist]

prelim results of v5. Introduce fueling from 2700+rpm


v5 vs Stock


v5 vs v4

[HyRax]

v5, v5a, v5b ROM update

Testing several variants of the same ROM this weekend. This one is all about torque tweaks.

• The v5 ROM concentrated on improving torque down low from 2,600-2,700rpm in general.
• The v5a ROM tweaked low end torque from 40% throttle application.
• The v5b ROM had some closed loop and open loop changes.

Long story short, the car is exhibiting noticeably stronger torque levels all the way through the rev range. This is best felt through drives that put a load on the engine as opposed to simple straight and flat runs. We're talking mountain climbs, long sweepers, etc.

I didn't have time this weekend to prepare a mountain road, so I tried a few local long uphill sweepers and some steep suburban back streets. The car just powers through these turns and thumps up hills with ease. The car was already feeling strong after v5, but v5b in particular felt like this strength was reinforced.

Edward did make an observation at one point that some of my power runs showed a slight degradation in performance which was causing some head scratching. While dirty fuel, old oil and original spark plugs were initially thought responsible (and probably still are), it is highly likely that my front tyre was more directly responsible for this degradation because in the past couple of days I somehow scored not only one, but TWO nails in my front tyre causing a slow leak which reduced the car's ability to accelerate and turn. By the time I noticed it, the sidewall had worn down too much to be safely repairable, so I had to get a new tyre. One of my back tyres also scored a screw through it, but that was repaired. Mental note - stay away from industrial areas when doing test runs!

I also finally burned up my suspected dirty tank of petrol and filled up at a different, larger BP that was more likely to carry better quality fuel. We'll see how this one goes, but at this stage I will need to sort out my next service (which will be a major one) which should improve things again. I racked up a total of 450K's on that tank, which as I mentioned before, was composed predominantly of lead-foot action during the meat of the tuning phase. I would never get even close to 400K's if i was doing that under the stock ROM! Once tuning is over, it will be interesting to see what distances I achieve on passive city and highway travel.

Right now I'm on another ROM, v5b1, which is some more fine-tuning of the v5b ROM. It's been just over a week now since we started this tune, and Edward is still sticking at it, showing me that he has a level of perfectionism that cannot be understated. The fact that he keeps giving me new ROMs almost every day with further fine-tuning shows how dedicated he is to the task and he will not stop until he is absolutely sure he has done everything he can. He is quite literally squeezing out every last bit of performance from my hardware! Of late he has had me reduce the total number of variables I'm logging to increase the resolution of the remaining variables he needs in the logs, and he has used this to great effect.

[west_minist]

I can say we are finished tuning and in many people eyes, we have accomplished what we wanted to achieve. Remember the objectives.

1) Better acceleration
2) Better DBW performance
3) Better fuel economy
4) A safer and stable car
5) Most of all, the customer is happy

For me personally, I want to know that I have improve all aspects of the car, even if the customer is happy. At the present moment, I am trying to improve from 2000-4000 range which is mostly city driving.

We are at v6 and I may have 2 more roms to go as we play around with gas. Good news is, we are almost back at v0 timing. Once the car is service, all will be well.

Some may ask if I could not have stop at v2 or even v4, yes, but the car is being custom tuned and not only that, its 100% stock. You cannot get anything better than that. If Hyrax decide to mod a bit, it will show us what this little NA motor can do with SOHC + I-VVL. But so far so good. Once the customer is enjoying his mountain climbing like how I do here in the Caribbean when I travel tuning STI's, I sure would love it http://www.youtube.com/user/westminist# ... yf1nY5TYdM

[HyRax]

v5b1, v6, v6a ROM update

Late Sunday I had an opportunity to take v5b1 for a spin on the Old Pacific Highway north of Sydney. This was a seriously fun drive with the car just egging me on to put my foot down. It was incredibly lively and most of the tighter low speed turns were easily tackled without any sensation of the car bogging down.

Going down the highway was a lot of fun, but of course very easy being a downhill affair. Coming back in a hill climb fashion was where the fun was really at. Once again, the car powered through the turns, effortlessly climbed the hills and responded with every small blip of the throttle. It wasn't a completely fair test of the car, though because I'm still on stock swaybars and I felt the car had a lot more to give if it were not for the body roll around some of the sharper turns, but what was there was awesome - the car hugged the road in typical Subaru fashion and you were able to easily brake late, leave it in third, low throttle into the turn, apply more throttle halfway through the turn and increase it to flat foot it on the way out with ease with no need to drop to second before the turn. It just felt really strong with absolutely no let down the whole way.

Edward also established from the logs that this tank of fuel I was using did appear to be better in quality to my previous tank and I'll probably write into BP to let them know about my local BP's bad fuel quality. There was nearly no pinging on this tank so what was left would probably be fixed with my next service which will include new quality spark plugs.

Late Sunday I flashed up v6a. This ROM was intended to re-test the v0 timings that were causing me to ping a lot on the suspected dodgy fuel I had when this expedition started. This time the pings were definitely reduced, but there was a very different feel about the throttle - it wasn't as "exciting" as the v5b1 ROM was. I gave this feedback to Edward who posted me back v6a with some fuel adjustments which improved the throttle down low but it still didn't feel quite right.

To test this properly, I established myself a repeatable "test course" comprising of slow roads, fast roads, hills and other areas where I could do a lot of stop-start action without bothering anyone. I performed several "laps" under v6a making a note of how this section of road felt, how that section felt under a maintained speed in fourth gear at 3,000rpm, how much "effort" was required to turn up this sweeper, and how easy it was to start from standstill, etc.

After doing about four laps of this approximately 3 kilometre course, I then pulled over and flashed the car back to v5b1 and drove exactly the same way through the course over another four laps, making note of what felt different.

Finally, I pulled over again and flashed back to v6a again and did another four laps for a final comparison to confirm my findings.

I deduced that both ROMs were essentially identical in their pull factor, both capable of hauling up to redline very quickly, however v6a's application was "softer" making the effort factor feel like the car/throttle was a little heavier. I noticed, for example, that I was putting in a bit more throttle in the stop-start tests to move the car under v6a than I was under v5b1 because it felt as though the car was picking up more slowly and therefore felt like it could stall as I released the clutch (this wasn't actually the case, but it felt that way).

I gave several pull logs and feedback to Edward who immediately took it onboard and sent me v7 to me this morning which contained an enrichment of fuel as the major change. This should effectively incorporate the frisky-feeling throttle from v5b1 with the fuel and timing changes in v6a.

The v7 ROM is on the car now and the throttle definitely feels better already in this morning's general driving. Tonight I will do the requisite pull logs and give final feedback to Edward. Unless he finds anything wrong in these logs, this should be the final ROM, though Edward will probably produce me a v7a ROM once I get my next major service done in about a month's time if it shows that further minor improvements can be made with fresh oil and new spark plugs.

Edward has been great at translating my very non-technical references of the feel of the car into the required technical modifications for the next ROM. On some occasions he's told me not to bother with any logs and just for me to tell him how the car feels here and there, but I've provided him logs anyway as I like pretty comparison graphs.

If this does end up being the last ROM, it's going to be a bit sad really - even though it's only been one and a half weeks, I would come home and gleefully check my InBox to see if a new ROM has arrived, so I could flash it up and have an excuse to go for a spin. Of course this has also been the only time I've ever had to fill up my tank more than once a week too, but the adventure of it has definitely been worth it.

[west_minist]

Thanks for the wonderful feedback. I can understand how you feel.

There is an area that I want to work on to tweet the performance in the 2000-3000 range that I know is needed in very tight corners. I drive mountain when I go to Trinidad, but I understand the need to have lowend torque. I would prefer a responsive car over a powerful car any time, expcept power drift for a 60 degree corner AWD drift

SO if time allows, it is that area I would love to look at and if fueling is a little to heavy (for we do not have a wideband like the Innovate LC1,) we can also improve the fueling more from the tq area to the redline.

Its been a pleasure tuning the 2.5i. All it needs is a Turbo or Supercharger. Raptor sells the SC. Hopefully soon, I can tune another SC to max.

I believe there will be a v7a, since I like to see Zero pinging as much as possible. The Subaru ECU does not have a per gear fuel/ign maps. Hence why v5b1 felt so good.

Good luck with v7. Will let you send me logs later on in the week if these logs are semi clean. I would schedule service like next week

[west_minist]

will rise the rev limit for v8 to an acceptable test one. Send me the results once I release it to you with Dyno's. I think you will love it if have those corners where the stock rev limit caused issues

[HyRax]

There is an area that I want to work on to tweet the performance in the 2000-3000 range that I know is needed in very tight corners. I drive mountain when I go to Trinidad, but I understand the need to have lowend torque. I would prefer a responsive car over a powerful car any time, expcept power drift for a 60 degree corner AWD drift

I need more mountains around here. My closest twisty drives are a minimum of an hour away to get to!

Its been a pleasure tuning the 2.5i. All it needs is a Turbo or Supercharger. Raptor sells the SC. Hopefully soon, I can tune another SC to max.

Haha - I may as well just go get a GT then! Funny thing is, extra insurance to cover adding a supercharger or a turbocharger to an NA car is actually cheaper than buying a factory turbocharged car!

It definitely has been a pleasure letting you tune my 2.5i - the transformation is just incredible, well beyond what I was expecting to be able to be achieved. It shows that the 2.5i is not a second-class vehicle next to the 3.0 and GT, and that the factory tune is extremely conservative. You've really opened my eyes on just how conservative it is and it's a shame the vast majority of drivers out there won't know what they are missing.

Good luck with v7. Will let you send me logs later on in the week if these logs are semi clean. I would schedule service like next week

I'd do the service tomorrow if I could - a major service is pricer than usual, so I need to gather up a few more dollars.

will rise the rev limit for v8 to an acceptable test one. Send me the results once I release it to you with Dyno's. I think you will love it if have those corners where the stock rev limit caused issues

I don't generally hit the rev limiter at all as I'm used to changing gear at usually no higher than 5,000rpm in really long acceleration as that's where power in most NA cars traditionally tends to soften up. I've yet to adjust my driving style to carry throttle all the way up to redline under the ROMs you've given me...! Only the logged pulls have seen me hit the rev limiter lately.