Tom- Impreza wagon project

[Stuart]

Ok,Ok. It can stay red........
Tom
There we are. Tom
Done.

[Andy916]

Oh yeah.........do classic Imprezas have low fuel warning lights?

Yes, but the gauge on mine goes to near zero before it comes on. Think my '95 had one too.

I'll dig out those 4-pots to see what condition they're in.

Andy

[Stuart]

How many miles of steady driving do you get from light on to conked out
Just interested to see how far my first tank of fuel will go. 190 miles so far!

[Andy916]

Not much over a gallon left on mine when light comes on.

Dunno what made me think of this, but I reckon it needs a white stripe Stu :-)

[Monster]

Tom?

I like the red too bud, just paint up the skirts etc with your weapon of choice - rattle, roller, sponge shapes

On the brake subject I'd have to agree with one of the earlier comments about later 4 pot calipers with bigger discs made up to fit. If you remember I ran big AP disc with custom bells using the stock Nissan 4 pots on the zed for years and they were bloody good, streets ahead of the std set up. From memory standard discs were 280, I put 330s on it with porterfield pads, lkept the std calipers and loved it.

Looking good mate, love the hoopage! Bet Dom will kick himself if he reads this for not polishing it up himself. He picked up his hawk eye wagon on sat tho...

[ScoobieWRX]

Get rid of that hair dryer for a turbo and fit this. Shouldn't be too laggy

[ESL]

With respect Francis, alot of this simply isn't true.

I found the stock 2 pot brakes are woeful on the road and dangerous on track.

The diameter of the exhaust will not rob torque.

There is no difference between any of the pre 96 short engines that I have seen.

It probably is a CDB, if there is hatching pattern visible on the block (on the web under the aircon compressor is the most visible place) then it is.

There are a lot of worthwhile mods to increase power you can do yourself from porting your exhaust headers and turbo/wastegate to fitting a decent topmount intercooler with some DIY mods to make it fit. Cold Air induction kit is a good idea when you're flushed unless you can find a 2nd hand unit in good nick. Failing that a decent flat panel air filter (K&N or Green Panel) in the standard airbox will do nicely.

IMHO wouldn't bother fitting larger brake discs with the standard calipers because all you're doing is adding weight. I don't think you can fit bigger pads to the standard calipers so standard rotors with good quality pads as has been mentioned already, and braided brake hoses all round should give you better pedal feel and increased retardation.

As for exhaust....I would get rid of the NURspec system regardless of noise, which i presume is a 3" system and therefore robbing you of torque, and go back to a 2.5" OEM spec tube diameter exhaust whether it's a decatted OEM system or aftermarket stainless steel jobbie. That should get you back under trackday noise limits, give you a beautiful burble and max torque which is just what you want for track work.

A 2.5" system would still be good for 340-350bhp and if as it is suspected, your car is a WRX and not an STi, your engine internals won't be forged anyway as has already been said, and unlikely it's a closed deck block (unless it's been retrofitted), and with 92K miles on the clock and without a rebuild it's maybe not such a good idea to push it too far in terms of mapping when you eventually get there. If you've done engine mods (exhaust/induction etc...) you should get it mapped if anything to get it running right.

If it has a TD04 you could still see c.270-280bhp and c.300-310lbft with mapping. If it has a TD05 16G and supporting injectors and intercooler fitted, with an STi engine installed, 320-330+bhp should be no probs all day long.

I can't remember if your car has camber bolts on the front suspension like the newage cars. If so wack them over to maximum neg camber adding a little bit of front toe out to negate excessive inside treadwear when you're not tracking it and that should help make it turn in nice and sharp whilst reducing understeer. It may even envoke some asre end out and decent 4WD drifts.

I've retired my car now and started stripping it slowly but surely for a more defined role in life so i feel myself being a bit envious of your excellent purchase you lucky so and so, and it's on the road too which must feel bloody brilliant.

Anyhow that's my 10pence worth.....Lovely car and welcome to the dark side. Nice one Stuart.

P.S. I have a version 2 ECU with fitted ESL board i collected back from a customer in scotland recently. He returned his car back to standard just before selling it. It comes with Z4 mapping (260bhp) as standard. Just swap over ECU's and you're good to go. That could be had for a very reasonable outlay and if you buy me an orange and passionfruit J2O i might possibly roadmap it for you too unless you have a preferred mapper nearby you would rather use. Anyway, the offer is there.

[ESL]

"The pistons have to work a bit harder to push exhaust gasses out and that's where the torque comes in."

If I have read the above right, it suggests that torque and load are a function of back pressure. This is not true.

The exhaust system rids cylinders of exhaust gas, encouraging inflow of charge. Remaining exhaust product will both dilute and transfer heat energy to charge, as well as interrupting flame propagation. There is a balance between flow rates and back pressure in NA SI engines.

However, in a turbocharged engine, the biggest restriction in the exhaust system is invariably the turbine. While you can tune the manifold to a certain extent, the best thing you can do post turbine is lower back pressure. This will be familiar to anyone who has removed the cats in a scoob, it has a pretty dramatic (positive) effect on performance.

The example quoted below for Group N cars is more to do with the inlet restrictor orifice than the diameter of exhaust fitted.

Engine load is directly related to the amount of air being crammed into a cylinder. Peak load corresponds to peak torque. Load tends to drop away at higher rpm as the VE falls.

The more practical issue for most of us in lowering back pressure is trying to get underneath the noise limits, as well as adding weight to the car, but notwithstanding that, I disagree with the recommendation at the end of this post.

Cheers

Andy

Keeping a narrow diameter exhaust system, like OEM tube size, creates more back pressure. On a lower power car with a standard turbo that's desirable. The pistons have to work a bit harder to push exhaust gasses out and that's where the torque comes in. If the engine works a bit harder you are seeing higher engine loads from lower rpms which translates into more torque.

3" exhaust systems let the engine breathe more easily and aid exhaust gas escape so pistons don't have to work so hard to push exhaust gasses out. Great for bhp higher up the scale but not so good for torque. Because the pistons aren't working so hard you see much lower engine loads and in effect make less torque.

Example: GrpN Subaru's run OEM diameter exhausts (2.5/8"), not 3". They make only c. 300bhp however they still manage to make between 580 and 600ftlb torque. Admittedly they run 25psi of boost from 2000rpm but that does make the engine work very hard from very low down. Trying to squeeze so much exhaust gas out the OEM diameter exhaust really works the pistons. Subsequently you see huge engine loads and in turn an abundance of torque.

That's why i recommended to Stuart that he runs an OEM diameter exhaust system over the 3" jobbie. Because the car isn't mapped, going back to the OEM diameter system will get the car running better, more smoothly, increase torque, be more fuel efficient, and pull more strongly from low down.

If you don't agree with me no worries, it was just my opinion.

[ESL]

"If your ECU isn't mapped to feed enough extra fuel on boost you risk causing Det (knock)"

The JECS ECU in a classic scoob compensates for this without requiring mapping as the fuel table is specified in AFRs, not IDCs.

In general, we take fuel out as Subaru tend to run low 10:1s, and more power is produced at 11:1 without inducing detonation, and fuel is saved.

I agree that pissing about with the MAF and induction can alter the load values that determines where you are in the fuel and ignition maps, with dodgy consequences. I also agree that checking the car on a calibrated wideband is a good idea to make sure all is well.

I hope this doesn't look like I'm picking on Francis, that isn't my intention, but I see so many misconceptions propagated on forums and then taken as gospel, and that winds me up. Which is why I generally leave the interwebz to it.

BR to all

Andy

The overboost created from running the 3" system on your average subaru shouldn't be an issue so far as turbo reliability is concerned unless it's trying to create too much boost and you start getting compressor surge or stalling. I doubt you're even getting fuel/boost cut from what bit of overboost youre getting.

The issue is with the extra air being crammed into the cylinders. You've got to feed that air with fuel otherwise you're going to be running lean. If your ECU isn't mapped to feed enough extra fuel on boost you risk causing Det (knock). If you run an induction kit as well that can contribute to increased lean running. Induction kits often come with larger than OEM induction tubing and although that increases the volume of airflow it decreases airflow speed and your MAF sensor will read that as same as or less airflow, and you get even more lean running.

It would be worth running a wideband up your exhaust and hooking a set of detcans to the engine, and taking it out for a blat just to see how it's fuelling generally and on boost. It may well be fuelling fine in which case excellent, however for peace of mind when hoofing it i would want to know that all is well. Best done on the road in a real world situation. At this stage I wouldn't bother doing it on a rolling road because you don't tend to see as much airflow, engine load or boost compared to running outdoors.

[ScoobieWRX]

I realise your knowledge on these matters is far superior to the rest of us hence why you do what you do, so i'm always willing to be educated by someone that knows more.

However, I didn't suggest engine load is directly related to back pressure. Engine load is related to airflow and an indicator of how hard the engine's working. I don't think what i wrote suggessted otherwise. I forgot about the restrictor on Group N cars, my bad. Torque is affected by length and width of headers and exhaust. Have i got this wrong?

I didn't infur Torque and load are a direct result of back pressure. Granted peak engine load is directly related to torque, i don't think i've written anything that says different.

When the JECS ECU senses knock i know that it pulls timing however, i thought rightly or wrongly that upon sensing knock it doesn't actually add fuel until it goes into some sort of super limp mode. Equally i realise AFR in JECS is used to measure fuelling, it's the same in newage. I never mentioned IDC's, I'm confused?

We must read some of the same reference materials on exhausts from time to time. Others might find it useful too.

http://www.probe.lv/faili/downloads/pro ... steema.pdf

Thanks for pointing out my errors. It's always useful to know where you're gone wrong