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Old 28 July 2005 | 04:52 PM
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Cool My own opinions on my specific mods.

Hopefully this will help some of the newbies that keep asking the same questions over and over again.

It will probbaly get moved to Technical but at least it will be referenced here aswell.

Here are some things I have found out and thought I would share with you all as this sort of information seems to be like rocking horse ****. I have found that if you ask direct questions on here you will get either, no answer, the wrong answer or just the bare minimum answer.



As most of you know I run an MY00 Impreza Turbo, fairly standard except for a few choice mods. Here is a list of my mods and the pros and cons I personally have noticed.



1)I fitted a Walbro 285 uprated Fuel Pump.



so far the only difference noted is that is has a much higher pitch whine to it than the standard unit, and TBH the standard pump is capable of pumping 5 times the pressure it is by default set to so in reality there is no real benefit to fitting an uprated pump.



2)I fitted Samco Water Hoses.



Now these are pretty and can with stand higher temperatures and pressures so are probably a worthwhile mod if you intend to tune your car over say 300ps.



3)I Fitted Samco Turbo Hoses.



again probably a good idea if you intend to run higher boost pressures and look a lot better than the black plastic intercooler Y pipe.



4)Perrin Crank Pulley



Now this mod is by far the best mod I have ever made to the car, the throttle response and gear change are very noticeable, the engine spool up is so much smoother and so much quicker I can not recommend this reasonably cheap mod high enough.



5)I fitted an MRT 4.5kg Lightened Flywheel.



This mod did not bring me as much pleasure as I was anticipating. Yes the throttle response is quicker and yes the engine does spool up quicker, but saying that it is harder to do fast take offs and gear changes need to be made faster, engine speed is scrubbed of a lot quicker so you need to either change gear like a mad man or change gear about 500rpm later than you normally would in order to keep up engine speed. Also I have ended up in moving my power curve about 1000rpm further up the rev range which is something I had not expected, anticipated or indeed wanted. The car is now more in line with the power delivery of an STi which for a GT driver is not what I wanted. The reason I liked my GT is because it came on boost at around 3000rpm and I could leave almost anything from a standing start, now I need to wind it up to 4000rpm to get the same result. on the upside I have a higher top end speed now but the car needs to be driven at much higher revs to perform like it did before this mod, which round town is not practical.



6)I fitted STi7 Brembo Front Brakes.



This is a fantastic mod except for the fact that getting wheels to fit over the calipers and clear the arches is no mean feat.



7)Goodridge Braided Brake Hoses.



Again another good mod as they can take a lot more pressure over the standard rubber brake hoses. You can feel a noticeable difference in your braking when you fit these. The brake pedal feels a lot firmer.



8)MRT Brake Master Cylinder Support Bracket.



Not got much to say about this mod as I have not really noticed any major difference with the other brake mods I have made. What I will say is that it is a ******* to fit and the instructions that MRT supply might as well be thrown away.



9)I have an FSE FPR.



But have not fitted it yet, but it seems that it is not really necessary at the moment as the fuel pump is delivering the right amount of fuel and the stock regulator is working fine. However I will be fitting it sooner or later.



10)Scoobysport Decat Downpipe.



This is a nice mod as it makes the car sound better and also aids turbo spool up by allowing the engine to breath more easily, a few more PS can be gained by just this mod alone. However this is not the best solution if you want to me more environmentally friendly. Leaving the CAT in the DP and removing the CAT in the mid pipe is a better solution, the CAT in the mid pipe is not as efficient as the one in the DP due to the exhaust gasses being cooler by the time they reach it.



11)Power Engineering T75 Backbox.



Again this is a nice mod, I personally like it because it keeps the twin exhaust pipes that the Scooby should have instead of the one huge outlet that makes the car look stupid. It has a wonderful sound and is very well made. However the noise that reverberates through the cabin can get too much on long motorway drives. I have no idea if this mod adds anything performance wise except for the whole exhaust pipe being the same diameter from start to finish.



12)STi Tail lights.



Purely cosmetic, makes the car look good as it does away with the orange indicator panel. The downside to them is that they are Japanese and do not come with a fog light fixture. This is easily overcome by cutting a hole in the back where the OEM one would be and fitting one yourself.



13)Morette Quad Headlamps.



Again another good mod when used in conjunction with high quality bulbs, I have the Philips 50% plus bulbs in mine and there is a big difference over the stack headlamps plus they look better and give the front a much better look.



14)GFB Hybrid Dump Valve.



Not to everyone’s taste and can be annoying when it vents to atmosphere constantly but can be fun to play with, some say that it just causes a placebo effect and does not gain you any performance over the stock one. This may be the case on some cars but after I fitted mine I did notice that there was a very noticeable decrease in turbo lag and the turbo responded a lot quicker.



15)22B Rear Spoiler.



This does actually produce downforce but the standard run of the mill driver will not notice any difference over the stock STi4 spoiler fitted to the car, except for the fact that the boot lid is now heavier. However, when driving down a dusty gravel road the car behind me could see the air flow going round the car and through the spoiler. So it does work. I am not an expert driver so AFAIAC it is purely cosmetic and finishes the car off.



16)22B Bonnet Vents



Again, purely cosmetic, except for the slightly bigger holes in the mesh.



17)P1 Front Splitter.



Cosmetic and finishes the front of the car off by closing the gap between the side skirts. However I have heard that if it is fitted properly it can increase downforce on the front of the car.



18)3 Port boost Solenoid.



Not fitted yet but will hopefully be done when I can get a remap around Christmas time.



19)APS Cold Air intake



Not yet but will be done when I can fit the boost Solenoid and get the remap.



20)PPP Resonated Mid Section



Hopefully waiting for me in Cornwall and will be fitted at Christmas.



21)PowerStation Bumpstear Mod.

Apparently a worth while mod, I have had it done but can not vouch for the effect as I had the suspension done and also the drop links and ARBs. On the whole my car handles like a go cart now.



22)KW Variant 1 Coilovers.



I can not rate these enough, the difference they made to my car is just amazing, This mod is by far one of the first things you should do to your car, forget changing the springs and keeping the stock dampers this is not the way to go, If you can afford a set of coilovers that have the springs and dampers designed to work in harmony with each other you will run rings round the same car with just lowering springs fitted.



23)ARBs and Drop links.



I changed both ARBs and the 4 drop links and the result was good the whole car is much stiffer now and can be thrown around a lot more aggressively than with the OEM parts fitted. I have the rear bar set on the middle hole and it suits my driving style at the moment.



24)Strut Braces.



I have the front one fitted and am not convinced it does very much, or at least nothing very noticeable to me as a fairly standard run of the mill driver.
Old 28 July 2005 | 06:05 PM
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Good post,but whats a hybrid dumpvalve?
Old 28 July 2005 | 07:51 PM
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I would have thought, with all those you'd have an after market air filter? And at what point would you suggest a remap for correct fueling?
Old 28 July 2005 | 08:45 PM
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Ok, so lots done and some good info....

Whats the extra bhp/torque??
Old 29 July 2005 | 10:26 AM
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I am currently running it with an STi panel filter in the OEM airbox but have removed the resonator section from the wing.

Hybrid is just the specific model of dump valve from the GFB range that I chose.

I currently have a TEK 2 ecu so most of the minor changes will be coverd by the off the shelf tek 2 map.

There are currently no performance mods fitted that really justify having the TEK 2 remaped which is why I have not fitted the boost solenoid or the APS Cold air intake.

When I get back to the UK at Christmas I am hopefully going to get them fitted and get the ECU remapped.

Also in my opinion the mods to make first are definately the Suspension, Brakes, Brake hoses, ARB's and Drop links.

Then you will have a car that has handles better and is a lot stiffer, but also has the braking power to stop when you start to add mods that increase power and performance.

You will also benefit from 17" wheels, I have no idea why but when I changed mine from 16 - 17 the car behaved completely differently with regards to eliminating tramlining.

after you have the rolling chassis sorted it is then down to you what you do next. Maybe a good start would be to replace the standard ECU with either a TEK2 or if you are feeling rich and adventurous one of the many other after market ECUs around.

Bare in mind that the more power you have the more pressure there will be in the hoses so maybe uprated silicon hoses would be a good next step.

Now I think you are in a good position to make your first power mod change and I would go for a decat downpipe, out of preference I would go for a single entry Downpipe and not the twin dump variety.

then maybe a backbox, this will not gain you anything except more noise, and if it is one of these ones you can park a mini in then it will also gain you tosser status aswell.

The next and probably most noticable thing you can do is to change the crank pulley from the 2.5kg OEM one to the 500g Perrin or GFB one.

now that you are starting down the slipery slope of performance mods it is probably about time to change the air filter system, either to an STi panel filter which will fit directly into the OEM airbox or to an induction kit.

Be carefull if you go down the induction kit route as they are not usually as straight forward as us mortals think!! aparently the K&N 57i is a straight swap and does not require a remap or flood the MAF sensor with to much air. The APS one however does need a remap otherwise it will kill the car.

I would wait until I have stockpiled enough parts that need remapping and fit them all in one go and get the whole lot remapped together, not only will this save you money but it will be one mapper that does the job instead of maybe 1 or 2 different mappers mapping various parts. Not that this should be a problem but as we all know no two people do things the same way.

Thats about it the rest is down to your own imagination, wants and budget.

Happy modding.
Old 29 July 2005 | 02:39 PM
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re the crank puley are there any cons of using an uprated one idling etc?
martin
Old 29 July 2005 | 03:10 PM
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Originally Posted by p1doc
re the crank puley are there any cons of using an uprated one idling etc?
martin
The idle speed stayed the same but I found that the engine felt a little bit lumpy abit like a v8 does but this can be compensated for by adjusting the tick over.

Here is a question that I sent to Damian Harty at Prodrive and below that is his answer.

Hi Damian

I have a question that I am hoping you can answer after not having any luck on Scoobynet.

I have an MY00 Impreza and have started to do little mods to it, the first one was to change the OEM crank pulley for a Perrin lightened on.

The OEM one = 2700g

the Perin one = 500g

now to me that is a major weight change from the front of the engine but the rear of the engine and flywheel are still the same weight.

I have noticed a smoother faster engine pick up but am also noticing the engine is shaking and bouncing a bit more than it used to.

So what I want to know is what would be the optimum weight for the rear flywheel in order to regain perfect engine balance from front to back, without losing the initial momentum of the flywheel when accelerating hard from standing.

I have heard of some flywheels being to light and warping or shattering and coming up through the cockpit.

Can you help me out with these maths.
And Damians Answer.


I can't always guarantee to answer such questions, but I have a moment this morning. As ever, the answers are frustratingly imprecise.

Engine balance is about making the moving bits of metal inside the engine compensate for each other in order to not have them shake the whole engine. There are many aspects to it, and much confusingly vocabulary that goes with it, so in order to illustrate what I mean I'll take a typical inline four cylinder engine ("I4") as an example. In an I4, there are two pistons going up and two pistons going down, so the engine has what is called "primary balance" - this means that in a over a whole revolution what is going up is balanced by what is going down. If you look at the long side of the block, then the pistions are arranged in mirrored pairs, so the engine also has no tendency to "see-saw" - this means it has what is called "rocking balance". However, if you now imagine only the connecting rods there remains a balance problem with the engine. Start with the connecting rod vertical and placed on a table (this is a thought experiment) - think of it in an imaginary bore. Then move the big end out to one side by a distance equivalent to the crank throw. If the small end stays on the line of the bore, then moving the big end out pulls down the small end. This happens twice during each revolution of the crank. If you think about an I4 then you will see that this effect is the same for all four cylinders - in other words they add to each other. This gives I4 engines their characteristic "buzz" and to fix it you need a "Lanchester balance shaft" - fitted on bigger/faster spinning four cylinder engines like Honda Blackbird, Saab 2.3, many Mitsubishis. It's known as "secondary imbalance" because there are two of these motions for every revolution of the crank and so those shafts are sometimes called "secondary balancers".

OK, so that was the first bit, now onto Boxer 4 specifics. The boxer shares many characteristics with the I4 - it has primary and rocking balance. However, it also has secondary balance because the piston pairs work in opposition to each other. There is a small rocking imbalance if you look at the engine in plan, caused by the bore offset between banks, but it is small in the overall scheme of things. This is one of several advantages the Boxer engine has over the inline engine.

So far, if you've been following this, you'll be thinking "so where does the pulley fit in?" The answer is that it doesn't. The flywheel has nothing to do with these questions of fundamental engine balance.

However...

The engine is "intermittent combustion", which is engineering code for there being a bang and a long period of coasting for the crank before the next bang. During the bang, the crank speeds up very quickly and then after the bang the frictional drag slows it again. If the engine slows too much, it stops before the next bang - this sets the minumum idle speed. The flywheel is an attempt to minimise these speed variations because there is an "equal and opposite" speed variation on the engine block. I put it in quotes because it's actually the force variation that is equal and opposite; the speed of the engine block is determined by the engine mount rates and its mass compared to the crank and so on. However, the point is that the bangs make the crank and block jump and the flywheel smooths it out. The flywheel mass is a compromise to get the idle speed low without a lot of dancing about by the engine, since the dancing is a source of discomfort in the car. Getting the idle speed low is good for emissions because they are basically proportional to idle speed during the idle part of the cycle. There's no reason at all not to take the flywheel and split it in two, putting half on the nose of the engine in an apparently overweight pulley and half at the back. In fact, for the health of the crankshaft it is often helpful to distribute the "flywheel" mass all along it - this is common practice in racing engines that use "internal" balance weights and very little by way of a phystical flywheel. Note that racing engines have a significantly higher idle speed (the WRC idles at about 2,300 rpm).

I've slightly simplified matters here because the intricacies are somewhat arcane (and I'm running out of time) - but basically your lightened 'flywheel' (i.e. pulley) will make the engine move more at idle. I'm betting that at 7,000 rpm you can't tell the difference? The flywheel mass is disproportionately important in the lower gears, and so reducing it will have a readily apparent effect on the pick-up of the car. My best advice is to lighten both the flywheel and the front pulley proportionally, and be ready to turn up the idle speed to make the engine not bounce on its mounts too much at idle. If you leave it bouncing on its mounts then you will wear them out prematurely, and you might notice some gear rattle in the transmission with the lighter flywheel, but this is a very low energy phenomenon and nothing a good stereo won't cure.

So, all in all that was a fairly simple answer - but I just wanted to lay the foundations to make sure you could see where I was coming from. Hope it wasn't too long-winded.

Regards,

Damian

P.S. If you could forward this on to Simon de Banke and ask him to put it on the board, that would be great - I'll leave it to him to decide where he wants it (or if he wants it at all!)
Old 29 July 2005 | 03:56 PM
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thanks-think iwill have to read that fully!
martin
Old 29 July 2005 | 04:40 PM
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Originally Posted by Wurzel
You will also benefit from 17" wheels, I have no idea why but when I changed mine from 16 - 17 the car behaved completely differently with regards to eliminating tramlining.
IMHO having just changed from 16" to 17" on my classic I haven't really noticed a huge difference, the ride does seem perhaps a bit firmer but may all be in my imagination. Haven't pushed it much yet though, waiting for the tyres to wear in a little bit first. I've never experienced tramlining and I'm not sure that it may be more down to tyre choice and pressures rather than the wheel size. I've always ran Goodyear F1's after getting shot of the rubbish that was originally on the car. I've had the geometry and bump steer mod. done by Powerstation, I guess that may also make a difference.
Old 29 July 2005 | 04:46 PM
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Originally Posted by Graz
IMHO having just changed from 16" to 17" on my classic I haven't really noticed a huge difference, the ride does seem perhaps a bit firmer but may all be in my imagination. Haven't pushed it much yet though, waiting for the tyres to wear in a little bit first. I've never experienced tramlining and I'm not sure that it may be more down to tyre choice and pressures rather than the wheel size. I've always ran Goodyear F1's after getting shot of the rubbish that was originally on the car. I've had the geometry and bump steer mod. done by Powerstation, I guess that may also make a difference.
You could be right there as I only used the RE050s or whatever they were that came with the car on 16s.

I switched to 17s and fitted S02s and they were absolutely awsome! pity you can't get them anymore.
Old 29 July 2005 | 05:29 PM
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Hi Steve,

Well-written, good summary, nicely done. Definitely a useful guide for people starting out with MY99/00 cars!

About tyres: the original Bridgestone RE010s were notorious for tramlining. I changed to Toyos and then Goodyear F1s and never had any more problems with this.

Air filter: I too have the STi one, after the other aftermarket one (one with an oil-soaked filter) caused my engine to blow up by killing the MAF sensor! So an important note to all people looking to change the air filter: GET A DRY ONE! The best one IMHO is the original STi one available from a few of the bigger Scooby specialists active on this BBS.

Uprated fuel pump: this I think is mainly for track use, or really hard road driving; it protects the engine (I think?) from fuel surge on hard cornering when you have less than 1/4 tank of fuel. Therefore 99% of drivers will not notice any difference tbh.

Bump steer mod: this, combined with proper laser alignment of all the wheels and toe-in/camber correction, revolutionised the stability of the car. All done in an hour or so at Powerstation.

Just a few thoughts there, will keep an eye on the thread...

Cheers
Richard
Old 29 July 2005 | 06:54 PM
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Most useful thread going since I joined this forum.
Top job certainly gave me a few ideas/advice on what to do next.

Ashley
Old 29 July 2005 | 10:18 PM
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indeed very useful re balancing of flywheel/pullley
martin
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