hi I am really confused now
I have a MY99 which as I understand have 2 Cats one in the midsection and one in the downpipe. I would like to take one of them out. according to the figures from pete's car he got more power and torque from the midsection not the downpipe. also the mid section is a lot cheaper. can any one comment on this please? and are ss backbox and midsection loud (I live in a quite area and I would hate let the Neighbours know of my timetable). does any one have them fitted around Dundee or Edinburgh to let me have a listen.

thanks


[This message has been edited by Sam Elassar (edited 23-09-1999).]

 

The dyno figures for Pete's car are misleading. They were taken on two seperate days. There were a number of other cars that had run the same two days as well. Most cars were down 10bhp on the second run, due to the heat. Additionally Pete's car did not sit well on the rollers the first time and gave high figures.

I would suggest that the downpipe would be more effective than a mid section. I had a downpipe on my RB5 Prodrive. You will get better pick up and it will pull harder.

Jonathan

 

Jonathan's right. The tests were done in very different weather conditions and this will always show a difference in output. On the first test, I got 171bhp at the wheels, which if pro rata'd to Ian Cooks 99 would give a flywheel figure of mid 250's. As the tracking was out, it wasn't possible for the computer to accurately measure the rolling resistance... despite Merv trying his best to keep the car straight.

On the second test, my car was fitted with an STi centre section. A customer, with an STi, wanted one of our centres fitted and we didn't have one made up, so he asked if he could swap with mine. When I drove home that night, the car was noticeably slower. On the rollers, he was up, by what I was down.

I will get the car re-tested soon, with our full exhaust system.

There are other car's on Paul's site that have the full system and you can see the gains.

Neither Dave Power nor I thought the centre section would make much difference, but it does. The STi 5 centre (as fitted to the 99 Prodrive Performance pack) is straight through, but the silencing seems to upset the gas pulsing and it does work better without the front silencer or cat.

Removing the centre cat will not affect emissions, but the downpipe will.

 

ahhh
that explains few things. the thing is I got in contact with Falkland performance centre in glenrothes and they said the same thing, however they suggested the magnex midsection as it comes with a silencer (as I don't want the car to loud). also they suggested a superchip. according to them the superchip is safe enough if you don't abuse it.

 

Hi there

I had superchip fitted 6 months ago, i woul recommend it, i have had no problems with my93wrx.
As long as it is not constantly thrashed i think it is a safe bet.
Great performance increase.

 

Yes you said it though a safe BET!!!! The number of horror stories about Superchips and holes in sides of engines is quite scary really. I certainly wouldnt have a superchip fitted to any Scooby because of the crude way in which it tricks the system into producing more power.

Darren

 

Any idea what is this crude way of Suoperchip ????

 

Whether or not the superchip method is a bad idea..the funny thing is that you can buy a bleed valve for £20 which will do exactly the same.
This is what I'm doing. I've put an article on my site which explains how to get the extra boost.

 

If you increase the boost on the Subaru, the ecu senses the increase, and thinks that something is wrong.It then tries to reduce the boost,and seems to reduce the fueling too.I've tried playing with boost, and I finally realised why HKS/Superchips/etc' use a gizmo to fool the ecu into thinking it's running less boost.This can actually be done for the cost of a bleed valve,and one cheap component.Less than £25 !!!.

The ecu know what the boost is via the 'boost map sensor'.This converts pressure into a voltage,which is read by the ecu.The 'gizmo's' reduce the output voltage,and the ecu thinks it's running less boost than it is.

This is where the problems arrise.If the ecu thinks it's running, say, 1bar of boost, when it's actually running 1.2bar, the fueling , and ignition advance are set to 1bar.Too much advance, not enough fuel.

If the gizmo is set to run a very small increase in boost, most people will be ok, as the Subaru is notorious for running rich.But not all do.

To SAFELY increase boost, you need to be able to adjust the fueling, and advance to match.On the Subaru this can only be done with an add on board, replacement ecu, or by adding a series of HKS type gizmos to artificially increase the fueling, and adjust the ignition.

If you like to gamble, go the Superchip route.If you want to drive your car as hard as you want, and not worry, go for a complete remap.

Mark.

 

Howdy...

The superchip (and others - eg PTS) conversion is a two part conversion.

It consists of a bleed valve and a fuel cut defender (Superchip call it the AVS board). This removes the ECU boost limit that cuts the engine (you'll know when this happens).

So... The bleed valve allows more pressure and the AVS clamps the signal from the extra boost, so that the ECU still thinks you are running lower boost. The problem with using the AVS is that the ECU has only got mapping upto the built in cut off point (virtually - can go a little higher). But after that the fueling levels out at the point the cut off level was set at.

So if you run more boost than the cut off point, no additional fuel in being introduced. Superchips dont alter the fuelling or ignition.

Scoobs do run rich, which is why superchips can get away with this method. But remember every car is slightly different - some run richer than others.

This method of tunning was first used on early turbo cars like R5's...very crude... There are far better ways of tuning which (remapping) which alters the fuelling and timing if required.

Another problem with bleed valves is that you are always venting... even at lower boost. Therefore the turbo is always working hard...and it will take longer to develop boost. A better method would be to fit an electronic boost controller (still really needs fuelling addressing), these devices keep the wastegate shut until the boost pressure has reach the preset limit.... then it opens it. This allows for boost to be developed as quick as possible without leaking/opening the waste gate.

Hope this helps...

J.

 

Hi,

Don't miss the point that whilst a bleed valve does take a small amount of pressure away the the actuator is not opening the wastegate as fast which allows boost to build up much, much more quickly thus overcoming the very small loss from the bleed.

Firefox's description of the Superchip is spot on, they limit the voltage output of the map sensor to either 3.9 volts or 4.2 volts dependant on car. This means that not only is the fueling and timing wrong but that the safety cut never works either, so who wants to work out what happens if a control pipe comes off then ? Even Superchips cannot (will not) state that the mod is perfectly safe. Re-mapping is the only real way to do it. Oh, BTW not all cars run rich.

 

I agree that using a Fuel Cut Defencer or similar device is a risky proposition and that an ECU remap is the way to go. However, I think that electronic boost controllers can still be useful. From personal experience with the HKS EVC4 on my previous RX-7 twin turbo and my current Evo4, it seems maximum boost builds much quicker with the unit in control. Furthermore, the set boost level can be held all the way to redline. Stock, my Evo makes about 13psi of peak boost, but can't hold this all the way through the rev range. So even if I set the EVC4 marginally higher, at say 14psi, the car feels much quicker. A full 14psi of boost builds very quickly and is held all the way to redline. I don't have to worry about fuelling issues because 14psi is well below the factory fuel cut and the stock ECU can easily cope. There really is a huge seat-of-the-pants difference in acceleration using the EVC4. Turning the unit off lets you make an easy comparison.

My advice for those who can't get an ECU remap is to consider an electronic boost controller, and to set the boost level just below the factory fuel cut.

 

Thank you for the advice
So are you trying to say I should get one off these HKS boost controllers, is that the same as a chip but safer as you can control the boost yourself depending to your driving needs??(Track, road, etc). Does anyone have it for a MY99? And how much does it cost.? Advice appreciated.
Also my clutch is making a squeaking noise when I change gear between 3000-4000 revs in 2nd and 3rd gears I have only done 800miles and it is going for its first service on Thursday.
Any comments will be of value as I am pretty new to this game.

 

Hi there,

As a few people now know.. I have a few HKS "gizmos" in my car.

I have been using HKS kit (inc the EVC IV) for quite a while.

I agree 100% with whats been said, it does maintain pressure right upto redline. And it does allow boost to be built more quickly (but not earlier).

I have an EVC IV for sale (I have another fitted to my car too).

I would like to re-iterate: THE EVC IV DOES NOT ALTER FUELING IN ANYWAY

It just allows more boost pressure to be generate. Aslong as you dont exceed the ECU pressure cut off point you will be fine.

I personally use HKS units as building blocks, becuase they allow me to add and change parts/kit with time.

The HKS EVC IV isnt ECU/Car specific (the same as any EBC isnt). It is real easy to install 3 pipes on the scoob, and a +12 and Ground wire... thats it.

The EBC has a self learning mode.... you put it in this mode... go for a hard drive, where you are making maximum boost and the unit learns the boost curve and max boost settings, etc...

The EBC has a high/low setting (so you can set it to run "no boost" for economy and high for road/track). It also has a safety boost level (if this is reached the unit is disabled and the car returns back to normal boost).

It also has a trigger (scramble) option, this allows you to run extra boost for a predetermined time.

Some people say the Blitz EBC is better. To be honest I've never used, I've always found the HKS to be fine.

EBC's arent keep... to be honest I would use it as a starting block to future tuning...

I'm not sure how much they are now... they arent cheap ...400+ quid.... a full remap is only 650 + vat

I hope this has helped?

Cheers,

J.

ps - In relation to your clutch... are you sure it is your clutch ? only those gears ? is it a screeching or whining noise ? what happens if you press your clutch pedal slightly ? 3000-4000 revs ? (its that valve again - on a MY99 ? LOL)



[This message has been edited by firefox (edited 26-09-1999).]

 

IMHO
If you want a reasonably priced boost control system contact Van Aaken Developments in Bracknell. Does nothing for fueling etc but is on of the best UK systems and its very easy to use and install. Had this on my Cav. Turbo, really good. they will tell you that its not suitable for the Impreza but it does everything that has been posted about here.

Boost controllers are, of course, useful aids to performance ... just get your fueling checked out before you rely on it !!

 

firefox
it is a screeching noise only through the gears if you try to change quickly. it is from may be 1/2 way to 3/4 depression.
what valve ?

so will i be able to get the same gains from the ebc or evc as from a chip?
thanks and [please bear with me it is all new to me ]

[This message has been edited by Sam Elassar (edited 26-09-1999).]

 

sorry, repeated message

[This message has been edited by Sam Elassar (edited 26-09-1999).]

 

Hi Sam,

A remap will be your best bet.... you can safely increase boost, to a higher level than with just a EBC because the fueling will be adjusted to compensate.

Chances are 1/2 is when your clutch is released... it sounds like it could be that, making the squealing noise. Have you got full travel on your pedal ?

Any clutch slip ? do the revs jump ? have you tried any quick starts ? slipped the clutch ? fried it ? How long have it been making the noise ?

Its to hard to say without being there.... best thing is to take it in quickly.... let a dealar have a drive...

EBC = Electronic Boost Controller.

Like Bob says, there are other manufacturers of boost controllers, quite a few that will be cheaper than the Japanese ones.

Cheers,

J.

 

Thank you firefox, Bob and everybody for their comments.
I will take the car to the dealer on Thursday, as the problem does not present itself all the time as a matter of fact I went for a drive today and the noise as reduced a lot (although it is still there).
I will take the car to a performance centre on Saturday to get the geometry settings done, and a silenced magnex midsection pipe. (I am currently waiting for ss box and boot spoiler but they are all out).

I am also toying with the bleed valve idea suggested by lee earlier. it sounds good, cheep, safe with reason and reversible come selling time. i will keep you posted if it works.

Cheers


[This message has been edited by Sam Elassar (edited 26-09-1999).]