Edcase

Ok, on my 02 WRX, to start with I don't want to change the turbo / injectors and fuel pump. I will change them, but that will be 2nd stage.

I am planning and / or already have a full decat, APS TMIC with scoop and splitter, 3 port solenoid and a decent set of equal length headers with a custom map.

I'm looking for torque more than BHP, I hate lag so am not keen on big turbo and FMIC. I want clean, fast spool up and decent held boost around 1.3 bar. Ideally I'd like to hit the magic 300/300 but figures don't really bother me. Driveability does.

Does any of that add up? Where does the standard turbo top out? Will the standard pump and injectors cope with anything approaching 300/300?

I have more questions...but after these

Thanks in advance.

Nology

Edcase,

I'm no ECU mapper but just wanna share...
The std TC ( if yours is still the TD04 ) flows approx 360cfm @ 14.7psi. It takes roughly 1.5cfm to make 1hp, which means to attain your magic nos, you will need ~450cfm. ( get a TD05, like what i'm trying to do now! )

Your stock fuel system will be struggling to support that figure too. With stock FPR, let say at 43psi(3 bar), BFSC 0.55 and IDC of 90%, the fuel barely supports 270hp....

On the other hand, when you up your boost on the std TC, with the pressure diff, you are actually moving towards surge line or moving away from your best efficency islands so temp rises.How far you are moving away from it you will have to look at the map.

When i couldn't find a good mapper to do the job for my scooby in my country, i gave John Banks a mail. He advised i could up my boost but get a KL!

Cheers
keet

pat

Edcase,

if you want a fast spool then using a set of headers isn't necessarily the best thing to do. Because the headers are designed to flow better, they tend to have a larger surface area, and because there are more tubes, the overall volume tends to be greater. This can delay the spool up of the turbo.

Since you don't want to swap the turbo right now, you won't see much benefit from the headers... of course if you were chasing horsepower and were changing the turbo and injectors, the headers will make a significant difference to the top end flow

With regard to torque, it is inextricably linked to boost pressure. Given that the torque peak always happens near the Volumetric Efficiency peak, the absolute value of the torque (at a given boost pressure) can only be altered mildly by changing the breathing (unless it was stupidly restrictive to start with).

You cannot hold 1.3 bar on the TD04L, it's simply too small for the job. Even if you wire the wastegate shut it just runs out of puff at the top. There is no problem running 1.3 through the midrange on it, and tailing the boost off at the top. If you want a turbo that will spool quite early, the VF35 may be an alternative; on a free flowing exhaust system we can get a bar of boost by 2600 RPM and it will be happy to hold 1.3 to the redline on a WRX.

The 300/300 figures are achieveable on your existing hardware, but I would not necommend that this be done as a permanent solution. It really is stressing the poor little turbo and your injectors will be flat out at the top. It will run ever so slightly leaner than it ideally should. At 300 BHP it will run about 6% CO on the stock injectors. To get the 300 lb/ft you'll need to run up around 1.4 bar.

You don't need to worry about the surge line, but the choke line may give you some issues because the turbo is so small. The stock fuel pump isn't the most impressive ever made and even with the smaller turbo and injectors I would suggest it a wise precaution to replace it. If you do a fuel pressure regulator at the same time you can run higher differential fuel pressure, which will help a lot with the fuelling at the top of the map. As for the injectors, like I said, in stock trim they're maxed out to make the 300, if you raise the fuel pressure you should be able to get that back down to 95% IDC.

I would suggest that although it is possible to achieve your targets simply by remapping, this is not the best way to approach it, you'de be pushing all the components very hard and putting a lot of thermal stress on the engine. It would be more sensible to fit components which are more suitable for your power and torque targets. Generally, the stock hardware will support a safe 280 BHP and around 270 to 280 lb/ft, after that it gets stressful.

Hope this helps,

Pat.

Edcase

Guys - many thanks for the answers, pretty much confirms my expectations, all apart from the headers which I was told from a trusted source would yield 25 ft/lb across the rev range. Maybe they thought I was uprating the turbo too.

So what is the absolute maximum achievable on a VF35 (2nd stage I was looking for about 360bhp which pretty much maxes out my aps top mount)

What are the boost characteristics of the TD05?

Pat am I correct in thinking you can map different boost values per gear?

john banks

TD05 reaches 1 bar about 100 RPM later than then VF35. I estimate the TD05 could run about 40 BHP more than a VF35, but we don't have VF35 compressor maps so that is purely my estimate. It outflows the VF22 by about 11% on dynos and according to the compressor maps, and the exhaust wheel is bigger and capable of supporting at least 430 BHP. The TD05 can hold 1.5 bar quite happily at 6000 RPM. But for this you need a beefier fuel system, good intercooling and good octane.

Per gear boost mapping is a UK STi and UK MY99/00 only feature IIRC.

The TD05 at 1.5 bar is plenty to trash a UK gearbox even on the standard clutch and without missing any changes, with good quality gearbox oil.

[Edited by john banks - 5/20/2003 11:23:29 AM]

[Edited by john banks - 5/20/2003 11:24:40 AM]

Edcase

So if I'm looking to crack 400 on stage 2, I'd be looking at a TD05? Will this bolt straight on to an 02 wrx?

I believe the APS tmic is only safely rated to about 360 horses (which, lets face it, is more than enought for most ) so if I decide also that is enough, then the vf35 should be capable of that kind of figure, with the APS and some headers?

Any issues with fitting the vf35?

I'll worry about transmissions later...

john banks

Depends on your dyno, but I think the TD05 would struggle for 400, maybe 380 is more like it running silly boost with a FMIC and lots of octane booster. You've not a snowball's chance in hell without a FMIC on a 2.0 otherwise IMHO. And if you engine holds together at that there will be other bits that fall off your car. IMHO you'd end up blowing >£10000 on your car to get a reliable all rounder 400+ BHP car.