i have a 2005 with a 3 1/2 aps tbe, aps cai,ecutek reflash. i was wondering what you guys suggest my next mods should be and what hp goal is good for if i want to make it fast and have it be a everyday driver.

 

This was my path... currently at 340 WHP and 328 ft-lb.

1) AEM Cold Air Intake.
2) DC Sport Catback.
3) PDE UP and Down Pipe.
4) EcuTek Reflash.
5) Dyno Tune.
6) Port and Pollish waste gate.
(running 110% Duty Cycle on Injectors)
7) Walbro 255 l/hr fuel pump.
8) Perrin 816 cc injectors.
9) Perrin high flow fuel rails.
10) Stainless braid fuel lines.
11) Tein Flex Coilovers.
12) Tein EDFC dampening control.
13) Perrin front and rear 3 point adjustable sway bars - kill the understear.
14) DC Sport equal length headers.
---> Oh the Blitz Sequential Boost Controler.
15) Perrin front mount intercooler.
16) FP Red Turbo upgrade.
17) Perrin MAF Ram air intake - replaced the AEM for better flow. (yes Ram air give you better flow than cold air - I can prove it with the ideal gas law)
18) Perrin Oil catch can and lines for new turbo.
19) Perrin dual gague pod w/ Oil temp and Oil pressue.

All of my upgrades have been performance geared. If you have any questions about the build up, PM me.

 

jw, did you dyno your car stock on the dyno you used to tune? if so what it dyno at stock?or if you know what sti's dyno at stock on that dyno?

 

I would go w/ the following: Where you can get about 400 hp, check this site...

http://www.vishnutuning.com/impreza_sti_stage2_v400.htm


Enjoy

 

Unfortunatly, no - I didn't dyno stock. I have heard that a good powertrain loss assumption is 20% to 25%. Simple math shows that most STIs will be in the 225 whp to 240 whp range. This fit with my car and here is what I learned.

The STI's (and also the WRXs - I think) stock EMS is brilliant beyond almost all other car manufacturers computers. It is able to determine when a change has been made and adjusts the cars timing and mixture to compensate for the change. This means that simple boltons don't do much to help us extract power from our cars.

I first followed the typical bolt on path of a air intake and cat back exhaust. I noticed an immedate power gain but after 30 or 40 miles, it didn't feel much different than stock - WTF!!!. Turns out that the AEM cold air and DC Sport cat back caused the engine to run a bit leaner - hince the power increase. The engine had adjusted timing and mix to compensate for the lean mix and brought power back to stock reguardless of the 700 bucks I just spent on bolt ons.

I then purchased a PDE up and down pipe from a local tunner shop - they highly recomended that after the instal to have the ecu-tech reflash done and tuned on the dyno. I did the install and brought it back to the shop. First run on the dyno was 235 whp (with the up pipe, down pipe, catback and intake!!!). After 4 more pulls and tunning, the car was ticking off 280 whp - still running at a conservative AF ratio.

The issue at this point, stock injectors were at 100% duty cycle so we couldn't push the engine further. With the fuel system upgrade (816 cc injectors, fuel rails, fuel pump, fuel pressure regulator) we were able to get up to 303 whp and 318 ft-lbs torque.

Hope that helps.

 

ya thanks dep do you think i should start on my fuel delivery or should i look into engine management?

 

Ok, you mentioned that you already bought the ecu-tek reflash right? If so, your stock computer aided by a solid tuner and the rights to the ecutek programing should be all that you need for engine managment until you get into serious mods.

First off, having an STI you are already limited with your engine managment options. Thank god that our stock EMS is probibly the best of all of the car manufacturers and can manage a car up to 400 whp (no water injector or NO2 capability). It can absolutly handle a stage 3 car (upgraded exhause, upgraded fuel delivery, upgraded turbo and front mount, even race gas maps). The reason why you can't use a plug and play ecu (such as the AEM) is that the STI has an electronic throttle control as compared to 98% of other imports which have a direct cable pull (most hondas and our little brother the WRX). There are piggy back ecu's you can use for tunning, but I would recomend a PhD corse in engine tuning before risking your 2.5 L by screwing up the maps and shooting pistons out the hood of your car. Bottom line, I suggest your local but capable shop tunes, via dyno, you car - Stick with the reflash for now.

So to make a long story longer, go fuel systems upgrade. Your stock STI injectors will be at 100% duty cycle by the time your hitting 260 to 280 whp. I would get some bigger injectors (minimum 600 cc) but if you have any need to go to 350 to 400 whp go with 800 cc. There are lots of companies who produce them for the STI but I would recomend Perrin. They have a great package - 816 cc injectors, high flow fuel rails, stainless lines. Looks great and is proven in the STI crowd. Complement it with a Walbro 255 L/hr intank fuel pump to provide the flow you will need and if your having problems with idle, a quality fuel pressure regulator at about 30 psi.

You have to have engine management to go this route to tell the EMS that your running bigger injectors and tuning to make it work well. If you don't have the reflash yet, its time.

Hope that helps - remember these are just my experiences - research it all for yourself so you can learn how each component can influance the others.

 

oh you may want to get an up-pipe as well. I went with PDE (good quality) and will help with spool up.

 

thanks alot dep i think i will finish my fuel delivery. i have a aps tbe dont i have a up pipe already? thanks again.

 

By "APS TBE" I assume you mean, an "APS" brand "Turbo back exhaust"? If this is correct, you will still need an up-pipe. Exhaust follows the following path,

1) Headers
2) Up-pipe
3) Turbo
4) Downpipe
5) Exhaust Pipe
6) Muffler/exhaust tip
7) Atmosphere

By TBE, I asume you mean 4,5,6 and of course 7. I won't lie to you, headers and up-pipe are not the huge bang for your buck like eliminating your cats with a DP and Exhaust but they do help with spool up. Everyone likes to yell and scream abou this but I would put some money down that headers (while they change the tone of the exhaust) will give you some 2-3 ft-lbs torque and 2 whp, the up-pipe will probibly give you quicker spool up and another 2 whp. It only applies if you already have the full TBE like you were saying.

 

The comprehensive APS DR Series 3.5" Turbo to Tip Race Exhaust system includes the innovative APS High Flow Turbine Outlet manufactured from Ni Resist iron, 3.5" internal diameter 304 grade down pipe, 304 grade 3.5" internal diameter intermediate pipe with true 3.5" internal diameter resonator, Highly polished 304 grade 3.5" muffler and tip assembly. no upipe in there is there? what kind do you suggest and could you do the headers and up-pipe seperate or is it good to put them on together. What kind of up-pipe do you suggest?

 

I posted on your new thread but didn't answer your other question on headers. If your going to install headers eventually, you might as well do it all at the same time. Especially because you have to loosen them anyway when you install the up pipe.

Hope all this helps.

 

thanks alot dep the sti's uppipe is good enough or should i replace it

 

The other guys are right in saying that up pipe and headers are not huge bang for your buck. Combining up pipe and headers will get you between 4 and 6 whp and about as much torque. Is it worth the money? Depends on your budget. If your going to build a complete car - your going to do it sometime anyway so go for it. Don't go cheep just to do it though.

Your fuel system is going to get expensive. Alot of people modify their stock injectors to stay in their budget. Be careful with this as you can cause one or two cylinders to run really lean or really ritch if they arn't perfect. Spend the money on manufactured injectors.

Bottom line, it blows me away how many people I meet on this forum who spent 33K on their car (one of the most expensive domestic Japanese import cars) and then go with cheep modifications or skimp on tuning. You nutted up for the car, take your time a build it right.

 

I say get a DB 20G, Walbo fuel pump, PE850 injectors and a Custom tune then call it a day with a nice streetable setup