GD 06 STi dynojet dyno- 296awhp, 278awtq

WRBSTi06

New member
Got my car baseline dyno'd with the AP stage 2 93 octane, Cobb intake, Cobb lightweight pulley, catless TBE, and a larger up-pipe. Weather was a cool 65?F. Numbers would have been slightly better but, I had a boost issue that wound up being the restrictor pill in the vacuum line on my turbo.
:lol: but since then, I've replaced the line with the restrictor pill and added a front mounted intercooler..so hopefully next time she's on the dyno, the numbers will be a little higher.:D
 
Fmic on stock turbo??? How late are you hitting peak boost??? You would be pushing better numbers with a top mount on top of spooling a lot quicker.
 

ICY STi

New member
You generally don't want to move to a fmic until your closing in on 400 hp to the wheels. You could be making more power if you stayed with the tmic.
 

HolyCrapItsFast

Drinks beer!
Those numbers are about right for an OTS map give or take. As suggested the FMIC is not going to net you any more power and is only going to serve to reduce overall performance. Here are some suggestions if you really want to squeeze more from your Stage two...

- Return to stock top mount or another good quality after market unit.
- Return to stock or good quality stock size up pipe
- Fuel pump
- 3 port EBCS
- Cobb Cold Air Box (to compliment your Cobb Intake)
- Possibly injectors but not often necessary. Have your tuner review your injector duty cycle to determine if you need them
- Have your tuner turn up the boost to 19psi

With these modest modifications this should net you close to 330-350 if your tuner is good. If you really want to wake that fucker up then definitely get yourself a set of injectors and have your tuner tune for E85 if it is available to you. Your other option would be meth injection. The advantage with meth is you don't have to replace your injectors. :tup:
 
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HolyCrapItsFast

Drinks beer!
I disagree. A competant tuner will be able to achieve his goals without maxing the injectors. I very rarely find a need to replace injectors on the stock turbo. Maybe if it was the 08+ but with the vf39 you will likely run out of turbo before you run out of injector. Im not saying this is the case all the time but i feel you should determine it by evaluating idc before making someone by some very expensive injectors.
 

Vermont

New member
I agree with Fuji on this one, I had my stock injectors maxed out on the stock turbo. I think that once you hit the base stage two (downpipe) if you want to improve power anymore you need to get either injectors or a fuel pump. While I know not all cars are the same, but so far all of the STI's I have seen at stage two have pretty much maxed their fuel system, with IDCs above 90%.

Also, where are you able to get anymore top end power from when you have no fuel up there? Even if you increase the timing up top and drop the boost off a litte, you are still going to running out if you try and go beyond a certain point of air flowing in. Too make more power you need to flow more air into the engine, that air then needs to have fuel to go with it, and if you are maxing out the stock fuel system at a OTS stage 2 then how are you going to be able to get anymore fuel for the increased air being pushed in?

The only thing can think of right now that might work would be leaning out the AFRs up top, but that sounds like a recipe for disaster on pump...
 

HolyCrapItsFast

Drinks beer!
It takes fuel to make power, if the injectors wont flow what the rest of the system does, that will become your limiting factor. It's simple physics. The only way to get more power out of the same amount of fuel is to get a more complete burn which raises exhaust temperatures. Down here near sea level, I have yet to see a WRX or STi that is not near maxing out their stock injectors. A VF39 will flow enough air at a low enough temperature to require more than 565cc of fuel. Hell, the old WRXs with TD04s will max out stock injectors. Naturally, a fuel pump is the first thing to look at to lower IDCs as it is cheaper and DW300 pumps I have seen reduce top end IDCs by 15%. Regardless, the stock fuel system has proven itself to me to be a piece of shit when it comes to making power. I still have yet to see people make decent power on stock injector cars without raising the base pressure.

There is an Ideal AFR for making power and anything more is compensating for either temperature or knock... and that is physics also. Just how much power are you talking here? Stage 2 power is generally made with 19psi or less and will usually not require more than stock injectors and I have proven that to myself several times. Again I am not saying that you will never need them. I have made 350whp on stock injectors no problem and I'm sure I can do it again. The stock turbo drops off significantly above 6000 rpm and the load drops off as well. The fuel requirements are not that great. Heck didn't Gino just make close to those numbers on a car with stock injectors. Of course if your looking for more power than this then injectors are a must.

Also the td04 wrx has significantly smaller injectors than the STi so that is not a good comparison IMO.

My point is I don't think it is in someones best interest to recommend injectors without first making the determination by simply observing IDC... Those things are expensive. That's why I say "Possibly" and the tuner will be able to make that determination.
 

HolyCrapItsFast

Drinks beer!
I agree with Fuji on this one, I had my stock injectors maxed out on the stock turbo. I think that once you hit the base stage two (downpipe) if you want to improve power anymore you need to get either injectors or a fuel pump. While I know not all cars are the same, but so far all of the STI's I have seen at stage two have pretty much maxed their fuel system, with IDCs above 90%.

Also, where are you able to get anymore top end power from when you have no fuel up there? Even if you increase the timing up top and drop the boost off a litte, you are still going to running out if you try and go beyond a certain point of air flowing in. Too make more power you need to flow more air into the engine, that air then needs to have fuel to go with it, and if you are maxing out the stock fuel system at a OTS stage 2 then how are you going to be able to get anymore fuel for the increased air being pushed in?

The only thing can think of right now that might work would be leaning out the AFRs up top, but that sounds like a recipe for disaster on pump...

Quit saying this. It is not a recipe for disaster if you use this technique wisely. I run between 11.2-11.8 wot depending on my strategy and I have even gone as high as 12... do you think this is to lean? If so I will never agree with you. I have so much exposure to so many other platforms and none of them use AFR's as rich as we do. I have been learning from these people and you know what? It works for our cars to.
 

Td_d

Commander In Chief
Hmm... now I'm interested - I had also noticed, whilst monitoring EGTs (albeit indirectly through the AF current and resistance) that it took pretty ridiculously lean mixtures to start hitting critical EGTs - I'm talking mid 12's here - but that's with meth injection.
 

HolyCrapItsFast

Drinks beer!
Yes, and he maxed out the injectors. The car only had a turboback exhaust and a fuel pump on it. Dont forget he upgraded the fuel pump, so its not a completely stock fuel system. An upgraded fuel pump can drop IDCs, but i have yet to see a car with stok injectors actually running efficient IDCs. Anything larger when it comes to cooler charge temps and you get more airflow. 19 psi with a larger intercooler on an older STi will for sure max out injectors with conservative AFRs.

I'll stick with 10.8-11.3 AFRs for stock heads on 93 octane or less. Cars in that range have proven the test of time. Also, have seen EGTs in cars with your target AFRs and they're out of my range of comfort for a reliable daily driven car.

The bottom line is that the stock fuel system is inadequate for a safely tuned stock car, and that for anyone I would recommend a slightly larger injector over just about any other mod.

I'm done here.

I hate statements like this! Coming from you especially. If you understand the relationship between fuel, timing, knock and EGT (And I know you do) you can use this strategy with amazing results.

Also you speaak as though I am staunch against replacing injectors... all I'm saying is investigate it first to see if you actually do. I understand that if I am 90% IDC today and it is 100* outside and I'm at sea level, I should replace my injectors because the moment it cools down i will likely be higher than 90% and likely exceed 100%. Or if I am 90% at altitude and I travel to sea level I will likely exceed 100%. But if it is winter and I am at sea level and my IDC is 90-95%, I won't bother.

What I am against here is blanket statements.
 
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