STi guys - save me 11 million searches on NASOIC

[.RJ]

Strut cars are a bit different, as there is no camber gain in compression as there is with a dubble-wishbone setup. You will almost always see a positive camber gain in roll due to deflection, but in a strut car its much more noticeable.

[G.Irish]

would a non-strut AWD car react similarly? i'm not familiar with the nuances of the camber curve in my car but i'm curious if the monster front bar would have a similar effect.

does the STi have a LSD in the front diff? the reason i ask is that i also wonder if the bar doesn't just work in a mechanical grip sense, but also in manipulating the AWD system. if, when cornering, the big front bar causes the inside front to be light under corner exit, would that not cause the diff to transfer power to the outside front and perhaps to the rear also? that would in turn cause the car to tuck in and possible oversteer on exit, right? :?

Scotty I've thought the same thing with the Subaru autox guys who remove their rear bars. Would a bigger front bar have the same effect on a BMW or Porsche? Or even a RSX?

[Andy]

Strut cars are a bit different, as there is no camber gain in compression as there is with a dubble-wishbone setup. You will almost always see a positive camber gain in roll due to deflection, but in a strut car its much more noticeable.

RJ,

I though DB Wishbones have natural negative camber so when loaded, the increased camber actually increases the tire patch. IsnÔÇÖt this the big advantage to DBW suspension?
Also, MacStrut setups have very little to non natural negative camber so when loaded, the overall positive camber minimizes contact patch. Is this correct?

[.RJ]

You have to separate compressoin (i.e. car on jackstands, the spring is removed and the suspension is free in motion) and roll (i.e the car is cornering).

You will gain camber in compression with a dubble wishbone car but not with a strut setup. You will lose camber in roll (overall) in both situations.

[G.Irish]

:?: But when you're cornering you're experience compression and roll so couldn't the net effect be zero or negative camber gain?

[.RJ]

The net effect could be negative gain, but that depents on the amount of camber lost in roll vs. camber gained in compression, type of bushings used, etc, etc...

[Beej]

intakes and BOVs are a no no on an otherwise stock boxer and can lead to some problems down the road.

Awesome, since these are apparently the two most common mods on these things. Now I know the basics of turbos and blah blah, but why is an intake bad? I can't seriously imagine that it screws up the tune.

Hard to find a car without one or both of these in the short time I've been looking.

[ScottyB]

Now I know the basics of turbos and blah blah, but why is an intake bad? I can't seriously imagine that it screws up the tune.

it might not be so much that it's bad as much that it provides no performance gain. this is the case with a couple turbo cars i can think of because the stock airbox is well designed and well heat shielded.

[Evan]

You will gain camber in compression with a dubble wishbone car but not with a strut setup.

thats incorrect, you do gain camber in compression with a properly designed macpherson strut, but it isnt as much as a double wishbone.

While the honduh guys love to talk about how much struts suck, a modern well designed strut suspension can be just as effective as a double wishbone. Porsche and BMW dont seem to have too many problems winning with them....

[G.Irish]

While the honduh guys love to talk about how much struts suck, a modern well designed strut suspension can be just as effective as a double wishbone. Porsche and BMW dont seem to have too many problems winning with them....

Eh, I kind of see it the same way I see Porsche's rear engine. It can work if you put enough effort into it but its not the ideal performance solution. Given a clean slate to build a supercar pretty much everyone would start with double wishbones. Exhibit A: Porsche's own Carrera GT.

For certain applications where durability may be more important or space constraints are a problem then the struts may be a better solution.

[.RJ]

Struts work a lot better in RWD apps where the front end isnt doing all the work.

[D_Eclipse9916]

Now I know the basics of turbos and blah blah, but why is an intake bad? I can't seriously imagine that it screws up the tune.

it might not be so much that it's bad as much that it provides no performance gain. this is the case with a couple turbo cars i can think of because the stock airbox is well designed and well heat shielded.

I have noticed that on a lot of turbo cars. intake does nothing on DSMs. The only reason we get different bovs is because the 2g plastic one doesnt hold anything over 15 psi, so basically its a first mod to replace it with a 1g, that can hold 25 psi crushed.

[ScottyB]

it might not be so much that it's bad as much that it provides no performance gain. this is the case with a couple turbo cars i can think of because the stock airbox is well designed and well heat shielded.

I have noticed that on a lot of turbo cars. intake does nothing on DSMs. The only reason we get different bovs is because the 2g plastic one doesnt hold anything over 15 psi, so basically its a first mod to replace it with a 1g, that can hold 25 psi crushed.

right, same deal with audis....our bypass valves are cheap plastic, meant to only deal with 8-12 psi or so. and the intake is right next to the hot ass turbo so unless you heat-shield and duct the hell out of a cone-style intake you lose alot of power. but the stock intake doesn't satisfy my inner-rice because the bypass valve sound is totally snuffed out

[Beej]

Yeah, I understand that they might not have benefits.

What I want to know is how they could possibly cause problems later on down the road. I just don't get it.

[ScottyB]

Yeah, I understand that they might not have benefits.

What I want to know is how they could possibly cause problems later on down the road. I just don't get it.

maybe they flow enough extra air to induce a lean condition? i dunno.

[Maengelito]

there was a thread on nasioc awhile ago about the k&n typhoon intake. a guy went to machv, dyno'ed his car in stock form. then installed only a k&n typhoon intake and dyno'ed it again. he ended up gaining like 13hp and 10 ftlbs of torque. i'd say thats an amazing gain for like $250. i was considering doing that.

[Beej]

Yeah, I understand that they might not have benefits.

What I want to know is how they could possibly cause problems later on down the road. I just don't get it.

maybe they flow enough extra air to induce a lean condition? i dunno.

But the air will still be metered...

[WRXtranceformed]

Yeah, I understand that they might not have benefits.

What I want to know is how they could possibly cause problems later on down the road. I just don't get it.

Subaru ECUs are extremely fine tuned to the stock airbox, and extremely fine tuned in general. They are unlike many cars in this aspect, in that the intake system has already been engineered for well over 300 horsepower at the wheels. Many aftermarket intakes change the velocity and / or entrance pattern of air into the intake which confuses the stock MAF sensor. This is why, with the stock ECU programming, adding the majority of aftermarket intakes onto the WRX/STI causes problems. Some people will tell you that they're using XXX intake and that they haven't had any problems, but guaranteed they have been running lean.

How can you fix this? Easy, get a custom tune. But, that would obviously be a colossal waste of money for just an intake. If you do more mods, such as a turboback exhaust and an intake, it might well be worth spending the money on a custom tune. I've heard really good things about the K&N Typhoon on the STI seeing some pretty good horsepower gains. The key is though, the ECU has to be reprogrammed or overridden because of the change in airflow from the intake.

Blow off valves are no problem, unless they were atmospheric, which is what most people do. At the worst they make you run very rich... I had a 100% atmospheric on my WRX and it stalled out at a stopsign because of it heh. At the very worst, on an STI, it will foul your spark plugs.

How can you fix this? Run a blow-through MAF setup like on my car (MAF sensor is after the blow off valve =p) Or, you can get an adjustable BOV like the Forge or GFB where you can set it to 75% recirculate 25% atmospheric. You would notice no difference really in performance.

Hope that helps.

[Nis01]

Any Intake system on the STi simply leans out the car and can produce gains... The K&N Typhoon does this and produces great gains but also seems to provide a lot of heat soak when the car is run hard for any period of time. The main problem seen is people want the cool sounds of the turbo and put a BOV on the car that runs the car rich between shifts. The stock BOV can hold more PSI than the stock turbo can throw at it so that has no need to be changed. As long as it is a high quality/tested intake (K&N, APS), you should have no problem... Issues seen by the leaning out are rough idling and code throwing caused by the changes of flow passed the MAF sensor... this is fixed with engine management (Cobb accessport, TurboXS UTEC). Pretty much anything you do to the car, at least get simple engine management for safety concern. Cobb accessport is like $500.00 and is a simple base engine management system. (simple flash of the ECU by a handheld device with pre-tuned maps). Pretty much point being, the stock system was designed fairly well and changing these specific parts does not provide many realistic gains. Also it changes the dynamics of the car that the stock ECU does not like and can effect performance negatively if not done properly.

EDIT: Lee beat me to the punch.

[Beej]

Yeah, I guess it all makes sense. Didn't think it would be THAT sensitive to things like that.

Finding a completely stock car is a pain in the ass.