Few Newbie Questions - Please Help (Long)

[kb8]

Hi everyone, I'm new here, and I just wanted to ask a few questions before I get into modding my Rex.

These may seem very 'beginner-like', but please don't mock or laugh at me. If you want to do that, please don't respond.

1. What's an uppipe, midpipe, and downpipe? Which is the most beneficial? I've been looking at Vishnu Performance's Stage Zero kit, and I believe it includes an uppipe. Why not a mid or a downpipe?

2. Does the downpipe lead to the exhaust? Is the wider the better?

3. What's the difference between a catback and a turbo back exhaust system?

4. Is a turbo timer really necessary? Subaru claims that for the '02 WRX, the turbo cools itself down w/out the need of a turbo timer.

5. What is the exact purpose of a blow off valve and is it really necessary, or more for noise?

6. Is a cold-air intake system necessary? Or maybe I should ask, when would a CAI become necessary?

7. Is messing with the turbo at an early stage a good idea? I mean, I've heard of kits to enlarge the turbo for $650. I think it's called a FP Hybrid. What does that do? Is is worth it?

8. While looking at the Vishnu website, I saw a $2475 TEC II system. What is that for? Would that give me more wheel HP just by buying the system? Or does the 'support' a more powerful WRX (400 HP or so).

9. How many wheel horsepower can I gain from investing $2,500 in my WRX? I realize that tires, lightweight wheels, driving classes, brakes, and other things are beneficial too, but for the sake of this thread...how many can I gain?

10. What's the main difference a manual boost controller and an electronic boost controller (besides controlling boost manually v. electronically). Is one safer over the other? Is one better than the other? Is it easy to damage the stock turbo with any of these?

11. Lastly, when would I need new STi injectors, fuel pumps, fuel cells, and all that other stuff?

Thank you so much everyone for being patient and reading this (hopefully). Any or all answers would be greatly appreciated.

Have a great weekend =)

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[K-WRX]

[quote]Originally posted by kb8
[b]Hi everyone, I'm new here, and I just wanted to ask a few questions before I get into modding my Rex.

These may seem very 'beginner-like', but please don't mock or laugh at me. If you want to do that, please don't respond.

As Roseanne Rosannadanna used to say: "you ask a lot of questions" I'll try to help get you started by answering a few:


1. What's an uppipe, midpipe, and downpipe? Which is the most beneficial? I've been looking at Vishnu Performance's Stage Zero kit, and I believe it includes an uppipe. Why not a mid or a downpipe?

]The up-pipe runs from the RH manifold to the turbo, and contains the 1st of 3 cats in the exhaust system. The downpipe is what exits the turbo and also has a cat; the midpipe is the pipe between the downpipe and muffler sections, and in the stock WRX, also has a small cat. The up-pipe and downpipes are probably the most restrictive part of the exhaust. Shiv (aka Vishnu Performance) is developing a downpipe for his Stages to come.

2. Does the downpipe lead to the exhaust? Is the wider the better?

Yes (see above) and most of the aftermarket exhausts or performance kits feature a 3" exhaust.

3. What's the difference between a catback and a turbo back exhaust system?

Turbo-back replaces the exhaust from the turbo to the muffler; Catback retains the stock downpipe and replaces the midpipe and muffler. Turbo-backs offer more performance increase, but Cat-backs are less expensive, and allow you to remain in stock class in SCCA Solo II for example.

4. Is a turbo timer really necessary? Subaru claims that for the '02 WRX, the turbo cools itself down w/out the need of a turbo timer.

As you say, Subaru doesn't think they're necessary; just remember to let the car idle for a minute or so if you've been hammering your turbo.

Well, that's about all I've got time for, maybe some others can help you out with the rest of the questions - or try a search.

[wackie]

Most of the answers to your questions can be found by spending a few hours surfing this board and doing some searches. But I need to kill some time at work so here goes.

1. Up-pipe, down-pipe, mid-pipe, etc are all a part of the exhaust system. The up-pipe and downpipe are named based on the direction the exhaust is flowing out of the system. The Up-pipe goes from the headers (exhaust collectors) UP to the turbo. The Downpipe goes from the turbo DOWN to the mid-pipe, that then feeds into the muffler. I can't speak for Shiv in why he included an up-pipe and not a down pipe, but I can say it was most likely with future upgrades in mind and to keep the cost of his kit down. Replacing either the up or downpipe will improve turbo spool up as well as noticeably increase horsepower and make your car much more drivable when you're not boosting. In the case of the up-pipe, you should see lower EGT (Exhaust Gas Temperature) readings if you replace the factory up-pipe with one that does not contain a Catalyctic Converter. Lower EGT's are good. This allows you to "turn up the volume" in your engine once you have aftermarket engine management.

2. The downpipe leads to the mid-pipe. Wider is generally better in forced induction engines. It has been said that 2.5" is all that the stock turbo will need to flow to it's full potential, but you can't go wrong with a 3" system. 4" would probably be a bit of an overkill, and I don't even know if you can find a bolt-on 4" system for the WRX.

3. Turbo-back systems replace the down-pipe, mid-pipe, and muffler sections (everything from the turbo back). Cat-back systems replace everything from the Catalyctic Converter, back. I believe this is the mid-pipe and muffler section on the WRX. I'm not exactly sure because I never looked into a cat-back system. The down-pipe gives awesome gains and I would definetly do that before a cat-back.

4. This has been debated quite a bit. I personally do not run a turbo timer. If I run my car hard and on boost I just make sure I let it idle for 30 seconds or so before I turn it off. I guess I do have a "manual turbo timer" of sorts. A turbo timer definetly wouldn't hurt.

5. Technically speaking the blow off valve just releases pressure that has built up in the intake system. The stock blow off valve (wastegate) can hold enough pressure for the boost levels you can run on the stock turbo, so there really is no use in upgrading it unless you're running some extreme boost pressures (truthfully I'm not even sure exactly how much pressure it can hold, but I know it's more than I run). One thing to watch out for is atmospheric venting BOV's. The stock BOV releases its pressure back into the intake system and recirculates the de-pressurized air. If you vent to the atmosphere (like a lot of the aftermarket units do) you end up running rich (wasting gas) because the ECU was expecting that air to be present and added more fuel accordingly.

6. There have been some issues with CAI systems leaning out the Air/Fuel ratio and thus possibly putting your engine into a dangerously hot state. This can be accomdated for with aftermarket engine management. Whether or not it's [i]necessary[i/] is really up to you. At some point a higher-flow intake could be very beneficial, like when you upgrade turbos. Before that point it should only provide marginal gains in output. Up to you. How much money do you want to throw around?

7. The Forced Performance Hybrid is a very nice turbo upgrade (from what I've read). I believe they estimated it could handle 350HP or so. I tend to like to let my engine breathe better and get some aftermarket engine management in place before upgrading something like the turbo. I can't stress enough how much finely tuned engine management will improve the power and driveability of your vehicle, especially with such a drastic change as a higher flowing turbo.

8. TEC II is a fully user programmable standalone engine management system. Basically you will be unplugging your stock ECU and hooking that up in its place. In itself the unit won't give you any more horsepower. However, with an experienced tuner (like Shiv at Vishnu or Mark at TurboXS, or Cobb Tuning, etc) you can see some very noticeable gains. Generally speaking people run this or a similar unit when they reach fuel delivery needs that are out of the realm of the stock ECU/Piggyback ECU, or just want to tune the engine themselves.

9. How much WHP for $2500. . .? That's a tough one. Look at some of the kits available (Vishnu, Cobb, TurboXS, etc) and that will give you a good idea. I don't think I'm qualified to answer that.

10. You can easily damage things with any boost controller if it's set too high. There are advantages to MBC vs. EBC. Those are discussed in great detail in numerous threads around here. One of the main advantages is the pricepoint. You can buy an MBC for $35 or build one for $5, and until recently EBC's were around $300. Check out the EBC that was just developed for our car, by an I-Clubber, listed in this forum here.

11. STI Injectors aren't a necessity, it's just a name brand (I believe Denso makes some for our car). But injectors that can inject more fuel will become necessary, as well as other fuel system mods, when you start sucking in more air than the stock injectors can handle. I believe this occurs with most every turbo upgrade. So to be safe, if you upgrade your turbo, upgrade your fuel system. However, this can only be optimally configured with an aftermarket engine management system.

HTH

JD

[IFANTIG]

umm what they said. If you're thinking about mods...uppipe, and turbo-back exhaust is definitely a great way to go. Just an uppipe alone will yield good results. Check out the car parts section and see what other owners are doing.

[kb8]

Hey thanks a lot guys for answering my questions...very informative =)

[xfactor834]

Nice list of questions. Nice list of answers too.