Boost controller

There are basically two types of boost controllers to replace your stock system. Manual and Electronic.

First of all, your stock system is set for 9 psi (91-93: 60 kPa ) or 10 psi (94-99: 69 kPa) of turbo boost pressure. This can be turned up but only so far. How far depends on the health of your engine and your fuel system. On a stock fuel system and engine you will NOT be wanting to turn it up past ~14psi due to this being at/over the 90-95% IDC of the stock 360cc injectors. In other words, this is the maximum you can go on stock injectors before you 'run out' of injector (or basically - fuel). Whether you can go to 14 or not depends on your car. What you are wanting to avoid is overboosting. Or basically "knock". This will ruin your engine.

Manual Boost Controllers (MBC) are just that. Manual. You install, set them, forget them.

Electronic Boost Controllers (EBC) are operated electronically from the cab and also perform some other nice functions. Most have a boost gauge or display also. They are a lot more money and for a good one the price averages $500-750.

This is also the point where having an accurate boost gauge is important. A good one, not a POS one that will ruin your engine because it is inaccurate. e.g. - 12 psi showing on gauge versus 15 psi (or more) being actual pressure in the engine = damage to your engine from overboosting. Or, you can just go with the one in the EBC itself but most owners want a gauge they can see easier than the built in ones on the EBCs. Most are hard to read or in a place not quickly visible and again, a good boost gauge will be the most accurate for setting and/or monitoring.

This is an item that gives you a big bang-for-your-buck. There is a BIG difference from 9psi to 14 psi (more than a 50% increase).

But again - turning up the boost will place much more strain on engine parts. If your bottom end has a lot of miles or you have other things that are worn then be careful. In fact you may want to consider not going all the way to 14 psi. The only way to really know is to monitor knock. You can do this with a logger system (big PITA IMO) , or, better yet - a scanmaster system. But in lieu of that you can just go to 12-13psi. talk to someone that knows about injector IDC and knock as it applies to your car and be guided by their advice.

Do not overboost your engine

Brand-wise I personally prefer the Blitz brand of EBC. Either the i-color one or even the model just prior to the icolor which has a nice limiter and interface. But there's always new stuff coming out so take a look at whatever are the top sellers at the time you go to buy. Many also have other features like multiple settings (ie - valet setting, and so forth), HP calculators from accelerometer calculations, and so forth.

NOTE: SEE PAGE 5 - if you are possible going with a new EMS (like the AEM ECU package) then you do not need an electronic boost controller. The AEM can do all of that for you. Save your money.

The stock BOV works pretty well most of the time. but when you start turning up the boost it will need a better one for the higher pressures. The BOV controls the turbocharged air when you let off the throttle (and close the throttle plate) so the air has somewhere to go. The stock system (MAF) is one that has the released air RECIRCULATED as opposed to released in the atmosphere. While some cars go open most will have some lag or stumble so to do it right you want to recirc the air. The only other way to not recirc is to go to a MAP system which usually involves installing a new EMS system (replacing your ECU entirely). This is beyond the average owner that does not want to install this many modifications and tuning requirements.

Your MAF system has already METERED the air once it goes into your intake. So when you let off the air is redirected back to the intake side of your turbos. Your ECU is expecting that air to be there. So if you do not recirc and blow it to the open air then that metered air must be made up to the ECU and it's calculations for your engine. That's the basics of why many can get a stumble if they do not recirc. Some report they don't but it is more likely that they just do not notice. The air that was already metered is lost if not recirc'd and that represents performance lost.

The most popular by far is the HKS SSQV BOV. It works very well for even high power cars. Beware black market knockoffs! eBay sells bunch of crappy fake HKS ones. Do NOT buy these! They leak and are junk. You risk damaging your engine. Pay the price for a proper quality BOV.

The other ones are the Greddy, which is okay but older style was best and now hard to get. Another is Tial and they make the best ones I think but usually these are only indicated on the very high HP applications. They can handle the big stuff (by that I mean 1,000 HP and higher). For most the HKS will do nicely.

There are a few others and some are really loud. While I realize some want that sound, it should NOT be a reason to choose one over the other. Besides, doing it right means you will recirculate it so sound means nothing. Leave the playing with car parts to make noises to the ricers and amateurs. If you do not recirc your BOV you will actually be losing performance.

The fuel pump modification is two fold. One is the pump itself. There is another model of Denso pump other than the one that came with your car that has a slightly higher output of fuel than the stock one in your VR4. It is sometimes called a "supra" pump because it came with those cars. But both (Your OEM one and the Supra one) are Denso brand pumps with different output specs. The higher output pump will basically 'drop in' to replace your existing one. Denso Part #195130-1270.

This isn't to say that the novice can take 20 minutes and do it because that's not the case. But it isn't a huge job and there's a few tips to make it easier and things to avoid.

There is also the walbro pump that many have used but I see no reason to put in a pump that isn't drop in and is really noisy. Plus the walbro can fail in a cavitation situation (as in low fuel in tank and a sharp corner). The only reason I see for someone to put in a walbro is to save $100 (or thereabouts). To me that is not a good enough reason. just spend the little extra money and drop in a proper Denso fuel pump. You'll be glad you did.

The other thing to be done is called Fuel Pump Hotwire. What this involves is simple. The stock wiring in the VR4 is a little too small for the power that the fuel pump pulls. Even more so when you go to a little bit bigger output pump. So what is done is a larger gauge wire is run from the front of the car, direct to the battery, back to a relay for the fuel pump in the rear. Always make sure to have a proper fused line (at least 30A) and seek the advice of an expert if you are not educated on working around gas tanks and power wires.

Some of the early hotwire kits had the little in-line type blade fuse holders. These melted and failed. They could easily cause a fire in your car (and actually has for some people). So make SURE and use a quality high amperage fuse in your hotwiring of your fuel pump.

Larger Turbos

The stock turbos (9b) are really not as bad as some people want to portray. They do however peter-out in the upper RPMs and are quite limited in what they can produce over stock levels. And it is usually easier to just replace worn stock turbos with ones a little bigger. Like some 13's. The other popular size is the 15g turbos. Both the 13 and the 15 are TD04 which means they will mount right up to your stock manifolds. They are bolt on.

Larger, like 16G, etc. are TD05 and require a lot more modifications. They are not fully bolt on and go turbos.

There are other ones too that utilize the makers initials or naming. But saying WHICH turbos is not the goal of this list. You'll have to figure out your goal and budget (remember?) and then go with some advice from owners of those turbos that fall into your goal/budget. Not all turbos in the same HP potential or price are created equal. And don't believe the internet racers on which turbo to get. I've seen one particular turbo be talked about like it is really great but my experience (in several installations) is that they are really a poor choice and have a lot of problems.

Be advised that you can run these turbos (the 13 or15) as you would your old 9b ones for now but you will not realize any higher potentials they have until you add in more fuel. Adding in more fuel (bigger injectors) is a big step in budgeting. But don't go too big on your turbos only to fall flat. You want to match up the turbos with your expected goals and fuel system plans too.

Lastly, make sure and get the full warranty info on your turbos. Most ALL turbo retailers will require you install brand new oil feed lines for the warranty. If not they may not honor the warranty. So ask before you buy what the warranty covers and requires before you buy them.

(REMEMBER - THIS GUIDE IS NOT HERE TO COVER EVERY TYPE OF MOD. Nor to address all options out there. It is for beginning people wanting to understand the basics of performance modifications. Things change each year and new things are produced and applied.)

I'm not going to elaborate here about the different turbos other than as above already. It is a lengthy topic and also depends on your other factors such as goals, fuel, street or race or both or.....you get the drift. First decision is size (ie - manifold mounting) being TD04 TD05 or even bigger like a single or custom. A fast bolt on to your car is TD04 (9b, 13, 15g, etc). If you want larger like 16 then those are TD05 and require all different manifolds in order to use them (read - add into the cost of the turbos).

This is a bried section on turbos. Consult in more detail with the supplier/builder oyu chose to go with and be guided by their expertise or advice.

On manifolds see next section:

OK, we talked about plug wires earlier. Now the ignition system itself. The stock coil packs are very good. All but the heaviest mod'd 3000 needs to change out the stock coils, but if you want to there is the MSD system that has been used by quite a few owners in the higher HP ranges. I am not going to go into detail on the MSD change as that is more complicated than we want to get here.

So the coil pack is good for most. Wires depends on your application and goals (see page 2). If you are going to be turning up the boost on your engine then you may want to at least move the plug gap a little closer. The other option is to install an ignition amplifier. One of the best is the HKS Ignition Amp. It is a terrific performer and I've never heard anything bad on them at all. They are pretty easy to install and will give your ignition one heck of a bump (so forget about changing your gap, you can keep it up there).

The only other thing would be to go a range colder on your spark plugs if you are going to routinely be running higher boost on 93 octane. This helps prevent knock. before going to change your spark plug heat range I'd advise to learn about what the heat ranges means and what you want to achieve. Until you turn up the boost to over 10 you needn't worry about a colder plug. If you go above 10psi to , say, 18+ then go 1 range colder to start. More than 24 and you go even colder. It can be trial and error by reading your plugs directly.

And contrary to what some say, stick with iridiums unless you are doing a lot of track work and want to change them out all the time. The base (aka 'copper', although they are actually nickel, lol) plugs are fine if you are a racer and change them all the time but most of the people reading this will not be those people. So decide on your heat range based upon your fuel/boost and go with the iridiums in that range. You can always look at a couple in front to see how they are doing (reading a spark plug reference for you HERE).

Somewhere along the line you need to pay attention to your clutch. The best clutch by far is the OEM kit from Mitsubishi.It lasts the longest and gives the best results. However, if you start approaching 400 and higher your stock clutch will not hold. You will have to go bigger. There is a range of clutches out there and brands. Suffice to say that this guide hasn't the room for a full clutch discussion or review. For the average performance mod'er SPEC makes a good line up of clutches. If you want a top end clutch that will hold most anything you throw at it (and is rebuildable for a low price) then the Carbon-Carbon by RPS is the answer. But initial cost is high.

So just realize in your planning that a new clutch system will be indicated.

Some people want to put on a big FMIC (Front Mount InterCooler) for looks (rice?). Which is rather stupid, especially if you are running stock turbos. You will actually LOSE performance. But there will always be those that think they can just buy and stick in a FMIC and 'be cool'. Same guys that use fake carbon fiber and vinyl wrap on their car, lol.

On your VR4 you will not need a big FMIC until you start putting out some serious HP on some pretty large turbos (like 16 and larger). They are just NOT necessary. Plus you introduce system lag (aka - compressor surge) which will reduce performance and give you grief (like chuff chuff chuffing at cruise levels). Not every car gets it or in varying degrees but it is present in a twin system so until you get some very large turbos I would advise to not put in a FMIC.

Another thing you introduce is blocking your radiator and reducing your cooling system's efficiency. This has to be accounted for or you may begin having overheating issues. Do if your build does not truly need an FMIC then don't put one on. You are spending money to reduce performance and introduce other problems.

Heat soak concerns are something internet racers talk about. Are you really going to be doing back to back drag racing? Probably not! So SMIC (Side Mount InterCoolers) do just fine. Seriously, are you building a dedicated drag car or just want some added power to your DD or weekend car?

You CAN upgrade the stock SMICs to larger ones that are custom made by a few people in the USA (like the "DSM" SMIC which are popular currently). They are quite a bit larger and deeper and do a great job for most turbos up to the 16s and 450-600HP ranges. HKS also made some but are no longer available except if you find a set used.

We could do a whole section on transmissions and mods but I'll be brief. As you start putting out more power you must be prepared for the rest of you drivetrain to deliver it to the wheels. So your transmission is the start of the process and will be getting hit harder as you turn up the power.

Making sure it is in good condition and nice clean oil is a start. There's not a lot you can do with it in the car. Once it is out you can get a bellhousing brace welded in, add in a 300M output shaft, or just send it in to 1 of 3 places that will currently give you a performance rebuild.

You can also upgrade the front and center differential in your AWD transmission. This will give you increased control and traction.

There's not a lot for me to address here as it isn't for the novice to do anything with.

As with the transmission, there isn't a lot to mention here. At a certain point if you are putting out a lot more power or wanting to do some drag launches you will want to either A) get a brace onto the transfer case, or, B) get a billet case.

Used by many owners. It helps take out oil fumes from re-entering your intake and therefore helps keep your intake cleaner. A simple add on that assists with maintaining your engine.

There are some 'loggers' but most are very clunky and there is a lot of limitation on what they can do for you. There is the Scanmaster which is very nice and can monitor knock live and display it. So for tools to monitor some engine parameters the scanmaset is one of the best. It reads stock O2 trims so you can tell if you have a vacuum leak and reads real time knock. Not to mention displays codes, volts, coolant temp, can be configured to read the wideband 02s on the front screen, can log and graph all parameters, etc. All for approximately $250 new! Note: You can't use it at all with a standalone EMS so if you are going to go that route with an upper build plan don't bother with this as your standalone can already do all this and more.

The basic idea is - having some way to start watching your engine performance in a few critical areas once you get to the upper HP ranges. This really won't be needed until you get into larger injectors But I mention it here anyway. If you go standalone EMS you won't need any of this (its all part of it). See EMS in the next section.

NOW ONTO THE BIG MODIFICATIONS
MORE POWER!

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