Larger Injectors

Now that you've pretty much squeezed the most out of the bolts ons and efficiency mods, if you want more power you've got to burn more fuel. Fuel produces the power. So you want to put more of it into your engine. You don't want to go too small for your expected goals but you also don't want to toss in huge injectors if that is not matching up with your turbos or your performance plans and goals. But this must be decided because the car will have to be tuned for them. Usually this is done on a dyno which is the most accurate and professional way to do it.

There are several brands out there and varying prices. Personally I recommend Injector Dynamics brand. They are more expensive than the others but they tune up quicker and nicer than any other injector around. They are also high impedance so you will want to remove your injector resistor pack under your hood too. Or you can go with a set of RC or other brand too. It's up to you but in my opinion the Injector Dynamic brand gives the best results and are nice and stable (and the battery offset tables are dead on which can't be said for the others).

Anyway, match up the size (550cc, 650cc, 750cc, 1000cc, etc) to your plan / goal.

Be wary of used injectors unless you trust the seller. Even then you might want to send them in to get cleaned and checked before using them if they are not brand new.

The problem is - to control it properly You cannot just put more gasoline into the engine and call it a day.

Your stock ECU is expecting 360cc injectors. That is what it bases all of it's calculations on. And there are many (remember the air calculation from the intake MAF v BOV?, things like that). So when you put in larger injectors you must add something to control them properly. See below.

Engine Management System
(EMS)

You have an ECU (Engine Control Unit) in your car now. It is a LOCKED system. Meaning you cannot 'tune' or adjust it. So how do you get it to work with larger injectors?

Two answers - A) piggybacking, or B) replace it.

A) Piggyback units like an aftermarket fuel controller (Apexi, etc) or The Greddy eManage, go in between your ECU and your injectors. They then translate the signals and "fool" your ECU into thinking the injectors are stock. That's it in a nutshell.

This is the lesser expensive way (initially) but not that much once you add up the added wiring and tuning time to get it dialed in. The other drawback in my opinion is that these devices always drift or are needing tweaking ALL the time. I've yet to see a high HP performance car with a piggyback in it that the owner wasn't fussing with all the time. To me that's a big PITA. But some have luck with them. They also couple it with a MAF translator too. By the time you are done figure on at least $800-$1500 (approximate).

B) Replace it with what's called a Standalone or EMS (Engine Management System). The one most people use in our cars is by AEM. But there are also other brands like Motec and Haltech.

The standalone replaces the entire ECU. It is open meaning that everything (and I mean EVERYTHING) is now adjustable / tunable! So you tune for the larger injectors directly. As well as your timing map, fan controls, knock sensing, O2 feedback, the works. You basically now have control over just about every aspect of your engine. It will control nitrous, transmission operations, boost (no need for a boost controller - you save 600-700 bucks right there!) and a huge list of other things.

The AEM serial gauges also plug right in and save you from multiple gauges (each one can monitor multiple parameters at once).

Your professional tuner at the AWD dyno will also be able to tune the car faster and better. AND it will stay dead on unlike the tweaking piggybacks.

So in the end it is actually LESS money to go standalone due to savings on boost controller, gauge abilities, tuning costs, and also many other things that would take too long to go into here.

The standalone is the professional way to take care of tuning your bigger injectors and getting the HP you want out of your engine safely and consistently. It is what I recommend. The EMS box and sensors will cost you approximately $2,000-$2300.

Considering it controls the entire engine and many other things too - doing it right the first time makes sense. Your VR4 depends on the ECU/EMS for so much that to go cheap just doesn't make sense to me. It is a critical component in the performance build.

Fuel Pressure Regulator
(FPR)

The stock fuel rails can handle a pretty good amount of fuel. There is a fuel rail loop that is popular due to the belief that the stock one (that joins the front rail to the back rail) is restrictive. I don't know when that would truly present itself but they aren't much money so it is not a bad idea. I don't know any numbers that anyone has produced that actually show this to be the case though.

The aftermarket fuel rails do look a lot nicer though!

As for larger fuel lines. All but the biggest builds go to new fuel lines and fittings and filters. Pretty much 1000 HP and higher are the ones that need to do this. The stock lines can easily handle a 750hp range build.

Radiator / Fans

Once you start making more horsepower you also create more heat. This is a direct relationship. So you will need a larger radiator when you get up into the higher numbers. The VR4 radiator is very efficient as stock and the fans are also very effective. In fact many higher HP cars prefer the stock fans over the FAL brand (Flex-O-Lite).

Most go with a multi-pass Aluminum Radiator like Koyo brand. And many go with the FAL dual fans because they have to fit in there! The bigger radiator gives problems getting in the stock fans.

If you are going for a very big build (~ over 700-800 AWHP)I recommend the Derale brand fans. They pull a lot more power though so you cannot use the stock wiring harness by itself. But they cool like no other fan I've ever used. You'll just have to do custom fabrication to install them.

Also see the information on your COOLING SYSTEM and proper maintenance plus other information.

Harmonic Balancer

Tuning

Planning for tuning costs is part of the build process. I've seen several people spend all their money on the car and/or engine but be left with no funds to get it tuned properly. Set aside some of your budget for getting tuned professionally on a dyno.

ENGINE INTERNALS
If you are going to be upgrading to the point of needing to protect your bottom end internals from a much higher HP output then you have to decide when you will be wanting to do this. Usually it is a good idea to get this done sooner rather than later because you really cannot seek that higher power output without risking damage to your bottom end/internals. So this area is separate as it is more the 'shortblock' build plan for a performance engine. Meaning if you are going to be going over ~500 AWHP or more then this is something you want to examine now. If you are not but you have high mileage then this work will probably be a good idea too but not necessarily all the parts like the pistons and rods will be necessary. Again this is very subjective to your overall goal, timeline, and budget.

If you have what's called a 4 block main block then you will likely have a forged crankshaft (some 1993s and all 1994-1999). If you have an older car then you probably have a cast crank. Most would agree that you should just put in a forged crank now if you are gong high performance. Sometimes the old cast can hold a lot of power so it's up to the owner. Just realize that if it does then you will have to rebuild all over again. A new forged crank from Mitsubishi is about $1,000 with tax, shipping, etc. (ballpark).

I am not going to address custom cranks or things like that here. If you are going that route then there is more to talk about than there is room for here.

The stock head bolts are pretty good up to a point. When you start getting into the higher boost pressures though you may decide you want stronger studs to hold your heads down. I recommend A-1 Technology head studs. A set runs about $800.

Ceramic coating or performance coating is a nice way to contain the heat in a turbocharged system. Increased performance is seen by keeping in the heat. Heat wrap is also an option. High HP builds get nice gains from this and the time to do it is when your engine is apart and getting rebuilt. Performance coating of pistons is not advised.

One of the biggest performance coating companies is right in Auburn, Washington. PerformanceCoatings

As mentioned above, usig race gas is a consideration for high HP builds. Not just racing. Of course if you are going to drive your car everyday then this isn't always an attractive option. But you CAN have two maps available if you run a standalone EMS (eg - AEM EMS) and use the pump gas map for normal driving and then switch to race gas for the track. A minor drawback is that you do have to drain your fuel tank to switch over each time.

There is a lot that can be written on race fuels. I personally prefer the VP brand fuels but they are also the most expensive (as in $15-20/gallon). But enough to note here that not all race gas is the same. Not even close. And you will have to dyno tune for the fuel so choose your fuel wisely. There is enough difference in them that you cannot tune on one brand and then switch to another without potential problems. I order my VP Race fuels and they deliver them to my door so that is convenient. Or if you always go to the same track, see what they might carry if you prefer. For more info see VP RACE FUELS or any other equally large supplier like Sunoco, Torco, etc.

Basics: Race fuel has a much higher octane (as in the 110-120 ranges). It burns slower. It prevents knock at levels that lesser octane fuels cannot. (note: this is also why your VR4 says PREMIUM FUEL ONLY - to prevent knock that the 92-93 octane can prevent and the lower octane pump gas cannot). It can help cool the cylinders (which is why WI isn't always needed on race fuels). You can also go with a leaded race fuel, but you should be committed to your car being race only if you do that (in my opinion). Those are just a few basic reasons for using race fuel. If you understand the differences and why it is used over pump fuel then it can help you decide on adding it to your overall goals/plans or not.

I'm sure there are things I may have missed and someone will tell me. Some things I have purposely left out.

NOTE: this isn't a DIY but a guide for those that are newer to the platform or performance concepts so there are things not included here.

So if anything comes up that I forgot to mention, or added info deemed helpful, I will add in here. Or, if you are on the NW's local 3000GT forum feel free to comment in there.

I hope this information has been helpful and informative for you.
If you have any constructive feedback or corrections feel free to email me.

Enjoy making, and keeping, your VR4 in nice condition and a high performance sports car like it deserves!

In summary, if you get nothing else from this site / writeup:

1) Know your goal ahead of time or at least the REAL expectation of what you want to end up with and what you can truly afford. FACT: Most "builds" end up costing 2X or more than what the new builder thought. Many are left with half done projects because they ran out of money. So.....

2) PLAN your build out on paper first (*I suggest a spreadsheet like Excel that will to the math totals for you as you work). Add in the little things the best you can. These "little things" add up and can push you well over your budget. Do this BEFORE you spend money buying parts!!! Round UP because there will be things that you forgot or will run into once you start disassembling your car/engine/trans. It's just how it goes. Plan on it accordingly with a buffer on your budget. If you don't then you will run out of money before completion or will have to take short cuts that sometimes have sad outcomes.

3) Get off the internet forums that are mostly huge collections of BS and and many times totally wrong. There are certainly times when there is good information there but be aware of knowing the difference or take into account the person handing out the advice. 90% of the time you get ridiculous advice from the nut-swingers and dreamers. If you know (or know of) someone that has a proven record of building and success then reach out and contact them.

One caveat when asking for advice - beware of people that are making thier living (or trying to) off selling parts or running a shop. While there are many trustworthy people there are just as many that are not and will over-sell you on parts of levels way above what you need. Keep in mind thier desire is to make a profit from your purchases so take the advice with some skepticism. Sort of a "trust but verify" attitude is in order. It's nothing against anyone personally but is just wise to keep these things in mind, especially on big builds that will exceed 10's of thousands of dollars.

Good luck on your build, whatever the level. Enjoy the process too!
I hope this has helped you out.
If any quesitons or mistakes that are mine please let me know.

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