GReddy FAQ

Disclaimer #1: This FAQ is meant only as a basic guide to the GReddy turbo kit for the 1.6 Mazda Miata. I am sure that the information and links will always be changing so this will really always be a work in progress. Where I can, I will attempt to put in approximate prices of things so one can get a rough idea of costs. Please feel free to e-mail me with pics, dyno charts, links, or other information so I can keep the FAQ updated at brgracer@comcast.net.

Disclaimer #2: Considering that we car folk can and will often "debate" anything, I will try to provide evidence when I can. Second best will be commonly accepted principles. Finally, we may just have to rely on the word of the so called "experts" who have a ton of miata knowledge such as Keith, Brant, etal...

Disclaimer #3: There is no "right" way to upgrade the Greddy base kit. Since many of us are on tight budgets, upgrade paths may be limited at first. I will try to give some basic outlines on common upgrades, but you should definitely look thru the entire upgrade section before deciding because depending upon your final power goals (which always is more than you think), you may find that buying a little more than you need at lower boost makes more sense in the long run (more on this later). If you have a particularly unique setup, please e-mail me and I'll make a link.

I. Base GReddy Kit Info

What is the base kit?

The base GReddy kit was designed to add some oomph to the stock 1.6L Mazda Miata so we wouldn't be outrun by minivans. =) It came with all the parts necessary to run 4.5psi of boost.

It was put together as a low boost kit built around the Mitsubishi TD04H-15G turbo. (compressor map here) Some of the early kits (before Dec 99) shipped with the TD04H-15C turbo (approx 8% smaller compressor) but these are pretty rare now. Pics of both turbos here. (15C is on the right)

Only the stock kit is CARB certified. (copy of that certification here) Once you start to modify the stock kit, it is technically not CARB certified so be careful here.

Price for the entire kit is around $1200. See this thread for links to some vendors.

Will the kit work for a 1.8L Mazda Miata?

This kit will NOT work with a 1.8L Mazda Miata without serious modification. Considering the extensive modifications to the original kit to get it to work for the 1.8L engine, it would probably be better to look into a complete DIY turbo kit built around a different turbo to suit your needs.

If you are still interested in fitting a GReddy turbo to a 1.8L, do a search for darth maulta's setup or check out his website here.

What does the base kit do for me?

The base kit will give you somewhere in the ballpark of 125-135 rwhp (see dyno here) assuming no other modifications.

Considering that the stock 1.6L makes somewhere in the ballpark of 90-100 rwhp (see dyno here), that's a 25%+ increase in power for a little over a grand. That averages out to about $40 per HP which is a pretty reasonable for forced induction.

What should I do before/during the install?

Before even ordering the kit, it is probably not a bad idea to check the state of your your engine. You can start with a simple vacuum test or check your engine compression to make sure that you don't have other issues before you add the turbo. Normal numbers should be in the range of 135-192 psi and the cylinders should be within 28 psi of each other according to the Mazda factory manual. You don't want to find out that have a major problem after installing everything.

It is probably a good time to take care of all needed routine maintenance since a turbo will only add extra strain on most of your car's systems. This would include but is not limited to:

oil change: Corky Bell recommends higher weight oil and more frequent oil changes for longevity. Also, synthetic oil will break down less at higher temps so you may want to consider that in choosing your oil. Your choice of oil weight all depends upon the conditions the car is driven. (daily driver vs. track car, regional climate, etc...)

trans/diff fluid change: extra power will put extra load on your drivetrain

water pump/timing belt (if needed): our cars have non-interference engines so a broken belt won't ruin your engine, but it will leave you stranded (at the worst possible time usually).

flush and fill your radiator: because turbos add lots of heat, depending upon climate and use, you may want to consider water wetter and running a ratio with more water than coolant

bleed your brakes/check your pads: extra power = extra speed = you need good stopping power

change spark plugs/wires: so you don't have to wonder if it is the plugs/wires causing your car to stutter, should also set your plug gaps to just a hair less than the .042-.044 stock gap

replace fuel filter: a gummed up fuel filter can give you fuel pressure issues

GReddy install directions in zip format here. (just in case you lost them or bought the kit used)

Switch over to premium gas (91/93 octane) one or two full gas tanks before the install.

It is highly recommended that you either buy an aftermarket air filter or loctite the nuts on the inside of the supplied GReddy air filter as two members have had their turbos destroyed by a loose nut coming off. Just imagine one of those nuts flying into a spinning turbo. You don't want this.

It is highly recommended to make the manifold cuts as seen in this picture. This will help prevent the manifold from cracking. The cuts go all the way thru and can be made with a hacksaw and some elbow grease or other similar cutting tool. Use a bit of oil to lube the hacksaw blade, stuff rags into the manifold, and clean it out afterwards with some mineral spirits so the metal shavings can't enter your engine or turbo. One other note about the manifold cracking, check your exhaust hangers and general quality of your exhaust supports since any problems with these will add strain on your manifold.

It is highly recommended that you replace the supplied GReddy bolts with grade 8 bolts since some people have had issues with bolts breaking after being exposed to the intense heat cycles near the turbo. Easier to replace up front than have to have a machine shop drill one out. You can get the stronger bolts at your local hardware store (if you can find them) or online. Sizes in the first post of this thread. Probably a good idea to recheck these bolts after the first 500-1000 miles and retighten them as necessary.

Tighten the wastegate rod pictured here. The wastegate should be closed and there should be no play in the wastegate rod at rest. Do not overtighten the rod (right now, later you probably will) as this may raise your boost above the stock level. To tighten the wastegate rod, you will remove the alligator clip and unhook the rod from the actual wastegate actuator circled in this picture. Make sure that you do NOT turn the rod that is attached to the part that looks like a can. Loosen the nut right next to the part that looks like this and turn that part on the threads so it is closer to the part that looks like a can, making the entire assembly shorter. Then retighten the nut and rehook the rod to the wastegate actuator. The wastegate should be snug, but not too tight or you might be running too much boost (as if there is such a thing...haha) for your current setup.

Set your base timing at 6 degrees BTDC as per the GReddy install instructions. Link to instructions on setting ignition timing. While this may take away your low end power when not in boost, it is for the safety of your engine so that the extra heat from the compressed turbo charge does not cause detonation. With 93 octane, cooler ambient temps, and constant listening for any engine pinging, you might be able to get away with a higher base timing, but why risk it at this point? We will get to other timing options later in the upgrade sections.

Check to make sure that the braided oil supply line is not rubbing against anything because it will act like a hacksaw on whatever it is rubbing against. Consider putting a length of fuel line or similar rubber tubing over the area that rubs if you can't route the line in such a way that it doesn't touch anything.

Check to make SURE (note the emphasis) that your oil return line has a downward slope as it goes from the turbo to the oil drain on the passenger side. The oil return uses gravity so any kinks or upward slopes will cause the oil to get backed up and damage your turbo. The other option is to tap the oil pan which we will get to later in the upgrade section. Also, it is probably a good idea to use grade 10 lock washers on the flange for the oil return that attaches to the turbo to avoid future oil leaks.

Make SURE (last one) that you protect your brake reservoir from the turbo heat with either the supplied GReddy blanket or some other heat shielding as seen in this thread. Not a bad idea to heat shield the other parts in the area as well like the heater hoses, brake lines, etc... You don't want this.

What should I do after the install?

While the GReddy instructions suggest that you stay out of boost for the first 300 miles, for the record, I think most of us waited until the end of the driveway.

Initially, you may see some white smoke from the engine bay as the residual grease/oil from the install and paint from the manifold/downpipe burns off. This is pretty common, BUT it should not last very long at all. Regardless, it is probably a good time to recheck to make SURE that your oil return line is not kinked and still has a downward slope, and to make sure that the smoke is not coming from another source such as a damaged heater line or oil leak.

As stated above many times, turbos get very hot, so after long boosted runs, it is a good idea to let your car idle for about a minute to keep the oil running thru the turbo until it cools down a little. If you shut the car off right away, the hot turbo can cook the oil sitting in it. Another option is a turbo timer as discussed in the upgrade section.

Probably a good idea to check your bolts once and retighten as needed after the first 500 miles or so as mentioned above.

Every now and again, it doesn't hurt to check your engine bay to make sure that there is nothing rubbing (i.e. oil supply line against something, downpipe against heater hoses, etc...), check for any leaks, and sit back and admire that turbo that you installed. Doesn't hurt (aside from the extra weight) to carry a set of basic tools to take care of small issues that may arise in the beginning.

Finally, enjoy the extra power, and save $$$ for all the upgrades as you WILL get addicted.

II. Upgrading 4.5-6 psi (125-150 rwhp)

Upgrade Notes (These notes apply to all upgrade sections)

Upgrades will be discussed by "appropriate" boost level which can be a bit subjective so your experience/opinion may differ. The FAQ's recommendations will always lean toward the conservative side so please take this into consideration. This usually means that if you are shooting for higher boost, you probably should have most of the upgrades in the previous section. Also, it probably never hurts (except in the wallet) to upgrade things that are needed at higher boost earlier than needed. (i.e. clutch, diff, etc...)

Upgrades will be noted as improving one or more of the following three categories: power, spool, and reliability/safety

Upgrades will be ranked as highly recommended, recommended, and coin toss. (Some of this may be pretty subjective so please bear with me guys. Again, remember that I will lean toward the conservative side for safety.)

How do I get to 6psi?

At this level of boost, it is pretty easy. Remember the wastegate arm that you tightened for the base kit, tighten it a little more until you reach 6psi. While you can get a mechanical or electrical boost control, it is not really "needed" at this point and will be discussed a little later.

Highly Recommended

Boost gauge: (reliability, ~$30+) Probably best to get one with vacuum readings as well so you can see small vac leaks before they become big vac leaks. Highly recommended because you won't know how much boost you are running without one, and too much boost without proper fueling is bad.

Heat shield: (reliability, ~$50+) Despite all the heat blanket that you used to protect things in the engine bay, that turbo is very close to the hood and a few old owners have had their hood paint wrinkle/warp from the heat. You can go as simple as a cake pan bolted to your hood as seen here with extra heat wrap, or choose the Bowser heat shield from FM here, or make a DIY heat shield. Also, some people have added extra hood protection by cutting heat blanket slightly larger than the hood open panels and sliding the extra blanket under the hood supports to stay in place as seen here.

Larger cat-back exhaust (power & spool, $250+): This is in the highly recommended section as it is probably the biggest bang for the buck at this level. Most turbo exhausts have less restrictive mufflers (as the turbo itself will quite down the exhaust a little, and usually come in 2.5" and 3" sizes. The stock exhaust is 1.75" and upgrading just to a 2.5" catback has been dyno proven to give 15+ rwhp and quicker turbo spool, so you get more power that starts earlier (does it get any better than that?).

Recommended

Coming soon.

Coming soon.

Coming soon.