In many places on this website you will see power ratings such as 350-500+ whp. What does the plus mean? Basically it means "it depends." Specifically it depends on how you use or treat the car. In the example of a our Stage 4 clutch the 500+ means we have never seen a problem below that number. If it will handle more is up to you and how you are using the car. Daily driving with 600whp the clutch does fine, drag racing with sticky tires at that level it's going to slip some.
Withholding information - simply don't do it. We have had a rash of this lately of people who don't bother to mention that their 1991 MR2 has a gen5 motor in it, or that the MR2 part they ordered is being installed in a converted ST182 Celica or that the Gen2 turbo kit they ordered is supposed fit an AW11. That stuff isn't normal and we cannot psychically obtain that information reliably. You need to let us know these things or you are going to get the wrong parts. We are US based, the "normal" for us is a 1991-1995 Gen2 MR2 Turbo. If your car or motor or transmission is differnet and it's not already covered in the item description please let us know so that we can do our best to get you the right parts.
We've shared some pretty good stuff over the years.
Shopping list for a 450whp 3SGTE: http://atsracing.net/Blog/View/26
360whp Gen4/Gen5 on E85: http://atsracing.net/Blog/View/28
3SGTE Horsepower Basics: http://atsracing.net/Blog/View/23
What oil should I use?: http://atsracing.net/Blog/View/31
Core Return Instructions: http://atsracing.net/Blog/View/29
Engine Break In Instructions: http://atsracing.net/Blog/View/27
Scroll though all of them when you have time, but I'll do my best to keep this list of popular ones at the top.
Not, MR2 specific, but MR2's aren't all we do anymore. I needed a place to summarize all the modifications done to my 1978 Ferrari 308, and share some of its story.
(Photo credit to Mason Bleasdell)
The current modification list (11/1/2020)
rebuilt transmission (but otherwise stock)
chromoly CV joints, inner and outer
Custom clutch using a V12 Daytona pressure plate, Centrifugal style weights (taken from a Centerforce clutch for a Mustang), Kevlar disk, and a stock flywheel
308 QV block with steel sleeves bored to 81.5mm, sleeves have grooves for stainless wire rings to seal against the head gaskets. If/when I do this again I will add a larger diameter o-ring to the head to get an interlock between them
348 heads with custom cams (and a ton of duration, currently it pulls only about 6" of vacuum at idle)
Custom Wiseco 81.5mm pistons with approx. 12:1 compression ratio
Copper head gaskets
328 oil pump
328 intake runners, ported to match the 348 heads
308 QV intake plenum
2019 Toyota Tundra 85mm electronic throttle body
Custom Aluminum radiator up front with Maradyne 9" fans (about 30lbs lighter than the stock radiator)
Turbo kit and exhaust
Precision 6466 billet wheel ball bearing T4 turbo with .82 exh housing
Kit uses stock US style 328 exhaust manifolds and Y pipe, turbo is mounted to a 2.5" J pipe that puts the turbo about where the 308/328 fuel injection meter would be.
3" downpipe out of the turbo into a Y pipe with an electric exhaust cut out. The other branch of the Y leads to a Summit 3" muffler. Currently there are two exhaust outlets (one muffled, one optionally open), but I have plans to redo the back of the exhaust into a more Ferrari like 4 tips.
Water to air intercooler mounted in the trunk. There is a radiator heat exchanger positioned between the exhaust tips. Wrapping the muffler in header wrap cut heat in this area and allows IC temps to stay reasonable.
A K&N filter behind the passenger side intake vent feeds the turbo through a 3.5" aluminum intake pipe
A rare, discontinued ZEN blow off valve is mounted on the cold side intercooler pipe
ECU, electronics, and electrics
Rebuilt stock alternator. My rebuilder was able to upgrade the internals to about 75amp (stock is 55)
Link G4+ Storm ECU with external throttle by wire module (I plan to change this to a Link G4 Extreme soon)
875cc high impedance top feed injectors using custom fuel rails and adjustable fuel pressure regulator
AEM 044 style fuel external fuel pump mounted near driver's side fuel tank
Toyota Tundra throttle body (electronic, no throttle cable)
Toyota MR2 MAP sensor (actually this is an aftermarket 4 bar unit)
GM style fast response intake air temp sensor mounted in original cold start injector spot
GM style water temp sensor mounted in the valley of the block
GM Flex Fuel sensor
Ferrari 360 throttle pedal
Toyota Tundra Denso Ignition coils (eight of them, no distributor)
Cam trigger is an aluminum wheel with a magnet in it that is attached to the end of the 348 cam, Sensor is a Norwood unit
Crank trigger uses a stock 308QV sensor on the flywheel, but the flywheel was modified to have 12 pins on the back (stock injected cars have two pins). I may change this to a 36-1 or 60-2 crank trigger later
Perfect Tuning CAN gauge replaces the factory water temp gauge and gives me instant access to (almost) all the ECU sensors and outputs, I typically have it set to view coolant temp, intake air temp, voltage, and manifold pressure
The engine is tuned for flex fuel and can run on 93 pump fuel or E85 Ethanol. On pump gas we have to keep the boost and timing pretty low because of the high compression ratio, but we still make a respectable 420whp at 5 psi. E85 is where the real fun is. On E85 at 16.5psi we make 678whp! With a 15% drivetrain loss (measured results on other Ferrari's is actually closer to 19%) we are at 800 flywheel horsepower. The torque is slightly limited because we were getting some clutch slip on the dyno (Kevlar disks take FOREVER to break in). I don't have to tell you that 678whp. 800 horsepower in a 3000 pound car is incredible. We tuned the boost to be both rpm and throttle dependent to make the power curve as predictable as possible. You can see it's very linear and looks similar to a 355, but on steroids.
Suspension, brake and body modifications after the dyno graph and engine pics
Body and wheel modifications
288 GTO style front airdam, foglights, front bumper and turn signals (I'd guess this saves 40lbs over the US bumber), and a grille that I hand made.
Euro style rear bumper (about 45 pounds saved here)
I cut the stock 1/4 window louvers out to look more like a GTB
Autostrada Modena 17x8.5 and 17x9 inch wheels with Toyo R888 225/45R17 front tires and 255/40R17 rears. These are mounted using adapter/spacers to get the correct fit. We machined custom sleeves to make them hubcentric.
Girodisk front brake kit, I tried their complete kit with rear rotors, but the front brakes severely overpowered the rear brakes. I think I'm using an EBC red pad up front
Superformance rear brake kit with EBC yellow pads. I went with a slightly more aggressive pad to get the balance perfect. I still can't get their parking brake kit to work very well, the 1978 style cable routing just doesn't seem compatible.
QA-1 coil overs with surprisingly soft springs. I think I went with 200/225 rates. I could probably go stiffer, but I really like the ride quality.
Poly bushings everywhere, plus all the ball joints, tie rods, and steering rack were replaced in 2016.
I have a Superformance quick ratio rack that I have not assembled or installed yet.
The aluminum calipers and two piece rotos saved about 40lbs off the car
Stereo and AC
Sanden style AC compressor, all new lines/hoses, condenser, fan, etc. Only the ducting and the evaporator remain from the original AC. My center vent is actually a 928 door vent and flows more air than the original 308 vent. Sanden compressor and bracket weigh 10 pounds less than the original York.
Alpine CD head unit with ipod control (old, like 2006 model), Clarion door speakers, and small JL 3 channel amp under the passenger seat, and a 8" JL sub in a custom box positioned where the original EGT sensor control boxes were at the front of the passenger footwell.
Smoking Tire One Take video: (skip to :44 to avoid watch advertisement) https://www.youtube.com/watch?v=ruBJ-MnYXis
Eagles Canyon Drive By: https://www.youtube.com/watch?v=KKYSGFe5pkE
RetroMod cars feature article: http://www.retromodcars.com/features/beautiful-beast
How I got it, the short version. The car belonged to a lifelong family friend and fraternity brother. He and his family died in an incredibly tragic plane crash in 2006. Our last conversation had been that he wanted me to work on the car, make a few improvements and make it a little faster. I spoke to his family and carefully brought up the car. His father replied "I was hoping you would ask about that." He allowed me to purchase the car from Jason's estate. I bought the car sight unseen. I didn't know it was blue. It was not running at the time, we had to tow it home from Wichita Falls.
I managed to get it running, replace a leaking fuel line, and do a basic tune up. I spent a lot of time on the dyno getting the ignition timing and carb settings as perfect as I could. The result was 187whp, not too bad for a car originally rated at 205 flywheel horsepower. I drove it like this off and on for eight years. Note the sleeping toddler in the passenger seat.
Rom Tune ECUs are no longer available. This pains me to write this, because this was one of our oldest and most famous products. We started selling these around 2005. Unfortunately, the “scramble chip” is no longer available and has been discontinued for years (like ten). I did my best to keep this product alive but we have finally run out of daughterboard inventory. There is a small group in the UK attempting to make a newer version, but so far it has not been compatible with the majority of US ecu’s.
We still have the hardware and software to do chip tuning, so if you have an ATS (or GForce) ecu we can still retune that for you. That page will remain active.
The bright side: We are changing our combo kits over to include plug and play ecu’s from Link and ECUMaster. We have been working with these brands for many years. They have great quality products that are easy to install and easy to use. We will be including base maps, but because these ecu’s are MAP based and not AFM based they will not automatically compensate for airflow changes like the rom tune so a wideband O2 sensor is mandatory for you to verify your tune. We also highly recommend our flat response knock sensor because the stock knock sensor is too noisy to provide viable information. The LINK pnp ECU fits inside the stock ecu case and is basically undectable when installed.
The brighter side: These are REAL ECU’s that are not locked or encrypted so they can grow with you and your needs. The ECUMaster EMU is the same ecu that I use on my 800+whp MR2. They are both MAP sensor based and eliminate the AFM. The Link can use the stock turbo pressure sensor up to 17psi of boost (3 and 4 bar map sensors available on the ECU accessory page), and the ECUMaster has a built in 4 bar MAP sensor that can read up to 45psi of boost! Both ECU’s can accept flex fuel sensors so E85 tuning is also possible (we typically see 360whp on a stock motor with CT27 and E85!!).
Over the next few days I will be updating our combo kits and their options.
Note - as of 9/23/2020 I have enough parts left to build 1 or 2 rom tunes. If you absolutely have to have one and cannot use a stand alone ecu then please email us at firstname.lastname@example.org
It has been a few years since I shared the article from Forced Performance on oil choices.We have been recommending Valvoline VR1 since even before that article. With the help of Daniel Satnik we have made some additional discoveries since then.
Even though Valvoline VR1 10W30 and Valvoline 20W50 show the same zinc content, the 20W50 has a stronger film strength that will offer more protection for your turbo. We are now recommending VR1 20W50 for anyone running over 17psi of boost/300whp.
Another thing we run into is: My upgraded turbo died after one week, but my old CT26 was still running fine on the same bad oil for 30 years. I'll admit this one stumped me for a while, but I think I have a handle on it. "Work Hardening" Basically the original turbo bearings were subjected to a fairly casual start of life, running stock boost for tens of thousands of miles. While this was happening the turbo was getting heat cycled over and over and over. This basically heat treated the soft brass bearings into something harder and stronger. New/rebuilt turbos are often subjected to immediate high loads/high boost. We are now suggesting a 500 mile break in at the lowest boost level you can run/10psi. This will give the new bearings some heat cycles and allow them to harden up a little.
Rotella Diesel Oil. I don't use it. I don't have an opinion of it. I don't really understand the appeal except that everyone tells me how cheap it is. I know it's $19/gallon, but six quarts of VR1 20W50 is currently only $33 shipped from Amazon. That's $22/gallon. Surely protecting your engine and turbo is worth the extra $3?
UPDATE: OK, so this opened up a few questions. First, I am personally using the conventional VR1. It's about half the price of the synthetic, and offers excellent protection. The synthetic might last longer between oil changes, but otherwise I don't see a need or value in it. I recommend changing at 2500-3000 mile intervals.
Stock - VR1 10W30 probably more protection than you need, but it's not a condom you aren't missing any sensation.
mild - up to 16.5psi and 299whp - VR1 10W30 has proven fine for these cars
maxing out the stock motor - 300+whp and 17+ psi - This is where I start switching to VR1 20W50
EXCEPTION #1 - ball bearing turbos don't need the thicker 20W50 oil so we actually run them up to about 450whp on VR1 10W30
EXCEPTION #2 - all ATS 2.3 stroker motors are built for 20W50 oil.
EXCEPTION #3 - Altitude. Thinner air requires more turbo rpm. Anyone above 4000ft elevation should be running 20W50. Just be sure to let the engine warm up before aggressive driving.
We recently regained control over shipping rates. We are using UPS for most international shipments and have negotiated lower prices. I have updated the web page to reflect this. In the past we have continued to refund the shipping costs when our website was wrong. We will continue to do this. In the case of some bulky or heavy items we may need to charge more shipping than the website calculates (the current algorithm is based on price, not weight/size).
Core return forms are mandatory to receive core credit. We have been getting too many random cores shipped from UPS stores (or similar) that we have no way of tracking down the sender/owner. If you are not sure how to package your cores properly, then pay the deposit and wait until you get your new parts. They will come in a quality box with quality packing materials that can be reused.
Several years ago Prime made the Gen4 swap extremely popular. Ironically they don't work on cars anymore, but the Gen4 and later Gen5 motors are here to stay. Just to quickly touch on both motors, they are very similar to the Gen3 but with more advanced ecu's, and coil on plug ignition systems. The bad news is that they come with smaller turbos (think original CT26 combined with CT20B exhaust wheel), and the weakest rods (and blocks) of any 3S motor.
Don't let that last sentence scare you too much. The block can handle 450whp/350lb ft of torque and the rods can handle about 300lb ft of torque.
The gen4 has a side feed intake manifold. The gen5 has an even more advanced ecu that has an immobilizer built in, extended tip injectors, and surprisingly went back to a center feed intake manifold.
The swaps can be done pretty cheaply; our basic, basic swap starts at $3800 installed. But what we usually do should probably be described as Basic++ We start with the Basic swap, add a side mount intercooler kit, downpipe, exhaust, fuel pump, maintenance package, and clutch package. The total is around $6500. This typically gets you 260whp/320 horsepower. That's enough for low 13's in the ¼ mile and 0-60 in about 4.7 seconds.
So what's the next step? Turbo, ECU and fuel. Let's hope you have E85 available near you because I personally don't like methanol injection, I've yet to see it last reliably. E85 has an effective octane capability similar to C16 race fuel so we can run a lot more boost without the fear of detonation.
ATS developed a plug and play kit for the ecu and fuel system that matches well with the stock gen4/5 pistons and rods on E85.
We paired our popular ECUMaster EMU with a custom set of 875cc high impedance top feed injectors that fit the stock rail. These will support 385-400whp on E85. That's a little more than I like to push the stock gen4/gen5 motors.
Combine that fuel system with our Sweet16/CT16 turbocharger upgrade and you've got a FAST spooling setup capable of 300whp on pump gas and 360whp on E85.Be sure to run a high zinc oil like Valvoline VR1 with this setup because you'll be making almost twice the original power and limited to a stock type thrust bearing in the turbocharger. GT/GTX series ball bearing turbo kits are also possible if you source a Gen3 exhaust manifold.
360whp is ~450 flywheel horsepower. That's enough to push a 2800lb MR2 deep into 12 second ¼ mile times even on street tires. These turbo's spool so fast that torque management in the ecu boost control strategy is a must. Basically use the EMU to build a boost curve that keeps the torque right about 315 max and you'll be fine.
Recently I've had a few people ask about engine break in. This is a touchy subject as everyone believes they know the right way. Here is what we recommend:
Check and fill all your fluids. We highly recommend Valvoline VR1 10W30 for stock to 400whp rebuilds, and 20W-50 for anything over 400whp. Start the car and let it run for about 30 minutes. Be sure to check for leaks. If there are any leaks, stop the car, fix them and start over. Watch the temp gauge, make sure the fans turn on at an appropriate time/temperature. After 30 minutes turn it off an let it cool off. Once it is safe to do so check your coolant level and change the oil and filter. Now drive 100 miles. Be as gentle or as hard as you want. Personally I prefer hard as I usually do this part on the dyno. After 100 miles change the oil and filter. Now drive 1000 more miles and change the oil and filter again. Then 2000 more miles and change the oil and filter again. At this point you’ll have a little over 3000 miles on your new motor and you can change to a synthetic oil if you want. Personally I stay with the conventional and just change it more often (about 2000 mile intervals instead of 3000)
ATS Racing and Exotics
With the publicity of Matt Farah recently driving Kenn Kite's ATS built 450whp MR2 we decided to put the recipe up there for people who want this build. The availability of E85 has made 450whp the sweet spot of bang for the buck MR2 performance. For example 450whp can happily run our $300 1200cc injectors instead of $900+ ID2000's. 450whp is also the limit of the side mount intercooler, and stock intake manifold. 450whp is also the limit for a single disk clutch, so you get a $500 Stage 4 instead of a $1400 twin disk. And finally 450whp is the practical limit for the 3S block, beyond this number we suggest upgrading to the 5S block.
This E85 build will make about 330-350whp on pump gas. If you are trying to make 450whp on pump gas, well bad news.....it's going to cost a lot more because you need to do considerable flow modifications due to the limits of 93 octane.
The block. We highly recommend going to a 2.2 stroker motor. There is no power benefit, but there is a spool benefit and it makes the car a better daily driver. The cost difference between a stroker and a forged 2.0 is pretty minimal. So buy this and upgrade to the Eagle rods and ACL Race bearings for a little extra insurance:
http://atsracing.net/Parts/Index/ATS22STROKER $3250 with Eagles and ACL Race bearings
By the way I am assuming we are doing the installation here, so no need for a core deposit.
Next thing is the Cylinder head. Buy this:
Get the Gen2 S1 cams. I don't care if you have a Gen3, Gen4, Gen5, The GEN2 S1 cams are the ones you want. They spool faster and make the same peak power at this level.
Get ATS cam gears too: http://atsracing.net/Parts/Details/E-ATSCAMGEARS
The price of cams is changing soon because GSC is going to billet blanks, but this head with cams and cam gears should be $1700 total.
Get the ATS head gasket repair kit for $325 here: http://atsracing.net/Parts/Details/TU-HG-KIT
That will get you a set of ARP head studs, ATS metal head gasket and a low temp thermostat.
You will also want:
http://atsracing.net/Parts/Details/TU-OILLEAK Oil leak kit $34
http://atsracing.net/Parts/Details/TU-TIMING-BELT Timing belt kit with seals $91
http://atsracing.net/Parts/Details/TU-IGNITION-91 Tune up kit $169
http://atsracing.net/Parts/Details/E-OILPUMP HV Oil pump with gasket $188
5SFE flywheel bolt set $43
Machine stock flywheel for stroker, plus resurface flywheel $200
I don't have a water pump on the website yet, but they are $125 for genuine Toyota. I have found the aftermarket ones come as only the front half and they tend to leak.
Running total so far $6125
On to the turbo kit: ATS Racing Garrett GT3071R. This thing spools very close to stock and will make just over 500whp if pushed.
The turbo kit comes with all the gaskets you need IF you can reuse your manifold gaskets. Just in case they aren't reusable here are the two:
http://atsracing.net/Parts/Details/TUR-CT26INLETGASKET manifold/adapter gasket $39
http://atsracing.net/Parts/Details/TUR-MANIFOLDGASKET gen2 exhaust manifold gasket $39
The ATS Top Mount Intercooler kit also includes a 3” intake that deletes the factory AFM. This intercooler is the best air/air solution available without cutting your trunk or going to a heavier and more expensive water to air intercooler package.
Get the optional Tial BOV, because it sounds cool.
Running total: $10,003
The ECU and fuel system is easy because I built a combo kit that has everything you need:
Drivetrain: I hope your stock E153 transmission is in good shape, because rebuilding them has become nearly impossible or expensive or both. Grab an ATS Racing Stage 4 clutch and a set of our CV joints:
http://atsracing.net/Parts/Details/DT-CM-STG4 Stage 4 clutch $499
http://atsracing.net/Parts/Details/DT-CVJOINTS ATS inner CV joints $399
http://atsracing.net/Parts/Details/DT-TRFLUID-MT90 Transmission refill kit $74
Running parts total: $13,320
We need to add about $150 for fluids like VR1 race oil, oil filter, coolant, clutch fluid.
If we do everything at once the total labor for engine removal, disassembly, cleaning, reassembly, is typically $4100, tuning for flex fuel is $1200. So assuming you don't have a car loaded with gremlins and previous problems your total price is:
Grand total $18,770
450whp is approximately 570 flywheel horsepower. Flip through the latest Car and Driver and find the list of 570hp new cars. It's pretty short. Now look and see how many of them are under 3000 pounds. 570 horsepower/3000 pounds puts the MR2 in an incredible power to weight class. At this power level the car is capable of 10 second quarter mile times on drag radials, but still has the drivability and reliability of the stock car. The one pictured above was build by ATS in 2009 and is still going strong today..
Recently I was asked for a recipe to take a 1991-1995 Toyota MR2 from bone stock (160whp) to 350whp on 93 octane pump gas. This is more than double the output of the stock motor. Believe it or not, it's possible. Here are the parts I would recommend:
GT3071R turbocharger kit
ATS ECUMaster ECU
550cc side feed injectors
Walbro fuel pump
170 degree t-stat
ATS modified fuel rail
Open element air filter - Apexi, or K&N. Do not use Blitz or HKS foam filters. They degrade rapidly, do not filter or flow well
ATS throttle body inlet - 91-92 only, the 93+ already has an ample sized inlet.
3" exhaust - the Ebay ones flow great, but tend to drone on the freeway. Berk is better about drone, but twice the cost
GSC/HKS/BC 264-268 degree cams
ATS adjustable cam gears
ATS Side Mount Intercooler with fan and shroud kit - I would prefer to use the top mount, but I put budget in the subject.
Total parts cost is about $7000. I have done this recipe many times over the years. The worst I have seen from this is 330whp and the best I have seen is 360whp. Now, if I had a little bit more in the budget the first thing I would change the fuel system, I would run a top feed rail and 1200cc top feed injectors. By switching to these items you open youself up to the possibility of E85 and lots more horsepower in the future.
We are also going to assume you have kept up with maintenance. So no 150,000 mile timing belts, no knocking, no overheating, no puking oil. No smoking. A few drips of oil here and there are acceptable (sometimes I think MR2 means "leaks oil" in Japanese).
The stock ignition system is really good on a 3SGTE. You will find lots of old articles about cap/rotor wear etc. Those were wrong. We routinely make over 700whp on basically stock ignition systems, and field tons of "help me" calls about malfunctioning aftermarket coil on plug systems. Coil on plug systems are available, but require stand alone EFI and additional hardware. That adds up to money that could be put to good use elsewhere.
ATS sells a full tune up kit here (for 91-92) or here (93+). The included NGK plugs are pre-gapped a little bit too big. They will work for stock applications just fine, but we suggest dropping the gap down to .028 inches. While you are changing the spark plugs you should take the extra time to do a compression test. This is a good basic indicator of piston/ring condition. You are looking for 140-185 psi of compression. And it's very important that they are all within 5% of each other. Compression testers are available at your local autoparts store for under $30.
Your car will be louder now. If you are not comfortable with a louder than stock car then sell it and go buy a hybrid. Removing breathing restrictions is fundamental to making power. There are some quiet exhausts occasionally available on the market, but everything will be at least slightly louder than stock.
Intake: You've got a few choices here. You can go with an Apexi bolt in open element air filter like here. They flow great and still filter well. Or you can make your own with parts off ebay. Be sure you have the skills and patience to make a bracket, otherwise your filter will beat itself to death on the fuel filler pipe, quickly develop a hole, and no longer filter. Filters from HKS, Blitz foam, and Greddy Airnex should be avoided.
What a cheap freebie? Take the stock air box base, cut or drill more openings, specifically on the front and outside sides. Remove the stock air bladder from the firewall and reinstall with a new genuine TOYOTA air filter. Be careful to leave enough base material that it can still be bolted down. This flows great, and filters as well as OEM.
Exhaust: The $199 Ebay dual muffler dual tip exhaust flows awesome. We have seen 800whp from these before. Seriously. The bad news is that they are LOUD, especially when combined with downpipes and larger aftermarket turbos. The Berk exhaust does not flow as well, but is much quieter. TCS occasionally offers two exhausts: a quiet SP style exhaust that looks like a 3" version of stock. This is my favorite. It's difficult to make it fit perfectly, but it is quiet and flows reasonably well. The other TCS is the 3.5" dual muffler, dual tip, it's beautiful and BOLD (read: loud).
Downpipes: I'll get to those later. An exhaust can be changed out in about 2 hours at home. A downpipe takes 2-3 times that amount of time. I will also note that adding performance exhaust parts like a downpipe or a 2.75" b-pipe in front of a stock muffler is dumb. There is almost no gain in power because you still have a big restriction at the end. ATS Throttle Body Inlet–hey, it's my page I can push my own products if I want–The 1991-1992 cars NEED this. It's a 4-5 horsepower gain. Want proof that it helps? Well the 1993-1995 cars have a redesigned throttle body inlet that mirrors ours.
You have three choices (for now) based on budget. There is almost ZERO natural air flow through the stock intercooler.
So a quick FREE modification is to unplug the temperature sensor on the engine lid. This will force the factory intercooler fan to be on anytime the engine is running (or key is in the on position).
Upgrade the fan. An 8” puller fan will fit on the engine bay side of the intercooler. These are $99. The install takes about an hour and hopefully you know someone with small hands willing to help you install the push lock mounting tabs. If you have the motor out, or you feel like punishing yourself you can fit a 9” pusher fan on the front side of the intercooler. It sounds like just 1” bigger, but it flows about 30% more air!
The ATS Side Mount Intercooler kit. These are on sale for $499. This upgrades you to a higher flowing, more efficient core, plus you get cool piping upgrades, a 9” fan with shroud as well as a mounting shroud to make sure we are getting the maximum flow possible through this core.
If you are shooting for more than 350whp in the long term will will outgrow all these options, but you will also outgrow the stock ECU, fuel system, stock pistons, etc, etc...there is already another blog about that.
Step 4: More boost. Finally we get to the good stuff. The stock MR2 runs about 9-11 psi in stock form. If you have been following this path you may have a car running as much as 13 psi even without a boost controller. First, buy a gauge. It doesn't have to be fancy, but avoid brands like GlowShift and Prosport (I've seen more broken ones than working ones). I like VDO, Autometer, and any of the big Japanese brands. Some electronic boost controllers have built in gauges, so that can offset some of the cost.
You will also have to disable fuel cut if you have a 91-92 car and want to run more than 12 psi. The 93+ cars have a fuel cut set right about 16 psi. For stock turbo people on pump gas, this is usually plenty. You can buy a fancy FCD (fuel cut defenser) or do a $5 zener (pronounced Zee ner) diode mod if you are handy with a soldering iron. Or you can just disconnect the vacuum hose that goes to the stock map sensor. That sensor does only two things: it runs the stock (useless) boost gauge and it activates fuel cut. Leave it electrically plugged in, remove and cap/plug the vacuum hose and voila: no fuel cut. Now to actually raise boost you will need a boost controller. Basically the stock turbo has a 7 psi wastegate actuator. When boost hits 7 psi the actuator opens up and routes exhaust around the turbine wheel to control the boost. The factory setup has a turbo VSV that bleeds off approximately 3 psi if all conditions are met (warm enough outside, warm enough coolant temp, no recent knock detections). This is typically disabled when you install an aftermarket boost controller. Again here are several choices in order of price:
Manual boost controller. The ATS MBC is a ball spring type for fast spool and accurate boost control. Not bad for $49. However expect boost to fall off 1-3 psi by redline with most turbos. This is because the exhaust back pressure increases inside the turbine housing and pushes on the wastegate flapper door. The ball-spring boost controller cannot compensate for this additional pressure on the wastegate flapper.
Electronic Boost controllers. These race in cost from about $329 to $600+. Greddy, HKS, Apexi, and Blitz all make or made electronic boost controllers. The old Greddy Profec B Spec 2 is probably the easiest to use ever, and the Apexi AVC-R has the most features, but is the hardest to setup. The HKS EVC4 has a somewhat difficult initial setup, but after that it is VERY EASY to change. I think it's the only one that you can actually just tell it what boost you want to run and it does the best it can to hold that boost all the way to redline regardless of gear.
Now before you go drop $600 on a new electronic boost controller, realize that is more than half the cost of a good stand alone ECU that will have boost control built it, or available as an inexpensive option. However stand alone ecu's require tuning and unless you do it yourself, that isn't free. Typically budget about $2000 for a full stand alone ecu with tuning and options (knock sensor, boost control, wideband)
So what is a safe boost level? Well that depends. On US 93 octane pump gas we typically quote 17 psi as the maximum safe boost level. The fact that 93+ cars had a 16psi fuel cut from the factory seems to agree with this number. However, as these cars get older we have seen some with excessive carbon build up that couldn't handle more than 13 psi before we heard detonation. I highly suggest renting some local dyno time so you can see how the car behaves under controlled conditions.
Step 5: Gauges: I already mentioned in step 4 that a boost gauge is necessary. The other gauge I recommend is a wideband O2 sensor. This will give you some insight into what the ECU is thinking as well as early detection of problems. There are lots of brands, Innovate is one of the biggest, and one of the worst. They eat sensors for breakfast. We have had excellent luck with PLX, Zeitronix, AEM, and recently a very affordable one from APSX. All of these have outputs that can be integrated into stand alone ecu's for later tuning use. Zeitronix and PLX offer logging software that can be VERY useful, especially if you are trying to street tune. So expect results of 14.7 at idle and cruise, and 10:1 at full boost. 11:1 is good (and safe) for full boost under most conditions, but you will need something to tune with to get there.
We've reached a fork in our path. You can proceed to step 6a or 6b, or choose to do both depending on your budget.
Step 6a: Tuning. The way we have laid out (and limited) these modifications you can stop at any point and still have a great running car. This step is really about optimizing it all and getting the most out of the investment you have made. Again, choices are laid out in order of cost:
nothing. It all runs pretty good as-is.
Piggybacks. Way back in the day we thought these could be the answer. Drop in some 20% larger injectors, and use an AFC to dial back the air flow meter signal 25% to correct the fuel map. The only problem is that the Air Flow Meter also effects the ignition timing map. So everytime we reduced the signal to lean out the air fuel ratio, we advanced the timing a little. This wasn't good. There is another complication that we didn't know about until we started doing rom tunes. There are TWO fuel and timing maps inside the ECU. When they ecu detects excessive knock it switches to a richer fuel map and more retarded ignition map. Even when tuning on a dyno it's almost impossible to know when this happens. Many tuners went along unaware and optimized the car to run great in it's limp mode...sounds fine until one cool day the car comes out of limp mode and suddenly there is too little fuel, and too much timing, and snap there goes a piston ringland. So two simple rules: 1. avoid them, and if you just can't then 2. don't use more than 10% correction (unless you have a way to compensate for ignition changes).
Rom Tunes ($800)– We've done literally hundreds of these. There is a better description on the rom tune product page, but the short version is this allows us to change the actual fuel and timing maps inside the stock ecu. So instead of manipulating a sensor we are changing the way the ecu thinks. They come pre-tuned for your car based on cars we have already tuned at ATS.
Stand alone ecu ($1000-$2500)– This used to be a huge undertaking. We had to build a new engine harness, people weren't sure if they could keep AC, or cruise control, no one knew if power steering of ABS would even still work. That is all fixed now. Link and ECUMaster both offer plug-n-play ecu kits for the MR2 (we developed the pnp for the ECUMaster so it is exclusive to ATS Racing), and all the original accessories and options still work. These come with a base map and you should be able to start up and run with an hour.
These start at a very reasonable prices (about $1000) but will require tuning. If you can do this yourself then great, but if not then expect to spend $400-$1000 at a local tuner. The other part of the price is the options. Things like boost control, built in wide-band O2, flex-fuel, knock sensor, oil pressure sensor, fuel pressure sensor, bluetooth or wifi output can be added to the emu. The best part about stand alone ecu's is that they can grow with your car without needing to be replaced. I run my 872whp MR2 on the same $1000 EMU that we put on near stock MR2's. There are other brands available. My experience with AEM, Megasquirt, and Hydra Nemesis are to avoid them. They may have a lower initial cost, or be available used because someone else already figured out how much they suck.
Step 6b: turbocharger upgrades
1. CT27 (or CT21 if you have a Gen3). This is a stock turbo that is upgraded on BOTH sides for additional flow. We replace the original compressor wheel with a larger billet wheel, and machine the compressor housing to match. We don't publish the exact size because there are many competitors out there who are willing to just copy someone's work instead of doing actual research themselves. We also do a CNC machine operation to the exhaust housing that optimizes the merge of the twin entry volutes. Don't try this one at home though, because if you overshoot the cut by .5mm (that .02 inches) you will ruin the exhaust housing. Externally these look like stock turbos so they are very popular in states with serious emission laws.
If you are doing the work to install a new turbocharger you should also install a 3” downpipe at the same time. The ATS downpipe is ceramic coated stainless steel and the wastegate opening/flow has been verified with each one. Berk makes a downpipe too, but the wastegate openings of the turbocharger must be enlarged because of an inadequate design or you will have boost creep (uncontrollable boost beyond target).
If you intend to run more than 15 psi we recommend the billet wastegate actuator and a 15 psi spring. I mentioned before that back pressure becomes significant at higher boost levels and can actually push the stock 7psi wastegate flapper open on it's own regardless of what signal you are sending from your boost controller. Raising the base spring pressure of the actuator will help prevent this.
The CT27 typically makes 250-300whp on pump gas, 350whp on E85/race gas and the current balls out fully modified everything record is 389whp
GT28RS Disco Potato – basically a ball bearing version of the CT27. Similar performance with slightly faster spool. Great for autocross or track days.
GT3071R – literally one of my favorite turbochargers. I have run these at 250whp on a bone stock MR2 and I have run them at 500whp on a fully modified MR2. This turbo has a HUGE range of power, really fast spool, and can grow with your needs, Plus there are options to upgrade it like the new line of GTX billet wheels. I haven't done one yet, but a 550whp GT3071R is a possibility.