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Lotus FAQs1. What is the status of turbo availability?
Toyota FAQs1. Where do I get all my information on the 4AGTE?
2. Which engine block should I use for a 4AGTE?
3. What exhaust manifold should I use for a 4AGTE?
4. What crank should I use for a 4AGTE?
5. What connecting rods should I use for a 4AGTE?
6. What bearings should I use for a 4AGTE?
7. What pistons should I use for a 4AGTE?
8. What piston rings should I use for a 4AGTE?
9. What about cylinder heads for a 4AGTE?
10. What head bolts should I use for a 4AGTE?
11. What head gasket should I use for a 4AGTE?
12. Which cam works best with a 4AGTE?
13. How do I control the fuel system on a 4AGTE?
14. Can the stock 4AGE ECU work with my turbo conversion?
15. Can an ECU from a 4AGZE be used on a 4AGTE?
16. What size fuel injectors do I need on a 4AGTE?
17. What turbo should I use on my 4AGTE project?
18. I still want to run a T-04 turbo. What do you recommend?
19. I have my turbo mounted on top of the engine... (insert rest of question here)?
20. I have my turbo mounted above the transmission. What can you recommend?
21. How do I get oil to the turbo?
22. Where does the oil drain from the turbo go?
23. What about a water-cooled turbo?
24. Where do I connect the water lines for the turbo?
25. Since adding a turbo, my clutch seems soft after extended driving. What's the cause?
26. My starter keeps going out since my turbo conversion. How do I fix this?
27. I've heard about moving the starter to the rear of the engine. How do I move the starter?
28. Which transaxle should I use with my 4AGTE conversion?
29. How much power can I put into a C-series transaxle?
30. What clutch should I use with my 4AGTE?
31. Should I use a light flywheel on my 4AGTE?
What is the status of turbo availability?
WC Engineering makes every attempt to have our Stage I turbos in stock. However, this is not always possible. The Garrett T-3 turbo used on the Lotus Esprit is a very unique unit. It uses a turbine housing (the hot exhaust part) that is only used on the Esprit and it is not commonly available.
When an order comes in, the turbo is shipped to you, the customer, or to a shop that you may be using for the work. The turbo can be swapped with a minimum of downtime for your car and when you're done you return the old turbo to us. When we receive the old turbo back, the cycle starts over again. As you can imagine, there is also some transit time involved in shipping.
However, if a customer doesn't install their new turbo on their car for a few days or weeks, it means that we don't have a core back to rebuild for other customers. This can cause significant delays. We have acquired a few spare "cores" that we use for upgrades and hope to acquire more to help reduce our turnaround time.
If you are considering of one of our units, we would be happy to hear from you. Please contact us and we will provide current inventory status. If we are out of stock we will make note of your information and be in contact with you as soon as we have an availability date. Sometimes we keep a list of interested parties. We do not require a deposit to be put on the list, but it is encouraged. Our busiest time of the year for turbos seems to be fall through spring, when people are doing upgrades and maintenance on their cars. Try to contact us early so that we can have a unit available for you when you are ready.[Back to top]
Where do I get all my information on the 4AGTE?
This is all from my experiences, not from looking stuff up online. It is all based on use of a 4AGTE in an AW11 MR2... specifically my 1987 MR2. If you are developing yours for another application, then some of my information may be helpful, but please do your homework first. If you are developing something on a budget, keep your goal realistic. There is no need to go buy a new 7 rib block if your only going to be making 10psi of boost. Read though this and feel free to ask me any questions. Your question and answer may end up in this list next.[Back to top]
Which engine block should I use for a 4AGTE?
The best one you can afford.
The later seven-rib blocks are, of course, stronger, so they are the natural choice. Some of them even have the under piston oil squirters. The five-rib blocks are fine up to about 180hp and I have run them there for extended periods with no problems. Above 200hp they start to flex like a bowl of Jello. So, a good condition five-rib block with stock internals can be used as a starting point. It is most likely that you'll will find other weaknesses before you find the limit of the block, crank or rods.
The best block to use is the latest seven-rib block with the oil squirters, if you can get one. Second would be the seven-rib blocks used in the MY 1987 and later MR2s both NA and SC.[Back to top]
What exhaust manifold should I use for a 4AGTE?
Before answering this you need to read "What turbo should I use?", then come back here.
The best turbo exhaust manifold for the 4AGTE in the AW11 body is the original HKS cast iron piece. Unfortunately, it is no longer available, and even when it was, they were very rare. (FYI: I have three of them.) This manifold has a flange for a T-25 turbo.
There are people selling exhaust manifolds that claim they are for the 4AGE, but most of them will only fit in the Corolla chassis. Be VERY careful when purchasing them online. Get good pictures upfront. Even more rare is the HKS manifold for the twincharge system. This manifold had a flange for a T-04 turbo on it.
Your second choice (or really first choice) would be to use one of Carl Crawford's Speed Source stainless steel tubular manifolds. This piece was made using an original HKS piece to make the fixtures. Everything on the manifold is excellent for the 4AGE conversion. It mounts the turbo in the correct location, high enough for the oil drain but low enough to clear the firewall. This manifold has a flange for a T-25 turbo and he has a downpipe available for it as well. See the section on turbos for more info on sizing them for the 4AGE.
For those of you making your own manifolds, go for it! I've heard of people using steam pipe and having good success with them. I have little to no experience with this. I'll stick with the HKS piece or Carl's beautiful duplicate.[Back to top]
What crank should I use for a 4AGTE?
The stock cranks are VERY strong. I do not know of a case of a broken crank. Obviously, if you are building a high output engine, get at least the later 42mm journal crank or one of the aftermarket cranks for the most reliability. I like the TRD billet crank but they have gotten a bit expensive.[Back to top]
What connecting rods should I use for a 4AGTE?
The stock connecting rods are almost as big as a small block Chevy (that isn't saying much for the Chevy) and I have had no problems with them at all when used with ARP fasteners. If going over 200hp you might consider an upgrade. There are several makers of rods: Carrilo, Crower and Eagle make excellent pieces. Again ARP fasteners are recommended.[Back to top]
What bearings should I use for a 4AGTE?
Have the crank and rods and main journals measured and use the correct size bearings. The stock Toyota ones are good, but it will take forever to get them from your dealer. Clevitte 77 bearings are great and are used by many engine builders. They are available in many sizes and are inexpensive.[Back to top]
What pistons should I use for a 4AGTE?
The stock 9.8:1 pistons can be used to start with and below 9 psi, but will require proper intercooling. Stock SC pistons are good pieces for raised boost levels and they are easily available and inexpensive. Higher performance will require better pistons. I have some sets of Cosworth dished pistons that are excellent, but they are no longer available. Many of the popular piston makers have good choices.[Back to top]
What piston rings should I use for a 4AGTE?
The factory rings are great on the factory pistons. Get a ring recommendation from your piston manufacturer and follow their specifications for a turbocharger or supercharger engine. There will be different ring end gaps for different applications.
I have used the Total seal piston rings with good results. Some people complain of ring seating problems, but this is usually not the actual problem. The Total seal rings create so much suction on the down stroke, they can pull oil out of the crankcase breather. This is another problem entirely.[Back to top]
What about cylinder heads for a 4AGTE?
First, if you ask me about "red top" or "blue top" cylinder heads, you're not going to get a response. If you ask me why you don't get a response, you won't get a response to that either. Let's just say that you need to do your homework.
There are different camps that debate the large port vs. small port heads to no end. I have only used the early large port cylinder heads, so I cannot comment about the later small port heads. I will say that the T-VIS system does improve the low-end response of the engine with the large port head.
Stock valves are fine for starters. After that, get bigger valves: 2mm larger at least. 1mm isn't enough of an improvement to justify the expense of installing them. If your keeping the stock cams, then the stock valve springs are fine.[Back to top]
What head bolts should I use for a 4AGTE?
The factory head bolts are fine for up to 10psi of boost. Beyond that, they stretch. Replace them with ARP head studs. APR studs can be used with a factory head gasket beyond 20psi of boost. NOTE: When using ARP studs, you will need to grind down one stud (the one that is near the distrubuter opening). If left the standard length, you will be unable to install the distributer.[Back to top]
What head gasket should I use for a 4AGTE?
The factory head gasket with factory studs is good to 10psi, beyond that you need studs. If you want an inexpensive way to lower your compression, you can use one of HKS's metal head gaskets. The 1mm and 2mm ones work fine, the 3mm one will require adjustable cam gears to get the cam timing corrected from the changed block height.[Back to top]
Which cam works best with a 4AGTE?
I would recommend going to the HKS 256 or 264 cams for a turbo application. The 272 can work but requires special timing to get them just right. If you're still developing your system, you can even use stock cams until you get all the other bugs worked out. These are the cams that I have used. I've heard good and bad things about the Web cams, so it's your choice.
Consider going to the TRD springs for better cam timing. If you want to spend the money you can use the double valve springs, but they aren't required unless you're raising the red line.[Back to top]
How do I control the fuel system on a 4AGTE?
One of the keys to a successful turbo conversion is to have proper fueling system. There are many different approaches to fueling and here is the information that I have put together from my many years with a 4AGTE. If you haven't read it yet, read the technical article on fuel pressure and return here after that.
The stock fuel pump and pressure regulator on an 4AGE AW11 is fine for up to about 200hp. After that, a larger pump, lines, and regulator should be considered. The use of a rising rate fuel pressure regulator is good only for small boost pressures (below 5psi).[Back to top]
Can the stock 4AGE ECU work with my turbo conversion?
The stock ECU on a 4AGE will not properly control the fuel needs for a boosted application. An add-on piggyback ECU or a stand-alone ECU should be considered a necessity for any turbo conversion. HKS originally offered their PFC-FCon piggyback unit for use on the 4AGE. There were two different EPROMs used with it: one for the stock injectors and another for the larger injectors.[Back to top]
Can an ECU from a 4AGZE be used on a 4AGTE?
I suppose, but why? If you are starting with a complete car (I do mean a complete, running car) that has a 4AGZE, then you could start there. You're going to run into the same limits that the NA cars has.
If you don't have the complete car, don't even consider this option. The time and money you will lose getting all the correct sensors and wiring will make the project unbearable. Go with a standalone system.[Back to top]
What size fuel injectors do I need on a 4AGTE?
The stock 220ccpm injectors are limited to about 5psi and any applications above that should use larger injectors. The 295ccpm injectors from the 1986-1987 22RTE turbo trucks work well. They are the correct size, impedance, and they have the same connectors on them. This injector is also what HKS used as their upgrade.[Back to top]
What turbo should I use on my 4AGTE project?
I get many questions on this and many people want to put a huge T-04 on their car. Go for it, I'll stick with what works best for me.
HKS originally used the Garrett T-25 on their kit for a few reasons. It was properly sized to the engine, it had good spool up and reasonable performance, it was a compact unit that fit in the space, and it was available inexpensively. These are good enough reasons to consider using the T-25 as well. The exact unit was used on the 1987-1988 Turbo 4-cylinder Sunbirds, Skyhawks, and Grand Ams, so it is commonly available. Many other versions have been used by Nissian on their 300ZX twin turbo and others.
Some people refer to the T-25 series as the "T-2 small." These people have not really looked into the parts, upgrades, and variants. You can get a good reliable rebuilt T-25 for as little as $400 and it will work fine up to about 175hp. You can have a larger compressor wheel put on it, or go to the T-28 selection, or even the T-28 with ball bearings and support over 300 hp. If you are planning on making over 300 hp with a 4ATGE, then you have the answers figured out already.
The "stock" T-25 is good for about 12-13psi of boost. Any more and it is terribly inefficient. An upgrade to the larger compressor wheel can go up to 15-17psi. Using the T-28 you can get upwards of 20psi of good clean boost with enough volume to hold the boost all the way to the red line.[Back to top]
I still want to run a T-04 turbo. What do you recommend?
Talking to someone who has a real big shoehorn.[Back to top]
I have my turbo mounted on top of the engine... (insert rest of question here)?
I don't know what to tell you... get the correct manifold.[Back to top]
I have my turbo mounted above the transmission. What can you recommend?
1. A good trans cooler, because the fluid in it is going to bake.
2. Moving it, because the heat loss from the engine to the turbine will be significant and you will have slow spool up.
3. Moving it, because the manifold desing creates a large heat build up near cylinders #3 and #4 and the manifold is going to crack and/or warp.
4. Good insulation on the coolant hoses because they are going to bake.[Back to top]
How do I get oil to the turbo?
No matter what turbo you choose, it will need an oil supply. This needs to be a pressurized oil supply, so don't think that you can tap into the oil cooler lines. This feed must come after the oil filter, so your simplest choice is to tap into the oil pressure sender port that is on the block. The second choice is to drill the block and tap into the oil passage over near cylinder #4, but only do this if the engine is out and disassembled.
When using the oil sender port, the hole in the block is 1/8" BSP 28 tpi, not 1/8" NPT 27 tpi. A 1/8 NPT fitting WILL leak. The best setup is to put a fitting into the block and come off of it with a #3 Earls stainless hose. Run the hose to part of the chassis and mount a distribution block. Screw the original sender into the block and run another #3 stainless hose feed to the turbo from the block. The feed to the turbo will need a restrictor in the line to reduce the flow of oil. The turbo only needs a small steady flow, not the full pressure.
Some have used a distribution block, or a "T" that is mounted directly on the block. DO NOT do this. It WILL crack off at the surface of the block and it WILL cost you an engine.[Back to top]
Where does the oil drain from the turbo go?
Well, where is the turbo mounted? If you're using an HKS manifold or a similar piece, it's easy. The turbo drain points down and you run a large diameter hose from the drain down into the pan. You will need to put a fitting into the pan, as high on the pan as possible but low enough that it is still below the turbo drain. It will be almost directly inline with the oil cooler return fitting. You will need to use a good quality hose. I have AN drain fittings and AN fittings on my oil pan and I use a #12 Earls hose between them. You cannot tap into the oil cooler line for a drain. The turbo needs a larger diameter hose.
The oil in this hose will be VERY hot and is about the viscosity of a McDonald's milk shake. It has to flow downhill on its own. If your turbo mounting is such that it cannot flow downhill to get to the pan (if the drain is below the oil upper oil level in the pan) then you will need to use a scavange pump. Tilton has a nice unit that works well with hot oil.[Back to top]
What about a water-cooled turbo?
Get a water-cooled turbo for two reasons: one, less oil coking and two, stronger center section from the water jacket ribbing.[Back to top]
Where do I connect the water lines for the turbo?
Good question, easy answer. There are two water lines that pass through the center tunnel of the car and come out in the engine compartment. They feed a constant supply of water to the heater core. The other ends of these lines are connected to the head and the thermostat housing. You can tap these two lines for a feed and return to the turbo.[Back to top]
Since adding a turbo, my clutch seems soft after extended driving. What's the cause?
The clutch system uses hydraulic fluid to move the slave cylinder. The hose from the slave cylinder to the chassis is rubber and with all the heat near the turbo the rubber gets soft and then it expandes when you step on the clutch pedal. Replace the line with a stainless one from Carl Crawford's Speed Source. Don't waste your time trying to make one. The fittings are not available anywhere; Carl has them custom made.[Back to top]
My starter keeps going out since my turbo conversion. How do I fix this?
Yes, and it will keep going out until you move it to the rear of the engine. The heat from the turbo is melting the varnish off of the windings on the solenoid and armature. (See "How do I move the starter?)[Back to top]
I've heard about moving the starter to the rear of the engine. How do I move the starter?
This is revelant to those people using the C-50 or C-52 transaxles. (See "Which transaxle should I use?") With the C-50 and C-52 transaxle the starter is mounted on the "exhaust" side or front of the engine. When we add the turbo, there is a great deal of heat generated and it will damage the starter in a matter of only a few hours of driving.
If you have a C-50, you're stuck... sorry. If you have a C-52, read on. The C-52 transaxle has mounting bosses for a starter on both the "front" and "rear" of the bell housing. You can mount a stock starter on the "front" and a starter from a 4AGZE can be mounted to the "rear" position. Depending on when your transaxle was made will determine if you need to drill and tap a hole in the mounting flange of the bellhousing. The mount will already have a pilot hole. You'll will need to drill and tap it for a 12x1.25mm bolt. You will also need to bore a hole in the backing plate to allow the starter nose to pass through to the ring gear. You should cover the hole on the "front" of the bellhousing. The wiring can be adjusted to connect to the rear mounted starter without any issues.
You will be surprised how much room is gained near the turbo without the starter in place.[Back to top]
Which transaxle should I use with my 4AGTE conversion?
Which one do you already have? If you are starting with a 4AGZE then you already have the E-51, and you might as well use it. It bolts up, it has the "rear" starter mount, and it costs you nothing. Remember though that there are VERY limited parts for this transaxle and almost no selection of gears or LSDs.
If you are starting with a NA MR2 then you either have a C-50 or a C-52. The C-52s started coming out in late 1986 and were in the 1987 model year in the US. These two are very similar in appearance and externally the only distinguishing feature is the bell housing opening. The C-52 has provisions for a starter on both the "front" or "exhaust" side and the "rear" of "intake" side of the engine. This is the preferred transaxle of the two. There are several differentials available for this unit, along with gear sets. It shares many parts with transaxles that are still in production. The C-52 also has slightly larger input and output shafts, so it is slightly stronger. The shift forks were also improved in them over the C-50s.[Back to top]
How much power can I put into a C-series transaxle?
This depends upon the use of the car and how well you drive a stick. I've seen people destroy a transaxle in a car in less than 5000 miles. Personally I've driven over 100,000 miles on a single stock clutch (in my tow vehicle). Different people drive differently.
Are you going to be drag racing? Go buy a Quaife dog gear box or a Lenco. Are you driving it on the street? The C-52 can handle upwards of 300hp. Are you road racing? Well, it can handle over 300hp, but you will need to rebuild it often. Adding a circulating pump and a cooler to the transaxle helps extend the life greatly. Use a good quality gear oil like Red Line MT-90 and change it often.[Back to top]
What clutch should I use with my 4AGTE?
This will depend upon what transaxle you use. I have preferences and so does everyone else. Pick a good brand and you should be happy. I've heard of very few problems with clutchs on MR2s.[Back to top]
Should I use a light flywheel on my 4AGTE?
A light flywheel will let the engine rise through the revs faster, and drop faster as well. This is great for racing as it frees up horsepower. It can also make driving on the street a bit difficult. If you have lowered the compression, changed the cams, and disabled the T-VIS there will be less low-end torque available and there may even be a roughness at idle. With a light flywheel you may have to rev the engine higher just to pull away from a stop sign. This means more wear on the clutch and fewer miles from it.
So, is the car driven mostly on the street? If yes, stick with the stock weight flywheel. For road courses, you might consider the light flywheel. All-out racing: get the lightest one you can. In any case, decide this when building your engine and bring the flywheel and clutch assembly to the shop when you have the crank balanced and have it balanced as a unit.[Back to top]
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