TOYOTA ENGINE SWAP: GENERAL
Left: Here's the finished product. I didn't do much along the way as far as pictures are concerned, but this should give you the idea that with a few minor exceptions, this was a pretty straightforward project.
The Toyota 4age engine is a direct descendant of the Ford Cosworth BDA. Same bore, same stroke, same valve sizes. Was this Toyota's last reverse engineered engine? I'm not sure and I don't think they would tell you. In the early 80's this engine was used in the AE86 rear wheel drive Corolla. Mid and late 80's the 1st gen MR2. It was also used in late 80's Corolla GTS's among other cars. Millions were produced, and it has been revered as a wonderful engine. Dual overhead camshafts, four (or five) valves per cylinder, belt driven cams, 1588 cc's. 81mm bore, 77mm stroke. The engine was used in RWD front engined, Mid engined, and FWD. It was supercharged as well in some MR2 models. It survived into the late 90's in Japan where it's final iteration had 5 valves per cylinder and an 8200+ rpm rev limit producing 165 HP. Long and short is that this baby is well suited to any engine swap for a lightweight car. Enter my 69 MG Midget badly in need of some power.
Right: So here it is. I fought with myself over whether to even do a conversion. Then once I decided, I fought some more over which engine to choose in order to retain the character of the car. The final two were the Suzuki Swift GT engine paired with a Samurai trans, and the 90's variant of the Toyota 4age engine. The tech support for the 4age is unmatched. The power is claimed by toyota to be 160hp but in practice, more like 150. I think the Swift swap can be done with less cutting and less PITA, but I figured if I was going to do this, I would need all the tech support I could get and the extra 50 HP wouldn't hurt either. Truth be told, the swift engine is lighter (all aluminum), it's 1300cc's, and more compact and is probably more true to the character of the car. I had to go with the vast tech support (www.club4ag. Com and www.mr2oc.com) and used engine availability of the 4age though and figured since I was doing all the work anyway, I might as well have a really powerful engine. www.venus-auto.com has the complete engines, harnesses, and ecu's for $600 + shipping.
Engine Details: 1991-1995 AE101 4age "silvertop" 5 valves per cylinder, individual throttle bodies (from the factory!).
Left: The Toyota weighs about 310 lbs with transmission and all accessories. Probably about 20 pounds less without the a/c like mine is setup. The MG engine and transmission it replaces weighs 290. Win-win? I think so. The engine seemed as if it was made for the car until I started in with th e radiator, exhaust manifold, induction piping, oil cooler piping etc.
So what's required to cut?
Heater/battery shelf: I removed and replaced with a coolant overflow tank. You could just fab up a smaller box there to just place the heater and put the battery in the trunk, but I am still fighting about that one. I have survived with no heater for a while, though I could certainly use one.
Passenger footwell: I cut a box in order to fit the intake airbox as stock. You could build an airbox out of fiberglass pretty easily to clear without cutting, or alternatively, use an aftermarket injection setup to use MAP (manifold absolute pressure) to measure airflow rather than the airflow meter. This would eliminate the need for the box and the associated piping.
Trans Tunnel: I cut the entire top out. Not quite necessary, but I had killed a datsun transmission with the driveshaft yoke which in turn killed my tunnel anyway. More on this later.
Pass Frame Rail: For clutch slave (pass or driver depending on bellhousing used).
Crossmember: I cut out the entire center of the rear crossmember and made a new one out of 2X2 steel tube with a notch in the middle to fit the transmission rear mount.
That's all the cutting.
BACK TO TOP
Right: Engine compartment is FULL!
I didn't talk much about the transmission. It is the Toyota T-50 model, as fitted to thousands of toyotas over many years. Their is a trick though. Several variants were made. You will want to take a look at some websites concerning the t-50, but here is the mix n match you want to end up with.
-'83+ T-50 22 spline (on the output shaft) transmission. Split case diagonal. Found on all RWD toyota corollas with an "A" series engine (3a, 4a, 4age...). Make sure you get the backplate and starter from that engine as well.
-Tailhousing, shifter, and shift forks from a 70-79 corolla. This will move the shifter about 6" forward. and it will come out of the stock hole. Save yourself some money by taking the whole day and doing the swap over at the junkyard. Pick n pulls in CA will charge out the behind for all these parts separately.
-Bellhousings from Toyota AE86 corolla GTS's will put the slave on the pass side, while the others will put it on the drivers side. I chose to use the GTS's bellhousing, as the engine is meant to be tilted slightly to the exhaust side, and I figured this would help out with slave clearance.
BACK TO TOP
Left: In order to mount the transmission, I cut the center out of the original crossmember. I built a new forward tunnel as shown. For the crossmember, I used a piece of 2X2 1/8" wall thickness tubing stretched all the way across the compartment, notched in the center for the transmission mount. I connected the two to make it look like a wider crossmember. I've since sealed with J&B Weld and bedlined the entire interior so it's difficult to tell that anything's different. Seats fit fine.
And after bedlining the interior.
Right: Air Flow meter tucked away inside the grille. Should get some cold air. Used old K&N filter with some thin aluminum for mounting. Connected to the intake box with dryer hose. The oil cooler is directly below in the "horn compartment". Horns are there too.
Left: Can barely tell its all there!
Right: I had to modify airbox to put inlet at the front. Dent is for hood clearance which is about an inch. Note the duct tape covered dryer duct Airflow meter hose. I needed something airtight to go from the surge box to the airflow meter in order to get a proper reading, but this is not as elegant as I would have liked.
Back to top
Where I took the inlet from, to move to the front.
BACK TO TOP
Picture of coil for Toyota engine.
Picture of "ignitor" and diagnosis box.
Picture of ECU. This is bolted to the passenger side inner fender.
BACK TO TOP
Picture of remote oil filter setup. You will need one of these if your car is LHD because the Stock filter location interferes with the steering shaft. This one incorporates a oil temp fitting.
BACK TO TOP
Picture of the header. To have someone custom build you one will cost a minimum of $500. I am fundamentally cheap (I say this while having stainless braided hose at $10/ft in the same picture) so I decided to build my own. It wasn't actually that hard, but it was mentally challenging. The pipes had to come up, forward, and then back down. Not the optimum primary length but I'll accept the two horsepower loss. The exhaust opens to a 2-1/4" pipe with a Dynomax ultraflo muffler. This is the limiting factor on ground clearance. Not much I can do about it as I have about 3-1/2" right now. Won't be rock crawling this car any time soon. So far, the exhaust is pretty tame at low speeds, but open her up and HOLY MACKEREL! It's "spicy" to say the least. I'm exploring options in this realm to quiet it down without losing ground clearance. I'm thinking about a Dynomax turbo muffler, only they don't seem to make those in the fully welded style, and I question the longevity of the system. Until then, I'll keep my eye out and earplugs in. The stainless tubing has since been covered with heat wrap to protect from header heat.
Here's the radiator. It's from an Audi 5000 and it's HUGE. I had to cut a few of the extra connections off and it's still a little wide at 26" total. I don't know if radiator shops can narrow radiators or what, but that's something I'm going to have to check into. The fan is a little hokey as well and doesn't pull enough air while I'm sitting still in 100 plus degree Sacramento summers, so I'll have to figure something out for that as well.
The expansion tank is a kit from Autozone for about $5. It's an interim solution until I can make something prettier. It sits where the heater shelf was before.
BACK TO TOP
Fuel Surge tank: I have built three different aluminum gas tanks to replace the original steel tank. All three have had varying degrees of success. The problem is that if the tank pickup is uncovered during cornering, the pump sucks air. The engine does not like this and will die.
Heater: I'm trying to find a small heater core that I could concievably fit below the dash inside the car so I don't have to further crown the engine compartment.
AFM Hose: Any suggestions for something better than duct taped dryer hose?
Tachometer: I didn't get it to work using the ECU's tach output. Also it "only" goes to 7000, and the engine makes max power at 7400 with fuel cut at 8200+.
Speedometer: I'm going to try and make a hybrid cable and see how that works for me. I'm not sure of the accuracy I'll get, but I'll give it a shot anyway.
Oil filter corner: I'd like to clean that area up a little bit. Might require going to megasquirt to get rid of the AFM and associated hoses etc.
Noise: I'm a little loud now. Either going to try a couple different mufflers, or reduce exhaust to 2" all the way through. OR go to a rotary muffler. More on that below.
Radiator: I've got an MR2 radiator with fans I'd like to try. Only it's just as wide as the current one. I'd like to narrow it about 5 inches, but I'm not sure that can be done. I'll have to check with a radiator shop and see what they can do. The current one is leaky anyway. Also I need to make a better fan shroud, as it heats up a little when stopped and outside temp is 100+
POWER!: I'm addicted! I was thinking of adding a "rotary muffler" in the form of a T-25 turbo from a 95-99 Mitsubishi Eclipse. This would simplify exhaust routing, quiet the exhaust, and add anywhere from 50 to 125 horsepower.
Fuel Tank: I found some carbon fiber and kevlar at work that I can use to mold a pretty cool tank. I also have an RX-7 2nd gen in tank pump I could shorten and use with the molded tank. We'll see how that goes.
Heater: No ideas yet, still searching.
AFM Hose: Found some aeroduct in some racing catalogs that would work at $5/ft. Or thinking of going to Megasquirt EFI computer to get rid of AFM altogether.
Tachometer: Palo Alto Speedometer claims they can re-face the tach to read 9000 and make it work with my ignition system. I'm very interested, as I don't care for the Autometer look. Smiths makes the best looking gauges I have found.
Speedometer: See above. They also claim they can make this work. I'll probably go with an MGB speedo to get the 120 mph markings.
Oil filter corner: As stated there... need to get creative and clean up.
Noise: !!!!
Radiator: Try and get a custom rad built? $$$
Things to do:
1)STUDY. Find all the websites below and print a copy of the pertinent information. Put it in a binder and study it. Spend months doing this until you've listed yourself into oblivion. This is not a project to be taken on lightly. It took me 6 good weeks of working every spare moment to get this on the road.
2) Try to keep it reined in. The temptation will be to do a ground up restoration at the same time. There is no greater way to kill motivation than this. On the other hand, this is a great time to clean up the front wiring and engine compartment.
Things to get:
1) 4age engine. I recommend the "Silvertop" AE101 engine. It is newer (90's), will have fewer miles and is much more powerful than earlier models. It's also relatively cheap: It is for sale for $600 at Venus-auto with harness, afm, ecu, and fwd transmission. Sell the transmission for $200, the starter for $75 and you are down to pretty dang cheap.
2) Transmission: described elsewhere this site and on Phil Bradshaw's site.
3) Heavier duty rear axle: My personal opinion is that you will need a heavier duty rear axle no matter what. I was snapping axles with the 1275. I decided (thought it would be a neat project) to build a Miata based independent rear (see elsewhere this site). An easier method would be to use a 1st generation RX-7 rear axle narrowed with the stock leaf springs etc and a panhard rod. Many have done this.
4) Driveshafts from both toyota and whatever rear you decide to use to have made into one. Mine cost $300 with re-useable u-joints.
5) Motor mounts. I used napa p/n 602-1061 They have pictures in their catalog. If you find a better one, then have at it.
6) 1-1/4" Tubing for cooling system and lots of elbows. These are more expensive than you think.
7) Radiator and electric fan. I would try for a VW Scirocco rad. They sell for $109 new in Summit racing or about $40 in your pick n pull. The Silvertop engine may work with an engine driven fan, but I haven't tried it.
8) Access to a welder. This is a valuable purchase. I have heard tale of using Harbor Freight Tools welders with great success. Flux core works ok, but finally a year after this project was "completed" I broke down and bought a Lincoln SP-135+ mig welder and use CO2.
Links:
http://www.club4ag.com
http://home.clear.net.nz/pages/phil.bradshaw/INDEX.HTM
http://www.team.net/www/mg/tech/midget/engswapa.html
http://www.billzilla.org/carindex.htm
http://www.venus-auto.com
http://www.onthenet.com.au/~paulp/Blacktop/
http://www.angelfire.com/az3/4doorae92/index.html
http://www.racingstrong.com/aw11/aw11parts.asp
http://www.toyotaworld.com
I won't pretend I did this on my own. I have found with this project more than anything that the internet has a vast wealth of information. Club4ag has an excellent tech reference. While some of the members are a bit green, they make up for it in enthusiasm for an engine that stopped being imported to the US in 1990! Pretty good source for used parts as well. Phil Bradshaw's page is an invaluable source of information regarding this project and was probably the largest source of information. He put a 4age into his Leitch Lotus 7 clone. He tells all about the transmission, engine, wiring etc etc etc. Of particular note is the ECU pinouts on both Phil's page and the tech page of Club4ag.com. The team.net page is what got the idea in my head. The gent there uses a slightly more rare and larger engine than the 4age, but there is good basic info about the engine mounts etc. that can be translated. Bill Sherwood's website is a great great technical reference about all things engine. The man knows his stuff and has taken the time to put it down for all of us. Venus-auto is next, and I only included them, because they have the cheapest prices I have found for the engine. I didn't personally buy from them, but this is here to prevent others from paying too much. The next is a link to the engine workshop manual on the net. Since these engines were never imported to the US, it is nigh on impossible to find a manual in english. Only other English speaking country they were imported to was South Africa. The next has part numbers and good general reference. The racing strong website has tons of diagrams for toyota engines. Go almost all the way to the bottom to MODS and you will see several VERY useful diagrams, the greatest of which is the "20v to 16v schematic MAIN". This is the efi diagram for the 20v engine. Find a way to print it out, as you will need it. The wiring isn't as hard as it would seem and EFI isn't a great mystery. Toyotaworld.com is a link to Jay Marks Toyota, where a man named Jeff can get parts for these engines even though they were never imported. Wahoo.
BACK TO TOP