The 7M Series Engine Swaps

 

Background

As a long time Toyota fan, I have had my share of gutless four-wheel drives. At some point I decided I wanted a project car, and I ended up buying a 1988 Supra turbo with some body damage pretty cheap. After fixing the supra and driving it, I knew I couldn't live without the power. However, a rear wheel drive sports car is not very practical as an only-vehicle where I live, and I didn't want to have more than one four wheeled vehicle while I am in school. So I did some surfing on the net, and found some information about other people swapping 7M-GTEs into 4Runners. I like 4Runners; I used to have an 86 that I liked very much aside from being gutless. So it was settled; that was what I needed to do. I watched the classifieds for a first generation 4Runner with a blown engine, found one, and the rest is history.

I originally swapped a 7M-GE into my 4Runner, which was a great improvement over the stock setup. But after getting used to driving the lighter supra with the turbo motor in it, the GE just wouldn't do. So I gathered the necessary parts for the next swap, and about six months later I swapped the GE out for the turbo model.

Because I did not have a digital camera when I did the original swap, I don't have in-process pics of most of the fabrication. I took lots of pics when I did the GTE swap though, and most of the modifications can be seen in them.

 

The 7M-GE Swap (summer 2003)

The original swap involved lots of modifications, the most daunting of which in my mind was the bell housing. Luckily, a friend of mine is a machinist and he was extremely helpful with that part of the swap. The problem is that there was no bell housing produced by Toyota to accommodate the combination of the 7M-GTE/7M-GE engine block and the R series transmissions. After a lot of mocking up and measuring, and many hours of cutting and welding, the bell housing was done. It's overall length matched that of the R150F, as its input shaft needed to be accommodated by the housing. The clutch assembly to be used is the one from the NA supra, and it fits inside quite nicely. Because the 7M-GTE and the 3V-ZE slave cylinders mount on opposite sides, a plate was welded in place for the slave cylinder mounting as shown. With the bell housing completed, I was ready to go full bore with the rest of the fabrication and swap.

Because the front to rear clearance does not lend itself to this engine, I decided to mount the radiator first, and then see how far back I needed to mount the engine. I used the stock supra radiator, as it is thinner than the v6 one, and it has the necks on the appropriate sides. This was also convenient since I could just cut some lower mounts off of a donor car and weld them on to the 4Runner. Later on I did quite a bit of cutting so that the dual pusher electric fan could have nearly full access to the cooling surface of the radiator.

With the radiator in place, I bolted up the engine block, bell housing, and tranny to see how things looked front-to-back. I also made a 1-inch body lift to aid in the clearance between the bell housing and the firewall. The engine mounts needed to be about 2 3/4inches behind the stock location, and the stock mounts were higher than I wanted the engine. So, I cut off the stock mounts but preserved the surface plates for reuse with my new mounts. The new mounts were 3/16-inch steel with gussets at the top.

To accommodate the relocation of the transmission, I made a temporary mod to my cross member. I would like to do something better in the future, but for the time being I used some 1/4 inch steel with supports as shown. At the time of the picture I had about 6,000 miles on it and it seems to be holding up great. The custom drive lines I had made seem to be very good as well. The tranny tunnel had to be cut out in the back to make room for the transfer case shifter. I also welded in a plate at the front to seal things up. I was lucky enough to have access to a plasma cutter during the swap; it really made all of the sheet metal hacking easy.

The next and fortunately last clearance issue was with the oil pan. My 4Runner is an 88, so it has independent front suspension, and the front differential sits right about where my oil pan wanted to be. I really mounted my motor low. With the body lift I could have mounted it an inch higher or more with no clearance issues with the hood. I had thoughts of a hood scoop and IC above the motor, which have since evaporated. That idea was my reason for mounting the motor as low as possible. At any rate, it was necessary to modify the oil pan, and in order to retain all possible oil capacity I decided to graft part of my v6 oil pan into the supra one, as the v6 pan has some very nice contours built into it to dodge the front differential. This was not an easy task at all. The oil pick up had to be moved since it would have hit the front differential too. The stock location of the pickup is here, and mine is here. Here is a pic of the pan installed. The pan mod cost me about 3/4 of a quart of oil capacity, which I really don't like. I plan to add capacity to the back of it and move the sump to the back, with a 'slosh baffle' and all. That should put me at more than stock capacity.

That's about it in the way of fabrication for the swap, aside from all of the minor things like intake piping, a bracket here, a bracket there, etc. I removed all of the stock fuel lines and ran lines off of a supra instead, primarily because I kinked one of my stock ones. I ran the lines on the drivers side frame rail rather than the passenger side since my exhaust runs down the passenger side until it clears the transfer case and crosses over. I used some of the clips from the stock supra lines to hold the lines in place.

The wiring was a bit tricky, and I was very glad to have Rob Jackson's help in answering questions that I had. The Toyota wiring books are a great help too, especially for wiring all of the gauges. I highly recommend coming up with the factory connectors for the accessory wiring. It is great to be able to preserve stock connectors and just insert the correct leads into the plug in the proper locations so that everything is easily removable in the event that the engine needs to be pulled. My v6 tach worked perfectly when I connected the signal from the GE ecu to it, and all of the other gauges worked properly as well.

 

The 7M-GTE Swap (December 2003)

With all of the hefty fabrication already done, converting to the turbo was not too difficult. I spent a few months gathering the necessary parts for the swap: ecu, mass air flow sensor, harness, etc; mostly purchased off of ebay. I ordered in a Japanese motor from GO-Motors (Los Angeles), with a 6-month warranty on the long block. Even with the shipping charges it cost under $900. The turbo had some shaft play, but it was not terrible. My motor did not have an alternator, power steering pump, or power steering reservoir, though I am told that they often do.

As a precaution, I changed the head gasket before installing the motor and it turned out to be a very wise decision to do so. The friend whose shop I was working on the 4Runner in is a Toyota mechanic at the local dealer, and after I pulled the head off he looked at the top of the block and showed me where the gasket was beginning to pull away near the number one cylinder. The gasket would have blown very soon. I had the head resurfaced and installed a new factory Toyota gasket. I replaced the timing belt as well, but did nothing special with the valves, cams, or block.

I also upgraded my clutch. I did some looking around and found a six-puck spring hub disc that is supposed to be good for 500 horsepower. Since my stock NA supra pressure plate was only six months old I decided to run it with the new clutch (bad idea). To support future mods I also upgraded to the Warlbro 255 liter per hour fuel pump, which was really easy to replace. I was able to get to it through the access hole under the back seat.

After swapping out the engines, I started working on my new down pipe. I purchased a flange from Rob Jackson, it's custom made to fit the outlet of the turbo with one hole about 3 inch diameter and another about an inch diameter near the waste gate outlet. I had contemplated venting the waste gate gases to atmosphere, but I am doing my best not to get too into this project performance-wise until I am finished with school and I have a different daily driver vehicle, so I decided against it for now. I bought a 3 inch diameter mandrel bend, and armed with that, Rob's flange, and some leftover piping from my old exhaust I started in. I made use of the waste gate gas hole by adding in a section and just joining it back into the main down pipe further downstream. To make the O2 sensor bung, I found some scrap 3/8 plate for the mating surface, and then used the old sensor for a template. After cutting and grinding out the flange for the sensor to mount to, I welded in some bolts as studs, ground the heads off and welded the whole thing into the pipe. I had the local exhaust shop run the exhaust piping from there back, but they welded it all - no flanges anywhere. Since it crosses over right behind my tranny that was a very bad idea. I'll cut it apart and weld in flanges in two places when I pull my tranny out.

The intake piping took some doing, mainly in rounding up all if the necessary piping, silicon hose, T-bar clams, and nipples. I used some leftover 3 inch tubing from my down pipe to make the pipe replacing the 'accordion hose' which connects the AFM and the turbo inlet. My motor did not come with a '3000 pipe', the pipe leading to the throttle body right above the valve covers. Since I would be making some of the intake piping anyway, I decided to run my piping an extra 10 inches rather than buy one. Next I purchased two 2 1/2 inch diameter mandrel bends and started cutting and welding. I liked the idea of making the piping one piece, so I started from the turbo outlet and worked my way toward the throttle body, making sure that I could still get it in and out OK before welding the next section on. To my immediate satisfaction I was able to make it work. But if I ever have to remove and reinstall the piping before adding an intercooler, I will probably cut it apart somewhere and put another silicon hose junction. It was a nightmare to get the two ends into the very stiff silicon hose at the same time, and certainly not something I want to do again. I forgot to take a pic of the piping before installing, but the installed views show it pretty well. I connected the PCV system as stock, but I really don't like the idea of introducing oil mist into my intake, especially in front of the turbo. I plan to install a catch can and route the lines to it instead, possibly with a drain-back system so that the oil will return to the oil pan rather than requiring that the catch can be emptied periodically.

 

For the electrical end of things, I had a couple of new problems to solve with the 7M-GTE swap. For some reason my oil pressure gauge displayed less pressure than it did with the NA motor. I connected a gage that displays the actual oil pressure directly to the pressure gauge port in the engine block and it was in spec, so I ignored the low reading on the stock gauge. The tachometer presented another problem. Because the 7M-GTE uses a distributorless ignition system, the ecu sends out a different signal to the tach. I have seen mods out there for the supra NA tach, listing which resistors to change out of the circuit board on the back to make it work properly with the turbo ecu, but the PCB on the v6 tach is different so those mods are not applicable. I recently did some quasi-educated guess and check mods to my tach's PCB, and the tach works. I can dial it in at a given rpm, but I don't know if it's accurate over the entire range. I need to get a hand held tach so that I can test it. (Now verified - it works perfectly. I will post the PCB mods and calibration method soon)

 

Results

I could not be happier with the performance of the 7M-GTE in my 4Runner. It is quite amazing to drive a Toyota 4 wheel drive with as much guts as it has. I have been able to pull any hill at 70 mph in 5th gear, without even flooring it. I drive it pretty hard, and my transmission needs to be rebuilt now, hopefully I will get to that one of these weekends soon.

I recently installed a boost gage - I have nearly 5,000 miles on the swap and have had no idea how much boost I have been running. My timing is advanced and I am running no intercooler for the time being, and because it doesn't ping I assumed that the boost pressure must be no more than the stock range, 6-8 psi for M/T. Last night I saw it boost up to 14 psi in third gear, I couldn't believe it. It will boost no higher than 10 psi in first gear, I think because it can't stay loaded long enough to spool up past that. It will take more investigation, but I am very surprised at the level of boost.

 


Visits since June 20, 2004