1988 Toyota MR2
I bought this Mr2 from a friend of mine who upgraded to an sc mr2 in 1998. It was a pretty rare 88 hard-top n/a with no options. This was a good platform to start with because it's as light as an 88 would get and I liked the subtle differences between the 88 and my current 85 mr2. My first mod to the car was to completely strip it off all climate controls (even the heater). The second mod was to get a more powerful engine. I found a small port high compression 4age in the local paper for $450. It was going to be the biggest project I had ever done. In 2 weeks I managed to put the small port into my 88 and put the old engine from my 88 into my 85. It was kind of like improving 2 cars at once. It's funny looking back on that, it takes only a day to swap out a mr2 engine now but I suppose you have to learn at some point.
Small Port 4age
The car seemed a lot peppier with the new engine. I took it out for it's first test drive and ironically the first light I pulled up to there was another mk1 mr2 who wanted to race. I pulled him pretty good up to about 60 when he gave up. It was a pretty easy race so now being all full of myself I called up my same friend who sold me the car and challenged him to a race. He drove my car around the block a few times and seemed impressed with the added power. His 89 sc had only a modified exhaust and he weighed like 280 pounds so I thought I had a good shot. I was mistaken. When we raced I learned a valuable lesson about boost. On paper power to weight wise it seemed like a favorable matchup, his car was so much heavier than mine and he only had 15 more hp, how could I lose? Boost makes torque and although it was relatively close he humbled me quite a bit. The next day he got his sc pulley in the mail which pretty much ended all possibily of a re-match. Un-detterred I wanted to make my car fast without boost. I ordered up a set of web 555 cams and aem cam gears. It loped a little with the new cams and seemed to lose a little power in the low end but it pulled hard past 5500rpm. I would drive around banging it off the 8200rpm rev-limiter all day long. At the track it ran a 16.488@84.36mph (insert 3100ft elevation disclaimer here) Still it wasn't fast enough I need to make more n/a power. This is when I began researching doing the 7age hybrid motor.
7age
7afe's are basically a 4a block stroked from 77mm to 85mm (1597cc vs 1762cc). Making yourself a 1.8l 4ag is pretty simple. Go find a 7a block from a mid 90's corolla, celica or prism and bolt a 4ag head onto it. It seemed simple enough. I couldn't find a cheap 7a, they were all good running engines, bummer. I had to pay $450 for one from a 95 corolla, it even came with a warranty (like I would need it). I took apart the 7a and threw away the head. Next I took apart the small port 4ag. I put the small port pistons in the 7a block on the 7a rods. You can only use 4ag pistons with a 20mm wrist pin on 7a rods, I think anything made from 87 up will work. You don't want to use the 7a pistons they are dished and with a 4ag head your compression will be under 9:1, not good. When you do this you have to get the wrist pins pressed in. I should have had them modify the rods to floating wrist pins but I had no idea at the time. Next I put the 4ag timing gear on the 7a crank added a set of arp rod bolts for a little extra safety at high rpm's. 7a's use metal head gaskets that look a lot like trd headgaskets so I bought one from the dealer with a full gasket kit for a 4ag head. Next I had a valve job done on the head, I wanted this enigine to run perfect. I used arp head studs to torque down the head and put in my web cams and cam gears. Finding the right timing belt took a few trips to checkers but a 86 porsche 944 belt fit pretty good. Since the deck height is higher on the 7a block the cams wouldn't line up, they were both off about 1/2 a tooth. This is no problem when you have cam gears and I would reccomend anyone doing this to either buy some aftermarket ones or slot your old ones.
Now the engine was all together I had to put on the flywheel and clutch. The 4ag flywheel wouldn't fit it has 8 bolt holes and th 7a crank had only 6 so I had to buy a 7a flywheel. Luckily the 4ag clutch does fit on the 7a flywheel, Toyota is good like that sometimes. The last problem I had was putting on my trd header (it was free, this guy just gave it to me, thanks bill). With the increased deck height the header was hitting the oil pan. Since part of the oil pan is aluminum and ribbed I took the grinder to it and everything fit. If your using the stock mr2 header you have to get the 2 exhaust pipes just below the header modified to clear the oil pan. I put in the new engine and broke it in, everything seemed to run good. I compression tested it at 215 in all 4 cylinders after 500 miles. This was up from 185 in the small port. With the extra stroke my compression was probably near 11:1. Once I started getting on it I noticed there was a definate loss in power in the low to midrange rpm's. I checked the plugs and it looked like it was running lean so I put in a set of supra 290cc injectors. It really brought the car to life, it would pull hard up to 6500rpm but then with all the extra gas it would start to miss in the high rpm's. I found the best solution on a budget was to run the stock redtop 230cc injectors at 50psi of fuel pressure. This way it ran good at redline but had only a small dip in power in the midrange. The 7a felt pretty torquey and in a race it beat my friends (and now mine) b16 powered del sol. I thought I had some sick amount of power and at the dyno it would be making crazy hp numbers. All that extra torque went to my brain and when it came dyno day the car only put down 121.9hp/111.4tq. I made something like 14 dyno pulls, setting my fuel pressure, timing and cam gears. This was way less power than I was hoping for but realisticly it was about a 25% gain in hp and torque for only an extra 180cc's and some cams. If I had to do it again some sort of piggyback or standalone would cure the spikes in the midrange and some bigger cams would wake it up on top. Web 555's are only like 256 duration, not a big difference over stock. I was pretty dissapointed when I left there. My dreams of beating down sc's in my na were gone. But cheer up, if you can't beat them join them.
Superchared 4ag
I found a wrecked (really big dent, I mean really big) supercharged mr2 down the street from me not running for $1000. It had all the maintinece records and a HKS exhaust, pulley and catalyetic converter. Someone had it all installed when the car was practically new. The interior was mint (black with cloth seat, my favorate) and it even had crank windows like my 88. I gave the guy the money and when he went inside I stared to troubleshoot why it wouldn't run. There it was right in front of me, one of the intercooler hoses had blown off. I tightened it down and the car started right up, lucky day! I actually felt bad and looked around for the guy who sold it to me to get back my money and give him his car (it was his baby). He looked pretty poor and really didn't want to sell it but he couldn't afford to fix it. He had taken off with his wifes car. No doubt now that he had $1000 in his hand he went to go pay bills or take the lady out to dinner. I decided it was best to never tell him what was wrong with it and just leave it at that. I drove it home and went to work pulling the motor. When you have 2 88 mr2's and one's superchared it's pretty easy to do the swap. I just pulled out ALL the wiring, interior, dash, guages, everything and put it in my n/a. The car started up on the first try and ran and looked like it was a superchared mr2 (with a hardtop and nice black interior). I took the old 7a and put it in my 85 mr2 minus the cams and cam gears, those went in the 4agze. Sadly the 7age met it's fate a year later racing Mat's S-Runner. Burying the tach in 3rd gear it spun a rod bearing. Oh well I didn't really care anyway. I sold the pistons out of it and sent my junky 85 off the crusher. I was addicted to boost now. I ordered up a 175mm crank pulley and took it to the dyno. It made 152whp, a big improvment but nothing spactacular. It wasn't until I went to the dragstrip that I fully appreciated the broad powerband. The car ran a 14.273@95.31mph. With the smallport it ran a 16.488@84.36. I never ran it with the 7a but I would guess maybe a 15.6-15.8ish. With our crappy track running a 14.27 seemed pretty good to me. Unfortunitly this was the last time my 88mr2 would ever race. I started my first turbo project and got in a little over my head. I ended up parting the car out for about $3500 and that was the last mk1 mr2 I owned until now.
Turbo mk1 Mr2
I just picked up this 89sc in July. This thing was beat to death. It only had 1st and 4th gear, perfect for a project car. I picked up a full n/a drivetrain and tranny for $75 and put it in just to get it running. Once it was running I pulled off all the sc stuff and went to work installing a turbo. I used a t3/t4 turbo I had sitting around with a custom log manifold. Next I moved the alternator to the intake side of the motor and installed a n/a 4ag intake manifold with the tvis plate removed completely (I had to weld it a little to seal it properly). The intercooler is in the stock location, and it's still using all the factory wiring and sensors. I modified the n/a throttle body to angle up towards the intercooler and moved the afm near the air vent on the drivers side to get some cold air and less intake piping.
For the exhaust it has a 2.5" downpipe with a 3" cat and no muffler. The car went together without too much work. There's definately easier cars to turbo (name one that isn't) and it ran on startup. Basically what I'm working on now is just getting it tuned and setting the boost. When I get it registered and running good I'll put up some dyno's and more info.
Turbo mk2 Mr2
This car was my girlfriends Mr2. She need something more reliable so she bought a Civic and I bought her Mr2. I wasn't real interested in doing a lot to this car. From having to change things like the timing belt, a broken turbo and the dreaded hose from hell, I was convinced that this car was sent from hell and was the spawn of Lucifer himself. I upped the boost to 15psi but it would only make 15psi up to a certain point then it would drop to 12psi. I think it was a faulty wastegate. Next I chopped off the muffler and added an intake. I had a 7mgte 60mm throttle body sitting around so I bored out the stock 3sgte intake manifold and had it made to fit the larger throttle body. This actually woke up the car more than any little bolt on I've ever done to any car. It was really amazing, and it was free. My only other mod to this was an S-AFC and a crappy Spearco side mount intercooler I got off e-bay. With all this it made 213whp on 15/12psi. The car actually went from a 15.3@92mph to a 13.874@100.12mph for basically no money. Too bad I already hated this car. It's not that I don't like mk2 mr2's. They are really good looking and handle great not to mention it's easy to make power. It's just that I hated this particular car from the start, it was always a thorn in my side and when I bought the Del Sol I sold this thing right away.