peano's 7G DOHC/ECU Swap - 2.5" Exhaust - project thread

[peanotation]

Earlier in 2009 on my way to a job my original engine from 1994 went out. The headgasket was definitely blown and any clutch engagement yielded major drops in the RPMs. Crankwalk? Who knows. Either way the motor was dead. It was driveable, but needed swappage asap.

I picked up an obd2 96 Galant motor from the yard for $600, delivered to me, and swapped it in just under 4 days in a buddy's driveway. I was rushed and completely overlooked the timing belt side of things. Since I knew nothing about this donor motor, besides for the immaculate compression that I verified right before pulling it, the timing belt and components could've been brand new, 70K+ miles old, or who knows.

Still, due to time constraints with work and needing my car, I dumped the motor in, only thing swapped over was my old intake manifold. Decided to cross my fingers and hope for the best.

The devastation of my original motor (15K miles of nitrous, 15K miles of turbo, exactly 200K original miles): https://www.thegalantcenter.org/showthread.php?t=39445

The new motor ran great and still to this day [hopefully] is doing well. In the back of my head I always had the timing belt bothering me, and not that that wasn't enough, my original downpipe from 94 had MASSIVE leaks. I'm talking leaks so big, you would give it gas and all you would hear is more air coming from the downpipe, and no power. Driving uphill was a struggle....

I figured the timing belt job had to be addressed asap. From buying DOHCStunr's original 94 GS from years ago, I had a GS ECU, GS DOHC Head, GS waterpipe, GS thermostat housing, GS intake manifold, and GS throttle body. Everything needed for a complete DOHC swap! Everything except the engine harness.

So instead of doing a plain jane timing belt job on my weaksauce SOHC motor, why not spend the same amount of money and swap over the DOHC and ECU? So I picked up an OEM DOHC GS headgasket, paid $200 to repair a few bent valves on the head and restore it to perfect condition, replaced valve seals too, and ordered all OEM timing components from mitsu. I had ARP headstuds still from my old motor, so those would be coming over too.

Rebuilt head:


Picked up a complete and perfect GS engine harness at the yard for $90. So lucky they happened to have a GS....

I will be honest, the swap took me 4 days. I spent a lot of time doing things slowly, cleaning a lot of things that had been neglected over the years, and had a nice casual time doing it. I was so disappointed in rushing the 96 motor swap, that I wanted this to be done right. Had everything been ready and nothing extra needed to be done, this could easily be done in 2 days. 1 day if you're a fucking madman.

Remember that 5 of the holes in the block need to be plugged (thanks to Seth for the picture!):


Difference in headgaskets:


Out with the old:


In with the new:




THE FUCKING GLORY:


I regret taking barely any pictures. I was so involved with the actual process that I never picked up my camera. I apologize :(

All in all the process was pretty straightforward. If you know your way around timing belt jobs, this will be a snap. You drop the new head on, torque down the headstuds, run your water pipe and belts, hook up the coilpack and power transistor, make sure you replace your injector o-rings and seals, and either swap in a new harness or hack up the old one to the new ECU.

At the end of the last day I finally got to start up the car. It started. Ran like total shit. Died. Check engine light comes on. Crankshaft position sensor fault. Poop! What are the odds that I happened to have another one?? Swapped it over. Started the car again. Ran like total shit, but in a different way. Died. Check engine light again. Camshaft position sensor fault! WTF! This I did NOT have an extra one of. Got a brand new offbrand one at Autozone for $55 with pigtail that directly plugged into the harness.

Started car. Ran like a dream. I came.

NOTE:To anyone thinking about doing this or in the process! Your original gauge cluster WILL NOT WORK. You need the gauge cluster from a GS. The tach pulse is on the same pin I believe, but it's a different signal.

~~~

Let's get one thing straight here. This will CHANGE your car. Even with the gargantuan exhaust leaks, the entire powerband is a whole different world. The higher the rpms go, the more power you get. It's exponential. All the bolt ons I've wasted money on over the years was exactly that: A WASTE. This finally has the power and pull that I want it to have.

But still, my exhaust was leaking more than my ex after her first gangbang, AND it was still 3" from the turbo days! Back pressure meltdown!

So on to the exhaust shop, but not before we get a few goodies!

Old header on the left, going to the original downpipe, new obd2 header on the right.


Vibrant performance muffler w/ 2.5" inlet and magnaflow 2.5" muffler, 36" in length:




All mandrel bent 2.5" piping ordered.


The install:










Many many thanks to DOHCStunr for the exhaust recommendation and pushing me so much to get it, because it is phenomenal. It was EASILY nicer, smoother, deeper, and quieter than my ex's Dinan exhaust on her BMW 325ci, and I thought THAT was nice. It is easily one of the top 5 exhaust notes I have ever heard in my life. Pops? Rasp? Not even a hint. WOT or cruising you can still have a nice conversation in the cabin, but you won't be talking at WOT because you'll be getting off to the sound. The tone and smoothness will have you creaming your pants every time you power through a gear. It is the nicest exhaust I've ever heard on a mitsubishi. OEM sounding, but enough of an edge to the growl to make the car next to you sound cheap.

The performance is unquestionable. With a bulletproof exhaust now, I've never felt a pull like this before. Sure, the turbo days will be missed. Nothing was more exciting than breaking 3rd gear loose and hearing the turbo whistle to pure power and glory. Even with my old 13g there was ZERO turbo lag. Instant power on tap all the time.

But this is different. This is POWER power. Every day I drive my car, even still, almost 3 months later after the swap, it is a thrill ride. Doing a pull in any gear is on par with a runner's high or slingshotting yourself into some cardio workout. Then it's over and you're left with the aftertaste of AWESOME. My car never felt so good.

Only long term problems that I'm still dealing with: Middle timing cover is impossible to put on. I have no idea how you can even get close to getting it on there with the motor mount bracket in the complete way. Also running no top cover cause I haven't bought one yet, and the O-ring on the water pipe is leaking at the thermostat housing. Other than that, this is tits.

[Galanttuner10]

look great man. great job.

[DOHCstunr]

I'm DOHCstunr and I approve this thread. x1000.

Gotta love that after all this time we refuse to buy new cars lol.
I love your G man. Love it.

[Shadow19]

Dude if you figure out how the fuck to put that timing cover on LMK. I had my gf's engine on the engine stand rebuilding it and still could not figure that out....................... Unless you take the motor mount bracket off and fight with it like that. I just super glued the shit out of it after she snapped it trying to put it on. Anyways nice write up and the 7g is lookin sexy as usual.

[Ivory8g]

Man you have a way with words (no homo) Now i want to dohc swap.....

[qnz]

the 7G, back to its former glory

[Exhaust power]

good build and a good read! do you have more plans for the engine?

[gtx]

Nice to see an update on your car, and especially one like this. Congrats!

[eksz]

Peanotation,
Watch that coolant leakage around the timing belt. Anti freeze will weaken/trash a timing belt and next thing you know you are replacing valves again. As far as putting the timing belt cover on I take end motor mount completely off when I change the belt and use a jack to raise and lower the engine as needed so I can reach all bolts. I also use a small 1/4" drive ratchet set to remove/install the timing belt covers. Its a pain, but I believe the timing belts needs to be protected from any possible contamination (oil, antifreeze, etc) that could shorten its life.

Great description on what it feels like to drive a DOHCs. Completely mirrors my expericences with my GS. I really have to watch my foot on the gas....its just too much fun ...that car just wants to run.

Glad there are still some 7g fanatics left. I use to say these cars could never become collectors items but with the stuff folks have done with their cars on this site I could see these cars holding their own for the next couple of decades.

[w/oarctic7g]

Inspirational! Well done and congratulations. I have only seen that header on the 98 though.

[evil-G-nius]

I still want to do the head swap eventually...and of course this is more motivation! I need to fix my other issues first but it seems doable...good write up and you know who i'll call if I hit a roadblock! LOL

[Predat-R]

i just saw the pull ur g did on the dyno and its just sex cant wait to boost mine.......ps great write up.

[kolio]

I demand videos!!!!!

[seth98esT]

Yeah, you have to take the driver side mount off and all the pulleys, then you can put the lower timing cover on. If you have a 1/4" socket or I use a 3/8" t-sliding socket wrench to put the cover bolts on. They are pretty handy in small areas.

http://www.amazon.com/SK-Hand-Tools-...0303682&sr=8-3

[johnygezony]

I want your car so bad !

[mysticj]

I demand videos!!!!!

+1
BTW, welcome to the club!

[4-G-rim]

Awsome job Matt.

After reading your story...I didn't realize how much a car could really make you cream you pants. I am actually a bit concerned with sexual reactions to your vehicle and how much laundry you did to rid the cream.

Either or man...great job

[peanotation]

Peanotation,
Watch that coolant leakage around the timing belt. Anti freeze will weaken/trash a timing belt and next thing you know you are replacing valves again. As far as putting the timing belt cover on I take end motor mount completely off when I change the belt and use a jack to raise and lower the engine as needed so I can reach all bolts. I also use a small 1/4" drive ratchet set to remove/install the timing belt covers. Its a pain, but I believe the timing belts needs to be protected from any possible contamination (oil, antifreeze, etc) that could shorten its life.

yeah well the leakage is at the thermostat housing on the passenger's side of the water pipe; but i amm worried about it dripping down to the otherside, probably replace it middle of december along with a new upper radiator hose.

Yeah, you have to take the driver side mount off and all the pulleys, then you can put the lower timing cover on. If you have a 1/4" socket or I use a 3/8" t-sliding socket wrench to put the cover bolts on. They are pretty handy in small areas.

Dude if you figure out how the fuck to put that timing cover on LMK. I had my gf's engine on the engine stand rebuilding it and still could not figure that out....................... Unless you take the motor mount bracket off and fight with it like that. I just super glued the shit out of it after she snapped it trying to put it on. Anyways nice write up and the 7g is lookin sexy as usual.

the thing with the middle timing cover, is the motor mount bracket is attached to one of the pulley's for the timing belt. after talking to DOHCStunr he said to remove the one bolt and two studs on the bracket and the middle timing cover should go on more easy.

If that doesn't work then the only way would be to install it BEFORE you install the timing belt and the pulley, and work around it the whole time. Retarded? Yes. Mitsubishi? You betcha.

[Blue Ice]

Peano is BACK!!! Great job Man!! Glad to still see you are still loving your car(literally :/ ...) The Blue looks to be holding up great still too!

[caribtokyo]

did you ever put it on a dyno to see the before and after power output? By the way, i plan to copy everything you just did.