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My 6g75 3.8L swap

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33K views 93 replies 26 participants last post by  6g75_3g  
#1 · (Edited)
I know that this is a fairly new topic but I did it and I willing to help answer questions about the swap on my 2g Stratus Coupe. My timing belt tensioner pulley bolt snapped and blew the timing belt off Monday morning. Thank god I was almost ready to drop in my 6g75.

This thread started as a swap thread and is turning out to be my project thread.

My semi before picture:
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My after pic:
latest car pic. now with some nice wheels and tires.
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as you can see, I am a Dodge guy. with my old Dakota w/227,000 miles and the corner of the hood of my 97 Stratus sedan w/194,000 miles on it.
 
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#3 ·
yeah so I thought I would post a couple of pics here of my 05 galant engine.

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This is the difference in coolant manifolds. The one on the block is a '74 coolant manifold and the one in my hand is the '75.

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You can see in the picture that I now have room for the dizzy and I removed the 6g75's cam sensor off the front head and replaced it with a plug from a 6g72 head.
 
#4 · (Edited)
I also angle cut my 3.0 altenator bracket to line up with the altenator. Die grinders work wonders! I maintaned a/c so I used my a/c bracket because they are different. I did have to trim a couple of bolt bosses off of the aluminum in that area. Off of the oil pump housing where the a/c bracket attaches. I add a picture of that if I can.
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#5 ·
This shows the differrent angles of the fuel rail. I cut and used a the fpr side of the 6g72 fuel rail on my swap. I put it in a vice and bent the tabs down and used a few washers for correct spacing for now. I was going to modify a couple of the plastic ones but ran out of time. I will work on that along with setting up and polishind some VR4 fuel rails.

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#6 ·
Mine is up and running! Wow what an animal! My sticky 235's don't stand a chance against torque and horsepower this thing has. I know many of you have a 3.0, but i had a temporary 6g73 2.5l 170 chp engine. This was an excellent swap. I would not even consider a 6g74 after driving this one. I haven't even done any tunning yet other than changing the injector scaling. Here are some more pictures.
all planted with 3.0 valve covers and intake.

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#7 ·
I had to use the 6g72 flexplate to bolt my torque converter up. The 75 has a 6 hole torque converter? I also had to add an inch to the tops of my down pipe/wye pipe beccause it hit the oilpan. The headers ended up being wider by a 1/2 inch and up about 3/4 inch. My engine came with the upper ps bracket, which is what I used. I swaped in the 72 lower bracket belt tensioner. I also had to shave the timing boss of the timing cover to clear the ps belt. I did not have time to play with the 75 uim, I will work on that in the future.
 
#8 ·
Also, just like the 6g74 swap, I had to grind half of the axle mount off to flush the face of it so my 3.0 axle support bearing would fit. This was easily fixed with the mighty Dewalt 4" angle grinder. I ground a little at a time and checked it with a straight edge.
 
#10 ·
Once again, congratulations! :woot: At least it's running. Now you just gotta clean it up. I see you're non-Mivec which is cool. In a couple of years I think I'll be upgrading to a 75 as well. I want to go MIVEC as silverside did however. If Pharm or someone else gets that MIVEC to reliably work consistently then the 75 MIVEC will be in my Spyder. Hopefully in a couple of years they'll be more aftermarket engine internal support for it as well.
 
#11 · (Edited)
Yes, non mivec, 82,000 miles on it. Yes it is dirty, its been raining alot around here so I have not been to the car wash in awhile. The intake will probably get changed in the next few weeks, I needed the car running to get back and forth to school. I have 2 accelerated Class this summer and they both bombard me with homework. No time to work on that stuff now. My tuning will consist of data logiing to and from school and tuning in my very limited free time. I would be tuning more right now but my wife had to take it for a ride. Engine $300+ aem cam gears $160+ new Dayco timing belt $26+ 6g74 coolant manifold $20. >$510 makes smiles ear to ear.
I have the injectors currently scaled @301. more tuning to come with time.
 
#13 ·
Yeah, it pays to know people. I have a pal at the sales desk in a local salvage yard. i can get a 3.5l for $175 any day of the week.
 
#15 ·
I will keep updating this thread and I am happy to answer Questions about my swap. It was fairly straight forward. I knew ahead of time what I needed to do and took my time to prepare. Then when it was done, I bolted it in and fired it up.
 
#16 ·
wow awesome man! What will you be tuning the engine with?
 
#17 ·
I am tuning with ecu flash and evoscan. I will analyze the data, document, flash, and test; then change the settings accordingly and start the process all over again.
 
#19 ·
Maybe if I find a donar car, I just may do that. The thought has crossed my mind a few times. What I could use now is a taller O/D gear.
 
#20 · (Edited)
tdevriesgb said:
txgt said:
What all did you have to modify and with what? From what I could see you did the following(correct me if I'm wrong):
-Shaved the engine mount bracket to connect it.
-Used the 3.0 Alt & AC brackets
-Used 72 upper intake plenum(why not the 75 fitment issues?)
-How did you increase the header length? Would you recommend 75 headers over any 72 setup? If so, then club4G has some cheap 300-500 dollar headers I recall.
-How did you get the dizzy setup? Did you transfer over the 3.0 heads or did you keep the 3.8 heads but replace just the covers with the stock 3.0's? Did you have to build a bracket to connect the dizzy to the rear cam sensor?
-You used the 74(3.5L) coolant pipe.
-Did you just change the injector size with ecutune or did you manually update the ROM?

Sorry about the long list. This is something I've been thinking about doing and it seems everyone and their mom has their own method of getting this done. I have a 3.5L in storage and if I can just transfer parts that'd be awesome savings for me.

Maybe, you should make your own garage section tutorial lol.

Overall, my goal is to fix up the 3G to get it reliable and on a good platform even if it's on a non-mivec rather than paying close to 30k for another car.
if you read my thread and the 3.8 swap thread you can get alot of the information. if you don't mind, I would like to post your question in my thread.
1. Get a 6g75
2. Get a 6g74 (3.5l diamante) water manifold and heater pipes.
3. Strip all brakets off
4. Remove the plug in the back of the head where dizzy is on a 3.0. Save the bolts to bolt the dizzy on.
5. Remove the cam sensor off the front head and replace with the 72 plug. Then bolt up the water manifold.
6. Get an alt bracket from a 74 or shave a 72 off at an angle to tip the alt bolt hole down.
7. Bolt on the 72 engine mount at fit the altenator
8. Shave the bolt bosses that interfere with the 72 a/c bracket.
9. Remove the the timing covers and the tensioner and belt. Remove the lower gear and crank sensor. Replace with the 72 parts. Order a new belt! I got a Dayco belt from Advance Auto for $27.
10. Carefully line up the timing marks and install the belt. Put the tension damper in a vice and slowly compress. Use a small nail to hold it compressed. Install it and pull the nail. double check timing marks and install timing covers.
11. Use the 75 or 74 upper power steering bracket with the lower 72 one and belt tensioner.
12. Use the 72 flywheel.
13. Modify the fuel rail to use your fpr and return system. I used the front half of a 72 rail and coupled it to the rear 75 rail. You could use a 74 fuel rail in place as I am told.
14. Grind the axle mount flat. Grind slowly and check often with a straight edge. Or you can use a Diamante mid shaft and bearing. Grinding is cheaper.

*I have not installed the 75 uim because the throttle body does not fit. The tp sensor hits the intake. I figure this could be remedied with a throttle body spacer of about 3/4". I have not got this far yet. It is in the works during my spare time.
*I currently have the computer flashed to scale the injectors at 305cc and I have advanced the timing 3* across the board. Continuing to tune everyday.
I also have spent the money for AEM cam gears.
 
#22 ·
I can't hand it to you any simpler than this on a silver platter. I am glad to help, just make sure credit is given to the correct people. Silverside (rest in piece pal) and Phamesis had broke this ground awhile back with there mivec ideas. I just furthered this with the non-mivec.
 
#23 · (Edited)
stratatk01 said:
Couple quick questions.
What headers do you have that needed to be extended? I have RPW headers coming as we speak and im hoping I dont have to hack them up too much to get things to fit.
Does the 75 have coilpacks for the sparklers or is that just on MIVEC 75's?
What kind of issue did you run into with fitting the 75 injectors into the fuel rail/and combining half the 75 original rail and your 72 rail? Besides the obvious picture you already posted. And if you know can you just use the 74 rail with the 75 lower manifold or do you need the 74 lower mani to work with the 74 rail? I really appreciate any insight and info I can gather I want to know what Im gonna run into when I can get the ball rolling on my swap.
I did explain the fuel rail issues in my thread but I will repeat. The best is to use a fuel rail from a 74, I didn't have one. What I did was cut a 72 rail in half and I cut the 75 rail in half. i joined the rear 75 rail with the front 72 rail so I had a fpr. I did have to bend the hold down tabs a little and spaced the rail with some washers. it is working well but I have a set of rails comming that I can modify to fit better. As for headers, I have some off brand 6g72 shorties that I got a deal on. I had to rework the wye pipe a little bit to fit the 75. The primaries were large tho and fit the 75 ports well. I varified it with our fiberoptic camera. The 75 is a coil pack motor, thus the reason my 3.0 valve covers went on and why I explained how to mount the dizzy on the non-mivec rear head. It is actually is not that complicated. I did my swap in 10hrs in the shop with all the tools ready and at hand. thats from start to running. Make sure you can flash you ECM so that you can change the injector scailing. THIS IS A MUST!!! It will not run correctly without this. You need a tactrix cable and ecuflash. Evoscan is a must to so that you can log, scan, and clear check engine lights. You will more than likely have lean or o2 sensor codes to clear the first couple days you run the car.
 
#25 ·
I assume your 74 injectors are scaled in though, correct? 74 injectors are bigger than 72 injectors and probably flow at a rate right now that is enough to keep your car running, however, you aren't getting full potential out of them without properly scaling them.
 
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#27 ·
I am running the 75 305cc injectors that would fuel the engine to death if it was not scaled in. Your 74 injectors are 275cc and are sufficent for the 75 needs. That scaling will be closer but still not right until you scale them. The ECM adjust the injector duration according to the input air flow, tps, mdp, and scailing to insure proper fuel loading while in cold run loop. Once it warms up, then the system fine tunes the afr to the O2 sensors.