Mitsi head swaps

[bonkas]

Did some searching but cant find the info I am looking for... Hopefully you guys can answer this quick question...

I have a 4g63b (SOHC) which is in the process of being rebuilt. Are there any bolt on head options with larger valves like 4g54 etc, do these fit?

[dwlee]

No, the 4g5x  (Astron) series have a completely different bore spacing to the 4g6x (Sirius) series. The bore spacing within a series is the same, but head bolt diameter can vary with earlier being 12mm  reusable and later being 11mm that requires replacement. Also, the inlet/outlet swap sides around 1996 in the 4g6x. Have a look around http://www.projectzerog.com/ as there it has a lot of info regarding a swap from SOHC to DOHC.

I'm not aware of any 8 valve SOHC 4g6x with larger valve but there is the option of 12 valve dash head with two lets valves.

[bonkas]

So any head from the same series engine you can guarantee will be interchangeable between each other? 4g61, 4g63, 4g64 etc?

[dwlee]

Definitely not guaranteed, but you're a lot closer to something that might work if its from the same series. The 4g6x series was in production for over 25 years and there were quite a few change over that time. Some are interchangable without and changes, some require minor changes and others require alot of work and not worth the effort. 

What was the donor car/year for the 4g63 engine you are rebuilding?

[bonkas]

Not sure on year.. but it's the same engine found in Sigma's, L300's etc.. 80's 4g63b.

 

Just researching ways to get a bit more performance out of the thing as it needs a full rebuild anyway.

[Ranter]

Any 1.8 or 2.0l 4g head will work turbo or non turbo, pretty sure other than mca jet types or dash heads all are the same though.   

[bonkas]

Do any 16v heads exist that still use a dizzy that bolt on? All the later model stuff is EFI as far as I can tell or has a cam angle sensor which I am trying to avoid as that required modifying the firewall to fit it.

Or maybe a late model 4g63 with a RVR Turbo CAS sensor to run the spark off of as I hear those are not as large?

[fuel]

It's actually the last of the first generation RVR (around '95-'97) that have the separate cam/crank trigger sensors at the front of the engine rather than a single CAS on the back of the head. The second generation RVR has the same head as an Evo4-8 with the sensors behind the cam/crank sprockets too, but that head is reverse flow and will not bolt on to the earlier block you have. 'Late model' RVR, aka the ASX has the 4B engine family so is completely different.

You'll need some kind of ECU to control spark at the very least with a DOHC 4G6x head so you may as well go the whole hog and convert to EFI to make the most of the better DOHC head anyway.

With the DOHC swap, you'll need the front timing components and if you are unlucky enough to have the earlier style 'short nose' crank you'll have to swap cranks to the later 'long nose' to use the DOHC crank sprocket etc.

If your current 4G63 SOHC (no such thing as a 4g63B, it's either a G63B or 4G63) is narrowblock (ie just in a 2WD van/ute/Sigma and not turbo) then you're better off finding a whole E33A Galant or N23W RVR 2L DOHC and putting it in complete, swapping over the sump/oil pump pickup and engine mounts.

You could also find a 4G64 SOHC 16V EFI from a 93+ L300, L400 or Triton. They are still SOHC but come with the extra torque or the larger 2.4L displacement.

[bonkas]

Yeah sorry my block is stamped with G63B, so converting this to dohc is not worthwhile and I am better off finding a later model 4g63 DOHC - Will my current mounts fit?

 

I wasnt aware the 4g63 swap required sump and pickup swaps also? This is all going into a Lancer EX - I have the mounts to mount the G63B into the EX.

[fuel]

The RWD mounts will bolt up to an E33A Galant 4G63 DOHC no problems, along with the early '91 and '92 N23W RVR/N33W Chariot with the 6-bolt 4G63 DOHC. Although I am fairly certain the RWD mounts do attach to the Evo1-3 style block (along with 93+ N23W RVR), you'll run into issues with which flywheel to use with your existing gearbox. If you can find a Jap import 93+ 2L 16V L300 van you could use that flywheel, but it will be heavy and ideally needs lightening. The 4G64 L300 flywheel is too large, and the FWD flywheels don't have the spigot bearing hole and are often stepped too.

As for the best early 4G63 DOHC to get, they generally come in two flavours - the 145hp big port 9.1:1 compression ratio found in most of the '87 to '92 shape Galants including the NZ-new GTi-16V or the higher compression 160hp big port 10.4:1 found in the late '90 onwards Galant VX-S and VZ-S. The 93+ 7-bolt N23W RVR Sports Gear has a 160hp small port 10.5:1 compression ratio engine which would be the best for N/A power delivery (much better torque curve than the big port engine) but again you'll have issues with the fly wheel etc.

If you want to do something different, I would get a 4G64 2.4L SOHC 16V L300/L400/Triton engine, swap a Galant or RVR DOHC head on and swap in a Starion wide block gearbox with lightened flywheel and convert to hydraulic clutch pedal set up. This should give you a small bump in power to around 175-180hp but also a big increase of torque.

As for the sump you may be able to get away with retaining the FWD sump, but bear in mind the FWD engine is mounted with a 15deg lean towards the front of the car and the sump is angled to suit.