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View Full Version : G63B SOHC to 4G63 DOHC head swap



superspook
09-28-2023, 09:53 PM
I have read the Zero G site and it didn't answer my questions so here I am.
88' G63B SOHC 5spd Ram 50, I would like to swap the DOHC head onto my block so I guess ill make a list of stuff I need clarification on.

1: Should the 6 bolt head should bolt on with the 7 bolt needing oil drain holes filled?

2: Will any modifications need to be made to the block or head for cooling, oil, etc?

3: Will any internal modifications need to be made for light boost?

4: What extra parts and/or brackets will I need (I mean stuff that relates to plumbing, sensors, timing, yada yada)

5: Will I have to run megasquirt or is there a compatible ecu that I can use instead?

6: I've heard the manual truck tans' are weak, what is a safe power figure they can handle and what swap options would be best?

I'm not aiming for any crazy numbers, 150-200 would be enough for me.

finalfighter
09-30-2023, 11:45 PM
1. i belive you have to fill the extra drain holes.
2. no.
3. no.
4. https://projectzerog.com/sohc-dohc.shtml
5. yes, the timing curve from the stock ecm is way to advanced for any level of boost.
6. ive heard 200 is about all you would want to really put threw them for daily driving.

SubGothius
10-01-2023, 12:03 PM
I've read the stock trans (KM132 or KM145) can withstand about 250 HP, but can handle more with a reinforced sump plate to replace the stock stamped pan on the trans housing.

Mitsubishi made a suitable "waffle pan" for some later versions of these trans, but apparently only for some JDM models, so you'd need to find a Mitsu parts dealer who's willing/able to import one of those or already has some in stock.

Aftermarket equivalents also exist, such as the Tuffpan (http://www.tuffpans.com/) (apparently out of stock) or the DfabDesigns pan (https://dfabdesigns.com/products/transmission-pan).

dash
10-23-2023, 01:35 PM
oem aluminium 'waffle pan' found on 88-89 usa starions. Legionelite sells aftermarket girdles also
well documented DOHC conversions, using donor DSM is your best route imo. MightyRam, hotrodcoffeshop etc... youtube series also
not the easiest conversion. From your questions, it'll work you out, but the info is there
Twincam head on SOHC block, lots done on austarion. More work, but staz G63 is wideblock, so useful to them...
DSM oe wiring fairly simple. Minor upgrades, stock motor, truck 5speed makes a torquey hella fun daily driver
I still see 2.6 starion drivetrains/donors for sale occasionally. Source a truck 'wideblock' 5spd to keep cable linkage & mount
Will have to convert to starion hydraulic pedal/linkage, to use starion 5speed. Waayyy better than clutch imo.
Need moded gbox mount & shifter also tho
Oe starion wiring simple enough. Motor straightfoward install. Run just as strong as 2.0 DOHC DSM with minor bolt-ons
Easily meet your power goals. Torquey, fun. Some guys had luck running $150 ebay clutches
As for TBI potential.... Some heavy starions crack 12s on stock motors. Low 11s on spray