1991 Mitsubishi Galant VR-4
Building a 6-bolt 2.3L 4g63 Stroker


Update: 1/25/05 - I told you guys this was a slow process. Now that the wife and are are both gainfully employed I dropped off the motor at the machine shop today. Rods are currently being machined at GRP and HO motors in Boulder is machining the block. Going to try another style crank as well with a lot of lightening done to it. Head is ready for installation minus a potential cam change.
Update: 7/12/04 - Pistons arrived today, so thanks Marco and Steve. Damn they are sexy and worth the wait after the first set was wrong. Now they're off to get coated and then time for machine work on the block. Only waiting on rods now.
Update: 5/18/04 - Head arrived from Forrester today. It looks great. Too bad there's nothing to install it on yet.
Update: 4/29/04 - Nothing left as the last update said it would. Grrr. Vendors usually have good reasons for the delay but sometimes it gets a little long. I rename this project "Project Long Delay".
Update: 4/21/04 - Head left Forrester today and rods from Pauter should ship today. Just waiting on pistons to be finished
Update: 3/18/04 - Crank and bearings have all arrived. Head left this morning with all the goodies to be totally worked over by FRH. Picking up block and engine stand this week to prep for machine work.
Update: 3/05/04 - Pistons have been ordered from Marco @ Magnus Motorsports. They are .060 over Magnus Spec Ross pistons.
Update: 3/03/04 - Progress has been slow but now I've got a backup car. Ordering the crank and bearings tomorrow, part numbers below.
Update: As of November 10, 2003 the stroker buildup continues. Parts for the head are almost totally purchased and the head will be ported and rebuilt by Dale @ www.forresterracingheads.com. The block machine work is being completed and the pistons, rods and crank will be ordered shortly.

Update: The stroker build up has begun on July 17, 2003 with the purchase of the block. Part costs and numbers will be posted as they are purchased.

These are the parts I am planning on using currently. This will be updated as the build progresses. The information is ONLY for stroking out a 6-bolt 4g63 block. It does not cover anything needed for swaping in a 2.4 L 4g64 or g64b block although such a thing is possible. Click on items for special notes and information. Prices from Boulder or Mile High Mitsubishi are with special CoDSM discount...

Engine Dimensions
Bore86.5 mm (bored 1.5 mm or 0.060 in over)
Stroke100 mm (increases from 88 mm)
Rod Length150 mm (same in 4g63 and 4g64)
Rod Ratio1.5
Displacement2.35 L

Comments on Rod Ratio:
So the rod ratio changes from 1.70 on the 2.0 L to 1.5 on the 2.3 L. What does this mean? The ideal rod ratio is somewhere around 1.75, with the ratio getting "worse" as it gets smaller. So I should expect catastrophic damage now? The short answer is no. In theory several things will happen to the stroked motor, however 1.5 is not that bad of a ratio and plenty of other engines run similar ratios. There will be more load on the pistons since the piston speed increases. Therefore you can't rev as high as a 2.0 L can. In reality, a DSM tranny isn't going to shift very long at above 9000 rpm and several people have already reved stroker motors above 7500 rpm with no problems (assuming a sufficent top end). Also the stroked motor may wear faster since the piston is being loaded more from the side as opposed to straight up and down. But again this hasn't been the case yet in the real world. All in all, the stroker is going to give you more displacement with to spool a larger turbo and more torque all around to make driving more fun. All you really need is the correct crank, custom pistons and maybe a little block clearancing to build your own 2.3 L 6-bolt DSM.

Top EndPriceVendor
1g 4g63 Head$80Good core from CoDSM member
ARP Head Studs$100Ray @ www.turbogarage.com
Cometic HP Head Gasket$100Marco @ www.magnusmotorsports.com
HKS 272/272 Camshafts$575Ray @ www.turbogarage.com
New Style Lifters$126.84Prime Automotive Wholesale: 214-441-1500
Crower Titanium Retainers$NANIB from CoDSM member w/ springs
Ferrea 1mm over Stainless Valves$384Marco @ www.magnusmotorsports.com
Crower Valve Springs$175NIB from CoDSM member
Rebuild and Porting with Bronze Guides$1050Dale @ www.forresterracingheads.com
Adjustable Cam Gears$??
Grand Total$2490.84

Bottom EndPriceVendor
1990-1992 6-bolt 4g63 Block$100Bought from from Ryan L of CoDSM
Machine Work$??
6-bolt g64b Crank$503Boulder Mitsubishi: MD080691
6-bolt g64b Main Bearings$65Boulder Mitsubishi: MD091399
6-bolt g64b Rod Bearings$55Boulder Mitsubishi: MD071298
Ross Magnus Spec Pistons 0.060 over$550Magnus Motorsports
GRP Rods$500GRP Connecting Rods
Balance Shaft Removal$42.00Boulder Mitsubishi
ARP Rod Bolts$45.00vendor
Mitsu Main Bolts $74.00vendor
4g63 Timing Belt$56.98www.partznet.com: MD326059
4g63 Timing Belt Tensioner$61.07www.partznet.com: MD164533
4g63 Timing Belt Tensioner Pully$20.12www.partznet.com: MD129355
4g63 Idler Pulley$24.58www.partznet.com: MD156604
4g63 Lower Timing Belt Cover Gaskets (3)$$$vendor
4g63 Water Pump$95vendor
4g63 Water Pump Belt$$$vendor
4g63 A/C-Alternator Belt$$$vendor
4g63 Front Cover$265vendor
Grand Total So Far$885.75