Rebuilding 4g64 SOHC for boost

[Suicidebenz00]

Rebuilding my 4G64 in my 2003 Mitsubishi Eclipse was going to rebuild it stock, but figured I should probably get some forged components so I can handle boost. Plan to only push around 6-9 psi.

Looking for forged rods, pistons, and should I get a Forged crank and cam?
The 4g64 only makes around 140 just trying to make like 200 maybe more

Any recommendations would be helpful

Never rebuilt engine before especially boosted one but of course I plan to do everything by spec.

For connecting rods, I’m looking to spend no more than 400$
Pistons no more than $500
And let me know if I should get a forged crank and cam or any other components

Also, since I do plan to rev this car to high RPMs, should I delete the balance shaft for insurance purposes?
I’m not trying to have one of them blow up and cause damage to the engine but I’m not sure. I’ve heard one of the balance shafts do good for the oil pump and of course they both keep the engine from jumping out of the car but I’m not trying to delete them. I’d rather keep them if it doesn’t mean major shaking of the engine

 

[Spleen8urLSX]

If you do polyurethane motor mount bushings (as you should in any fwd you try to go faster in) you’ll never notice any extra vibration from not having balance shafts as it will already vibrate a little, delete them and it’s an extra potential issue eliminated.

As far as reving high, there’s nothing to gain there on that low of boost, any turbo that is in its efficiency range at that low of boost isn’t going to carry out much higher than what the stock stuff can rev to so it’d be pointless to build for that high of rpm as you’d be throwing money at it for no reason at that point and killing off power where something is going to shine at your desired boost level. I’d recommend going to the 3g forums and doing a bit more research on the topic before you start endlessly throwing money at it.

 

[1990TSIAWDTALON]

When you make a good "goal" and try to stay to it you are doing good!
If you decide you need a crank, I have a 4G64 Eagle in stock, but that's another discussion.
You don't need "forged" cams but to do a turbo you do need bigger cams for it to perform at best.
@BLACK'98DSM is a super good resource on our N/A motors.
Maybe he will chime in with any knowledge/recommendations he has.
Marty

Edit..... @Spleen8urLSX has great advice.

 

[BLACK'98DSM]

200hp is not a huge goal and should be easily achievable with a turbocharged application. It isn't a matter of if the engine will produce, it's a matter of it lasting. I don't think a forged crankshaft is necessary. I would add headstuds to the parts list though. Remember to re-gap your plugs as well. With higher cylinder pressures you want a smaller gap. I'm not sure what size injectors are standard on those engines but I would definitely get those upgraded to avoid max duty cycle. Also get a wideband AFR gauge to monitor. Running too lean conditions is almost as likely destroy the engine as weak parts.

I would probably just use a basic cast iron manifold for this application. It's not worth the heat soak or extra cash for a tubular manifold, though it would help the turbo spool quicker.

There aren't many (if any) members of this forum turbocharging a 3g but it's just basic info that applies to most 4 cyl turbo projects. Build it right and provide enough fuel, you'll reach your goal and last a while.

 

[Spleen8urLSX]

Also do a little digging on YouTube and such, a guy named Travis Hurst threw a PTE 6766 and Shearer fab forward facing manifold on the Hyundai/Kia 2.4 (essentially a DOHC version of the 4g64) and it held 600 at the wheels for some time in an older Kia Optima. This was a stock engine with head studs, cams, and springs, stock crank, stock pistons, stock rods. Not saying EVERYONE could or should do that but just to give an idea of what the later 4g64’s are capable of. Keep in mind he did the cams and springs to make it capable of reving out a bit higher to make use of the powerband with the 6766, not for overall durability. Gave me a lot of motivation to keep pushing the stock NT 4g63 bottom ends without doubting them. In all reality a stock rebuild in good health with a proper tune I wouldn’t hesitate to throw 200 at all day, at that level health of the engine and the tune is really the key over stronger rods and forged pistons, I wouldn’t even second guess the stock crank as they seem to be just as stout as the 4g63 crank and many in the Evo community have no issue making big power with the stock 4g64 crank from that generation in built 4g64 bottom ends or using it as a stroker crank in the 4g63. EvolutionM would also be a good forum to dig in as again, many Evo 4-9 guys build that same 4g64 bottom end opposed to using a 4g63.

 

[DSMPT]

Looking for forged rods, pistons, and should I get a Forged crank and cam?
The 4g64 only makes around 140 just trying to make like 200 maybe more

With that goal 200hp, you don't really need aftermarket forged internal parts. Your rods are the same as turbo 4g63, the crank is the same as the one many DSMers run on their stroker setup. I even personally use the same rods and crank as yours on my 2g without any issue. The crank is even cut by .010". The build quality would be more important in your case.

Also, since I do plan to rev this car to high RPMs, should I delete the balance shaft for insurance purposes,

You rev this engine higher than the factory redline won't give you any gain but trouble unless you have all necessary supporting parts/mods. 4G64 is totally not ideal to rev high, especially SOHC. If you would like to make it as a higher rev engine than the stock, you would probably want to de-stroke and/or swap the cylinder head with a DOHC head at least. The head components and valve timing are very important to rev higher than the factory redline. But you won't find off the shelf aftermarket parts for sohc. With a dohc head you would have more options for the parts since you can use 4g63 parts.

 

[Suicidebenz00]

Thanks so much I’ve looked in to swapping the head before but now I’m more interested

 

[Suicidebenz00]

Also do a little digging on YouTube and such, a guy named Travis Hurst threw a PTE 6766 and Shearer fab forward facing manifold on the Hyundai/Kia 2.4 (essentially a DOHC version of the 4g64) and it held 600 at the wheels for some time in an older Kia Optima. This was a stock engine with head studs, cams, and springs, stock crank, stock pistons, stock rods. Not saying EVERYONE could or should do that but just to give an idea of what the later 4g64’s are capable of. Keep in mind he did the cams and springs to make it capable of reving out a bit higher to make use of the powerband with the 6766, not for overall durability. Gave me a lot of motivation to keep pushing the stock NT 4g63 bottom ends without doubting them. In all reality a stock rebuild in good health with a proper tune I wouldn’t hesitate to throw 200 at all day, at that level health of the engine and the tune is really the key over stronger rods and forged pistons, I wouldn’t even second guess the stock crank as they seem to be just as stout as the 4g63 crank and many in the Evo community have no issue making big power with the stock 4g64 crank from that generation in built 4g64 bottom ends or using it as a stroker crank in the 4g63. EvolutionM would also be a good forum to dig in as again, many Evo 4-9 guys build that same 4g64 bottom end opposed to using a 4g63.

Thanks so much I’ve looked in to swapping the head before but now I’m more interested

I’ve been reading about it definitely first step with swap the head not sure exactly what I’m looking for though some people swap the 4g64 head for the Kia sonata dohc, and some people swap for the Evo, I’ve you have any info about what head I should get and exactly what model I should be looking for that would be awesome