420A 420a rebuild then turbo plan help

[Brad Bell]

This is my first post on this site btw. Now I know ditching the gs and going for a gst or gsx is better but I have already committed to going down this route. I have questions on what a good plan would be to turbocharging my 97 eclipse gs 420a, I currently have two engines both with around 130k miles. My current plan is to install some forged internals first, probably a set of forged wiseco pistons and eagle rods like so --->http://realstreetperformance.com/Sh...s-Eagle-Rods-Combo-Dodge-Mitsubishi-420A.html

Anyone else that has installed forged pistons and rods. What bore size and compression ratio should i go with? In the link I have few options to choose from. This is my first time modified internals in a car.

Is this a decent way to go? Down the road I want to install a turbo kit of some sort set to only about 8-9psi, should i go with the forged internals or just stay stock? What else will I need to upgrade for a turbo? I wouldn't be changing the psi on the turbo higher than 10 anyways. I really need just a plan on what to do for a decent turbo setup and what should be done to engine before turbo installation. Thanks.

 

[Andrew_99_GST]

There's a guy local that's gone down that road. He's over $15K in and only makes 350 hp. This engine just plain isn't worth it.

 

[Brad Bell]

There's a guy local that's gone down that road. He's over $15K in and only makes 350 hp. This engine just plain isn't worth it.

only 350hp? Thats actually alot for a 420a. Anyhow i'm not looking for that much hp, low 200's are my goal.

 

[BlackKnight2013]

first off, welcome to dsmtuners.
starting off with forged internals is a good idea for a non turbo engine. the rods in the 420a engine are one of its weakest links. factory compression for a 420a is 9.6 to 1. looking at the link you have provided, you have a choice of 9.0 to 1 and 10.5 to 1. everyone has a different preference in compression choice. for me i would stick around 9.0 to 1. with 10.5 to 1 you would have to run 93 octane or better to prevent pre ignition and detonation, especially with forced induction motors. if you turbo charge the 420a you will have to run 93 octane anyways. factory piston size is 87.5mm, .020" oversized pistons would be 88mm and 040" oversized would be 88.5mm. i am currently running 88mm pistons in my new turbo built 420a engine (though it's still on the engine stand as of now). here's a link to find out static final compression ratios as a general idea of what compression ratios you can have for each combo offered for standard size, .020" oversized, and .040" oversized combinations and assuming the cylinder head combustion chambers cc out to 50cc's (if the head has been milled once for .010" taken off), and factory head gasket is 0.040" with same size bore as the cylinder bore: https://www.rbracing-rsr.com/compstaticcalc.html

for me my preference would be 9.0 to 1 compression pistons and .020" oversized. one reason is i can stay near factory compression ratio which will help spool a turbo set up a bit faster than a compression ratio of 8 to 1 area, another reason for oversize would be to bore the cylinders into a true circle and cut out the guessing of cylinders being out of round and tapered. to me .040" may be a bit over kill.

a few things you might want to look: a good set of main and rod bearings that will hold up to what our power level goal will be, arp main and head studs will be a nice investment and an mls head gasket if your going to turbo. a set of turbo grind cams from will help your turbo set up a bit, as well as better flowing cylinder head (such as larger valves and porting). a word of advise, i would use the updated hydraulic lifters to improve valve train control and eliminate the tick tick tick the old outdated original factory lifters have.

if you want some ideas and have time to browse a bit you can read through my build journal and get some ideas. i do warn you the engine i'm building currently is heavily modified, and i do apologize in advance for some of the unwanted cluttered posts in my build thread.
http://www.dsmtuners.com/threads/1998-eagle-talon-street-build-monster.469506/[DOUBLEPOST=1415931732][/DOUBLEPOST]

There's a guy local that's gone down that road. He's over $15K in and only makes 350 hp. This engine just plain isn't worth it.

dude, your forgetting about dsm-zero, the guy has a 420a and makes 661hp but the engine is heavily modified and has more than roughly 25k in it.

 

[Brad Bell]

first off, welcome to dsmtuners.
starting off with forged internals is a good idea for a non turbo engine. the rods in the 420a engine are one of its weakest links. factory compression for a 420a is 9.6 to 1. looking at the link you have provided, you have a choice of 9.0 to 1 and 10.5 to 1. everyone has a different preference in compression choice. for me i would stick around 9.0 to 1. with 10.5 to 1 you would have to run 93 octane or better to prevent pre ignition and detonation, especially with forced induction motors. if you turbo charge the 420a you will have to run 93 octane anyways. factory piston size is 87.5mm, .020" oversized pistons would be 88mm and 040" oversized would be 88.5mm. i am currently running 88mm pistons in my new turbo built 420a engine (though it's still on the engine stand as of now). here's a link to find out static final compression ratios as a general idea of what compression ratios you can have for each combo offered for standard size, .020" oversized, and .040" oversized combinations and assuming the cylinder head combustion chambers cc out to 50cc's (if the head has been milled once for .010" taken off), and factory head gasket is 0.040" with same size bore as the cylinder bore: https://www.rbracing-rsr.com/compstaticcalc.html

for me my preference would be 9.0 to 1 compression pistons and .020" oversized. one reason is i can stay near factory compression ratio which will help spool a turbo set up a bit faster than a compression ratio of 8 to 1 area, another reason for oversize would be to bore the cylinders into a true circle and cut out the guessing of cylinders being out of round and tapered. to me .040" may be a bit over kill.

a few things you might want to look: a good set of main and rod bearings that will hold up to what our power level goal will be, arp main and head studs will be a nice investment and an mls head gasket if your going to turbo. a set of turbo grind cams from will help your turbo set up a bit, as well as better flowing cylinder head (such as larger valves and porting). a word of advise, i would use the updated hydraulic lifters to improve valve train control and eliminate the tick tick tick the old outdated original factory lifters have.

if you want some ideas and have time to browse a bit you can read through my build journal and get some ideas. i do warn you the engine i'm building currently is heavily modified, and i do apologize in advance for some of the unwanted cluttered posts in my build thread.
http://www.dsmtuners.com/threads/1998-eagle-talon-street-build-monster.469506/[DOUBLEPOST=1415931732][/DOUBLEPOST]
dude, your forgetting about dsm-zero, the guy has a 420a and makes 661hp but the engine is heavily modified and has more than roughly 25k in it.

Alright, so if i do go with oversized pistons such as 88mm .020", i will need to bore my cylinders .020" correct? I'm a newbie sorry ;D

 

[Andrew_99_GST]

Yes you would need to get them machined. I didn't want to come off wrong, I wish you luck!

 

[BlackKnight2013]

any time you get over sized pistons, you will have to get the cylinders bored out. if you do get oversized pistons i would suggest taking the block and the pistons to the machinest so they can bore the cylinders out properly and also to get the right piston to cylinder wall clearance. too tight of a clearance and the engine can lock up, too loose of a gap can cause piston slap/shimmy.

 

[synthetek]

Have the block checked out before you buy pistons, if it has already been bored before or if there are any deep scratches or damage to the cylinder walls you may have to go a different size.

 

[tec_41]

You have heaps of research to do, my friend! I would suggest starting here to learn all of the stuff you'd need for a turbo kit - http://www.dsmtuners.com/threads/how-to-build-a-420a-stage-2-turbo-kit-for-under-1000.181134/

Quite honestly, spending all that money to build a forged motor and NOT turbo'ing it is a lot for very small gains. You won't be content. You'll have slightly more displacement but the lower compression pistons will actually net you less power. But they are good for boost.

One of the biggest hurdles with a 420a is fuel management. Megasquirt is the only standalone choice...There aren't really any good piggyback options. On low boost levels you can get away with an FMU (fuel management unit) and bigger fuel pump and stock injectors. That would get you to that 200hp goal, but don't expect anything beyond that.

I ran stock internals for over 20k miles on boost no problem. What ultimately took my engine out was a bigger turbo (more air flow) and not enough fuel. It was no fault of the engine internals, just running way too lean.

 

[rough]

You can buy and install a 4g63 cheaper then turboing a 420a.

I use to think, man I'm going to turbo this 420a! Once you price out just the bottom end, going the 4g63 route is the way to go!

Once you price out the bottom end and the price of machine work, That GST is looking better already.

What you do is on you, but I will tell you from walking down the same road you are walking, you will regret not getting rid of that 420a!

You got two motors, sell one, buy a 4g63 and go from there!

You can probably find a complete drivable GST for 1500-2k

Once you read the Vfaq on turboing the 420a, your about 3 grand in and not even felt boost yet.

 

[tec_41]

You can buy and install a 4g63 cheaper then turboing a 420a.

I use to think, man I'm going to turbo this 420a! Once you price out just the bottom end, going the 4g63 route is the way to go!

Once you price out the bottom end and the price of machine work, That GST is looking better already.

What you do is on you, but I will tell you from walking down the same road you are walking, you will regret not getting rid of that 420a!

You got two motors, sell one, buy a 4g63 and go from there!

You can probably find a complete drivable GST for 1500-2k

Once you read the Vfaq on turboing the 420a, your about 3 grand in and not even felt boost yet.

No offense at all, but I was able to turbo a 420a with quality new/used parts for mayyybe $1200 when all was said and done. If you factor in the price of a built motor then yeah, that'll put you closer to $3k.

A 4g63 swap is way more involved than a turbo kit, which is why not many take that route. You can certainly make more power, but it's much more complicated than take engine A out and put engine B in.

 

[Christoph]

I always wonder why people even think about putting a turbo on a 420a, for about 3-4k you can Evo swap. Yes there is some work required but it is ultimately a much better decision. It is a very well documented process, all you have to do is search around on here and google. If this interests you and you want to know more info I believe I have some links on a few people who have evo swapped their Base/RS/GS Eclipse.

 

[Wrathofwalrus]

Too be different and because building things is fun duh.

 

[tec_41]

A simple turbo'd 420a is faster than a stock 4g63. It's cheap, easy, and pretty darn reliable if you don't get too greedy. Calling the platform "garbage" is a little ignorant...

An evo swap is far more work, and more expensive. A turbo kit you can piece together as you have money, which is a big part of it for many.

People don't come here to be told "sell it and but a gst". I have no regrets turbocharging my esi, and I own a tsi awd now. I got a hell of a lot more satisfaction keeping up with the 4g63 guys with my 420a than I do with the tsi.

 

[AlwaysSunnyOhio]

A simple turbo'd 420a is faster than a stock 4g63. It's cheap, easy, and pretty darn reliable if you don't get too greedy. Calling the platform "garbage" is a little ignorant...

An evo swap is far more work, and more expensive. A turbo kit you can piece together as you have money, which is a big part of it for many.

People don't come here to be told "sell it and but a gst". I have no regrets turbocharging my esi, and I own a tsi awd now. I got a hell of a lot more satisfaction keeping up with the 4g63 guys with my 420a than I do with the tsi.

I don't think he was stating that the car or engine was garbage. It was more of a personal preference as in not worth his time or money. Maybe I'm the one who interpreted it wrong.

As for me I've done it with an older celica. Instead of doing a 3sgte swap I tried to turbo the 5sfe engine. i spent about 4 grand in parts. I ended up selling all the parts for less than a third of what I had in them. So from my personal experience I would say keep the money buy a gst while they are still around. If this car means something to you then keep it clean and stock.

If you must go down the turbo road id say a full kit is your best bet. The piece at a time stuff is just a headache.

 

[Wrathofwalrus]

Personally I really could care less how the 420a compares to the 4g. Id be fine with a nice 300whp 420a turbo, I dont need a 800whp Monster.

 

[Andrew_99_GST]

Which in the end it's the OPs decision.

https://omaha.craigslist.org/cto/4762449592.html

"Honestly, too much money! it's best just to sell and buy a turbo model. I have spent over 15k to get this car to be a reliable 300+hp."

From the owner himself.

 

[99RedGs]

I went down this route. It shouldn't take anywhere near $15k to hit 300whp you are probably more in the $6k-7k range and less if you go second hand. You can see my mod list in my profile.

That said, I built this car, broke the timing belt, rebuilt forged, boosted and tuned it, and it has sat for the past 2 years. I literally drove it for 6 months after spending $7k on the rebuilt haha. I ended up buying a new '13 Genesis 2.0t and dyno'd 320whp/356wtq with just bolt-ons and a tune, many forum members are running 440+whp/360+wtq on the stock block with just upgraded turbo and fuel system. LandoAWD (old mod) made the same move. I can't tell you how nice it was to spend $1000 and increase the power by 40%.

If I was you, think about how you want to spend your money. Do you want to invest $5+k into a 17yr old car that has low potential, dings, and broken things? Or would you rather take that $5k and put it towards a car that is maybe 0-5yrs old with more creature comforts, more potential, and less mechanical issues that will arise. You have to remember, this car has 130k miles, not just the engine, but the suspension, cooling system, paint, chassis, interior, etc.. You are going to get nickle and dimed from here on out as things start to break. I wouldn't even buy a GSX anymore, you can find EVO's that are in better shape for reasonable pricing now. Also, keep in mind that just because you put $5,000 into the car doesn't make it worth $5,000 more. You will be lucky to get half of that back assuming you part it out before you sell it.

I chose 10.5:1 comp for off boost power, and especially if you don't plan to turbo right away you will want the extra compression. Let's be honest here, most people that say "Planning turbo mod in the future" never actually turbo their car. By going high compression you can still enjoy driving the car while it is not boosted, and if you never end up boosting it then it at least still makes stock horsepower. I've only needed to run 93 on mine and never see detonation.

I'm not sure of your age, and I'm not that old myself (27), but in all honesty at this point I don't see it making any financial sense to invest loads of money into this car unless you have excess cash (meaning no debts) and some kind of sentimental attachment to it. You'll notice the entire site here is pretty dead, people have moved on to new platforms. You aren't going to have as much support troubleshooting as in the past, it will come down to how well you can search and hope there are no dead links.

Cheapest most cost effective way to reach your ~200whp goal wold be:

Stock rebuild ($500 parts + $300 machining, assembled yourself)
Hahn Stage 2 turbo kit @ 8psi ($2999 if Hahn even still sells it), but you can piece your own together for cheaper.
Some kind of fuel cut defender - $50-100
3" exhaust - $500
Stage 2 Daily clutch from Southbend - $380

That puts you at about $4500, and I would say add an extra $500 for things like assembly lube, break in oil, new fluids, gauges, and misc. pieces you miss.

I am not trying to be a douche, I am being as realistic as possible and speaking from experience. I just spent $2,000 getting this car repainted with all new bumpers, fenders, and hood because my GF is attached to it and won't let me sell it. I regret spending the money, but thankfully I make about 10x what I used to when I bought this car 7yrs ago.

 

[Christoph]

God have mercy, the amount of money that has gone into putting turbos on these cars is really depressing. If that isn't enough information by 99RedGs to make you change your mind then I wish you good luck and I hope you enjoy your time building it.