420A Turbo my 420a

[TCJProductionz]

Hey Guys whats going on I have had my car for about 2 years now and I have come to the decision to turbo my 420a I know it going to take a lot but im still down for the ride here are my goals

Turbo setup
anywhere 200-300 hp
daily 6-8 boost

I know im going to need
forged internals
I want to go standalone
turbo
downpipe
turbo manifoild

my main qeustion are with forged internals what are the specs I should go for
piston size
bore size
piston ring gap
what bloeoff valve
and any informatio regarding standalone pcm due to the fact im completey new to them

 

[Canadian_CD9A]

This forum tries to be helpful, but man this topic is honestly covered every single month. Overbore is determined by condition of the bores themselves, your machine shop will tell you. Ring gap as called for by the manufacturer. BOV make is largely irrelevant as long as it isn’t a cheap turd. Stand-alone - consult a tuner if you have no experience. It’s not something that beginners should do themselves.

 

[TCJProductionz]

Ok Thk for the help man much appreciated follow up question as I was looking for forged internals I don't believe I saw any forged pistons that were stock size which is why I was saying what would be the recommended bore size

 

[pauleyman]

Ok Thk for the help man much appreciated follow up question as I was looking for forged internals I don't believe I saw any forged pistons that were tock size which is why Iwas saying what would be the recommended bore size

Even if you found stock size you still wouldn't know. That's why yiu tear it down first and order parts second. Machine shop will have to measure to determine what you can use. I also wouldn't bore any more than you have to if any.

 

[curt-s]

Legit question: can you even make north of 200hp on the 420A with only 6-8lbs of boost and not be a lag monster (ie. big turbo)? I suppose if you push timing pretty hard..

There's also a huge difference between 200 and 300, so shooting for "anywhere" inbetween can mean the difference between and .

 

[BLACK'98DSM]

Why limit yourself to that boost level if you'll be using forged internals and tuning? That's the level most people recommend simply because of common connecting rod and piston ringland failure at higher boost. The crankshaft can handle north of 400hp. Get some Eagle H Beams and forged pistons of your choice. ARP headstuds & MLS headgasket. There's no reason you can't run at least 15psi. A previous member on this site was running 23psi with a fairly basic setup on MS3. Looked like a blast. If you have an RS, it's the lightest submodel and doesn't take a ton of power to scoot ass.

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[TCJProductionz]

Why limit yourself to that boost level if you'll be using forged internals and tuning? That's the level most people recommend simply because of common connecting rod and piston ringland failure at higher boost. The crankshaft can handle north of 400hp. Get some Eagle H Beams and forged pistons of your choice. ARP headstuds & MLS headgasket. There's no reason you can't run at least 15psi. A previous member on this site was running 23psi with a fairly basic setup on MS3. Looked like a blast. If you have an RS, it's the lightest submodel and doesn't take a ton of power to scoot ass.

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yoooo thats wild and im definity going to look into that because I wanted to get ass many forged parts as possible side qeustion with the forged conecting rods work with stock crank shaft

Legit question: can you even make north of 200hp on the 420A with only 6-8lbs of boost and not be a lag monster (ie. big turbo)? I suppose if you push timing pretty hard..

There's also a huge difference between 200 and 300, so shooting for "anywhere" inbetween can mean the difference between and .

Not gonna lie man II have no clue I think I saw somewhere that Guy had daily 220 hp 420a rnning 8 psi

 

[BLACK'98DSM]

side qeustion with the forged conecting rods work with stock crank shaft

Yes. Have a machinist measure/inspect the crankshaft journals for bearing size, but the stock crankshaft can be used.

 

[TCJProductionz]

Yes. Have a machinist measure/inspect the crankshaft journals for bearing size, but the stock crankshaft can be used.

pk great man thx for the help

This forum tries to be helpful, but man this topic is honestly covered every single month. Overbore is determined by condition of the bores themselves, your machine shop will tell you. Ring gap as called for by the manufacturer. BOV make is largely irrelevant as long as it isn’t a cheap turd. Stand-alone - consult a tuner if you have no experience. It’s not something that beginners should do themselves.

hey man thx for the help

 

[Sirius1995]

You can run 6-8psi on stock internals, just get MLS head gasket and arp head studs, megasqruit is a good standalone system, put your money on a good tune @ Dyno and use good parts, non of that eBay junk and you're good, but yea, you will need a lot of other parts and some fabrication skills, almost nothing is straight bolt-on, get also good set of wideband sensor + gauges, again.. you get what you pay for, I think for that little of boost you might hit 180-ish horsepower (which is reliable) and forged internals are not needed but if you want +200hp, then you might want those, but personally I'd put that money on a good tuner, I think you might not even want more than that, it would be really fun daily!

 

[TCJProductionz]

You can run 6-8psi on stock internals, just get MLS head gasket and arp head studs, megasqruit is a good standalone system, put your money on a good tune @ Dyno and use good parts, non of that eBay junk and you're good, but yea, you will need a lot of other parts and some fabrication skills, almost nothing is straight bolt-on, get also good set of wideband sensor + gauges, again.. you get what you pay for, I think for that little of boost you might hit 180-ish horsepower (which is reliable) and forged internals are not needed but if you want +200hp, then you might want those, but personally I'd put that money on a good tuner, I think you might not even want more than that, it would be really fun daily!

Ok man thz for the info follow up qeustion tho how do you feel about the AEM standalones and also where would I even get a mega squirt stanalone also when you say wideband sensor you mean?

 

[curt-s]

You can run 6-8psi on stock internals, just get MLS head gasket and arp head studs, megasqruit is a good standalone system, put your money on a good tune @ Dyno and use good parts, non of that eBay junk and you're good, but yea, you will need a lot of other parts and some fabrication skills, almost nothing is straight bolt-on, get also good set of wideband sensor + gauges, again.. you get what you pay for, I think for that little of boost you might hit 180-ish horsepower (which is reliable) and forged internals are not needed but if you want +200hp, then you might want those, but personally I'd put that money on a good tuner, I think you might not even want more than that, it would be really fun daily!

Q, since I'm not that familiar with the 420A, is the suggestion to get a MLS gasket (which requires a very fine RA finish on both the block and the head) because there isn't a composite gasket available for the 420A that is of the same strength and quality of either the OEM or Felpro 9627PT for the 4g63? Those are easily capable in the 20s, but that engine was designed for boost so perhaps MLS is the only way to go?

As well, keeping the wastegate shut until 6-8psi might also be a challenge as that is such light pressure the exhaust gases might partially open it just on spool.

These will be the last things I say/ask on the matter because this subforum is full of useful information from people more knowledgeable in the engine

 

[Sirius1995]

Ok man thz for the info follow up qeustion tho how do you feel about the AEM standalones and also where would I even get a mega squirt stanalone also when you say wideband sensor you mean?

Aem is a good brand, a lot of potential, but ms squirt is commonly easier and cheaper, but aem provides more tune options, but I don't think there's plug and play kit for 420a so you need to do wiring yourself pretty much

Wide and will measure your afr after turbo and you need that for the tune as well, you don't wanna run engine too rich or lean, aem, innovate etc are good affordable ones

Q, since I'm not that familiar with the 420A, is the suggestion to get a MLS gasket (which requires a very fine RA finish on both the block and the head) because there isn't a composite gasket available for the 420A that is of the same strength and quality of either the OEM or Felpro 9627PT for the 4g63? Those are easily capable in the 20s, but that engine was designed for boost so perhaps MLS is the only way to go?

As well, keeping the wastegate shut until 6-8psi might also be a challenge as that is such light pressure the exhaust gases might partially open it just on spool.

These will be the last things I say/ask on the matter because this subforum is full of useful information from people more knowledgeable in the engine

When you apply boost on non turbo engine, MLS gasket is almost a must as it has higher compression than factory turbo engine, and yes, both engine head and block surfaces have to be straight, but that's pretty much the work you have to do, 420a composite gaskets are available and all stock ones have those, even 4g engines have composite gaskets from factory, and just for records, 420a and 4g63t are not compatible at all

And you can change wastegate springs to be stiffer and loose, most of the small turbos run around 8psi so I don't see that to be a problem at all as long you don't get eBay turbos with some knock off wastegates attached to it, also he might wanna do external wastegate which just open more better options

Hopefully that answered for your questions

 

[Canadian_CD9A]

Q, since I'm not that familiar with the 420A, is the suggestion to get a MLS gasket (which requires a very fine RA finish on both the block and the head) because there isn't a composite gasket available for the 420A that is of the same strength and quality of either the OEM or Felpro 9627PT for the 4g63? Those are easily capable in the 20s, but that engine was designed for boost so perhaps MLS is the only way to go?

As well, keeping the wastegate shut until 6-8psi might also be a challenge as that is such light pressure the exhaust gases might partially open it just on spool.

These will be the last things I say/ask on the matter because this subforum is full of useful information from people more knowledgeable in the engine

Back in the 1990s, Chrysler and Mitsubishi used what is effectively the same 2.0L engine - 420A for Mitsubishi and ECB/ECC for Chrysler. Chrysler thought they were clever by pinching pennies and installing composite head gaskets on early Neons, whereas Mitsubishi went the MLS route on the 420A DSM. Predictably, the composite gaskets on the Neon failed quite quickly and frequently, particularly in warmer climates - to the extent where Neons with original head gaskets are an extremely rare find these days. Chrysler’s fix for the Neon 2.0L engine was a revised MLS head gasket, which has been the mainstay ever since. There is only one composite head gasket available for Neons, predictably the cheapest, but they’re tainted by the history and it’s unclear whether they’ll actually hold up better than the original. And considering a FelPro MLS gasket can be had for $38 CAD regular price on Rock, why even risk it?

Yes they require a specific RA, but the FelPro is coated to help cover flaws, and the Mopar gasket takes a copper spray to do the same, so it’s not a concern unless the surface finish is abysmal.

 

[curt-s]

I was just going to say it didn't answer my question about the gasket, but here @Canadian_CD9A comes with the last second goal. You know a scary amount sometimes.

wrt. to the wastegate, yes, you can change springs on a wg that supports it. 6-8 may very well hold shut with even a mid-grade gate and not open too early. Granted, 200-300hp isn't exactly pushing a LOT of exhaust gas, so you're probably fine with respect to creep, but it depends on the gate quality and size.

I don't agree with 180hp being fun especially after a lot of $ and effort getting a turbo onto the engine. When dialing in my VE table, I start off at 10psi (basically a straight line to the 14b/16g wastegate) and I'm getting gapped by grannies on motorized scooters.

 

[BLACK'98DSM]

180whp is fun enough with an NA engine that delivers it well. I'd be aiming for at least 225whp with a turbocharged application. At 20psi and a proper tune you will reach 300whp minimum. I don't get staying at 6-8psi if you bear the means to produce much more. Unless it's simply fuel efficiency that you're aiming for. But that's usually the last thing on my mind for a car I call "fun".

 

[Spleen8urLSX]

When you apply boost on non turbo engine, MLS gasket is almost a must as it has higher compression than factory turbo engine, and yes, both engine head and block surfaces have to be straight, but that's pretty much the work you have to do, 420a composite gaskets are available and all stock ones have those, even 4g engines have composite gaskets from factory, and just for records, 420a and 4g63t are not compatible at all

And you can change wastegate springs to be stiffer and loose, most of the small turbos run around 8psi so I don't see that to be a problem at all as long you don't get eBay turbos with some knock off wastegates attached to it, also he might wanna do external wastegate which just open more better options

Hopefully that answered for your questions

Might want to clarify your answer is more engine specific, I’m not real 420a familiar but I see a lot of 420a guys opt for MLS which I’m assuming is safer due to the overall design. In a 4g63 that’s simply not true, know several instances where guys are using 9:1 and 10:1 compression pistons with a composite gasket, myself included and that’s with 9:1 compression non turbo pistons seeing boost from various turbo set ups, felpro composite head gasket has never been a failure point. We have had a handful of cars here in shootout country make 700+ on a heartbreaker dyno with aftermarket higher compression pistons with a basic Felpro composite gasket and standard ARP studs, head gasket never failed by itself, any that did in those scenarios was from tune related issues or something else failed mid rip resulting in detonation that in turned popped the gasket and even then they were usually glad they had a composite gasket as damage could have been way worse.

 

[Sirius1995]

Might want to clarify your answer is more engine specific, I’m not real 420a familiar but I see a lot of 420a guys opt for MLS which I’m assuming is safer due to the overall design. In a 4g63 that’s simply not true, know several instances where guys are using 9:1 and 10:1 compression pistons with a composite gasket, myself included and that’s with 9:1 compression non turbo pistons seeing boost from various turbo set ups, felpro composite head gasket has never been a failure point. We have had a handful of cars here in shootout country make 700+ on a heartbreaker dyno with aftermarket higher compression pistons with a basic Felpro composite gasket and standard ARP studs, head gasket never failed by itself, any that did in those scenarios was from tune related issues or something else failed mid rip resulting in detonation that in turned popped the gasket and even then they were usually glad they had a composite gasket as damage could have been way worse.

I partly agree but it depends on many factors, I never got rods to bent but I blew head gaskets on some na engines I turbocharged when using composite but i never had that problem with MLS, but I suppose we're both right, but again, it all just depends on how and how well the setup has been put together and tuned, but I would go with MLS whenever I can personally, and I thought I was being pretty specific on my answers as I was talking about OPs car, also yes, 4g engines have really good OEM composite gaskets, I'm running OEM on mine as well

 

[TCJProductionz]

Ok I want to thank you all for the information it will help me out a lot to answer one qeustion I was aiiming for 6-8 boost because I was told it was safer for the 420A mabye they meant without forged internals and also 1 last qeustion what compression ratio should i shoot for when buying my pistons im still new to rebuild engines

 

[Sirius1995]

Ok I want to thank you all for the information it will help me out a lot to answer one qeustion I was aiiming for 6-8 boost because I was told it was safer for the 420A mabye they meant without forged internals and also 1 last qeustion what compression ratio should i shoot for when buying my pistons im still new to rebuild engines

Yea they've meant as stock block, as you're still new in the game, id recommend to save money and buy 4g63t platform eclipse, but if you really wanna turbo your 420a, I would just service the car, put turbo parts on it and run it on 6-8psi and if you break your internals, then you can start rebuilding, it's not easy or fast process, thousands of dollars when we're talking about forged internals and turbocharging NA engine, you will need a good tune and machine block and head, 4g platform is already turbocharged and you can more easily just upgrade it

 

[MitsuRX]

Put a snail on it and run it 6/8 psi all day long. Anybody that tells u to sell ur 420a and buy a 4g just ignore. Believe me they both have their downfalls.

 

[Sirius1995]

Put a snail on it and run it 6/8 psi all day long. Anybody that tells u to sell ur 420a and buy a 4g just ignore. Believe me they both have their downfalls.

I agree