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420a motor prep for tubo upgrade

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1999Eclipse

Probationary Member
16
0
Aug 2, 2009
Lynnwood, Washington
Hello everyone,

I did a search in the forums and didn't find what I was looking for. If I missed it please for give the noob:D

I am wanting to do a turbo upgrade to my GS. I already found the turbo kit I am going to get. I am wanting to know what parts I will need to upgrade the 420a motor to handle the extra horse power and not burn up the motor before its time. I am thinking about buying a 2nd 420a motor to have it build for the turbo and then install the motor after it is ready.

Thank you for a list of parts that you all might recommond I use. This will be my first engine rebuild.

Till later:D
1999Eclipse
 
Aftermarket Rods
Low Compression Pistons
Build your head with full SS Valvetrain (aftermarket Cams,springs,retainers,valves)
Get your cylinder head PnP
Thicker Headgasket
Get Engine management to tune it.
 
minimum requirements are better rods and pistons. those are the 420a's weakness. the rest are ok, but arent really necessary. you could get a set of cams but i think the stock 420a cams would be ok for less than ~275hp
 
you may need to upgrade your exhaust to 2.5 inch to help with the extra flow out of the motor, and depending on how much boost you are planning on running you may need a new fuel pump, afpr, and injectors. I currently have a second motor that i picked up complete for 75 bucks that im building while driving the car i mean it was only 75 dollars and i dont have any downtime yet a great plus.
 
he'll need a fuel upgrade regardless. i dont know how good stock 235cc injectors will hold up.
 
Wow gentlemen,

Thank you for the very helpful info. I was thinking of buying a 2nd motor as well and build the motor for the turbo. Because my car is also my daily driver to work.

brassc2007 where did you find your 2nd motor at?

Anyone recommon a place to get a 2nd motor from. I am in the Seattle Wa area. Would like to find a place near me. But am oopen to online ordering as well.

till later,
1999Eclipse:D
 
You're head will be fine in stock form for you to make circa the 500whp mark. It really depends on how much your goals are. A stock rebuild will be fine for ~250whp ~8-12psi depending on your turbo and tuning.

Vague list of things you might want or need in the engine if you want to hit the 300 mark:

-Fuel management (Injectors, fuel pump, control of some sort [MSnS, SMFU, Portfueler, etc..])
-Rods
-Pistons
-ARP head studs

-Then your obvious other things
 
I am going to through a 420a build as well. List of things I came up with.

ARP Head Studs
Head Gasket
Rods/Pistons/Rings
Lower Bearing Kit
FMIC and Piping
Injectors
FMU
Oil Pump
Gasket Set
Manifold
Turbo!!

Then the small stuff...

Boost gauge
Wideband
BOV
Wastegate

List keeps growing.
 
you should use a 2.4L block, LOL

I'm not exactly sure so pardon me if I am wrong but isn't the 2.4 block out of the SRT4 or the Turbo PT? If so that why would the guy want to drop like +/- $10,000 on a new stock motor. He can pick a used 2.0 from almost anywhere if you are going to mod it. They are in neons and those p.o.s. are in EVERY junkyard. LOL

I also have a GS and I plan to someday turbo it. Keep us updated on how the build goes with pictures. I would love to see them. Good luck man. :thumb:

Take Care
 
cwdrake, 2.4L blocks are a dime a dozen, they dont have to be out of a SRT4, there are a lot of (much cheaper) chrysler cars that use 2.4's. if the internals out of SRT4's fits without a lot of work, it wouldnt be that much more expensive to rebuild using oem srt4 rods and pistons and have a stronger engine to start with.
 
The stock 420a, depending on the condition, can handle 7-8 psi and about 250-275hp. If your looking for more than that, then worry about rebuilding it. Of course, if you have the money, its always nice to have a fresh newly rebuilt engine.
 
The stock 420a, depending on the condition, can handle 7-8 psi and about 250-275hp. If your looking for more than that, then worry about rebuilding it. Of course, if you have the money, its always nice to have a fresh newly rebuilt engine.

What he said/\/\/\/\ I was wondering what took so long for someone to say this. I had my 95 GS turboed with an HRC turbokit @75,000 miles, after it was hydrolocked at low speed, and it held up fine for about 6 years before I had the engine totally built. BREAKAGE WAS NOT THE CAUSE of the rebuild!!!!

Depends on your goals for the car.
 
420a's handle boost w/out issues. If you want higher then 275-300HP you need to upgrade the lower end. That being said, you can easily push 6-8 PSI through the stock head/block without any issues.

Just look up the upgrade path for the 420a, there are plenty of threads talking about what is needed to boost your 420a. Google search,"Stage 2 turbo kit for under $1000" and you will find a step by step on how to do it!
 
I would like to comment on the LACK OF KNOWLEDGE getting thrown around this thread, particularly by the 4g63 owners.

420a's handle boost w/out issues. If you want higher then 275-300HP you need to upgrade the lower end. That being said, you can easily push 6-8 PSI through the stock head/block without any issues.

Just look up the upgrade path for the 420a, there are plenty of threads talking about what is needed to boost your 420a. Google search,"Stage 2 turbo kit for under $1000" and you will find a step by step on how to do it!

Good luck man, and all you idiots should keep your opinions to yourself. If you don't really know, your now supposed to be posting it!

Most useful post so far.

To the OP:
Stock Block will handle 12lbs. Any more and the Rods and Pistons begin to fail.
Stock Fuel system will handle 8lbs. Injectors and ECU are the weak link there.
Stock Head will handle a conservative 400HP. I recommend getting a PT(2.4) Valvetrain.
I highly recommend building a second block for boost. Figure out a solid route you want to take to your goal of power and then research the hell out of it. From built 2.0 to a stroked 2.2 to a 2.4 swap, all of the info is here.

For the record: Yes, the Neon did have the Transverse Head 420A DOHC. However, the 2.0L DOHC 420A was a pretty rare engine for the Neon. Only about 10 percent of ALL Neons actually have it under the hood. So the chances of finding it in junkyards EVERYWHERE, are actually pretty slim to none.
 
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