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420a motor rebuild

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Thee_burns

Probationary Member
10
0
Sep 29, 2015
Lockport, New_York
Hey guys I have a 99 eclipse rs with a 420a motor in it ... I was wondering I've heard and seen many posts similar to what I'm about to say but none that have answered my question all people trying to be cheap ... I was wondering if I could get my engine to 400 hp this includes a rebuild and a turbo .. the whole nine yards ... my question is whether this is achievable and if so where should I start .. also what do you think price would be for all the parts I'm looking at (no labor I'm installing and everything myself) and after the motor is rebuilt what mods I should start adding to achieve this goal
 
One last thing I forgot to mention ik it'd be cheaper to buy a gsx but I'd like to have something a Lil more unique plus looking for the experience
 
In short: Yes its possible, but it won't be cheap.

The bottom end is where you'll need to start. Get a set of forged pistons and rods, and a forged crank. Once you have the solid foundation, then you can build around that. I.e. head work, cams, turbo size. You'll also have to find a way to control it. Iv'e heard megasquirt works great.

For an example, the other half has a dodge daytona with a 2.4 swap. This engine was originally a N/A engine from a plymouth breeze. He built it with aluminium rods, forged pistons, forged crank, heavy port work on the head, BC 280 cams, and uses FAST EFI to control it. He also is running the older turbo dodge A568 transmission that was was custom fitted with the SRT4 Quaiffe LSD and SRT4 Driveshaft Shop Level 5 axles. You also need to remember that in order to use that power, the drivetrain also needs to be upgraded. Car runs a GT35R turbo, and puts down a little over 600HP. Traps 143mph in the 1/4.

Honestly, I'd look into a SRT4 swap. I've been toying with that idea for the non-turbo eclipse I have, since I happen to have an SRT 2.4 laying around. ;)

hope that helps some.
 
In short: Yes its possible, but it won't be
The bottom end is where you'll need to start. Get a set of forged pistons and rods, and a forged crank. Once you have the solid foundation, then you can build around that. I.e. head work, cams, turbo size. You'll also have to find a way to control it. Iv'e heard megasquirt works great.

For an example, the other half has a dodge daytona with a 2.4 swap. This engine was originally a N/A engine from a plymouth breeze. He built it with aluminium rods, forged pistons, forged crank, heavy port work on the head, BC 280 cams, and uses FAST EFI to control it. He also is running the older turbo dodge A568 transmission that was was custom fitted with the SRT4 Quaiffe LSD and SRT4 Driveshaft Shop Level 5 axles. You also need to remember that in order to use that power, the drivetrain also needs to be upgraded. Car runs a GT35R turbo, and puts down a little over 600HP. Traps 143mph in the 1/4.

Honestly, I'd look into a SRT4 swap. I've been toying with that idea for the non-turbo eclipse I have, since I happen to have an SRT 2.4 laying around. ;)

hope that helps some.
I was thinking of doing the srt4 swap but heard it's not an easy swap .. it's easier than a 4g63 swap but still difficult because obviously that engine would be bit better with the stock internals (still rebuild it, but would be to necessary off the bat)
 
Yeah, the head on the Chrysler engines are "on backwards" - for lack of better terms. But the mounts would be on the correct sides. I agree that it wouldn't be super simple. I just happen to like the Chrysler 2.4L. :)
 
Yeah, the head on the Chrysler engines are "on backwards" - for lack of better terms. But the mounts would be on the correct sides. I agree that it wouldn't be super simple. I just happen to like the Chrysler 2.4L. :)
I'll have to take a look what would you think I'd need to replace internal wise to get to that 400 hp mark
 
Dont do an SRT4 swap or 4g swap.400hp on a 420a is very possible, but it depends if you are able to run megasquirt. Do you have inspection where you live?
 
Being in NY he will have inspections. Being a 99 he will have to pass OBD2 which will make the megasquirt a bit harder since it doesn't support OBD2 and probably never will.

OP, 400 is very possible with a turbo. Don't bother looking for a forged crank... you won't find one for the 420a but a few people have run the 420a up to 500-600 hp and didn't have crank issues. The weak point is the rods and pistons. they just aren't designed for boost. Some Eagle rods and Wiseco or JE pistons. Crower stage 3 cams are a popular choice. 2gnt has plenty on information.

Here is some on the rockers and lifters to look at for upgrading:
http://www.2gnt.com/index.php?d=Rockers

You're going about it the right way. the guys that get cheap crap and throw it together never stay around to long because the car breaks and they throw in the towel.

One thing you will need to plan out is engine management. There is nothing plug and play for the 420a unfortunately. Personally I run a megasquirt MS3X as a stand alone and I absolutely love it, but I don't have inspections here in Ohio which is super sweet!
 
Being in NY he will have inspections. Being a 99 he will have to pass OBD2 which will make the megasquirt a bit harder since it doesn't support OBD2 and probably never will.

OP, 400 is very possible with a turbo. Don't bother looking for a forged crank... you won't find one for the 420a but a few people have run the 420a up to 500-600 hp and didn't have crank issues. The weak point is the rods and pistons. they just aren't designed for boost. Some Eagle rods and Wiseco or JE pistons. Crower stage 3 cams are a popular choice. 2gnt has plenty on information.

Here is some on the rockers and lifters to look at for upgrading:
http://www.2gnt.com/index.php?d=Rockers

You're going about it the right way. the guys that get cheap crap and throw it together never stay around to long because the car breaks and they throw in the towel.

One thing you will need to plan out is engine management. There is nothing plug and play for the 420a unfortunately. Personally I run a megasquirt MS3X as a stand alone and I absolutely love it, but I don't have inspections here in Ohio which is super sweet!
OK sweet so my question to you is how much you think the rebuild will be I'm not loaded with cash and this is actually my daily so summer time because of college is the only time I can work on it without it being an inconvenience so I was just looking to see how much price wise for parts you think I'd be looking to expect
 
In that case you are probably best picking up a block and building that so your car isn't down except for the swap.

You can price everything out online besides machine shop work on the block.

You could always leave the head stock for now and upgrade it later if you wanted.

Rough guesstimate

Rods - $350

Pistons - $500

Bearings, rods - $50

Bearings, mains- $50

Have the machine shop check out you crank - $?

Machine shop bore, deck, line hone - $? ( mine was $450)

Oil pump $100

Water pump $50

Gates timing belt kit with mechanical tensioner - $150

Gaskets - varies by kit brand, quality and completeness. Spend the extra money here. Nothing sucks worse than a freshly built motor that leaks.

So with just that your looking ~2,000. not cheap but it never is to do it the right way.
 
In that case you are probably best picking up a block and building that so your car isn't down except for the swap.

You can price everything out online besides machine shop work on the block.

You could always leave the head stock for now and upgrade it later if you wanted.

Rough guesstimate

Rods - $350

Pistons - $500

Bearings, rods - $50

Bearings, mains- $50

Have the machine shop check out you crank - $?

Machine shop bore, deck, line hone - $? ( mine was $450)

Oil pump $100

Water pump $50

Gates timing belt kit with mechanical tensioner - $150

Gaskets - varies by kit brand, quality and completeness. Spend the extra money here. Nothing sucks worse than a freshly built motor that leaks.

So with just that your looking ~2,000. not cheap but it never is to do it the right way.
OK sweet so I'll prob do most this over the summer turbo won't be for a Lil while hard to save 5000 while at school LOL so get the rebuild out the way another thing what's a good exhaust for the 2nd Gen eclipse (full exhaust header to the muffler and price range)
 
if you plan on going turbo you can get a 3" cat back back, it will hurt performance a little on a stock N/A car and even a built N/A. Any GST cat back will fit. Many people like the thermal R&D, plenty of people will say just go ebay a pipe is a pipe... but fitment is really what you're paying for.

I went the ebay exhaust route and after about 1 ish years it just sounded like crap. fitment was crap as well.

I ended up redoing it from the axle back with a borla pro xs muffler. I love it. Definitely getting another borla when I get my turbo on and make the switch to full 3".

header... why waste the money. if you really want one get an ebay one and save your money for a good exhaust header.

You really won't see much gains in hp from a 420a with some bolt on's until you have a way to tune it. That's really the key piece to the puzzle.
 
if you plan on going turbo you can get a 3" cat back back, it will hurt performance a little on a stock N/A car and even a built N/A. Any GST cat back will fit. Many people like the thermal R&D, plenty of people will say just go ebay a pipe is a pipe... but fitment is really what you're paying for.

I went the ebay exhaust route and after about 1 ish years it just sounded like crap. fitment was crap as well.

I ended up redoing it from the axle back with a borla pro xs muffler. I love it. Definitely getting another borla when I get my turbo on and make the switch to full 3".

header... why waste the money. if you really want one get an ebay one and save your money for a good exhaust header.

You really won't see much gains in hp from a 420a with some bolt on's until you have a way to tune it. That's really the key piece to the puzzle.
Yeah ik the struggle of the eBay fitment I have an eBay header now and the down pipe is shit and header fitment is ass .. it took 6 hours to finally get it together because of trying to figure out a way for it to go on .. but I don't want a loss in power even if it's not a lot
 
The amount of time and money required to swap a 4g into a 420a chasis is just not worth it AT ALL. If you want a 4g63, find a 4g63 shell.
 
He's most likely doing a type of 4g swap. The 420a and 4g63 have different orientations.
 
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