420A 420a forged internals for cheap

[DrewmHolland]

I’m currently looking at turbocharging my slow 420a, I won’t be doing much I only want 7 or so psi but I figure it’s better to go ahead and rebuild my motor with forged internals to be safe. My problem right now is the price of pistons is stupid high ($700-$900) does anyone know where I could get forged internals for less?

 

[BLACK'98DSM]

I don't think there are any cheaper brands. The only options seem to be limited to JE and Wiseco these days. Just remember, you get what you pay for. And don't fall for the "high performance pistons" on Ebay. They are regular cast pistons, almost replicas of OE. So not forged.

You could try and find used parts but I don't recommend it unless you can handle them before purchasing. The pistons could have worn wrist pin areas and slap/knock. The wrist pins should be an extremely tight fit and require being pressed in. If they slide in by hand then the pistons are worn beyond safe use. If you order these online, you'd have no way of knowing this issue until receiving them. It's not a good idea to buy used pistons anyway.

For the rods, there's usually no major risk in getting used ones. Unless it had a horribly spun bearing and damaged a rod, but it's unlikely and the Eagle H beams are sturdy units. The rods are fairly cheap to buy new though.

The stock pistons are definitely the weakest point. The ringlands tend to break. So you could probably get away with using stock rods if your budget is really tight, though I don't recommend it of course. They are fairly tough but there's no way I would tear down a 420a to be turbocharged and re-use stock rods.

 

[DrewmHolland]

Yeah I think I’m just going to fork out the money on new forged internals unless I can find some used in great shape.

 

[DrewmHolland]

I ended up finding a set of pistons, never used 8.8:1 compression for $450 and new rods for about the same so I went ahead and bought both.

 

[jesse12345]

I just bought an eclipse with the 420a and previous owner put a turbo on it. He said he slapped in neon pistons which have a slightly lower compression. I don't know how true that is as I'm still learning but it's held up on 7 pounds for 10 plus years. I to am going to re buy some forged pistons and rods. I sold my setup last week not knowing I was going to end up with another non turbo. Everything happens for a reason. I may just go for a 2.4 swap who knows.

 

[DrewmHolland]

I’m wondering if I’ll need to do head studs or not and if arp makes head bolts that are stronger than factory

 

[1990TSIAWDTALON]

Pardon Our Interruption

Pardon Our Interruption

 

[jesse12345]

If I were you I'd do main and head studs arp makes both. Marty beat me to it.

 

[BLACK'98DSM]

Main studs aren't really necessary unless you're looking at north of 400hp... And that's probably a conservative number. I don't see the crankshaft leaving the block at any achievable power number for your turbo setup (the crankshaft itself is a concern when the hardware is). The bed plate bolts are technically reusable but always a good idea to measure the threads and make sure they aren't stretched.

I'm not advising you against using main studs, just saying it's far from necessary on a street build. I have never installed them on any version of my engine even when the budget was there.

If you've really got extra money to spend, I'd worry more about having a way to actually tune the car

 

[Canadian_CD9A]

ARP main studs require an align-bore procedure on the crank journals at a machine shop, since they affect the clamping of the main cap. This will run another $100+ depending on what the local machine shop charges.

 

[jesse12345]

Honestly guys I'm glad you said something about that. I'm going to assume that's why my oil pressure was real high when I used main studs. I didn't know you had to when using main studs but now I know. I still don't know this engine very well but I'm learning.

 

[DrewmHolland]

i'm probably just gonna do the head studs since ill be pulling the motor apart in the car so I can't do any machine work

 

[curt-s]

I’m currently looking at turbocharging my slow 420a, I won’t be doing much I only want 7 or so psi but I figure it’s better to go ahead and rebuild my motor with forged internals to be safe. My problem right now is the price of pistons is stupid high ($700-$900) does anyone know where I could get forged internals for less?

Which turbo & wastegate?

 

[Canadian_CD9A]

i'm probably just gonna do the head studs since ill be pulling the motor apart in the car so I can't do any machine work

Forged pistons call for a specific piston-to-wall clearance that requires (at the very least) a hone to achieve. You won’t be able to do this yourself. If you’re not willing to take it to a machine shop, just don’t do it. This engine won’t last long.

 

[DrewmHolland]

i've already honed my cylinders once, my block also has 220k miles on it so the pistons are gonna have a loose fit to them

 

[1990TSIAWDTALON]

If you are putting in pistons, they will have new rings and it will require the cylinders to be de-glazed with a hone in order for the rings to "seat" and seal. Just wanted to point that out.

 

[DrewmHolland]

I know that much, and I just honed them less than a thousand miles ago but ill do it again to be safe, as for the pistons, is their a feeler gauge set I should use to check clearances and a specfic measurement ill need for a small turbo build

 

[DrewmHolland]

Main studs aren't really necessary unless you're looking at north of 400hp... And that's probably a conservative number. I don't see the crankshaft leaving the block at any achievable power number for your turbo setup (the crankshaft itself is a concern when the hardware is). The bed plate bolts are technically reusable but always a good idea to measure the threads and make sure they aren't stretched.

I'm not advising you against using main studs, just saying it's far from necessary on a street build. I have never installed them on any version of my engine even when the budget was there.

If you've really got extra money to spend, I'd worry more about having a way to actually tune the car

thanks but engine management is kinda crazy expensive so ill just be using 93 octane and crank up fuel pressure with an fmu

 

[97egl]

I know that much, and I just honed them less than a thousand miles ago but ill do it again to be safe, as for the pistons, is their a feeler gauge set I should use to check clearances and a specfic measurement ill need for a small turbo build

You need to measure the pistons diameter and then your bore diameter. Then subtract the piston diameter from the bore diameter and devide that by 2. This will give you your piston to wall clearance.

You need to go off the specs from the piston manufacturer, not the Chrysler service manual specs. Forged pistons expand more than cast factory pistons.

i've already honed my cylinders once, my block also has 220k miles on it so the pistons are gonna have a loose fit to them

The pistons wear the cylinder into an egg/oval shape. There is a reason people spend money at machine shops.

 

[curt-s]

There better not be a thread later on saying "wtf DSMs suck, my engine blew" that follows this one.

 

[jesse12345]

If your building the engine trust me that 7 pounds of boost is going to turn into 20. The bug will get you I'd at least look into megasquirt, unless your willing to take that chance.