Building the 420a

[Wherestheboost]

I currently have a 95 ESI, of course with the 420a motor. It has around 175k miles on it. Not too worried about power right now, just trying to keep it alive. I DO however in the near future build a turbo kit for it. In the mean time, would building the whole long block be in my best interest, or is the bottom end strong enough at this currently mileage to handle boost in the near future if i decide at the moment i just wish to work on fuel management and the head? I want to build on a spare head at the present moment regardless, but should also build the bottom end too?

 

[JayRolla]

I would not boost that motor with that high mileage. Im not saying it cant handle low boost application but it sounds risky to me. If I where you I would rebuild the bottom end and through in some turbo safe pistons(lower comp).

 

[DSMcrazy3]

Do a compression test. That will help let you know if you're safe to turbo or need to rebuild.

 

[Strife]

I agree with DSMcray3, check your compression first. But if you are going to boost I would still rebuild with forged internals with lower compression pistons because it's easy to keep turning up the boost.

 

[dr1665]

I'd pick up a used block and build that while you drive the car. Then swap it in before you blow the old one (emergency back up motor at this point), and buy the turbo kit. By the time the kit shows up, your motor will be good and broken in. Ready to rock and roll imo.

 

[Wherestheboost]

I'd pick up a used block and build that while you drive the car. Then swap it in before you blow the old one (emergency back up motor at this point), and buy the turbo kit. By the time the kit shows up, your motor will be good and broken in. Ready to rock and roll imo.

Thats why i was asking earlier if it was possbile to just build the head. I figured I could pick up a spare head and build on that. I read a previous thread, not sure at tthe moment, about rebuilding a motor prior to turboing the 420a. It stated honning, piston rings, bearings and let the bottom end be.

I see and understand your idea about another longblock and building on that. The only problem with that is I'm having a hard time finding a decent website that sells spare long blocks and junkyards around here are asking 2,000 for one. I check the classifieds and ebay daily, and although i see good deal, at the present time im just not finicially ready to pruchase one. I just look around to see my ideal monotary goal.

 

[DSMcrazy3]

PM Paul(Velocita paolaorhoweveryouspellit) he might be able to help you out finding a spare block to build.

 

[dr1665]

You should leave the head alone. The turbo will do the most damage to your bottom end. You will need more than a hone and rings to handle anything more than 7psi reliably. 7psi is nice for a while, but you're going to want more. Ask any turbo guy if he would like more boost and he'll tell you, "Hell yeah, man."

Forged pistons and rods are a must. You should expect to spend about a grand between them. Budget for machine work - +0.020" over to be sure the cylinders are true, a hone so the rings bite in for a tight seal, hot tank and decking for the head gasket. You might even feel saucy and decide to pop for some balancing. Replace the bearings, the oil and water pumps, and you should be good to go.

Leave that head alone until you're going all out.

 

[VelocitàPaola]

I have a spare block laying around... it has a screwed up crank snout, but you can either replace it, or possibly get a machinist to fix it. Like Josh said... PM me.

 

[htaracing]

Forged pistons and rods are a must. You should expect to spend about a grand between them. Budget for machine work - +0.020" over to be sure the cylinders are true, a hone so the rings bite in for a tight seal, hot tank and decking for the head gasket. You might even feel saucy and decide to pop for some balancing. Replace the bearings, the oil and water pumps, and you should be good to go.

I agree. The bottom end is where my turbo did the damage on my stock internals. Build it and do it right the first time . Besides 7 or 8 psi wont be enough after a while, you'll want more and more.

 

[Wherestheboost]

So even just replacing the valve train with OE parts, i shouldnt worry about?

Not really experienced with anything inside of a longblock, but i don't plan to stage the head or anything just perhaps attempt to replace at least valve seals and clean up the head a little.

 

[VelocitàPaola]

Nah, the head is the least of your worries... I mean, most people will agree that "most power is made in head upgrades," and they're right (more so if you're staying N/A), but the stock components are pretty strong as long as you don't significantly raise the redline or anything. Flow is pretty good in comparison to other engines too.