Hey im in the process of rebuilding a 420a for turbo. Obvisiouly i have a budget and can't spend to much. Im shooting for 230-250 horses. What all upgrades will i need to do to ensure its not going to blow.

 

completely replace all internals with ones that can take the power.

If u cant spend too much, its not gonna happen.

 

I know i need to replace the internals. I need to get my head redone? And what pistons and rods are good?

 

dont have a 420a. Cant help you any further than that

 

i'm no expert by any means, still well in the learning curve but this is what i've heard of - bore the block, forged pistons, rods, bearings, new crank won't hurt. i think the head can take up to about 8psi for a while but new cams, lifters, valve job should get you movin pretty quick. not to mention the turbo that you have to throw on there - please anybody correct me if i'm wrong or off track lol

 

Your close, The hahn stage two kit runs at 8 psi which is just shy of 200hp. For 250ish your going to need to run at about 14-16psi.

For the motor the bare minimum that you need to replace are the piston rings, pistons(J.E. 8:6:1 compression), rods(eagle forged rods) and the upper and lower bearings. The block may need to be bored but if your on a budget you can use a ball hone which will do an ok job. If your not a mechanic I would recomend that you get it asyembled by a shop, their are special tools needed to press the pistons into the block. The crank is fine, the 420a dosent need a new crank unless you storke it. The head is fine for any psi, I would recomend replacing the valve seals while you have to motor apart their not too expensive and help.

Thats all you need, but if you get the hahn stage 2 kit, a bov, and a mbc with that fuel system you can only bring her up to 15psi, after that at a minimum you need to get bigger injectors, a safc(or something similar) a ingtion box with a ignition retard.... then a dyno tune. But if you get some bolton's like remove the cayt of the already 3" exaust that you have, intake manifold, 60mm tb, crank pully, adj. cam gears and a port/polish on the head you can make 250hp under the 15psi mark.

Lastly the budget and 420a turbo dont go togather, for a good asyembly and internals your looking at least 2000 bucks, and a turbo kit is 3000 bucks so your already in the hole for 5000 where you could probally sell your car and with that cash plus the 5g you could get a gst... and with 1000 in mods it will be faster then the 420a turbo and more reliable.

 

Slow is the resident 420 expert lol... Listen to him and take at least some of his advice....

 

I've already put tons of money in my car and love the way she is. Im not trying to make it a speed demon, just want to make it have respectable horsepower. I'm not gonna do it cheaply, i obviously wanta do it right. I'd love to have 250 horses

 

In that case I would recomend a howellautomotive.com bottom end rebuild, a hahn stage two fmic kit, bov, walbro 225lph intank pump, wide band kit, the hahn portfuler kit, crane ingtion box, a mbc, and a new clutch... then you will be able to reach 250hp with out a problem.