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420A Max boost on 420a with forged pistons and rods

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jakelandry

jakelandry

10+ Year Contributor
976
157
Oct 13, 2009
Minden, Louisiana
Ok ive been saving all summer and was considering stroking my motor, but have decided to just keep the stock crank and upgrade my rods and pistons.

I have 2 questions here really.
1 is are wisecos reliable in your opinion? ive done searching and ive heard that wisecos are the cheapest forged pistons you can get, but ive also noticed the people having problems are the ones who dont have propor machine work done or are running too much boost. I really want je's but i am indeed on a budget and found wisecos for cheap.
2 is just how much abuse, boost wise, can a 420a take with just a basic forged bottom end build ( pistons, rods, bearings, gaskets, bearings, and possibly oil pump)? I want to make between 225 and 250 hp safe if possible, not trying to get insane just want a more fun driving experience out of my dd.

I also want to say thanks to everyone that has answered on any of my threads previously, ive nearly had my dsm for a year now and thanks to this site ive learned so much.
 
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my friends running weiscos in his build, he hasnt had a problem, nor has he stripped down his block to see their condition. I am running evo 9 pistons and they are forged.

You probably find more info here
420a-turbo-conversion


Also I heard that 420 are prone to head gasket oil leaks, so I wouldn't running too much psi. 10 at most maybe
 
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10 at the most is on a stock bottom end, and with that you will be making around the 200whp mark. With pistons and rods 250 should be an easily obtainable number.
 
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Ok well as of now my plan is build the bottom end then turbo so i should be able to reach my hp goal without worrying about reliability issues? Also does anyone have an actual number on psi limit w/ a bottom end build?
 
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wow i didnt know that... so i dont understand why they would sell them for soo much to have them machined... HMMMM something to think about.. i thought i would have been direct replacement...

thanks for the info guys.. DSM
 
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Run weisco pistons they run a. Bit cooler since the skirt is coated I've never had issues 28 pounds of boost no problem at all now 420as are well know for shooting rods I ended up going aluminum custom grp rods No more eagles for me there bound to break at high hp. I'm not sayin they won't work but for ## app 200-400 hp is good I'm sure and eagles will work for now dsm zero is at 600 hp with eagles they ruined a kelleys stroker crank 900 dlls down the drain I shot a rod. Stick to wiesco as je takes for ever to help u out if something goes wrong weisco backs there piston up
 
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Rst303 said:
Run weisco pistons they run a. Bit cooler since the skirt is coated I've never had issues 28 pounds of boost no problem at all now 420as are well know for shooting rods I ended up going aluminum custom grp rods No more eagles for me there bound to break at high hp. I'm not sayin they won't work but for ## app 200-400 hp is good I'm sure and eagles will work for now dsm zero is at 600 hp with eagles they ruined a kelleys stroker crank 900 dlls down the drain I shot a rod. Stick to wiesco as je takes for ever to help u out if something goes wrong weisco backs there piston up
Click to expand...

If im not mistaken Eagle claims theyre good for 800 hp..
 
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Yeah 800 hp but only for a while until they go snap But ## only looking for 2-250 whics ain't much ull be good but dint let others tell u things won't work when they will Im even using oversized valves and nothing touches the pistons
 
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A stock 420a is roughly 150hp . the 4g63 stock with stock boost puts out about 215hp. now u take a stock 420a and put the same boost that comes stock to a 4g63 .it puts out around 286hp my 420a has eagle hbeam rods and je pistons and I run 35lbs of boost just fine .on a oringed block and copper head gasket I would say the eagle rods r fine and wesco pistons should definetly work fine for 300+ HP
 
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sick95talon said:
A stock 420a is roughly 150hp . the 4g63 stock with stock boost puts out about 215hp. now u take a stock 420a and put the same boost that comes stock to a 4g63 .it puts out around 286hp my 420a has eagle hbeam rods and je pistons and I run 35lbs of boost just fine .on a oringed block and copper head gasket I would say the eagle rods r fine and wesco pistons should definetly work fine for 300+ HP
Click to expand...

your numbers are to the crank (and brand new).The Average stock 420a now adays puts between 100-120hp to the wheels. A stock 420a with a turbocharger does not get you 280hp, and PSI does not equal hp.
Lastly this thread is from 2010...
 
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sicktalon: ## running 35lbs? jesus fn christ. i have to disagree with the last post, tho it may not mean guaranteed hp numbers, 35lbs means you are def making a TON of power. youd have to be atleast 375whp or better. all depends on tune and flow beyond that.
yes, i believe my old 98 gs was making about 130whp stock. it was in excellent mechanical condition too. and yes, psi for psi the nt engine will make more because it has a higher compression ratio to start with. but 280 crank at 10psi is way high. i would think more like 225, just a guess
 
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35lbs makes a lot of hp, if its still utilizing the turbocharger properly, you can actually make more hp with less boost than more depending on the turbocharger. Or maybe if I say it this way, each turbocharger has an optimum boost level, if you go over that you actually begin to lose hp. Therefore, boost does not equal HP. As for guessing HP, come one now, we should know better than that. Only way to half ass guess hp numbers is by looking at numbers of proven engines with similar mods and even that isn't that accurate.
 
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i dont understand why people are so hung up on psi like that actually means anything by itself.

"dude im running 40 psi!!!"
* on a turbo flowing 30 lbs a min and way outside it's optimal range...

"yeah i'm at 20 psi."
*on a huge 68 lbs a min turbo


which do you think is better? 40 or 20?
in this case 20 all day long.
 
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Why do I have the urge to call BS on the poster claiming they are running 35psi boost on their 420A?

You are saying you are running 35psi on a 20G? That is way off the map.

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What fuel? How much air are you moving? Dyno #s? 60-80 time?

Or are you just throwing numbers out there?

And what necrotopsy said.. 20psi on a 42R =/= 20psi on a T25

Not only that but running 30psi on a 42R with 21* timing and 12.0:1AFR is a completely different animal than 30psi 8* timing and 10.3:1AFR
 
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Fotowntalon said:
your numbers are to the crank (and brand new).The Average stock 420a now adays puts between 100-120hp to the wheels. A stock 420a with a turbocharger does not get you 280hp, and PSI does not equal hp.
Lastly this thread is from 2010...
Click to expand...
Boost doesn't equal hp but the engine wouldn't run... it wouldn't have enough energy unless it had major upgrades to fuel around it as well...so in order to run 35lbs of boost on a 420a you must certainly have much more horsepower or it would be impossible. Engine would drown under 10:1 afr maybe even with a bit more air and it would suffocate at anything above 15 and bog out(ask me how i know). In order to have 35 lbs of boost you would need atleast 70psi fuel and injectors that can handle that and probably an ecu and lots more. Otherwise it would just defy physics. 35lbs of air+80 pounds of fuel exploding in a 2 liter space = high hp.
 
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LandSpeed-DSM said:
Why do I have the urge to call BS on the poster claiming they are running 35psi boost on their 420A?

You are saying you are running 35psi on a 20G? That is way off the map.

You must be logged in to view this image or video.


What fuel? How much air are you moving? Dyno #s? 60-80 time?

Or are you just throwing numbers out there?

And what necrotopsy said.. 20psi on a 42R =/= 20psi on a T25

Not only that but running 30psi on a 42R with 21* timing and 12.0:1AFR is a completely different animal than 30psi 8* timing and 10.3:1AFR
Click to expand...
Max on a 20g is 22-23psi on a 420a. I don't think it is a 20g.
 
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calebjying said:
Boost doesn't equal hp but the engine wouldn't run... it wouldn't have enough energy unless it had major upgrades to fuel around it as well...so in order to run 35lbs of boost on a 420a you must certainly have much more horsepower or it would be impossible. Engine would drown under 10:1 afr maybe even with a bit more air and it would suffocate at anything above 15 and bog out(ask me how i know). In order to have 35 lbs of boost you would need atleast 70psi fuel and injectors that can handle that and probably an ecu and lots more. Otherwise it would just defy physics. 35lbs of air+80 pounds of fuel exploding in a 2 liter space = high hp.
Click to expand...
🤨
 
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