My blow thru build

[WarWagon]

That's cool, I like that you built this setup and yours is only the third one in existence I know of and smart with the 4.1L I like the big bore. I really like the Mallory 685 ignition, it's been reliable and has great useable features for the price but I think they quit selling them.. or at least it's super hard to find. J&S Safeguard Is a few hundred more but probably the best, always the old MSD btm too but It's not nearly as fine tunable as the Mallory and has no knock retard capability like the J&S.

 

[walkmang]

Got a new exhaust installed today and the engine really breathes good now, turbo spools really nice and builds boost amazingly, unfortunately now there is more pressure in the cylinders and blow-by has increased like crazy. Looks like I'm going to have to start a rebuild before I do some real damage to the block. One thing is true...you start doing upgrades you will quickly find the weak link.

 

[supstanman]

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[eastwoodad]

Looks great, this is kind of where I think I am headed with my build at some point. I bit the bullet and built the block the best I could afford at the time, and am glad I did. Keep us in the loop on the build progress. Would love to hear some 1/4 mile times too!

 

[walkmang]

Pulled motor and trans, taking the block to the local machine shop to get checked out to see what damage I caused. If all is good then we can start talking bore and piston sizes.

 

[walkmang]

I'm guessing this is the ring material in the bottom of the oil pan

 

[walkmang]

..

 

[walkmang]

#6 piston, 1, 2, and 5 all have cracks near the rings

 

[bison]

Those are NA pistons.


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[84beastregal]

Bison yea n/a Pistons


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[WarWagon]

Conditions of those stock NA 4.1 pistons looks typical with knocking detonation. Do you know the casting number on your 4.1 block Stan? How many miles on this engine?
She will be much better soon and tolerable of boost when you rebuild this engine. Full throttle among others have a nice rotating assembly for the 4.1 with forged crank and pistons.

 

[walkmang]

Yeah #1 #2 & #5 all had cracks but not as bad as #6. 15lbs of boost and some detonation. I really stretched the limitations of the block.

 

[walkmang]

Had about 150k when it happened Adam.

 

[walkmang]

These were all the numbers I could see, could there be more on the block

 

[walkmang]

#1 #2 & #5

 

[WarWagon]

You have a 291 casting block Stan and don't look to awful bad for 150K mi.
I have this same 4.1L engine (291 casting) that came from a '84 LeSabre. I only used it in a factory draw through turbo setup and I bet the pistons in mine look as bad or worse, I have never had the bottom end out of it yet to see.
I like the progress and direction this is headed. Keep it up!

 

[WarWagon]

Seems the majority or 4.1L builds go to a 4" bore if the block is good enough for it. Makes piston ring selection a lot more numerous, of course once you get the word from your machine shop that it's current bore is OK or needs bored out.
You do have the good 2 dot rods already and a rolled fillet crankshaft from factory like all 4.1L

 

[walkmang]

Thanks i will keep you updated