Starting rebuild after spun bearing

[dcskater180]

My car has spent the spring in my garage with me waiting to see the damage. Upon first inspection seemed not bad spun one bearing and walls didnt seem too bad to me (untrained eye). Took the trip to a machine shop they told me my pistons were shot my block needed a bore and my crank was pretty bad but could be fixed so that was a disappointment . I originally planned to do rods use old pistons and put good bearing and rings call it a day and re build it but now i need new plans. What im thinking is Wiseco 8.3:1 with Scat H beam .020 over from what he said ACL Race rod and main .010 oversize from what i read this seems to beas a cheap and easy setup to make a pretty strong bottom end. Im only at maybe 250hp all i have is 14b intake 3" turbo back and FMIC so it should last a while i hope. Is there any advice or tips from people that know this motor better than I do. Its a 94 block with 2g head. Head is also getting full rework hot tank valve job and pressure test. Any help is appreiciated sorry if this is a common thread.

 

[BogusSVO]

For 250 hp goal??? Thats a bit over kill for the build.

 

[Twinturbo120]

Just do a stock rebuild with npr pistons and your h beam of choice. Sounds to me like you'll be fine with that.

 

[dcskater180]

250 isnt my goal its just my current level estimated I just want to have room to build on and not a have to go back into the internals any time soon sine im already here plus stock isnt much cheaper than forged.

I don't see the point in putting stock and then having to go back and pull the engine again when I want more power I want the peace of mind that its strong enough for whatever i throw at it up to 500-600

 

[staztrx250]

If you have the money to do right, then do it right the first time. You are most likely going to get a bigger turbo at some point, you'll push harder etc. A stock block will meet your needs, yes if you are going to pay for the machine work you might as well build it up.

 

[bigbird94]

Looks like a good plan but I would change a few things.

Try to find an uncut oem crank and run standard size bearings. This will probably be close to the same price as getting yours turned.

Oem bearings

Higher compression pistions, 8.5 or even 9:1

 

[dcskater180]

too late on the crank they got started right away. I'm not definite on the pistons i might get different CR. why the OEM bearings though seems i've always read that ACL tri metal are the best.

I see the recond kit form dsm graveyard now for 290 but i got it turned for 200 so i guess it will be a learning experience but im sure it will be just fine for now i'm a student in college so i doubt it will see much power anytime soon.

 

[bigbird94]

Honestly, I have no numbers or info to back this up, though I have never heard of people blaming oem bearings for an engine failure. Maybe I'm just a purist but I can't imagine an aftermarket company can produce a precision part like an engine bearing as accurately or consistently as the original manufacturer.


Edit***

I'd even still try to find an oem crank. You could sell the one you are getting redone, being that it's new and you will have a receipt for the work done you should get most of your money back.

 

[dcskater180]

Do you know where a good place to look for an OEM uncut crank will be?

 

[bigbird94]

The classifieds on this site, craigslist, or even the junkyard. You can use the NT 4g63 cranks too.

Id look for a complete NT engine, you can find them cheap and could use the crank, rods, and have a spare head.

 

[BogusSVO]

Do not worry about the .010/.010 (.25mm/.25mm) crank you have, it will be fine.

Make sure the shop removes the oil galley balls in the rod throws of the crank so the crud cnan ge removed, then have the holes tapped and plugged.

 

[bigbird94]

I hate to disagree with you bogus, but I'd never run a cut crank. Maybe the poor machine shop work I have dealt with locally over the years has deteriorated my trust in such cranks?

 

[dcskater180]

I've decided to use the recond crank I have and just do NPR pistons and 7 bolt rods save the money. I probably wont put too much power on this car I'll get a 6bolt AWD later when im out of college tobuild for power.

 

[mchustle]

I would honestly still get some h beam rods for piece of mind the 7 bolt rods are crap. At the least you could go 6bolt rods on 7bolt pistons for a cheaper and beefier option. You can easily get a set of 6bolt rods in the classifieds for $50.

 

[donniekak]

I would honestly still get some h beam rods for piece of mind the 7 bolt rods are crap. At the least you could go 6bolt rods on 7bolt pistons for a cheaper and beefier option. You can easily get a set of 6bolt rods in the classifieds for $50.

You can't run stock pistons on aftermarket rods. They have no grooves for wire locks, or spiral locks to retain the piston pin. Stock rods have the piston pin pressed into them so they aren't needed.

 

[BogusSVO]

I hate to disagree with you bogus, but I'd never run a cut crank. Maybe the poor machine shop work I have dealt with locally over the years has deteriorated my trust in such cranks?

I can understand what you are saying. I have built engines with ground cranks with out issue.

My thought is on most import style cranks have a cross drilled main and rod with an intersecting oil galley to flow oil from the main to the rod. Now with the cross drill passage in the rod throw, there is a "dead" passage between the cross drill in the rod and the end of the rod throw.

This dead passage will gather crud and turn to a "plug" of sorts.

During the crank grinding process, a coolant is flowed over the grinding stone and the bearing surface being ground.

In this dead oil passage bits of stone and metal flake can and will become part of the crud packed in there.

Then the fresh oil from priming/start up gets picked up and shot into the rod bearings, causing the crank to fail.

I personally think that is what caused the "Polish std crank only" in the engine builds.

Polished or ground, really doesn't matter, the key point in ant build will be getting the oil galley balls out and cleaning the crank properly.

 

[little-razcal]

I totally agree with BogusSVO.

IMO..There is nothing wrong with cutting a crank .010. There are a lot of people that will tell you otherwise, because of what they have READ, but 90% of them havent even had experience with this.

I run a cut crank, my buddies all run cut cranks, and I know plenty of high hp people running cut cranks. Im about 600-650whp I'd imagine at this point. As long as the crank is cut correct and cleaned right as Bogus stated, you will be fine.

DO NOT FORGET TO HAVE IT BALANCED AFTER CUTTING.....