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Kyle_Privette

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Discussion starter · #1 ·
Ok, so here is whats up. I spun a rod bearing, number 1 (which seems odd from all of the research ive done). Well damage to the crank wasnt too bad, its at a machine shop right now, they are grinding it .010 under on all rod journals, and ill be running appropriately sized bearings for the machine work. So obviously ill be getting new pistons, and while im at it, im going to get some new rods (might as well, one is damaged and why not have some security with my rebuild). I am leaning towards manley turbo tuff rods, and maybe the turbo tuff pistons or a set of mahle pistons. I will probably get a slight over bore (.25-.5 mm, so 99.75-100 mm) to get some fine scratches out and to make sure the bore is round. (64xxx on stock block, bought it used with 63xxx). With my build i am looking to make 400 awhp on 91 (Flame on!). I dont have access to 93 or E85, so ill be looking into water/meth manly for det reasons. So, lets hear your thoughts on my rod/piston combo, also if you have different suggestions, lets hear them and the reasons why. I searched and found a few threads, but they either got hijacked or there was no real reason why someone chose what they did, other than so-and-so has had good luck with it.
Also, my turbo is pretty well toast, so lets here some suggestions on those, i would like to go rotated but i also know there are some good stock location turbo options.
There is currently a turboxs fmic, catless up pipe, hks hi-power tbe, cobb sf intake and cobb ap.
So lets here it people. Thanks.

Also, admins, i think this is in the right area, if not, sorry, move as needed.
 
#2 ·
I went with the .25mm over pistons, no real benefit to go to straight 100mm bore. in case you do have something happen again you can bore to .5mm, after .5 youll have to add sleeving. i went with 99.75 JE pistons and Manley rods
 
#3 ·
Has the shop inspected the block yet? I recommend they do so before blindly picking a piston size. For starters, PTW clearance on the stock pistons can be very tight, much too tight for stock bore forged pistons. It is very possible you could freshen up the hone and use stock bore pistons with the correct PTW clearances depending on the current condition and how much work is needed for them to have a nice cross hatch and be in spec. Also, coatings can influence this greatly. Worst case you should only be using 99.75, there is no reason to thin up the cylinder walls any more than necessary especially when you are still looking to make some good power.
 
Discussion starter · #5 ·
I still have the block halves in my garage, I am waiting to see how the crank turns out before i take my block halves to them. The scratches arent too bad, but they are there. Like i said in my first post, id like to go no more than .25-.5 mm over stock, .5 being the worst case senario before new case halves or sleeves. But i know the final cylinder machine work will depend on my piston choice as far as ptw clearance goes, and it depends on the alloy used in the pistons to determine how much expansion, hence one of the reasons why i like mahle pistons, since they have two different alloys for their pistons, one low expansion and one with a little more expansion, both are forged however, and for my slightly modest goals, their low expansion alloy should work fine. I would like to measure the block myself, but all of the precision measuring tools i would need are at my work, which is 125 miles away, and they probably wouldnt appreciate it if i borrowed them.
 
#6 ·
Kyle_Privette said:
I still have the block halves in my garage, I am waiting to see how the crank turns out before i take my block halves to them. The scratches arent too bad, but they are there. Like i said in my first post, id like to go no more than .25-.5 mm over stock, .5 being the worst case senario before new case halves or sleeves. But i know the final cylinder machine work will depend on my piston choice as far as ptw clearance goes, and it depends on the alloy used in the pistons to determine how much expansion, hence one of the reasons why i like mahle pistons, since they have two different alloys for their pistons, one low expansion and one with a little more expansion, both are forged however, and for my slightly modest goals, their low expansion alloy should work fine. I would like to measure the block myself, but all of the precision measuring tools i would need are at my work, which is 125 miles away, and they probably wouldnt appreciate it if i borrowed them.
Click to expand...
No one needs to know your borrowed them :lol:

My recommendation is obvious, I will say, please disregard comments saying Manley pistons are significantly heavier than any others. Outfront Motorsports disproved that bullshit in a thread on NASIOC. The rods on the other hand are a bit heavy but you will pay a good chunk more for ones that aren't yet are still rated the same so there is a trade off and it depends on your budget. Both are proven products, you wont go wrong choosing them.

As for size, you got it, I would be very surprised if you needed 100mm pistons after a spun bearing but no ringland/piston damage. Keep coatings in mind when sizing as well, real coatings not break in coatings that actually influence PTW clearance. I would consider if you are close to being able to use stock bore pistons to add a coating and make it work rather than over boring, just my two cents on that subject. Anything else feel free to ask.
 
Discussion starter · #7 ·
The main reason for the overbore would be to insure I have a true round cylinder with no taper. I will definately remember the coatings when I'm looking at PTW clearance, that is good advice. Now I know mahle and possibly even Manley pistons come with skirt coatings, but with it coming from a manufacturer, will they have already factored that in when they size the piston? And any additional coatings if have done would be to the piston top.
 
#8 ·
That is why I am saying to measure them as is or have the shop do so before any machining is done on them. See if they are in fact out of round or tapered, with a TQ plate on and the case halves together using the proper fasteners.

Once you have them measured and know where you stand you can make a decision on what size piston to use and you can order the pistons then measure those to determine the final dimensions on the cylinder. Make sure a TQ plate us used even during measurement.

You do not need to worry about coating thickness on a Manley piston. I was referring to a case where you would have a place like swain tech do an aftermarket coating. I wouldn't even bother ceramic coating the tops, it doesn't last half the time but that's up to you.

You can always take the easy route and order 99.75 off the bat and just bore it out, lots of people do it but IMO there is no reason to overbore if it isn't truly needed and its worth the time to just measure before hand.
 
Discussion starter · #9 ·
Good points, I do want to see the quality of this shop with my crank before I give them any more work. It's not that I don't trust them, but I live in Casper Wyoming, and we don't have any import specialty shops anywhere close by, in fact after I get everything back together I'll have to load up and head 4-6 hours away just to get a tune in colorado (either the boost creep or Mac auto sports). Heck, I'm not even sure if this shop would have a torque plate for an ej25. If I go with them I might have to buy one for them to use. And I will have it measured before I buy new pistons, but my gut is telling me it will have to have a small overbore. But I should probably go ahead and get my new block bolts and bolt the case back together before measuring, as well as some head studs. Now would you recommend half torque since its not final assembly, or risk stud/bolt stretch with full torque.
 
Discussion starter · #11 ·
That is true and have looked at that option, but I would prefer to do it myself. I have built other engines before, but of the heavy diesel type. Older d series cat engines, 3400 and 3500 series cat engines. But I'm new to these odd little boxer engines, so I want to do it myself, you know the old mantra, built not bought, it's a pride thing
 
#13 ·
Kyle_Privette said:
That is true and have looked at that option, but I would prefer to do it myself. I have built other engines before, but of the heavy diesel type. Older d series cat engines, 3400 and 3500 series cat engines. But I'm new to these odd little boxer engines, so I want to do it myself, you know the old mantra, built not bought, it's a pride thing
Click to expand...
Finally someone who gets it! :tup:
 
#14 ·
As far as the shop, we dont have many import focused machine shops here either. Biggest thing I have seen is the following:

-TQ plate is a must, this will mean you will probably need to buy one, TeamScream on NASIOC is your guy for that.

- Surface finish on the deck needs to be perfect, most "V8" shops here dont know what perfect means, that needs to be stressed to them.

- The actual bore/hone process should be straight forward to them other than the the TQ plate

- Make sure measurements are done with the halves bolted together and a TQ plate on when measuring roundness and taper.

There is more but that will get you started, I would not shy away from at least finding a machine shop that is familiar with this engine even if you want to do the final assembly yourself.
 
Discussion starter · #15 ·
RecceRS there are few of us out there, I hope others realize I'm not bashing others by saying that.

I know I'll have to find a torque plate, not that big of a deal and I can probably get away with taking it off on my taxes as a tool, yay for being a mechanic. And as much as I wish I could do everything on my own, I am not a machinist nor do I have the pricey tools to do it with. But final assembly will be handled by myself. I will have to ask the machine shop if they can/are able to get a good surface finish on the block.
 
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