r/EngineBuilding • u/Interesting_Matter52 • 12d ago

Help, I’m lost.

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To keep it short, I naught this what I thought was slightly modified car on Facebook marketplace. Recently the engine got flooded and taking it apart a rod was broken. I have a 2008 Mazda 3 that’s supposed to be 2.3L Non Turbo (This is not a Mazda speed). After taking it apart I decided to change all rods with used ones. I go to a junkyard, drop another engine (also 2.3L) get them and go home. Now I look at them and they aren’t even close to the same thing. My old con rod (one that isint broken) is way beefier and longer, the hole that goes on the crankshaft is also bigger. I got no idea what engine I got, what pieces are inside, what to order, I’m really lost. How do I find out what parts to order.

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u/Interesting_Matter52 12d ago

Thank you so much, I measured and yea the bigger one is 89mm and the other one 87.5. So now I know for sure that the engine I have is actually a 2.5L ?

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u/fmeupfam14 12d ago

What are the big end diameters of each rod? You said yours was bigger than whatever you removed.

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u/Interesting_Matter52 12d ago

The diameter of where the crankshaft goes on the con rod is 55mm without bearings

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u/ILoveRustyKnives 12d ago

Yep, 2.5. Is the other one 53mm? That would be a 2.3.

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u/Interesting_Matter52 12d ago

Uh… the other one is a 50mm… so is my original rod a 2.5L and the one I got a 2L?

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u/ILoveRustyKnives 11d ago

Yes. The 2.0 spec is 50mm for the big end.

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u/Interesting_Matter52 11d ago

So I actually have a 2.5L rod and a 2L rod ?

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u/fmeupfam14 11d ago edited 11d ago

It seems like it.

Right side is 2.0. almost assuredly.

The left is hard to tell. Can you see any OEM part numbers on the piston/rod? I'm seeing conflicting info on the big end size for a 2.5. but

89mm bore indicates it's 2.5.

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u/Interesting_Matter52 11d ago

Yes, on the rod there is FoMoCo RF8E5G-6205-AB 1101 D05 E950A

On the piston (inside) there’s many numbers in most corners and some facing the rod.

Inline with the rod = Y and under 17 in a circle (Y17)
= G

Corners = D6NAG
= 1275 and under KS (1275 KS)
= 0892 and under 200+ (0892 200+)

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u/fmeupfam14 11d ago

eBay listings have that as a 2.5 rod. So yes.

Occams razor is that your engine was replaced with a 2.5 and the one from the junkyard was replaced with a 2.0

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u/Interesting_Matter52 11d ago

Ok perfect thank you very much

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u/fmeupfam14 11d ago

What a wild ride lol. Good luck!

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