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Old 05-01-2006, 07:15 PM   #1
2phless
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Default USDM 2.5 STi connecting rod length / and mahles...

So I'm desperately trying not to buy the wrong part, with a sprinkle of trying not to spend too much money. I have perfectly good forged Mahles in a good block that had the #4 rod bearing get a little wiggly on me.

I have a new OEM STi crank already on the way.

I was about to order some Eagle rods when I was told they are too short. Ok. I've been measuring and digging through everything google has on connecting rods and I have found this:

My stock #3 rod is about 5.142" c to c. That's 3.613" opening to opening w/o bearings. (The 3.613 measurement is more accurate with my mic. )

Currently, with the Mahles in, stock rods, stock crank, I can see (example used is viewing #1 at BDC) the bottom and corrugated oil rings through the wrist pin access hole in the block but not quite the top oil ring. So I don't think I have much play left.

Researched lengths:

Eagle c to c = 5.137" (which as fasr as I can tell is 2.0 sized) That price was sooo sweet too

Crower c to c = 5.185" which is either stock or a smidge longer, which according to Cobb's website, is the direction to go, but they ain't talkin' .

Oliver's STi rod = 5.180" which is par I guess, along with some others.

And Carrillo which seems to make 1 rod for both 2.0 and 2.5 at a middle ground of 5.1563" (so I hope that .0003 is really there )

I like the idea of Crowers at this point. But I'm tired and cranky. Anyone have any input as to what will and won't work?

Here's a picture of Godspeed's measurement of a Crower... afaik. Which shows that I might have some of my math off a bit... but I don't care anymore.

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Old 05-01-2006, 07:33 PM   #2
2phless
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Worst part about it is, of course, that I'll be stuck with 4 rods that can't be used as coozies.




And that's just wrong since this car has most definitely driven me to drink.

At least I'm not researching chevy 350 rods, where the information would be overwhelming AND accurate. We are so lucky that only 4 or 5 companies make (or rebadge) our parts, and we can cut right through the crap and figure out pretty quickly how and where we'll get screwed.

And who can tell me if the stock rod pictured above is forged or not . I think the bottle is at least. But was that bottle forged from the factory? Yuejinglebellings says yes... but I say nay nay.
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Old 05-09-2006, 02:46 PM   #3
2phless
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Latest info shows the Eagle Rods are only .001" shorter than the 2.5 STi stockers. Which I guess means it's time to buy some better calipers.
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Old 05-09-2006, 11:34 PM   #4
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The Eagle rods are fine for the STI, but n2xlr8n is the only person I know that's used them. I called Eagle and even they could tell me they fit into an STI, even though they should since the rod length on the EJ20 is exactly the same as the STi rods. The main issue I had was the "cap" on the big end and whether it would clear the crank. I wrote to some guy in Greece and he sent me a picture and some measurements. In the end I bought Oliver rods for another reason and never looked back.

Then some other guy was using the Eagle rods and Steve said he had used them too.
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Old 05-10-2006, 12:27 AM   #5
mick_the_ginge
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I'm running Oliver as well... No issues to date but I have no idea how they match up to stock.
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Old 05-10-2006, 07:30 AM   #6
Wagun
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The photo of godspeed's measuring method is flawed. Rod length specs are center to center, that photo shows a measurement from little end inner ID to big end inner ID, so it's useless.
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Old 05-14-2006, 01:56 PM   #7
Marnix
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True.

All the 2.0L rods and the 2.5L STI rods are equal in length (130.5 mm) big end center to small end center. All the 2.5L non-turbo rods are a smidgen longer at 131.6 mm big end to small end. Mind, the Phase I EJ25 rods (DOHC) have the small big end bearings, the later Phase II EJ25 (SOHC) rods have the same big end size as all the 2.0L and 2.5L STI rods.

So far I have been using Carrillo rods only for really stressed engines, but a friend also uses Eagle without problems.
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Old 05-15-2006, 02:08 AM   #8
2phless
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Quote:
Originally Posted by Wagun
The photo of godspeed's measuring method is flawed. Rod length specs are center to center, that photo shows a measurement from little end inner ID to big end inner ID, so it's useless.
"Useless" is posting something as stupid and obvious at that.

I don't know why I'm even bothering to elaborate, but his mic shows 3.6115" and my inside to inside measurement is 3.613" and to interpolate and compare all those C to C measurements that are over 5" I could take the ID of both the big end and the... oh fck it

order this book and don't post anything you learn from it.

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Old 05-15-2006, 12:47 PM   #9
bboy
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With the EJ257 block you want 5.135 inch rods and Mahle pistons. You can't use the longer rods unless you build the pistons to work with them.

You are mixing several rods here. Phase 1 2.5L engine rods (read NA 2.5L engine) and some company's "long" rods that they have made custom pistons for.

You've got the Mahle pistons, now you need either the stock STI rods or their equivalent.
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Old 05-15-2006, 11:52 PM   #10
2phless
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Stocks went in with clevite bearings. Drove it out of the garage this evening. It all runs fine but I have no faith in these silly little motors anymore. Turning the Deadbeat Kong II down to 14.7 and removing my delusions. "Import performance?" HA! I'd have to move to another country and buy an american car to make that moniker plausible.
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