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Old 05-05-2001, 07:52 PM   #1
Scoobie Steve
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1998 11.87@112mph
Subaru L Ver 6 STi Type R

Unhappy Rod knock in 1999 2.5l

I bought a 1999 2.5l engine from a junkyard to put in my dune buggy. It came out of an Outback that was hit hard in a front end crash/rollover. The engine seemed fine and it only had 7000 miles on it. I swapped the Dohc heads for a set of P&P 2.2l heads. I also converted to a distributor ign. I cut the top off of the intake and mounted a Carter 500cfm carb on it. After countless hours of tuning i finally got it to run good. Then it happened, after a long wide open throttle run i started to hear a knock. By the time i got it home it was horrible. I had good oil pressure up to the point it started to knock. The only two reasons i can come up with is 1. The compression was too high with the 2.2l heads and it was detonating and i couldn't hear it because of the loud exhaust or 2. there was some unseen damage caused by the wreck. Any other Ideas?
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Old 05-05-2001, 08:03 PM   #2
dandbest
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Well, I don't know if this helps any, but right after I bought my 01 RS at about 500 miles I started to hear a loud knock, just like a bad connecting rod bearing, so I brought it to the dealer, where it turned out to be a bad timing belt tensioner. Ever since they replaced it, I've had no problem.
I guess give that a try and see what happens.

Sorry I couldn't help you more.
Danny
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Old 05-06-2001, 01:27 PM   #3
bobjr94
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2.5 do have worse lower ends than 2.2..Next time try to use a 2.2 block..Sure its not a bad pistion, 2.5 do have pistion problems.. ..how bad did the motor get hit, could it have dammaged the oil pump, maybe slightly bent the nose of the crank

but with 2.2 heads, your compression must be like 11 or 11.5...But with 2.2 heads your loosing most the power your gaining from a 2.5 vs a 2.2..The 2.5 valves are bigger, and the head ports are much bigger..With nothing else changed, a 2.2 vs 2.5 is under 8hp, and 12 ft lbs....or want to have fun, buy a import turbo motor and trans, there around 1200-2200$ for 220-260hp..
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Old 05-06-2001, 01:54 PM   #4
Peaty
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Mine sounded like a rod knock to me too but it ended up being the cam tensioner too.

Check out this for some soundbites and info:
http://www.i-club.com/ubb-files/Forum1/HTML/019512.html
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Old 05-06-2001, 06:18 PM   #5
Scoobie Steve
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Update:
I split the block today. The #2 rod bearing was hammered to nothing. the other 3 rod bearings were spun. the mains are ok but worn more then they should be with only 7k on them. i think it was lack of oil. Does anyone know where to get oversized bearings? Subaru probably wants $500 for a set
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Old 05-06-2001, 07:25 PM   #6
Aspen_2.5RS
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Scoobie Steve,

How about some pics of this wild dune buggy. I'd be interested to see how it's all put together. btw: I've got a 72 VW rail buggy. These things are so much fun.
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Old 05-07-2001, 01:37 PM   #7
ColinL
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Question

What model year did your 2.2L heads come from? It's quite possible that they pushed your CR very high.

I'm trying to imagine how you could have fabricated something suitable for carburetion or TBI using a rear TB mount PFI manifold. I assume you put spacers on there or built up the intake plenum somehow.

Did you come up with this idea on your own or are there people successfully running a setup like yours?
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Old 05-07-2001, 06:37 PM   #8
Scoobie Steve
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The heads are off a 90 Legacy. I'm sure the CR was high because it cranked hard. I came up with the intake design myself, although it would be better if i had an intake off a newer 2.2 because it wouldnt have to suck the gas up the intake runner. The gas tends to "pool" in the bottom of the intake at low rpms.

Here are some pics
<IMG SRC="http://www.zing.com/picture/p840c5070804aacda96d297979f4ef8a3/fe8cb0e7.jpg.orig.jpg" border=0>

<IMG SRC="http://www.zing.com/picture/pe0597fb544e40ca9a47e3ba9fe03ab82/fe8cb1d8.jpg.orig.jpg" border=0>

<IMG SRC="http://www.zing.com/picture/pffbfc7b7b0b3624a172418ad5bf3f190/fe8cb262.jpg.orig.jpg" border=0>

<IMG SRC="http://www.zing.com/picture/pfd102d4a76910337111212ebf751ab14/fe8cb2e2.jpg.orig.jpg" border=0>



[This message has been edited by Scoobie Steve (edited May 07, 2001).]
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Old 05-08-2001, 12:40 AM   #9
BJamerican
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My family's 2000 Outback 2.5 began making a horrible knocking sound after only 9000 miles. It turned out the cam belt tensioner failed, just like Peaty's and Dandbest's. It seems to be a very common problem with newer 2.5L engines?
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Old 05-08-2001, 04:12 AM   #10
randy zimmer
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If you're going to carburate, why don't you try two ida webers? The manifold was never meant to do more than air and the plenum is a real problem (as you know).
Linkage would be challenging but distribution and tuning would be so much better.
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Old 05-09-2001, 01:33 AM   #11
Big Tee
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You mentioned fuel 'pooling' and long hours of tuning etc. Is it possible that running rich allowed fuel to contaminate the oil and wipe the bearings? Can you smell fuel in the oil?
You put in lot's of thought/work for that result, too bad
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Old 05-09-2001, 06:26 AM   #12
ColinL
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Tony-- fuel won't flow upwards easily, the manifold is intended to flow air only. Some of it can't get up the runners and simply pools in the plenum.

Next time you see a turbo or nitrous guy using add-on throttle-body injectors, you'll know why to wince...
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