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Old 08-14-2012, 12:05 PM   #1
lgt2000
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Default 2005 Legacy GT V8 Build (LS2/LQ4)

I have been working on a few V8 build recently and have decided not to rebuild my legacy back to the 2.5L Turbo but to swap it out for a 6.0L V8.

We are building everything ourselves and are working on a V8 Miata at the same time.

The engine is going to be an Iron LS2 or LQ4 which will have headwork and cam done to produce around 450 rwhp. The transmission will be a T56 6-Speed.

The car will be RWD due to space constraints and will fit what I need it to do. I am going to run the GM ECU and interface it to the Legacy cluster.

The front accessories are from a C6 LS3 Corvette to save space.

If you want to see quicker progress buy my stuff haha )

Here are the specs on what I have so far:

2003 LQ4 6.0L Short block with dished pistons
2006 GTO Front Sump Oil Pan and Pickup
2010 Corvette Water Pump and Harmonic Balancer

The head will most likely be 243/799 LS2 heads but I may go to LS3 head depending on what kind of deals i find. Once the heads are bought I can decide what direction to go in as far as a cam

The heads will be milled in any case and the goal is to run around 11:1 compression and stay on 93 octane

The T56 will most likely be the CTS-V unit since it has a shifter setup similar to the Legacy and is improved over the F-Body units
This will send power through an LS7 Corvette clutch

Here is a picture of the first quick mockup we did once the mockup engine arrived. We are going to modify and reinforce the subframe to move the engine back another 3 inches and we are also going to use outback pieces in order to drop the subframe an inch lower

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Old 08-14-2012, 12:05 PM   #2
lgt2000
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Here are few more pics we took when we were doing the initial quick mockup. This is without squaring off and center the engine and before the subframe modification and Outback subframe drop. Once all those modification are completed and the hood is swapped for a scoopless one we hope to be able to make everything clear under there.

That motor mount bracket in the middle of the firewall is now drilled out and the area patched as it was in the way




Last edited by lgt2000; 08-14-2012 at 12:10 PM.
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Old 08-14-2012, 12:06 PM   #3
lgt2000
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Reservedb
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Old 08-14-2012, 12:39 PM   #4
EvileyeZ88
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Sweet raptor Jesus this looks like it'll be some fun
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Old 08-14-2012, 01:58 PM   #5
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woahhhhhhhh O.O
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Old 08-16-2012, 05:03 PM   #6
DeleriousZ
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Was about to ask why you weren't moving the engine down and back. Then I read your post instead of looking at pictures lol. Interesting project!
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Old 08-20-2012, 03:18 AM   #7
climberd
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Subscribed, mostly interested in your wiring choices to get the LGT ECU to play nice and not freak out with cam sensor missing.
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Old 08-21-2012, 01:18 AM   #8
Skrane
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Why iron block?
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Old 08-21-2012, 01:40 AM   #9
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And so it begins...


This is awesome, I will keep checking back for updates, and can't wait to see this thing up and running! Good luck with the build!!

Thanks,
Rick
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Old 08-21-2012, 06:52 AM   #10
Patrick Olsen
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Quote:
Originally Posted by Skrane View Post
Why iron block?
I was wondering the same thing. I understand the iron block would be cheaper, but it shouldn't be that hard to find an aluminum engine, and the weight savings on the nose is more than worth it IMO. The aluminum 5.3L engines (LM4) can be had for $500-800 complete, for instance, and will make tons of power just like the other LS motors.
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Old 08-21-2012, 11:33 AM   #11
KONKILR
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If he plans to turbo it the iron block will hold more power, but is it really needed?

jake
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Old 08-21-2012, 11:53 AM   #12
Skrane
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Quote:
Originally Posted by KONKILR
If he plans to turbo it the iron block will hold more power, but is it really needed?

jake
Why would the iron block hold more power
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Old 08-21-2012, 12:28 PM   #13
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Quote:
Originally Posted by KONKILR View Post
If he plans to turbo it the iron block will hold more power, but is it really needed?

jake
^the turbo? yes, yes it is.

Can't wait to see this through its build process!

Quote:
Originally Posted by Skrane View Post
Why would the iron block hold more power
Less flexing in the sidewalls.
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Old 08-21-2012, 12:38 PM   #14
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Not enough to justify having an iron block. Unless he got a great deal on it or something haha
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Old 08-21-2012, 12:54 PM   #15
KONKILR
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The iron block LS engines are way stronger than the aluminum block. Plus you can safely overbore the iron block. And the iron block engines are ready to spin to the moon and boost like crazy with no issues.

jake
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Old 08-21-2012, 01:00 PM   #16
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At this point I really don't care if he does aluminum, iron or purple monkey dung. I just want to see it happen.
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Old 08-21-2012, 01:20 PM   #17
GT35RHybrid
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Holy smokes in for updates.
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Old 08-21-2012, 05:38 PM   #18
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I dare not mention nor view this thread anywhere near my GT for she will feel inadequate
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Old 08-21-2012, 05:49 PM   #19
KONKILR
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Unfortunately I need my subaru to be AWD, otherwise my newly acquired LGT might get this treatment!

jake
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Old 08-21-2012, 06:41 PM   #20
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not to pee in your coolaid but

"I am going to run the GM ECU and interface it to the CAN BUS Legacy cluster."

thats going to be tough
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Old 08-21-2012, 09:59 PM   #21
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Quote:
Originally Posted by Jaxx View Post
not to pee in your coolaid but

"I am going to run the GM ECU and interface it to the CAN BUS Legacy cluster."

thats going to be tough
I'm not so sure. The CANBUS interface is an industry standard, so the communication should 'just work' with a bit of research. After that you need the commands to do as intended.

A person with the right skill set can sniff the CANBUS of both to figure out what each command does for each brand. Then said skilled person can build a 'translator' that accepts the GM ECU commands and repeats out the Subaru translation for the cars systems.

It's far beyond my skillset, but the type of guys that can reverse engineer complete ECUs should have a head start. The question is....does the builder have the know-how or the connections?
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Old 08-21-2012, 10:09 PM   #22
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Quote:
Originally Posted by Turn in Concepts
At this point I really don't care if he does aluminum, iron or purple monkey dung. I just want to see it happen.
^this
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Old 08-22-2012, 12:24 AM   #23
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Quote:
Originally Posted by Turn in Concepts View Post
At this point I really don't care if he does aluminum, iron or purple monkey dung. I just want to see it happen.

LOL best quote I have seen in a long time. Thanks for that, I needed it tonight haha!

Rick
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Old 08-22-2012, 07:55 AM   #24
GT35RHybrid
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Is it just me or does it look like there is gonna be some fitment issues at the front?
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Old 08-27-2012, 12:41 AM   #25
climberd
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There is plenty of room. The problem is going to be getting the GM ECU to talk to the Subaru ECU. It's possible, sure. Yet that solution posted above is by far the hardest thing I can think of to make for a Subaru, or for any modified car project. Back to reality, the only "good" solution I have found to this problem (and I have put very serious research into this) is to do the simple old cam trigger and crank trigger wheel/sensor faking. Feed the Subaru ECU just enough so it will a) crank the starter, and b) not throw a CEL code. The cam trigger is the key. You can clear away any other code, but you're not going anywhere without a cam signal unless you completely bypass every Subaru ECU function. Let's say you do that, no Subaru ECU outputs except CAN, no inputs except GM ECU's tach output (which has a different logic of trigger wheel shape)... you would have to find a way to get the cluster to come alive. Any way you cut it, short of hiring a software/hardware engineer, you may be best off just adding a crank trigger and cam trigger wheel in the Subaru format. If anyone has a plan that would work better, I would love to hear it.
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