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Turbo, LS swapped Impreza RS
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Discussion Starter #1
Hello again rs25! I'm not new here and already have an on going build here:
http://www.rs25.com/forums/f145/t173568-rowdy-burnouts-loud-noises-lsx-rs-swap-project.html But I've got myself into another project. If the title hasn't already given it away we're doing a turbo bobber build in 30 days and premiering it at SOWO in Georgia. The bike in question is owned by my roommate and is what we believe to be a late 80's cb650.



We found it on craigslist today at 3 and made the 45 minute trek to get it. The plan behind the build is an old school hard tail bobber with a stretched front and a little bit of a twist. We're strapping this to it:


It's the tdo4 that used to be on my rs. It was sitting in the parts bin and can't be sold for much so we figured that a old school bobber that can still hold its own against 600 sport bike. Teardown starts tomorrow!
 

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Turbo, LS swapped Impreza RS
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5,172 Posts
Discussion Starter #2
Pulled the tank off and pulled and labeled the harness.





 

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2001 Coupe
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1,258 Posts
Should be fun to tinker with. What do you have to do to the carbs to make them take the blow-through setup work?

With a tubing notcher I'm imagining an old school log manifold. Should look bitchin'.
 

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Turbo, LS swapped Impreza RS
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5,172 Posts
Discussion Starter #8
The stock intake box uses 4 rubber grommets that press fit into it and are able to clamped on the carb ends. I'm going to build a aluminum box manifold with the press fit grommets and a tube coming off the rear for the turbo inlet.

The stock Wrx bpv is going to be mounted directly underneath the manifold and will be vented to the atmosphere.

Saturday we're chopping the frame and I'll start mocking up the cardboard for the manifold.
 

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EJ205 1996 Brighton coupe
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663 Posts
What are you plans for fuel? Fancy pressureized carbs? ITB's and PFI?

Also, air cooled engine, water cooled turbo... any thights on that?

Maybe just run it without coolant and just run a meaty oil cooler? You can get sandwich plate oil coolers from 80's cb900, that fit directly onto cb750's, i would assume its the same for a 650. I still have the one laying around i bought for my cb750k.
 

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Turbo, LS swapped Impreza RS
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Discussion Starter #10
We're using the stock carbs and I've got a intake box in the works that will bolt up to the carbs and still utilize the stock silicone sealer.

For SOWO were blocking the water lines and running a universal oil cooler. Afterwards without a time constraint I've got an idea to use an electric water pump and a mini aluminium catch tank and run the water through a dirtbike style radiator.
 

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EJ205 1996 Brighton coupe
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663 Posts
I was refering to how you intend to make the stock carbs with boost?

Pressurize the bowls, pressurize the whole carb inside a sealed box??? I've seen a few creative ways oldschool guys make carbs work with turbos. running positive pressure (boost) through a conventional carb will force the fuel back through the bowls and fuel feed lines, resulting in NO fuel going into the engine when ever you hit boost.
 

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Turbo, LS swapped Impreza RS
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Discussion Starter #12
I was refering to how you intend to make the stock carbs with boost?

Pressurize the bowls, pressurize the whole carb inside a sealed box??? I've seen a few creative ways oldschool guys make carbs work with turbos. running positive pressure (boost) through a conventional carb will force the fuel back through the bowls and fuel feed lines, resulting in NO fuel going into the engine when ever you hit boost.
I've been doing a lot of research on blow through car set ups and a lot of guys are blocking off any atmospheric ports on the carbs which allows them to hold positive pressure along with deleting the choke. They also get a bigger main jet and block off the rear jet.

With the ports blocked off and the a sealed box on the carbs *in theory the carb should be able to suck the fuel and build pressure without forcing fuel into the tank.
 

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EJ205 1996 Brighton coupe
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Very interesting. I can't wait to see you attempt it. Hope it works!

I've also heard mixed reviews on blocking off the atmosphere ports, and pressurizing them.
Ps, I've never turbo'd a carb either, so this is all speculation :)

Another idea, I've seen a lot of drag cars run carburators on top of thier Supercharger. If the routing is short without many bends or intercooler, I wonder if you could run one large carburator BEFORE the turbo. Then just have a 4to1 manifold after the turbo outlet. i'm sure it would be a nightmare to tune though..
 

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Turbo, LS swapped Impreza RS
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Discussion Starter #14
Haha I've never messed with carbs especially with forced induction involved.

Ideally a suck through setup would be easier to make work with carbs but all the extra piping is out of the question with the limited space we're already working with.
 

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Turbo, LS swapped Impreza RS
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Discussion Starter #15 (Edited)
Started on the bike's manifold today. I really wanted to do to it all in aluminum but the lack of local metal suppliers and a 30 day deadline we chose to go with sheet metal instead. Thursday when I finish it up, it will have a nipple welded on for a boost gauge and the stock Wrx bpv will sit next to the turbo inlet side. I've never liked welding without filler but it worked really well with the thin sheet.



 

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Turbo, LS swapped Impreza RS
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Discussion Starter #17
I haven't touched the car in two weeks because of the bike :( ... But the frame on the bike is coming together nice.

 
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