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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 01-10-2012, 01:03 PM   #21
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One of our customers has the world record 2v mod motor mustang, it had an 88mm non ball bearing precision on it and it ran 8.85. He went to an 88mm ball bearing and it went a 8.66. But more importantly he has a back pressure sensor in the collector which showed a huge drop in back pressure even with the same size A/R just going from journal to ball bearing, with billet wheel and he was able to give it more timing without detonation as a result.
400whp i can imagine would be extremely difficult to reach with a t2 frame turbo <Edit> Without e85.
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Old 01-11-2012, 02:26 PM   #22
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Originally Posted by 1slowna View Post
One of our customers has the world record 2v mod motor mustang, it had an 88mm non ball bearing precision on it and it ran 8.85. He went to an 88mm ball bearing and it went a 8.66. But more importantly he has a back pressure sensor in the collector which showed a huge drop in back pressure even with the same size A/R just going from journal to ball bearing, with billet wheel and he was able to give it more timing without detonation as a result.
400whp i can imagine would be extremely difficult to reach with a t2 frame turbo <Edit> Without e85.
Interesting. Thanks for the info!
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Old 01-11-2012, 02:50 PM   #23
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I noticed that between yesterday (when Precision got back to me recommending the PT5858 CEA for my 2.5) and last week, they went thru and deleted quite a few turbos from their website's listing, especially in the "450-600" category. I am looking forward to seeing what they come out with in the T2 size range and their "3-4 months out" stainless vband housings (their current vband housings are not stainless).
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Old 01-11-2012, 05:12 PM   #24
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Originally Posted by Faeflora View Post
I'm not sure that your idea about the turbine speed affecting backpressure that much is correct. A/R makes sense.

Data point- it was very hard for me to hit 400hp with my GT30 and log manifold.
Your going to need a tubular manifold to go further. a GT30 ( 57mm compressor wheel) can easily reach 400 horsepower. What size backhousing are you using? I assume 0.63 AR? You can try jumping to the .81 to bump the top end power, but the money is better spent on a new manifold id think. Last turbine housing I bought by itself was almost 400 bucks lol. Alot of money for a small change.

I made 374 WHP on my honda (1.8) @ only 11.5 psi using my GT3076 with a 0.63 backhousing on a tubular manifold.

Last edited by SupraTim; 01-11-2012 at 05:32 PM.
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Old 01-11-2012, 05:27 PM   #25
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Your going to need a tubular manifold to go further. a GT30 ( 57mm compressor wheel) can easily reach 400 horsepower. What size backhousing are you using? I assume 0.63 AR? You can try jumping to the .81 to bump the top end power, but the money is better spent on a new manifold id think. Last turbine housing I bought by itself was almost 400 bucks lol. Alot of money for a small change.
Search for Failfloral's current 100 page build thread. He dumped that old setup a while ago; he's currently running one of the slickest equal length manifolds and a gigantic twinscroll Borg with a quickspool valve. And he knocks while cruising.

Your information however is still valid, don't get me wrong.
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Old 01-11-2012, 06:24 PM   #26
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I made 374 WHP on my honda (1.8) @ only 11.5 psi using my GT3076 with a 0.63 backhousing on a tubular manifold.
Honda 1.8 =/= Mazda 1.8 :( :( :(

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And he knocks while cruising.
Cheap shot!
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Old 01-11-2012, 06:39 PM   #27
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yes Honda 1.8 =/////////////////////////////////////=mazda 1.8
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Old 01-11-2012, 06:59 PM   #28
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Supratim, what 's your hold?
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Old 01-12-2012, 12:15 AM   #29
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Originally Posted by 1slowna View Post
At least this is my understanding, correct if incorrect.
Consider this your correction - it's completely wrong. When you hydrolock, it is absolutely a massive downward force - it is the force of the (essentially) incompressible water acting against the inertia of the piston. Decreasing the backpressure in the exhaust manifold by a few PSI (even 10+psi in extreme cases) is like rearranging the deck chairs on the Titanic when you compare it to the hundreds of PSI the engine experiences during the combustion phase.

There is nothing magical about the people making huge power on factory motors - they are either lucky, not running the motor very hard, or not telling us about it when it finally explodes.
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Old 01-12-2012, 01:59 AM   #30
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Its a concept the honda guys got figured out but big turbos do not work well on road courses so most people building a setup for their miata will go with the tiny turbo and cast manifold which greatly limits the power capabilities of the stock motor IMO. Just think about how a rod bends when you hydrolock, the rod bends on its way up, not on its way down due to a massive thrust downward. At least this is my understanding, correct if incorrect.
Okay dude, thanks. We have absolutely nothing in common with Honda engines...nothing.
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