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Old 05-27-2012, 02:04 AM   #1
Flat 4 Motorsport
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Default ALL Hybrid 2.5L Shortblock & 2.0L Cylinder Head INFO Thread *POST HERE*

I'll start helping you guys out by compiling the mounds of threads into one easy to read thread with all the info you need for your Hybrid builds.

Threads are getting cluttered up with mis-information and whatnot.

If you have a informative post please PM me and I'll add as we build it up.

I hate searching as much as you guys do but starting a new thread every time, just mucks it all up.

-Phil

Last edited by Flat 4 Motorsport; 05-27-2012 at 05:51 PM.
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Old 05-27-2012, 02:04 AM   #2
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Last edited by Flat 4 Motorsport; 05-31-2012 at 11:22 PM.
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Old 05-27-2012, 10:44 AM   #3
bryan1242
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im on a 2.5 block with 2.0 heads i cnt find a straight answer as to what thickness head gasket to get and where to get block is stock and so are heads i have fp18g turbo and pink sti injectors
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Old 05-27-2012, 11:55 AM   #4
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did you deck the heads and block?

did you machine and chamber match the cylinder heads?



Use better grammar dude. Very hard to understand what you're asking.
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Old 05-27-2012, 04:05 PM   #5
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Quote:
Originally Posted by bryan1242 View Post
im on a 2.5 block with 2.0 heads i cnt find a straight answer as to what thickness head gasket to get and where to get block is stock and so are heads i have fp18g turbo and pink sti injectors
Use OEM STI Head Gaskets and get your heads combustion cambers matched to the block by ASF Machine.
Equilibrium Tuning's Head service is good but I went with ASF Machine and the job/service was EXCELLENT!!!
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Old 05-27-2012, 04:56 PM   #6
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Really the only hybrid specific questions most people will have pertains to combustion chamber work, head gasket thickness, compression ratio (you could throw piston dish in here), and crank case/head breather routing.
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Old 05-28-2012, 12:43 AM   #7
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Outfront Motorsports cut my chambers to STI specs and car runs well so far. No knock problems.

Not sure if this type of "Where can I get my heads worked on for a hybrid?" info should go into this thread though.
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Old 05-28-2012, 01:04 AM   #8
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^^ this is good, this is exactly what this thread is meant for.


Please post up results, reviews and info pertaining to any hybrid setups.


It makes it so much easier for people who are searching to just go to one thread for all their questions.


-Phil
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Old 05-28-2012, 09:31 AM   #9
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This is good stuff. Very broad topic and hard to search for answers sometimes...

Thanks Phil!

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Old 05-29-2012, 02:00 PM   #10
wrxkid2003
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Should become a skicky
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Old 05-29-2012, 04:36 PM   #11
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Im just finishing building a Hybrid 2.5 block with WRX heads. What spark plugs do you recommend?

I be running E85

Thanks
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Old 05-29-2012, 06:05 PM   #12
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2L heads use 2L plugs

-Phil
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Old 05-29-2012, 08:13 PM   #13
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Sure thing guys, if anyone has info they want to include post up or PM me and I'll put it in the first post.

-Phil
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Old 05-29-2012, 09:23 PM   #14
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It might also be nice if people could post their "recipes" for their hybrid builds. Like what compression pistons, head gasket and thickness, machined heads or not, etc.
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Old 05-29-2012, 09:31 PM   #15
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Quote:
Originally Posted by Jirv311 View Post
It might also be nice if people could post their "recipes" for their hybrid builds. Like what compression pistons, head gasket and thickness, machined heads or not, etc.
OEM Shortblock
CP Pistons 9:1 CR
Stock STI head gaskets
Combustion Chambers cut to STI specs by Outfront Motorsports

Car is running great. Higher CR is definitely nice for autocross even with pump gas.
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Old 05-30-2012, 10:09 AM   #16
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Quote:
Originally Posted by KpT KiM View Post
OEM Shortblock
CP Pistons 9:1 CR
Stock STI head gaskets
Combustion Chambers cut to STI specs by Outfront Motorsports

Car is running great. Higher CR is definitely nice for autocross even with pump gas.
Are you sure you maintained a 9:1 CR even after having the cc's worked?
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Old 05-30-2012, 12:41 PM   #17
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Quote:
Originally Posted by Zackbo View Post
Are you sure you maintained a 9:1 CR even after having the cc's worked?
^^^ this. I had a guy bring me his car to tune because nobody else could get it to make decent power for his setup. I started the tune and right off the bat I knew something was different. I asked for his build specs and ends up he had over 10.5 to 1 compression. The guy thought because he bought a cosworth shortblock with flat top 9.5 to 1 pistons that his compression ratio would be 9.5 to 1. Wrong! He didn't take into account gasket thickness or head cc size before he bolted the heads to the block.
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Old 05-31-2012, 06:45 PM   #18
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Quote:
Originally Posted by fastblueufo View Post
^^^ this. I had a guy bring me his car to tune because nobody else could get it to make decent power for his setup. I started the tune and right off the bat I knew something was different. I asked for his build specs and ends up he had over 10.5 to 1 compression. The guy thought because he bought a cosworth shortblock with flat top 9.5 to 1 pistons that his compression ratio would be 9.5 to 1. Wrong! He didn't take into account gasket thickness or head cc size before he bolted the heads to the block.
So if stock STi compression is 8.2:1 and I use 8.5:1 pistons with 02 WRX heads undecked, stock STi head gaskets, what CR am I looking at? I've heard with stock STi pistons (at 8.2:1) it's around 8.96:1-ish so would 9.26:1 sound about right?
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Old 05-30-2012, 06:50 PM   #19
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Quote:
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Are you sure you maintained a 9:1 CR even after having the cc's worked?
Good question. I'm betting so as my 205 heads are now like 257 heads without AVCS. I used OEM 2.5 L headgaskets and the CP pistons are designed for the 257, so I believe everything that could cause higher compression is taken care of. I didn't mill the heads or anything.
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Old 05-30-2012, 04:20 PM   #20
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My question would be: what view are the pro engine builders taking with regard to lobe centres on a 2.5 with 2l non AVCS heads. Kelfords seem to be the cam of choice here in AUS, but from what I can find on their site all there 2.5 cams are built for AVCS. Do you go a 272 that matches the 2l heads rather than the 264 for example? If you know what I'm saying.
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Old 05-31-2012, 03:58 AM   #21
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I ran the Cosworth non-AVCS 2.0L cams in my 2.5L hybrid in the past and also in the new engine going in my STi right now. The last engine screamed and made good power considering Cali 91 octane and only 21 psi. This time I will make more.
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Old 05-31-2012, 09:18 PM   #22
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Nice thread Im hoping we get some great info in here. Ill post up some info in my old hybrid, and my new hybrid build soon.
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Old 06-01-2012, 09:06 AM   #23
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Thanks for posting this, good info for those of us about to start a hybrid project.
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Old 06-01-2012, 09:06 AM   #24
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Thanks for posting this, good info for those of us about to start a hybrid project.
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Old 06-01-2012, 07:47 PM   #25
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I'd seriously consider cnc work on the heads. Any unevenness will create hot spots, and minor differences between cylinders is problematic as well. Another thing to keep in mind is the quench surface dimensions and difference between 92mm and 99.5 mm piston quench area.
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