So I have a D16Y8 that I want to rebuild. My goal is going to be a ~300whp daily driver. This will be my first full engine build. I had a STi back in the day and had to pull the head to replace the HG, disassembled/reassembled the head and did some light porting, so I'm pretty comfortable taking on a D16Y8 build. I plan to get to ~300whp by turboing it, but I think I want to run the block 500-1000 miles before I add the turbo.

So far this is the list of parts I plan to use:
Bottom end:
Eagle Rods
Wiseco Pistons (8.4:1)
A6 Crankshaft (I would reuse my Y8 crankshaft but read about an issue last night with only one oil hole per journal versus the A6 crankshaft has 2 per). Is there a process to modify my Y8 crankshaft to add another oil hole?
ACL Race Oil Pump
ARP bolts/studs for all bolts/studs
Which bearings should I use?

Top end (I know I don't need to build the head to achieve my goal, but I want the engine to be able to handle around 500whp to make sure it's reliable):
Supertech Valves
Supertech Single Valve Springs
Supertech Ti Retainers
Supertech Valve Seals
Any reason to even buy a cam?

What compression ratio should I shoot for? Stock is 9.6:1, so I think I want to be around 9-10:1. I'm thinking since I'm running forged pistons and don't plan to max out boost I should be able to go up to 10:1. With the Wiseco pistons getting me to 8.4:1 can I get the rest of the way to 10 just using a headgasket? Which HG would you guys recommend.

Trans:
Synrotech rebuild kit
Which clutch and flywheel would you guys recommend for a 300whp daily? I spend a LOT of time driving, so I don't want something too stiff for stop and go traffic.

 

nope with 8.4 pistons you have to do head milling about 1 mm in order to get at about 9,5-9,7:1. Don't use thinner than 0,5 mm head gasket. since u are planning to install forged internals, use closed to stock CR

 

I wouldnt trust ST valves.
Now on piston rods i would definately run the tried and true "custom length rods/ vitara pistons". Super cheap and very reliable.You will probable crack the sleeves before the pistons...
Id stuck to low compression since the D series heads xreater a little more knock due to smaller chamber but this wont be a big problem unless you do a high back pressure turbo setup (we will talk later abou this.)
I would get an aftermarket cam since the oem cam limits you. Buts thats a later matter.
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Your thinking is correct. Keep the compression up in the 9-10:1 range. There is no need to use a forge piston and go down to 8.4:1. There's no need to take 2 steps backwards to the land of Vitara.
Bearings, most will use OEM or ACL.
Supertech valve train pieces work fine. At 300whp a cam isn't "necessary". The "basic" upgrade would be a 105300 comp cam or a regrind.

 

Thanks guys! Sorry to take a while to get back to this thread. I'm working 3 jobs currently and spending what little free time I have working on one of my Civics (mainly my daily) and sleeping.

I went ahead and ordered the Eagle rods Friday and the ACL bearings last night, so this build is officially in the works now

 

ST Valves would definitely suffice for a 300WHP build and be an upgrade over OEM. They're not Ferrea, but they're not bad by any means either.

No need for custom rods IMO. Get an off the shelf rod/piston combo and be done with it, aim to get around ~10:1 for your compression. Cams are definitely not needed for the 300, but could always be improved on for better efficiency and power curve down the line.

Agreed on the sleeves. I'd recommend the CSS process for a "cheap" D sleeve upgrade.

 

Looks to be a nice build always nice to see someone doing it differently and building a Y8.

I would probably look into a Competition stage 3 or 4 clutch at that power level, but I prefer to make sure there is plenty of clutch there to hold the power or potentially a little more if you decide to turn it up later.

I like my Action Clutch setup right now, but the 1MS might be a little too light for 300 and the 2MS is a pretty stiff clutch for a daily.

 

+1 for action. My 1MS is awesome.