Build or rebuild?

[Gar9854]

I purchased a blacktop dirt cheap from a storage auction, turns out the engine had bad compression and the headgasket was the issue but I've always been told rebuild the head and the bottom end will give out quickly. I've completely dissembled the bottom end and here's my delimia.

I'm wanting 300-375 TOPS
I know I'll need
a metal headgasket
Arp's
Injectors 700cc or bigger to keep to duty cycle as low as possible
Turbo
a full exhaust
And a great tune.

My question is should/could I rebuild the bottom end (hone the cyclinder walls/line hone and polish the crank) new rings and bearings.
Or build to bottom end with a 86.5 bore (if needed) rods ect ect?

I've got a flame suit on stand by.

[Dan3312]

Personally I'd price up at set of rods and pistons. I've seen broken rods at 15psi on an otherwise stock SR20. If you have it apart, now is a great time to throw some new stuff in there and have it last for a very long time at those power levels.

[Croustibat]

Do what is needed; by that i mean first check for damage and clearances.

If you dont know how, get the engine to a machinist. Have bore to piston clearance, bore roundness checked. Get every crank /rod bearing check for scoring and clearance (use plastigauge), and check if it is not bent. Get the block checked for flatness. Get the head checked for flatness and integrity.

When you know the condition of the engine, decide what you want.

If cylinders and pistons are ok, just get new rings. If crank is bent or its journals are not round or scored, get a new engine.

If you need to rebore, just go with what is needed, and eventually get forged pistons.

BTW you will also need a new MAF (Z32 is quite commonly used).

For the kind of power you want, a gt2871r will be perfect.

[Mikester]

^^This.

Take it to a machine shop and have everything measured out and go from there...

Since you have it all apart, I would recommend a full rebuild. To rebuild for 300 - 400hp, you will need:

- OEM Nissan gasket kit
- MLS HG is not necessary- ARP studs & good tuning is key... but if you decide to go ahead and do it, make sure not to cut corners and prep everything properly- There are countless threads/writeups for this. If you don't go OEM HG, use Tomei, Cosworth or APEXi (proven HG's).

- OEM Nissan bearings

- Pistons/rods/rings (full kits are pretty cheap; the ones that come with Eagle rods also come with ARP rod bolts)

- ARP head studs

- Z32 MAFS

- Fuel pump

- injectors (your idea is spot-on keeping duty cycles low & leaving room to grow)

- Turbo- Like he^^ said, a 2871 is perfect for what you're looking for

- Tunable standalone

- Rocker arm stoppers

- Good 3" exhaust (does not have to be loud, just flowy)

Provided everything measures/checks good on the head, you can put that back together stock & be fine... The OEM gasket kit comes with new valve stem seals & whatever else you will need.

Good luck~

[Gar9854]

Thank for the input guys
I'm leaning towards wiseco (stock compression)/eagle bottom end with Nissan bearings and arp main&head studs
Cosworth 1.1 HG
Upgrade the valves,springs,and retainers and use stock cams on a t25 until after break in period is done then toss in tomei 256 or 260's just for a little more response if needed

[Mikester]

Thank for the input guys
I'm leaning towards wiseco (stock compression)/eagle bottom end with Nissan bearings and arp main&head studs
Cosworth 1.1 HG
Upgrade the valves,springs,and retainers and use stock cams on a t25 until after break in period is done then toss in tomei 256 or 260's just for a little more response if needed

My build is with the Wiseco/Eagle kit w/OEM bearings as well. Haven't installed the motor yet, but expecting good things. You may have to hunt a bit for the 8.5:1, 86.5mm pistons; I remember when I was looking, I ended up getting the 9.0:1 b/c I couldn't find them w/stock compression... although I am sure they exist=)

There is no 'break-in' for SR's... Only period where it is crucial to enable the pistons to seat at certain rpm ranges. During that period, run regular oil, not synthetic (like 1,500mi IIRC)... but you can still drive the shit out of it.

If you want to get cams, just get cams. To run the Tomei 256's (Poncams), you don't need aftermarket springs/retainers. Anything beyond that, stiffer springs are recommended. They will improve your midrange power at the expense of a little bit of low end... They are perfectly suited for the kind of power you are looking to make.

Also, so long as your head measures out & leak-checks good, there is not a reason to change the valves. OEM SR valves last forever- If it ain't broke, don't fix it. Make sure to put fresh vavle stem seals in when you put everything back together (they come with the OEM gasket kit).

When you do the MLS HG, MAKE SURE you have the front oil pump cover machined level with the deck of the bottom end. If not, it will create a weak spot in the seal between there & the #1 piston. Also, make sure everything is machined as smooth as possible; or to the recommended spec if there is one for the Cosworth HG.

Sounds like you got a good plan now... Good luck to ya~

[Gar9854]

Didn't even think to ask the machine shop about the front cover fitment with the mls HG. Thanks for all the input.

[idahotuner]

i raised compression on mine its right around 9.2 to 1 now