sr build question

[vincerr]

i recently spun a bearing on the crank so i've taken it upon myself to rebuild. so far i've narrowed it down to reconditioned stock rods w/ARP bolts, 87mm cp piston kit (9:1 compression), 1mm headgasket, ARP headstuds, etc.

how does that sound? should i increase the compression? what's safe? i want something that can handle 450hp but downtuned to maybe 360.

a friend suggested some amc pistons with 12:1 compression instead. i'm on a budget so naturally i can't have everything i want.

any advice would be helpful.

thanks/aloha.

[axiomatik]

why would you run 12:1 compression on a turbo car?

[sepulchral]

9:1 compression is good higher is still good but dont expect to be running more boost safely with 93 octane. stick to the 8.5:1 - 9.5:1 range.. personally i would stick with 9:0 - 1

make sure your oil clearances are correct and you get the right oversized rod and main bearings after having your crank turned, and check to see if the head is warped and put a straight edge on the block to make sure its fine too.. also replace the waterpump while your at it.. let us know ifyou have questions

[sepulchral]

oh yeah and 12:1 compression is ridiculous don't listen to your friend.

[fliprayzin240sx]

Your friend drives a HONDA huh? Also dunno bout running 87mm pistons. From wut ive been reading, 87mm and they absolutely encourage you to start thinking bout sleeving the block.

[vincerr]

thanks guys. my friend was just fk'ng with me about the 12:1 amc's. i'm not sure there is such a thing. disregard.

i was planning on getting the head done, new seals, valve guides, machined, etc. the same shop that's doing the block and crank will be doing the head as well. package deal.

another concern is about the piston size. is 87mm too big without re-sleaving the block? does size really matter? (ha.ha.ha.)

i don't have any estimates for that kind of work yet but imagine it costing way more than a bore job.

i'm buying most of the parts from enjuku.com. their prices seam resonable. but one thing tripped me out though. the headgaskets only come in 87-88mm clearances. in theory that would leave a gap with the 86.5mm pistons. that doesn't sound right.

i'd prefer to get it right the first time. i don't know if i could handle fucking this up.

[Ghost Dancer]

Why don't you ask a shop in Hawaii with a good reputation these questions? Building an engine is a big effort if it's your first time and the last thing you want to due is screw it up because of bum information random people throw at you.

Just to clarify! I am not saying anyone is giving him bum info. lol.

Now my turn. Are you wanting to build the motor to handle 450 just to be safe or are you planning on going for that 450 later on down the road? If you plan on staying at that 350PS and since you say you are on a budget I would forgoe the pistons and stick with the stock SR pistons. The SR is a pretty stout motor and can handle much of what's thrown at it if the tuning and rebuild is good. You don't have to bother with increasing displacement or compression. A rebuilt to stock bottom end with the right fuel and turbo will make 350PS without breaking a sweat. You'll definitely want to look into some valvetrain work though. Alot of people seem to build motors without even thinking about the heads:p

[Steeles]

not to disagree totally with ghostdancer but if your going in there to build the motor.... fucking BUILD the motor. 86.5mm 9:1 Cp pistons rods if you have the money, ARP where needed (carefull with the mains I don't know if they ever fixed the too long issue with the RWD ones... Search Freshalloy for more info) this alone on the bottom end will be fine for you. proven to handle at LEAST 450 so 350 should be easy as stock. some mild porting and polishing of the head get a new oil pump/front cover all new gaskets new water pump, timing chain kit... should do you great

[vincerr]

after hearing what you guys have said and talking with others, i'm not sure i want to increase the compression. i might be trying to get more out of this than i can afford.

since increasing compression would change my fuel management i'd have to get it tuned. in hawaii that's about another 300bones. it's a slippery slope into debt because why would i want to tune a stock ecu when i could potentially go power fc and get much more than i can bargain for?

anyway.

i'm getting the head re-done, new seals, grinded and that stuff. the crank machined, balanced, fitted. 86.5 bore and hone. resurfacing. hot-tank for everything. i can't really upgrade much 'cause the budget is running thin. i'm not drifting far from stock, besides the ARPs, pistons, and head gasket. new seals here and there of course and a timing chain.

i see it now as walking away with a new motor, at least as close to crate as i can afford. plus, the sr is a trooper, right? i'm not planning on taking it over 400 (yet), but when i get to that point hopefully it'll just be a matter of bolting it on (via gt2871r/power fc).

thanks again guys.

[statik]

I just rebuilt my motor, so perhaps I can help you...

CP 86.5mm 9:1 pistons
Eagle rods
ARP head studs (I wouldn't do main's because of the stories i've read on FA and they are not necessary IMO)
Cometic 1.2x87mm HG
boil+polish+balance crank (If you polish the crank you WILL need oversize bearings than the factory ones for your block, I can guarantee it.)

For the head I did:

HKS valve springs (or so I thought...)
HKS RAS
Crower titanium retainers
New oem intake valves
Supertech inconnel exhaust valves
JWT valve guides
New valve seals
New shims/retainers
HKS step 1 264 Cams

That, and I replaced just about every part I could order.

Greddy Intake Mani (obviously not required, but for your future power goals...)
Water Pump
Front Timing Cover/Oil Pump
Oil Pickup
Oil Pan (greddy ftw)
Rear main seal
Timing Chain/guides
New style sr20 chain tensioner
Good injectors (I went with Nismo 750cc)

I _think_ that's about everything. Like Steeles said, if you are gonna build the motor, do it right. Im not saying all of that stuff is necessary, but to me (minus the valves/guides) that is a basic SR build, nothing special. The 9:1 CR will not effect how much boost you can run really, it can def handle a ton of boost. VW GTI's come with 9.5:1 stock CR, you will have no problems.

As for tuning, I went with enthalpy again (did my tune before i blew my rings), he can tune for 9:1 CR so you won't have to worry about retarding the timing at all.

Also if you wanna see any pics of my build, check my sig and browse the rebuild gallery.

[jdm_s14_zenki]

9:1 compression pistons will do just fine. The point is to raise compression and lower the boost. You will make more power with higher compression pistons with lesser amount of boost. which in my opinion is good. same with the port and polish head idea.

[vincerr]

when i asked the machine shop to port/polish the intake they said it was good already, "big enought" in their opinion. the suggested it wouldn't make much of a difference.

i trusted them on it since i'm the one spending the money.

has anyone port/polished their intake?

my friend had also mentioned the same thing about upping compression to lower boost. seems logical and a safer.

are their any other advantages to upping compression?