piston replacement

[assAssasin]

alright heres the deal i am building up my tt motor, and i am going to need forged pistons. i am stuck at deciding if i should get bigger pistons and have the heads bored or keep it stock bore. i need some advice on what to do so somebody please help. the major upgrades are the gt 675 turbos downpipes etc dual intakes 58 mm throttle boddies bigger plumbing lightened fly stronger clutch im also trying to decide on the cam shafts. lightened pulleys and various other crap. please give me some input on what to do

[vulcanrush]

alright heres the deal i am building up my tt motor, and i am going to need forged pistons. i am stuck at deciding if i should get bigger pistons and have the heads bored or keep it stock bore. i need some advice on what to do so somebody please help. the major upgrades are the gt 675 turbos downpipes etc dual intakes 58 mm throttle boddies bigger plumbing lightened fly stronger clutch im also trying to decide on the cam shafts. lightened pulleys and various other crap. please give me some input on what to do

most forged pistons are 87.5mm+. generally, most people overbore.

[assAssasin]

what would be a good bore size to go with in your opinion, im aiming for around 600 hp safely but im also not looking to go to crazy. the main thing for me is to get forged pistons so i can actually use the hp

[vulcanrush]

what would be a good bore size to go with in your opinion, im aiming for around 600 hp safely but im also not looking to go to crazy. the main thing for me is to get forged pistons so i can actually use the hp

i would say as small a bore size as possible, 87.5mm+, bigger bores don't mean more power, imo.
if anything, smaller bore sizes mean more room later for another rebuild.
fyi, 600rwhp or 600hp? on what kind of fuel, race gas or regular gas?

[es.biggs]

Yeah the good thing about having it bored is not necessarily the power/displacement gain (tiny as it may be) but you will have a perfect circle, the equivalent of brand new.

[CrazedZ32Owner]

hmm might have to watch this thread.... mirrors my plans for my car

[vulcanrush]

the two best pistons, imo, are cp and arias. arias is quieter, more silicon content, expands less. cp's are stronger, but noisier due to piston-slap? i'll let you know how the cp's are, but every big build that i've seen ---- supras, skylines, etc. use cp pistons.
nothing beats oem in terms of longevity and quietness.

[es.biggs]

Would you recommend forged pistons for a 600whp build?

[vulcanrush]

for sure, i think the oem stock pistons are capable of handling up to 600hp, that's what i've heard, but they're 20-year-old engines+.
also, Ethan, 600rwhp is no joke, the biggest limitation is the fuel you can get, imo.
400rwhp is no joke, i see people throwing around these numbers like it's nothing.
Harry over at ztuner said anything over 500rwhp takes a lot of work, i mean, 17-18-psi is the safe limit for 93-octane gas.

[CrazedZ32Owner]

well w/e i can get on 93 thats what i am aiming for....don't mean to thread jack on OP just stating

P.s that sounds so childish lol

[vulcanrush]

one thing you can look into is e85 fuel? the bde fuel rails are perfect for that, i'm running nismo740cc's because i'm not looking to make a lot of power, but the bde fuel rails are pretty cool.

[assAssasin]

i was talking to steve over at z1 last week and we were going over some plans on my car and he told me a few guys there run the gt675 kit which comes from the 700 hp kit in there builds without forged pistons, one tech was pushing 650 wheel power with stock internals minus the cams i believe and he told me he has had no problems what so ever, so with all the mods i have i beleive 600 wheel hp is achievable on around 18-22 psi safely. and i usually only run 93

[vulcanrush]

i was talking to steve over at z1 last week and we were going over some plans on my car and he told me a few guys there run the gt675 kit which comes from the 700 hp kit in there builds without forged pistons, one tech was pushing 650 wheel power with stock internals minus the cams i believe and he told me he has had no problems what so ever, so with all the mods i have i beleive 600 wheel hp is achievable on around 18-22 psi safely. and i usually only run 93

18-psi is a lot on 93-octane. any more than that, and you're asking for engine knock.
on 100 octane, they run maybe 20-psi+.
i wouldn't run anymore on that unless you're planning on getting methanol injection.
http://specialtyz.com/blog/?p=896 ---- 100 octane, 20.53-psi
http://specialtyz.com/blog/?p=501 ---- 100 octane, 20.84-psi
i'm not a big fan of z1, what they're telling you is crazy, imo.
you're tripling power output, and they're telling you it's ok to run stock internals?
give kyle at ipp a call, or greg and sebastian over at specialtyz.

[assAssasin]

well they were not necesarilly telling me to keep stock internals, in the beginning i was not planning on opening the motor up that deep, and we opened up the thought of replacing pistons to keep the motor strong. he mentioned that its not the best thing to do but you can if your on a budget. i should have mentioned that, i was just tryin to keep it short and sweet. Pretty much once i started the swap i whent from keeping stock turbos to spending another 5k in parts. s*** more addicting than crack lol

so what do you think the best option is, keep stock bore w/ low boost on 93 this will be a summer driver

[vulcanrush]

i'm not trying to discourage you or anything like that
it's just, i don't want you to destroy your car, and have to rebuild.
and there's a lot of crazy advice going around, especially on these forums.
one really good piece of advice i got was, figure out what the safe limit for boost is on a given fuel type, and run a few psi beneath that for safety.

[assAssasin]

no its cool your not discouraging me and i really appreciate the advise, alot of people do seem to talk out there a** on things they do not know about, like telling somebody they should do this that and the other thing and a month later BOOM, so i can really appreciate somebody like you giving me a piece of advise that would be wise for anyone building their motor up to know. thanks

[vulcanrush]

2.5'' intercooler's, 3'' exhausts, msp's, ebc, it's not cheap
and there are things like bde vtc intake cam gears (575 bucks+ for adjustable ones), ati dampers (450 bucks+).
my dd right now is 280hp to the crank, so i think 400rwhp is plenty fast for me.
plus the faster it goes, i think the more problems it presents....like fuel management, you have to get tires more often, etc.

also, i'm not an expert at all, but i'm just learning through a build of my own, the engine is almost done, will be installing it.

[assAssasin]

ya this car is def getting expensive real quick, but its def going to be worth it when its done. i just cant wait to drive it. what year is yours

[vulcanrush]

1993 na conversion to tt.

[assAssasin]

is there anything you recomend i do or should know for the install for my swap

[vulcanrush]

is there anything you recomend i do or should know for the install for my swap

get the 120k pack from ipp with the rameyz idler studs (pretty cheap insurance)....http://www.importpartspro.com/raz30upidst.html
i'm sure more will come to my mind as i remember.
and for sure, don't run more than 18-psi on 93-octane (without methanol injection), i'm probably going to run 15-psi at most, but i'm pretty conservative. until you can get a dyno tune, turn the boost down. get new-style fuel injectors, nismo740cc's etc.

[Z31toZ32]

great conversation here. one thing i was wondering about is the street-ability of the gt675s... im hoping to put down 400 this spring when i bust my z out, but my longer term plans include popping on some bigger turbos so i can hit 500. davis recommends the 675s because you can hit 500 (not a dyno queen 500 with race gas, but on tap all day every day) or maybe slightly more on the stock internals at a 93 octane safe 18psi. im wondering if anyone has any input on how much fun the 675s are on the street? im fearing the turbo lag and lower street power in the reasonable rpms.

[vulcanrush]

your z1 intercoolers might be a limiting factor, i think?

[assAssasin]

i did buy a 120 pack, and let me say this what took me days to do with a motor in the car took me hours with it out. i completely stripped the motor down yesterday in about 1 and a half hours lol. no busted knuckles either haha

[vulcanrush]

im also trying to decide on the cam shafts. lightened pulleys and various other crap. please give me some input on what to do

i got jwt500 cams, and also instead of lightened pulleys, i got the ati race damper (it's lightened too, but it's really a harmonic damper).

[assAssasin]

nice, what do you think about the cams ? how are they through the rpms

[vulcanrush]

nice, what do you think about the cams ? how are they through the rpms

my engine isn't running yet, still being rebuilt....i've heard the jwt400 and jwt400+ cams are too mild, not really an upgrade from stock.
the more crazy cams (tomei, jwt solid lifters, etc.) are just too much work (or sounded like too much work for me), so i went with the jwt500's.

[assAssasin]

lol i was feeling the same thing about the higher cams, but im glad you said that bc i thought the 500's needed the solid lifters springs and adapters also. how long have you been rebuilding

[vulcanrush]

ugh, for a year+.
wasted a lot of money, but i also learned a lot.
the best piece of advice i can give you is, get an engine from kyle at ipp, takes all the guesswork out of it.