was wondering how many 3rd gens out there are running boose on stock motors and if they hear a light rattle during boost, i went to 91 oct and it went away a little, ive also noticed that it only comes when the engine is hot just wondering what it could be because its driving me crazt, i deffinately know that it is not the turbo(swapped in 3 diff ones) wondering if it could be the spark plugs(ngk for the turbo 300zx) maybee the feul pump its still stock, so now im all out of ideals anything would be appreciated


thanks.

 

are you saying you were using something lower than 91 octane before? that's what that statement implies.

 

pinging maybe

 

i was using 87

what could be the causes of pinging

 

Using 87 octane on a turbo motor.

 

well im using 91 now whch is the highest i can get but its still there

 

How are you controlling your setup? I'm not real familiar with your engine. I know 91 is the best you can do in California. Is your motor stock? It sounds like your getting pinging, which is the same thing as detonation. Your getting pre-ignition of the fuel mixture. How you fix that depends on your setup.

 

Thats sound odd I ran up to 12psi with no pinging on my 3rd gen, but I did have 370cc upgraded fuel pump and 93oct.
WE need more info :
what injectors? how much fuel pressure?
how much boost and from what?

 

everything is stock 84 3000zx stuff, 93 w/block and pistons

injectors
turbo
about 10 psi max
from a nissan 300zx t3
84 turbo heads


i kno that im running high compression and i had an intercooler but San Diego, Californian smog shops are deterred to smog anything with an intercooler if it didnt come stock, so i took it off until i get it smogged(still having trouble finding places with the engine swap)

so if im pre detonating then i shouild retard the timing right?


but the funnt thing is that when im in overdrive (on freeway) its not there as much but when im not in reg mode when the tranny downshifts its there then i let off boost into the vaccum no noise but as soon as i hit 0 boose to starts back up again.

if this is too confusing then ill just take a more detailed vid of it tomorrow and show yalls...

but thoughts would be great

 

heat can cause pinging also, aka summer, aka high intake temps

 

it is hot here, how in the hell do you cool this **** down add a nother radiator?

 

well its not your engine temp thats primarily causeing the knock, and by the way it is definatly knock/detination. I would stop boosting all together until you figure it out. first thing, dont boost unless youve got an intercooler, those turbos are small so right now your just pumping alot of hot air in there... Also.. do you have a wideband on it, if you dont... GET ONE. you need to know your air/fuels. If your any leaner than about 11.5 you need to richen it. If your running a Stock turbo ecu, then you need to make sure your engine is timed to factory turbo specs maybe a bit retard. at idle that is...

The 9:1 SOHC VG can take boost.. alot of it.. BUT!.. only if your air fuels are good (preferably in the 10s), your timing is right and the air going into your engine is cool. I know this from expericence, right now ive 16-17 psi going into my completely stock 9:1 VG.. and its holding it great. this weekend im going to tune it for 18 and go to the track with slicks. I can say it enough.. Rich/ factory turbo timing if not a few degrees retard/ and cool air.. if you cant get those things.... DONT BOOST unless you want to put another engine in..

 

It's the air going into the engine that you have to cool down, not the engine itself. Everything jeremy said above is true. You are detonating from having crappy gas and high IATs. You're going to ruin your motor if you don't fix those IATs and stop that detonation (and never, ever put 87 in that car again, that's just crazy).

 

DETONATION!!!!!!!!! BOOOOOOOOOOMMMMMM

u should never put 87 in a nissan period. why starve ur car of the octane it needs for a few pennys a gallon. your losing out on not only a possible motor, but the higher octane the less knock u get and the more timing ur ecu runs...

 

ok then screw cali im going to put the intercooler back in if they dont understand then oh well, i aint puttin another engine in this **** its to tireing,


thanks for the info maxmaxima91 and it is all factory tuning with the ecu so i guess ill retard it by like 5 and see how it goes

well see what happens orgers thanks for the help

 

I run 87 in my 90 max and 90 240sx. Both have 9:1ish compression and are NA. So go back to reading. 89+ would only hurt performance in my case.

For boost yes, never lower then 91.

Niel- it could be heat soak too. Sitting in traffic and everything is hot for a minuet, and there you go a perfect condition for detonation.

Bigedog- I would put that IC back in there right way! and never boost without it!! That tiny little t3 is just a heat factory with out one. And definitly check your idle engine timing and make sure it matches or is retarted (by 1/2 deg) compared to the turbo car's.

~Alex

 

Also.. Please try and get a wideband on that thing.. you need to know your afrs.. if not AT LEAST up the fuel pressure a little.

Jeremy

 

If I remember correctly, I believe the minimum octane Nissan recommended for the 3rd gen is 89 listed in the owner's manual. I could tell a very noticeable difference between 87 and 89 in mine when it was stock.

 

Or, you can invest in a water/methanol injection kit. I use it as my primary form of cooling. Been like that for bout 7months, no problems.