Jump to content
SAU Community

Loud Bang From Zorst

Tbetts
 Share

Recommended Posts

Tbetts Contributor

Tbetts

Posted
Posted

Hey Guys,

Ok so I'm reasonably new to the jap car seen and need some advice and please forgive the ignorance.

So when my car is under heavy acceleration I get a loud Pop/bang from my exhaust when up shifting in the higher rev ranges 5k+.

The only mods i have done engine wise is a 3inch turbo back stainless steel system with a massive jun-bl cannon on the back courtesy of Exhaust Technology and a Apexi power intake pod.

The Exhaust specs are , 3inch bell mouth dump and front pipe into a 100cell cat (unsure what brand) then to a single mid mount lukey oval muffler and then straight to the Jun-bl Cannon ( dunno actual sizing but it was the biggest one there)

O and by the way the Car is a R34 Gt-t sedan with a trip tonic auto trans. ( i know a trans conversion is on the cards but not right now).

So yeah is this normal it doesn't happen all the time just when its under load and only if i don't take my foot off for the gear change.

Please Help and thank you

Tom.

Link to comment
https://www.sau.com.au/forums/topic/369972-loud-bang-from-zorst/
Share on other sites
GTSBoy Grand Master

GTSBoy

Posted
Posted

He said a "100 cell cat".

Anyway, an upshift backfire is not uncommon on auto Skylines, especially with a big exhaust. Not normally a really loud bang though. Usually just a sexy little pop thud. My R32 used to upshift dead on the rev limiter (while it was still auto) and the sound was the only good thing abotu the auto.

Tbetts Contributor

Tbetts

Posted
  • Author
Posted

He said a "100 cell cat".

Anyway, an upshift backfire is not uncommon on auto Skylines, especially with a big exhaust. Not normally a really loud bang though. Usually just a sexy little pop thud. My R32 used to upshift dead on the rev limiter (while it was still auto) and the sound was the only good thing abotu the auto.

Yeah I was hoping it was just that I googled it before and it's came up with alsorts of stuff about transmission mounts on the way out.

Thanks man

Tbetts Contributor

Tbetts

Posted
  • Author
Posted

there could be a leak in the exhaust system somewhere.. that causes bangs.

Gahh i would hope not i got it less then a month ago lol

And yeah its been there since i have had the new zorst put on But its got louder which i put it down to Carbon build up Still makes me abit nervous.

And with the Ecu that definitely sounds possible it would explain the bang probably needs a re tune soon any way I reckon i will do that After i get my FMIC put on in a week or 2.

Sunkist Grand Master

Sunkist

Posted
Posted

did you re tighten them after it was warm? steel expands bud so things loosen themselves.

also ECU could sound right as when high in the revs you will get an injection pulse when you release the accelerator. i think its to cool down pistons or something but i know it does it

chiksluvit Experienced

chiksluvit

Posted
Posted

ECU on auto skylines retard timing on upshift to protect the gearbox

manual doesnt

retarded timing on 0 load high rpm creates the bang

so its just the ecu, nothing to stress about

anyone who has a power fc in their manual, try changing the timing advance in first row to 0, it'll do the same too, refer to paulr33's PFC FAQ

Tbetts Contributor

Tbetts

Posted
  • Author
Posted

Ok so i checked it out and yes it is the ecu!

Sooo with tax time conveniently placed just around when i need a tune i think i might invest in a EBC, Nistune and have a FMIC already then i just need it all fitted.

Fingers Crossed for 180-200kw at the wheels :banana:

Thanks for the help :thanks:

bubba Grand Master

bubba

Posted
Posted

ECU on auto skylines retard timing on upshift to protect the gearbox

manual doesnt

retarded timing on 0 load high rpm creates the bang

so its just the ecu, nothing to stress about

^^ this.

also ECU could sound right as when high in the revs you will get an injection pulse when you release the accelerator. i think its to cool down pistons or something but i know it does it

^^ not this.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Erelyes
      Ceramic turbine damage to engine - what did yours do?

      By Erelyes · Posted

      Ha, well, it's been.... a bit of a journey. Things have taken much longer than I'd hoped. I'll probably put up a thread at some stage. Hopefully soon. The car's not done any kms since my update in June though, put it that way.
    • Dose Pipe Sutututu
      M35 Aftermarket Fuel Pump

      By Dose Pipe Sutututu · Posted

      Here's the chart for fuel pressure vs. current draw, assuming your base fuel pressure is 3 bar and you run like 0.5bar boost on WOT, you should only momentarily hit 9amps here and there. (Ignore my prev post, I cannot read a chart these days it seems)
    • GTSBoy
      RB25 Drama's

      By GTSBoy · Posted

      Those comp test results are not hideous. Whether they are accurate or not (ie, when that comp tester says 140 psi, is the real pressure120, 140 or 160?) is unknown to us. The state of the battery used to crank it over is unknown, etc etc. Many people around here would say that the absolute values and the spread are perfectly fine to just add boost and keep going. I personally would be happier with a narrower spread than that, but even the diff between 125 and 145 is not terrible. That one cylinder at 125 though, has probably copped some damage relative to the others. You should inspect the valves seeing as you've got it open. Do you know how to measure installed ring gaps? That, and an inspection of the rings themselves, is how you will determine whether they need to be replaced. If you're not good to do these things, take the block and the pistons and rings to a shop that is, and ask them for the go/no-go on them. Do the bores need a hone at all? If so, you might well be justified in getting some different pistons in order to get away from the ring supply problem. Whether you're happy to spend a lot more money right now, on more gear, rather than less money, but an amount that looks stupid given that you will only get a handful of rings in exchange for that money, is for you to decide.
    • iain_ST44GA
      M35 Aftermarket Fuel Pump

      By iain_ST44GA · Posted

      also possibly backed up to my filler and shat down it! 🤣
    • Julsmadrid
      RB25 Drama's

      By Julsmadrid · Posted

      Ok so i would love some advice here please, i purchased an R33 a few months back and its had a few mods done to the engine, its an RB25det running a Master ECU, 1200cc injectors, bigger turbo, oil cooler, oil filter relocation kit, Spool H-beam rods, acl/ross pistons. When i removed the motor from the vehicle (as its getting a respray) i thought i would compression test it and these are the following results. Cylinder 1-145psi, Cylinder 2-143psi, Cylinder 3-125psi, Cylinder 4-145psi, Cylinder 5-140psi, Cylinder 6-135psi this test was done with the motor on the ground and powering up the starter motor. I dropped the sump and found broken oil squirters on cylinder 3,5 and 6. I was told my rings are probably worn so i stripped the motor completely to get a new set of rings for it. The trouble is no one has these rings anywhere and they have to be custom made by Ross over in the states and will cost about $600+$200 delivery. My question is how can i tell if my rings are at fault and if they are still ok and is this price ok for a set of rings?
×
×
  • Create New...