Jump to content
SAU Community

Recommended Posts

Hey guys I have been on this page for a little while but only used it for a reference sort of thing. But now I thought I would try my luck asking a question. I recently got my 33 gtst tuned and it has a flat spot in power curve. I basically just want to see if someone has had a similar problem and what they did to resolve it.


Mods are.

•Haltech platinum pro plugin.

•Hypergear atr43g3 on standard exh mani

•Nismo 740cc injectors

•Ebay intercooler kit

•3" bellmouth single piece dump pipe to 3" delete pipe and steps up to 4" before rear muffler.

•Standard plenum

•3" intake to pod filter and 2.5" cooler piping.

•Tomei fpr


Car makes 255.7rwkw on 20psi with bp98 which seems low compared to other peoples results.


Have checked for boost leaks with none found.

Tuner said that he thinks restriction is exhaust manifold but have heard of standard ones still getting 300kw etc.


Has anyone had something similar?


Regards Spencer

post-104841-0-31871700-1384330400_thumb.jpg

Link to comment
https://www.sau.com.au/forums/topic/434952-flat-spot-in-power-curve/
Share on other sites

Na I didnt drop the exhaust because I was pretty confident it wasn't a restriction at the time. Might do it once I get it back on the dyno after I change induction pipe to 4" and maybe see if there is a pressure drop through intercooler

I have seen over 400kw through a 3 inch intake too, infact the 430kw 33 had a Z32 afm... No point going bigger than the AFM unless you ditch it and go MAP sensor.

Just looking at the graph, it seems you are missing a chunk of boost in the midrange, did you get a boost plot by chance?

  On 13/11/2013 at 10:53 AM, superben said:

That is a whack result. Scottynm35 has seen huge power through stock mani, Not sure what your issue is, many things to check but I hope you can get it sorted out.

E85 is a hell of a thing. Can't compare a car which is tuned on petrol with one which is tuned on ethanol - the nastiness which is the stock manifold gets covered up a bit if using a very knock resistant fuel.

E85 coveres up 200kw... Yeh right. :P

Anyway, 250 isn't it's limit surely, not to mention, where is his midrange? It either has no boost in the midrange, or no timing, probably due to a big restriction somewhere. Cam timing?

Did I mention my closed 1.5 inch Varex exhaust makes more than 250? ;)

I wasn't referring to the 250kw thing specifically - so much as how ridiculous comparing a big turbo high octane combination with a small turbo pump gas setup... there is an issue there, but mentioning a 400+kw ethanol setup is probably not being helpful for perspective.

  On 13/11/2013 at 11:17 PM, Lithium said:

I wasn't referring to the 250kw thing specifically - so much as how ridiculous comparing a big turbo high octane combination with a small turbo pump gas setup... there is an issue there, but mentioning a 400+kw ethanol setup is probably not being helpful for perspective.

It proves the standard manifold can flow a lot more than the power he is making. Many people (myself included) have made much more than 250kw through standard manifolds on 98. Why argue against scottys valid point that in this case manifold flow is not the restriction?

  On 15/11/2013 at 11:08 AM, mark33gtst said:

It proves the standard manifold can flow a lot more than the power he is making. Many people (myself included) have made much more than 250kw through standard manifolds on 98. Why argue against scottys valid point that in this case manifold flow is not the restriction?

Because I was bored at home with manflu and brain wasn't working very well - my bad! Forgot I even posted that. There is clearly an issue that isn't the exhaust manifold causing it.

post-104841-0-53226600-1384589445_thumb.jpgI changed my induction pipe to solid 4 inch yesterday instead of it stepping down to 3 inch. Tuner is going to print me out a picture of boost plot so will show that when I get it. Also going to change actuator to 14psi and run an eboost street to have high and low boost and get retuned.

Here is a photo of my timing map

That timing map is pretty average. Looks like a huge reduction at around 5krpm-20psi drops like 3-5deg then back up at 6k. I'd imagine that'd feel pretty flat through there.

Did the tuner say anything about the engine wanting to knock?

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


  • Similar Content

  • Latest Posts

    • Hi all,   long time listener, first time caller   i was wondering if anyone can help me identify a transistor on the climate control unit board that decided to fry itself   I've circled it in the attached photo   any help would be appreciated
    • I mean, I got two VASS engineers to refuse to cert my own coilovers stating those very laws. Appendix B makes it pretty clear what it considers 'Variable Suspension' to be. In my lived experience they can't certify something that isn't actually in the list as something that requires certification. In the VASS engineering checklist they have to complete (LS3/NCOP11) and sign on there is nothing there. All the references inside NCOP11 state that if it's variable by the driver that height needs to maintain 100mm while the car is in motion. It states the car is lowered lowering blocks and other types of things are acceptable. Dialling out a shock is about as 'user adjustable' as changing any other suspension component lol. I wanted to have it signed off to dissuade HWP and RWC testers to state the suspension is legal to avoid having this discussion with them. The real problem is that Police and RWC/Pink/Blue slip people will say it needs engineering, and the engineers will state it doesn't need engineering. It is hugely irritating when aforementioned people get all "i know the rules mate feck off" when they don't, and the actual engineers are pleasant as all hell and do know the rules. Cars failing RWC for things that aren't listed in the RWC requirements is another thing here entirely!
    • I don't. I mean, mine's not a GTR, but it is a 32 with a lot of GTR stuff on it. But regardless, I typically buy from local suppliers. Getting stuff from Japan is seldom worth the pain. Buying from RHDJapan usually ends up in the final total of your basket being about double what you thought it would be, after all the bullshit fees and such are added on.
    • The hydrocarbon component of E10 can be shittier, and is in fact, shittier, than that used in normal 91RON fuel. That's because the octane boost provided by the ethanol allows them to use stuff that doesn't make the grade without the help. The 1c/L saving typically available on E10 is going to be massively overridden by the increased consumption caused by the ethanol and the crappier HC (ie the HCs will be less dense, meaning that there will definitely be less energy per unit volume than for more dense HCs). That is one of the reasons why P98 will return better fuel consumption than 91 does, even with the ignition timing completely fixed. There is more energy per unit volume because the HCs used in 98 are higher density than in the lawnmower fuel.
    • No, I'd suggest that that is the checklist for pneumatic/hydraulic adjustable systems. I would say, based on my years of reading and complying with Australian Standards and similar regulations, that the narrow interpretation of Clause 3.2 b would be the preferred/expected/intended one, by the author, and those using the standard. Wishful thinking need not apply.
×
×
  • Create New...