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Hi Guys,

I just thought I'd share my little journey with my R34 and the new exhaust I bought for it. I had a little problem, got it sorted, all is good... although I'm thinking I want more! (the bug has bitten again). Enjoy and I hope it might help one of you out there!

David.

Started with:

R34 GTt 1999

Stock with Nismo option exhaust (with Exhaust Control Valve)

K&N Panel Filter

No base power run, but I suspect I had a bit more power over stock as I had the Nismo option exhaust (which I believe is much better than stock stock but not as good as a full 3" system).

Added:

Bosimporting (BATMBL) Split front/dump pipe (stainless)

CATCO High flow cat (small)

Custom 3" cat back with Magnaflow muffler and resonator (Waverley Exhausts)

Observations:

More power

More boost

Boosting earlier

Louder - should fit middle muffler as I prefer a quieter car

Car misfiring/hesitating at 4000-5000rpm

Suspected coil packs after reading the forums

Corrective action:

Regaped spark plugs to 0.8mm - suggested by Ray from RE Customs

Removed misfire/hesitation

Dynoed:

Discovered big dip in power curve possibly due to ECU engine retartation,

Found boost was too high after new exhaust

Corrective action:

Reduced boost (by restrictor)

Dynoed again:

Nicer power curve without big dip, although less down low

Max power 164.7rwkw (RE Custom Dyno Dynamics, warm day 28 degrees)

Air/fuel not too bad, but room for improvement

Final thoughts:

I was really enjoying the car (below 4500rpm) prior to correcting the issue. If the 'before' power curve went all the way I'm guessing it would have reached a maximum of ~185rwkw. Obviously driving the car at those boost levels was unsafe and would reduce the life of my turbo/engine. If I want to have this type of power day in day out then I need to think about more modifications.

I'm considering an Intercooler and Power FC. This would be more power than I think I want however I'm thinking I'd be unhappy with the type of power curve an Intercooler alone would give me (i.e. running too rich, driveablity, etc) and Power FC alone probably wouldn't get me to where I want to be. I also think a SAFC wouldn't quite give me what I'm after. I'd say I'd be happy with manual methods of adjusting boost as long as the curve can be held reasonably steady (like it is now - see graph).

One Nismo option exhaust in great condition (less than 30,000kms) soon to be for sale!

post-518-1158716178.jpg

post-518-1158716205.jpg

Edited by McCracken
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https://www.sau.com.au/forums/topic/135049-r34-gtt-full-exhaust-mod-1647rwkw/
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i've done the exhaust too, turbo back which increased the boost but i haven't experienced any misfire, going to change the plugs this weekend but as far i know there still the stock (1.1) gap ones. how did you restict the boost btw?

ah, yeah i might invest in one of those electronic types. btw, did your turbo make loud, almost like grinding plastic gear noises when you gun it after the splitdump/front pipe install?

Ummm... it's always had this 'whistling' noise on boost. Even from stock. Like a really quiet 'Whizzzzeeee', like an electric engine would make. I think it's different from what you described.

Personally, I'm only going to bother with an EBC if I must (i.e. boost all over the place).

Edited by McCracken

it makes that vacumm cleaner like noise at low/mid acceleration however, having an auto, when i kicks down and the revs shoot up it makes that noise similar to a supercharger belt. turbo still makes boost so i guess its ok...

Any other GTt owners gone the path of the full exhaust + Power FC with stock intercooler?

What sort of power would this get? Would I reach 180rwkw?

I know of a R33 GTS25t with a full exhaust + Power FC + AVC-R + stock cooler getting 175rwkw on the same dyno I did my 165rwkw.

I know it will mean an extra tune session if I do go up to a FMIC later on, but going FMIC + Power FC (over 200rwkw) will also mean buying a new clutch and perhaps other expensive issues - and considering I don't really want that sort of power anyway...? (well, yet).

Pretty much the same kind of mods and same power figure. I never had any misfire though.

Only thing different is I have a small flat spot around 5000rpm.

I am in exactly the same boat as you, a little moer power wanted without the extra hassles.

I think running a elec boost controller would be good to bring on boost earlier and bypass the factory 2 stage boost control. I believe our SMICs are fine up to around 200rwkw, might stuffer a little during summer though.

I might head for the SAFC route as its cheaper, easier to tune, and for a max power figure of 200rwkw I think it is fine. I wont be chasing any more than this.

Hehe, yeah, it's pretty rude! The tuner said the new exhaust is just flowing so damn well the turbo boosted waaay too much. You can see the boost graph on the charts... it got up to 12psi at it peak and was reduced to 9psi (is this too conservative?).

200rwkw with stock cooler!?!? What sort of boost levels? If so, that's awesome. That's exactly what I want. I just want the odd squirt, not race-track 'lap after lap' performance, so I don't think heat soak is an issue for me.

I really didn't think you'd get that power without extra boost, and that I shouldn't boost more than I am without cooler air. If I can get that power on around 9psi via better ECU tuning that's exactly what I want - my idea of working smarter rather than harder.

Would the S-AFC really get there without being able to control IGN? I thought there was a lot to gain in the ignition.

Edited by McCracken

The best back for your buck is most certainly the PowerFC.

you wont make much extra power just by fitting the FMIC.

Fitting the PowerFC will allow you to pick up upwards of around 20-30 kw, plus allow you to eliminate the Rich and Retard of th stock computer.

Hence allowing you to make the power on the boost you are running.

I made 200rwkw with 11psi, stock dump, aftermarket front, highflow cat, PowerFC with boost controller.

One thing. I can deduce from my dyno graphs that a 9psi -> 12psi boost increase will give me a max power increase of around 20rwkw alone. So, in going from 165 up to 200, the boost increase from 9psi -> 11psi would probably account for 13 of those kw (I know this isn't exact science, just my dodgy maths).

11psi would only be safely achieveable with a FMIC, so yeah, it looks like the Power FC is the best bang for buck. If I could reach 190rwkw or higher and have great driveability with a Power FC, stock cooler, full exhaust, panel filter, no EBC and still run say 9psi I'd be very happy.

What would happen if I was driving around on a hot day with the stock cooler and Power FC? Would it just run slightly worse (like it would today) or are there issues with knocking/engine damage as all of those stock 'engine protection things' like rich and retard are no longer there? I'm looking through the Power FC FAQ but it's assuming a FMIC be in place to start.

Nah, best to get the PowerFC first.

You will eventually buy the FMIC, don't kid yourself that you wont, cos everybody does :(

You will get much better results from the PowerFC.

Get the FMIC later

would a SAFC2 be a better choice for the auto's? (as in, do enough with it to give it a decent tune) seeing how alot of people say the pfc doesn't work too well with them, hard gear changes or something.

Edited by RyanN
I had 189rwkw with ROM tune, 12psi, standard cooler.

Ahhh cool, so I could expect a similar figure by adding the Power FC. Did you find the heat soak an issue in your daily driving? I mean, could it even be tuned properly (wouldn't the cooler be heat soaked after one run?).

are you looking at a fmic down the track? probably better off getting the fmic at the same time as the powerfc to save 2 tunes

with full exhaust, filter, 10 psi boost and some sort of ecu, you should get what you are aiming for easy

edit: oh, and when i up'd the boost to 10psi, i also had missfire which was quite violent on some days (to the point where the car would just miss from the lights) and non-existant on others. Regapped plugs to 0.8 but didnt do much so got new coils which fixed the problem

Edited by ecl
Regapped plugs to 0.8 but didnt do much so got new coils which fixed the problem

I take it you went the splitfires? Did you try to tape or epoxy them first?

For me the regap and boost reduction for the most has fixed the issue, although I got the enging warning light (code 21 - Ignition) again so this bandaid didn't fix it entirely. Just unsure to bite the bullet and order splitfires or to try the tape/epoxy fix.

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