Jump to content
SAU Community

Recommended Posts

  • Replies 51
  • Created
  • Last Reply

Top Posters In This Topic

JAS-25T, If you want to increase the boost my first suggestion is to regap your spark plugs to 0.8mm. Doing this with the standard ECU should allow you to run about 10-11psi. After that, as others have already mentioned, "overboost protection" sets in and misfire problems occur.  

I upped the boost with a bleeder (to about 9psi) and ran into misfire problems above 4500rpm. I then regapped my spark plugs and could run 10-11psi without it being an issue. However, the real gains from the boost increase were noticed once I got a hold of a chipped ECU which has far better ignition timing than standard. Boost comes on earlier, more midrange responsiveness, and redline is acheived quicker. I can now also up the boost until the turbo goes bang :( I'm currently running 13psi.  

Regapping the spark plugs to 0.8mm can help (and is cheap i.e. $0) but better engine management is the real key.... if only the stock ECU could be reprogrammed....

this is the exact kind of answer i was looking for

thank you very much

Hi GTRman1992, sorry for the sarcasm, I couldn't resist it.

I have never tuned a Skyline that gained less than 20 rwkw (average from 4,000 rpm to 7,00 rpm) from correcting the A/F ratios and optimising the ignition timing. The more modified the car, the higher the gains from tuning. Thus far, my highest ever increase in average power from tuning alone (ie; no extra boost) was 150 rwkw. Your car would fall somewhere in between, looking at the mods you鈥檝e listed between 30 to 40 rwkw would be my guess.

As for which ECU, standard or aftermarket it really depends on the quality of the tuner and whether or not your are going to do more mods. If you have finished upgrading then a good tuner will be able to extract the max from the standard ECU for around $800. If you have more mods to go then it will cost $350 to $450 every time it needs a retune.

In that case it would be cheaper to go for an aftermarket ECU (my recommendation would be a Power FC), cost around $1100 plus tuning $200 to $300. As you can see you get the extra expenditure back pretty fast if you have a plan of further, ongoing mods.

Hope that helps

Thanks for that SydneyKid, finally a definitive answer on the subject!

All I'm really planning to add to the car is bigger injectors (550cc to 600cc), a 600x300x97 intercooler, better intake plumbing to the air box some adjustable CAM gears (an article in ZOOM claimed 20rwkw without loss anywhere in power band - they had dyno prints).

All I'm after is around 600HP at the flywheel.

Oh yea, I also plan on adding my direct port, 3D mapped water/methanol injection system once I build it. I'm thinking of using it to get more aggressive timing as I think 20psi boost is heaps.

Hi GTRman1992, it is not really an issue of how much boost, but rather one of how much efficient (not overheated) airflow. I haven't seen anywhere near 600 bhp from a pair of turbine only, upgraded standard GTR turbos. Around 550 bhp seems to be their limit. With set of N1 (or LM) internals, they are OK for a bit over 600 (625) bhp.

Most I have ever seen out of adjustable cam pulleys only, was 40 rwkw, max at one rpm point. I didn't work out the average, unfortunately.

Hope that helps some more.

Ok, I thought more boost = less engine life. So you say more boost as long as air temp is ok. Interesting. Maybe I can aim for my original 23psi - 25psi limit.

My turbo's have an interesting background. They are genuine ex-gibson units. Back when the GTR was banned from racing, Gibson motorsport had an action and unloaded all their stuff, anyway someone I know bought a set of turbos and put then away for a special day. That day never came and he offered them to me. I had them rebuilt etc. So they should be good for 600HP at 23psi boost as that is what I think Gibson was running.

The article on the CAMS said 4deg retard on exhaust and 2deg advance on the inlet was ideal.

can i pull back this very technical (for me) thread with a biasic question? (lol)...

If i wanna take my r32 gtst from stock (10psi) to say about 14psi... what would you suggest (ps i have a BUDGET)...

I was thinking AVC-R + AFC?

or should i get a chipped ecu?

who can chip them in syd? or should i get one from a wreckers?.... doh! i'm losing myself now..... lol

Nah, i'll be putting on a nice FMIC first... but i don wanna use a bleed valve 'cause i don't want all that boost spike and crap, i want it done properly.... and when i said budget, i just meant i can't afoord a worked GTR running 20PSI like some (i think thats a strong case of jealosy there)....

riggaP:... from what i understand (please correct my errors), bleeders 'trick' the car into thinking it's still running 10psi while it's actually running, say, 12 etc.... I just don't trust something that is tricking my car... i'd prefer the car to know it was running 12psi.... sounds stupid but i'm sure you can understand what i'm tryin to say.... can you elaborate on this?... thanks.

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

    • Well, after the full circus this week (new gearbag, 14 psi actuator on, injectors and AFM upgraded, and.....turbo repair) the diagnosis on the wastegate is in. It was broken. It was broken in a really strange way. The weld that holds the lever arm onto the wastegate flapper shaft broke. Broke completely, but broke in such a way that it could go back together in the "correct" position, or it could rearrange itself somewhere else along the fracture plane and sit with the flapper not parallel to the lever. So, who knows how and when exactly what happened? No-one will ever know. Was it broken like this the first time it spat the circlip and wedged itself deep into the dump? Or was it only broken when I tried to pry it back into place? (I didn't try that hard, but who knows?). Or did it break first? Or did it break between the first and second event of wierdness? Meh. It doesn't matter now. It is welded back together. And it is now held closed by a 14 psi actuator, so...the car has been tuned with the supporting mods (and the order of operations there is that the supporting mods and dyno needed to be able to be done first before adding boost, because it was pinging on <<14 psi with the new turbo with only a 6 psi actuator). And then tuned up a bit, and with the boost controller turned off throughout that process. So it was only running WG pressure and so only hit about 15-16 psi. The turbo is still ever so slightly lazier than might be preferred - like it is still a bit on the big side for the engine. I haven't tested it on the road properly in any way - just driven it around in traffic for a half hour or so. But it is like chalk and cheese compared to what it was. Between dyno numbers and driving feedback: It makes 100 kW at 3k rpm, which is OK, could be better. That's stock 2JZ territory, or RB20 with G series 550. It actually starts building boost from 2k, which is certainly better than it did recently (with all the WG flapper bullshit). Although it's hard to remember what it was like prior to all that - it certainly seems much, much better. And that makes sense, given the WG was probably starting to blow open at anything above about 3 psi anyway (with the 6 psi actuator). It doesn't really get to "full boost" (say 16 psi) until >>4k rpm. I am hopeful that this is a feature of the lack of boost controller keeping boost pressure off the actuator, because it was turned off for the dyno and off for the drives afterward. There's more to be found here, I'm sure. It made 230 rwkW at not a lot more than 6k and held it to over 7k, so there seems to be plenty of potential to get it up to 250-260rwkW with 18 psi or so, which would be a decent effort, considering the stock sized turbo inlet pipework and AFM, and the return flow cooler. According to Tao, those things should definitely put a bit of a limit on it by that sort of number. I must stress that I have not opened the throttle 100% on the road yet - well, at least not 100% and allowed it to wind all the way up. It'll have to wait until some reasonable opportunity. I'm quite looking forward to that - it feels massively better than it has in a loooong time. It's back to its old self, plus about 20% extra powers over the best it ever did before. I'm going to get the boost controller set up to maximise spool and settle at no more than ~17 psi (for now) and then go back on the dyno to see what we can squeeze out of it. There is other interesting news too. I put together a replacement tube to fit the R35 AFM in the stock location. This is the first time the tuner has worked with one, because anyone else he has tuned for has gone from Z32 territory to aftermarket ECU. No-one has ever wanted to stay Nistuned and do what I've done. Anyway, his feedback is that the R35 AFM is super super super responsive. Tiny little changes in throttle position or load turn up immediately as a cell change on the maps. Way, way more responsive than any of the old skool AFMs. Makes it quite diffifult to tune as you have to stay right on top of that so you don't wander off the cell you wanted to tune. But it certainly seems to help with real world throttle response. That's hard to separate from all the other things that changed, but the "pedal feel" is certainly crisp.
    • I'm a bit confused by this post, so I'll address the bit I understand lol.  Use an air compressor and blow away the guide coat sanding residue. All the better if you have a moisture trap for your compressor. You'd want to do this a few times as you sand the area, you wouldn't for example sand the entire area till you think its perfect and then 'confirm' that is it by blowing away the guide coat residue.  Sand the area, blow away the guide coat residue, inspect the panel, back to sanding... rinse and repeat. 
    • The detail level is about right for the money they charge for the full kit... AU$21.00 each issue, 110 issues for a total of $2,300 (I mentioned $2.2K in the first post when the exchange rate was better). $20/week is doable... 馃槓
    • If planning on joining us for the day(s) please indicate by filling in this form. https://forms.gle/Ma8Nn4DzYVA8uDHg7
  • Create New...