Ideal Ignition timing , for a Nistuned GT35 1bar boost on a 7.8 to 1 bottom end

From the tuners I spoke to, it behaves very similar to the rb30et… so any tuner familiar with that should have no trouble

no real responses ehh? I am also looking for some timing map ideas as well.. Though compared to my maps and reading you are running a bit excessive on the retard side. I have always been advised to try not to go under 13 as it starts to cost you power/efficiency. you can run a full 20-25 deg fo quite a ways up rwithout retarding so dramatically with good fuel. DO you have a WIDEBAND O2? The way we have tuned on the street is set our max boost say 15psi and drive the car around doing some runs watching the 02 meter then kept adding fuel to it until it was nearly pig rich around the 12.7ish then go back and add ignition timing "advance" until either det occurs or the meter reads at desired AFR.

IF i recall correctly the vg30 doesn't reach Peak pressure until right at 14-15degrees after TDC due to combustion chamber design and modern fuel changes. Thats why we can advance the timing out so far on the N/A engines. High octane fuel would extend that out a tad more.

It is safe to say you can easily add ~4 degrees in the lower ranges and 2 on the top. I always run pretty advanced up to 5psi to spool up quicker then retard. as my map sensor I can adjust every PSI of boost to a set timing. But I strongly suggest getting a wideband pouring fuel down its throat and adding timing. this keeps it to adjusting 1 variable at a time. I dont have picture of my maps sorry. and I am resinstalling my stand alone in a new car so it will be a week or 2 as i need monies.

What the guy above me and ge said. L28 engines are similar as well. Best thing you can do is build yourself a det can. Old school copper tube style or electronic. Choice is yours. When you hear light knock, back off timing a degree or 2 and leave it alone if the afr is where it needs to be. That's the rule of thumb i've always been taught. Everyone's map is gonna be different.

L engines have horrible combustion chambers and non-crossflow design. You can run a crap more timing and compression on RB30E(T) and VG3xE(T) heads without issues than you can with Ls.

Yep Tech Edge Wideband, and usb consult Nistuned.


Interesting, I was under the impression in the 10 AFR's was pig rich and that around 11.5's were ideal for around full boost pressure. It sounds like the fueling side of it is safe enough to leave alone for the minute, and to start adding some timing up to around 5psi of boost.

With the GT35 it always made the boost pressure nice and early but it felt lazy until about 10psi. In general terms above 4000rpm always felt really strong. So I'm not familiar with these old school det cans.

Since I posted this i have pulled the car down for tube manifolds and a 600x300 inter cooler with associated piping. I am hoping that with more timing and less back pressure i can really make some power.

Cheers, James

Most power will be had at high 12's as they precede the boost ramp with extra fuel then… the only reason to touch 11's is for extra chamber cooling, useful if you haven't got your timing right or your intercooler isn't as effective as it needs to be

Listen to G-E. He's right on the money.

As far as det cans go, electronic will give you an unmistakable sound once you start knocking.

Electronic (diy modified mechanic's stethoscope)

http://www.youtube.com/watch?v=t4mZ2FMLC4A[/video]]

What it sounds like

http://www.youtube.com/watch?v=GGJZ6kKzLus[/video]]


The copper style sounds like bb's bouncing around inside the tube. Just keep advancing to where you are BARELY hearing knock then go 1-2* under the knock limit. Add fuel if you need it. Timing will change afr. Still fairly new to tuning these motors but the basics apply to all engines....unless you're rotary. Any knock is bad. In boost that spells end game more often than not. I run a very paranoid 15* base timing on my 10:1 vg30et. Max advance at low boost at 6800rpm is something like 25-26*. Lol.

I would NOT tune a turbo car for AFRs in the mid 12s at peak boost prrssure. That will be a recipe for disaster I can assure it.

you should be in the 11.5-11.0 range in boost wot. Part throttle, 12's are acceptable.


we should have a stickied map sharing thread with rules/guidelines posted.

I agree with what they say, sounds like your on the right track. I said 12.7 though i may have ment 11.7, it has been 5-6 years since i last tuned an engine. but i remember something about 12.7 pretty vividly, maybe i was having DET at 12.7 been a while. either way you can add some timing just keep watching your afr, it likely feels sluggish because of the amount of retard. you are better off advancing your timing and adding more fuel then retarding your timing, to an extent of course its give and take.