Sydneykid

What you are describing is closed loop tuning, or Self Tune as it is called in Motec and Autronic speak. You set an A/F ratio target and the ECU self adjusts until it achieves that target. For example you pick 12 to 1 A/F ratio and the ECU merrily goes off and tunes to that A/F ratio as you drive around. It is surprisingly quick, I saw Ken Douglas (ex Motec GM) tune a production Mazda in 2 laps of Bathurst using self tune. The problem is the engine will not produce its best power at 12 to 1 A/F ratio at all rpm ranges, sometimes it needs 11.8, 11.9 or 12.1 to produce the most power. What you are aiming for is a smooth power curve, not a smooth A/F ratio. To achieve that you need a dyno. What I have been doing for a few years now is tuning on the road (and/or track) then going to the dyno and tidying up. Whether I use self tune or not, I always find (actually Dyno Dave always finds) a few more horsepower on the dyno. Check out the Tech Edge thread for more details cheers

That’s exactly the problem, think about this question; I had the standard turbo at 10 psi with no “boost cut”, why do I get “boost cut” at 10 psi with my new (larger) turbo? Well that’ because it’s not boost that is the problem, it is excessive airflow. The new (larger) turbo flows more air at 10 psi than the standard turbo. The only fix is an AFM voltage bender, rechip (if possible) or aftermarket ECU. But everyone told me it was “boost cut”, so I spent all my money buying a new turbo to I could make more power at the same boost and not get “boost cut”. I don’t have any money left to buy an ECU………….. Do a search I will bet you find 50 posts with exactly that problem of misunderstanding. Which is simply avoided by using the correct terminology. cheers

The 180 kph speed limiter is also a problem in 4th gear for cars with standard ECU's. cheers

All that means is instead of wearing the tyres out fast only on the inside, it wears out the whole tread fast. It’s a band aid, the proper answer is to fix the excessive camber cheers

Nope, just program the speed camera, if there is a car in front doing the same speed, then the car behind has no choice. Hence no infringement notice issued. Only the first car in the traffic jam gets booked. cheers

Don't ignore suspension set up in the quest for traction. Excessively hard rear springs, too much negative camber and sloppy rear subframe bushes certainly don't help. cheers

The problem is when someone is told it is a “boost cut” problem the first thing they think is there is some hard and fast boost limit that they can’t exceed. Then we get silly stuff like; 1. I have been told I can run 1 bar before I will get “boost cut”, is that OK? 2. My mate runs 12 psi and doesn’t get “boost cut” and I run 11 psi and get “boost cut”, why ? 3. Something is wrong with my engine I get “boost cut” at 10 psi ? 4. GTR’s don’t get "boost cut" until 1.1 bar, so why do GTST’s get "boost cut" at 11 psi ? and 100 more equally wrong questions per week, every week. The reality is we need to get people on SAU talking about excessive airflow, boost is irrelevant. So if the regular posters don’t use “boost cut” and use the correct terminology then eventually we won’t have to spend time writing explanations as to what it really is and why boost is irelevant cheers

Then we should have a minimum speed limit as well as a maximum. cheers

Genuine or copy? cheers

You need to talk to your EMS tuner, as to how he wants to control the idle rpm. The standard RB20/25 throttle body closes completely. So the standard ECU (and Power FC) controls the idle rpm by opening and closing various valves that bypass the throttle body. So when it is cold the ECU advances the ignition, richens up the A/F ratios and increases the airflow into the engine to increase the base rpm and give stable idle. Similarly, when the engine is up to operating temperature, the ECU increases the airflow into the engine to increase the rpm for air conditioning, power steering and electrical load. I haven’t studied the idle control circuitry in great detail, but my simplistic understanding is the ECU open up various different sized valves depending on the idle speed demand for air flow. This is different to many other engines that use a stepper motor to open the throttle butterfly to achieve the airflow changes required. The EMS’s that I have dealt with don’t have the feature of staged valve openings to control idle to a number of preset rpm's. So the tuners tend to use a throttle stop to hold the throttle butterfly open, then use A/F ratios and ignition retard/advance to achieve idle stability, hot or cold. So talking to your tuner is always first on the list when looking at idle speed control cheers

What's the front grill? Looks good. cheers

The common solution is to use a throttle stop on the XF throttle body to control the idle rpm and piss off all of the ECU controlled idle speed hardware. cheers

Torque is multiplied though the gearbox ratios and the diff ratios when running on a dyno. Hence not comparable to engine torque quoted by manufacturers. cheers

What throtte body are you using? cheers

Boost cut = 2 words “boost” and “cut” Boost = The R33GTST ECU has no idea what boost the engine is receiving, it doesn’t do anything about boost, it doesn’t care. Cut = reduce to zero Reduce what to zero? Fuel, nope the ECU doesn’t do that Ignition, nope the ECU doesn’t do that either. What you are describing is excessive airflow as sensed by the AFM. When the ECU sees excessive airflow for the rpm and throttle opening it moves to Rich and Retarded mapping. This is done to protect the engine from what the ECU thinks are faulty sensor reading. Either the TPS or the rpm sensor or the AFM (or all three) are reading incorrectly based on the ECU’s programming. Note the words used “When the ECU sees excessive airflow for the rpm and throttle opening its moves to rich and retarded mapping.” That is why you get a drop in power (R&R mapping) just after the boost has peaked. This goes on for a few hundred RPM, then the sensor readings (the TPS, rpm sensor and AFM) start to line up again. So the ECU returns to more normal (non R&R) mapping. This is even more proof that there is no such thing as “boost cut”, otherwise it would stay “cut” for as long as the boost was high. But it doesn’t. Repeat after me; There is no such thing as boost cut…………. cheers

450 bhp = 336 kw – 70 kw for drivetrain and roller losses (Dyno Dynamics) = 266 rwkw cheers

Glad you bought that point up, traffic determines speed limits, interesting………… If that is the case, shouldn’t a road with a 60 kph speed limit in peak hour have a higher speed limit outside peak hour? cheers

Don't know, never tried it. I do know 2 bar, 9.0 to 1 and Shell Optimax Extreme 100 ron is not a problem. cheers

ECU rich and retard mapping due to excessive airflow as sensed by the AFM. cheers PS, write 50 times......... There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut There is no such thing as boost cut

So what determines the speed limit? It can’t be stopping distance, otherwise why does a 2.5 tonne Land Cruiser have the right to do the same speed as I do, in a car that weighs less than half that, with twice the braking performance? It can’t be manoeuvrability, for exactly the same reason. It can’t be maintenance, I bet my cars are maintained far above the average land Cruiser. The issue is the reality that everyone knows, some drivers and cars are safer at 100 kph than some other drivers and cars at 60 kph. That’s a fact, but there is no method that recognises it. The speed camera still goes flash at 60 kph, no matter what I am driving, how well my car is maintained or how good a driver I am. So I am constrained to the same ridiculously low speed limits because me and my car are being judged by the lowest common denominator. cheers

There's a problem, what does "speeding" actually mean? Is it simply driving over the speed limit? No, I don't think so Because sometimes the speed limit is too high for the conditions (eg; fog) Many accidents are put down to "speeding" even though the vehicle was no being driven in excess of the speed limit. So the "authorities" even admit that "speeding" is not simply driving over the speed limit. So, does the converse apply?" Exceeding the speed limit is not "speeding" The "authoriites" have admitted that some roads have lower than necessary speed limits. Think of the statistics, more than 50% of all accidents happen at less than 20kph (ie; the average is, if I remember rightly, 18 kph). So doing more than 20 kph could be considered safer than driving at less than 20 kph. (ie; less accidents happen at more than 20 kph). Lastly, the safest road in the world for distance travelled over time is the Autobarn which has no maximum speed limit. But it does have minimum speed limits. Excessive speed for the conditions is the real problem, not doing more than the speed limit. Something to think about cheers

Turbos on the wrong side cheers

I don't work for GCG, I really have no idea what they do, I have never asked and they probably wouldn't tell me even if I did ask. Theirs seems to be the most respected of the high flows, there are probably many competitors out their who would like to know what GCG do. Does it really matter? It's a ball bearing core, obviously very effective, I have never heard of one failing. It bolts onto everything exactly as the standard turbo does. There must be at least 30 pople on here that have used GCG ball bearing high flows and they all bolted them straight on. If you look at the dyno results you will find 10 or so guys have posted up their results. So it fits, it's reliable, it produces the power and it costs $1750. Sounds like a pretty safe Group Buy to me. cheers PS, if you want t to know more, please give GCG a call on 02 9708 2122.

So what, how much ignition timing have they pulled out of it? How rich are they running it? What's the average power? What's the response like? In the US they chase the max horsepower number, they don't care about anything else cheers