into the 10's

[Ben D]

Ok, not really into the 10 sec bracket, but solidly into the 10L/100 km zone, a worthy goal for all stagea owners.

Here's the data from my trip to willowbank a couple of weeks ago. Fill up with 98 octane then drive to track, do 4 passes for best of 15.19 at 91.1 mph, then drive home again (sunshine coast), a few days tootling around town then down to Brisbane again, fill up with 57 litres, travelled 533 km. Thats 10.69 L/100 km. The car shows around 175 awkw on the 91.1 mph pass, given it weighs 1800 kg with me and the tow bar. 60fts piss poor 2.3 sec due to auto, the thing would run 14's if it were manual. Couldnt stall it up any more as it would drag you through the lights.

Mods, jaycar digital fuel adjuster, K&N panel filter in stock airbox, aquarium bleed valve and 8 psi boost (spikes to 10 psi on gear changes), split dump, high flow cat and 3 inch mild steel exhaust. Tuned A/F ratios on the road using a wide band. It cruises happily at 15.5:1 AF ratio and I have 12.5: 1 on boost until around 5800 rpm, after which it richens up into the 11.5:1 area. Total cost of mods approx $700 (got the 3" cat back exhaust cheap off Lone).

I rigged up the digital fuel adjuster so I can turn it on and off while driving , which requires inserting a diode into the output signal line to stop the ECU getting feedback when the DFA is turned off. Did one run with the DFA turned off at the drags for a 15.8 at 88 mph. My calcs suggest the Jaycar unit improves fuel economy around 12% and gives 20 hp (approx + 9% ) at the wheels. Neat stuff

[ian]

Ok, not really into the 10 sec bracket, but solidly into the 10L/100 km zone, a worthy goal for all stagea owners.

Here's the data from my trip to willowbank a couple of weeks ago.  Fill up with 98 octane then drive to track, do 4 passes for best of 15.19 at 91.1 mph, then drive home again (sunshine coast), a few days tootling around town then down to Brisbane again, fill up with 57 litres, travelled 533 km.  Thats 10.69 L/100 km.  The car shows around 175 awkw on the 91.1 mph pass, given it weighs 1800 kg with me and the tow bar. 60fts piss poor 2.3 sec due to auto, the thing would run 14's if it were manual.  Couldnt stall it up any more as it would drag you through the lights.

Mods,  jaycar digital fuel adjuster, K&N panel filter in stock airbox, aquarium bleed valve and 8 psi boost (spikes to 10 psi on gear changes), split dump, high flow cat and 3 inch mild steel exhaust.  Tuned A/F ratios on the road using a wide band.  It cruises happily at 15.5:1 AF ratio and I have 12.5: 1 on boost until around 5800 rpm, after which it richens up into the 11.5:1 area.  Total cost of mods approx $700 (got the 3" cat back exhaust cheap off Lone).

 

I rigged up the digital fuel adjuster so I can turn it on and off while driving , which requires inserting a diode into the output signal line to stop the ECU getting feedback when the DFA is turned off.  Did one run with the DFA turned off at the drags for a 15.8 at 88 mph.  My calcs suggest the Jaycar unit improves fuel economy around 12% and gives 20 hp (approx + 9% ) at the wheels. Neat stuff

The more I read about that jaycar unit, the more it looks like a good idea...

2 questions - what stagea do you have (year, type) ? And would you like to post EXACTLY what you did with the diode, as that would help none 'electronic type' car owners do the same?

Ian

[Sydneykid]

Ok, not really into the 10 sec bracket, but solidly into the 10L/100 km zone, a worthy goal for all stagea owners.

Here's the data from my trip to willowbank a couple of weeks ago.  Fill up with 98 octane then drive to track, do 4 passes for best of 15.19 at 91.1 mph, then drive home again (sunshine coast), a few days tootling around town then down to Brisbane again, fill up with 57 litres, travelled 533 km.  Thats 10.69 L/100 km.  The car shows around 175 awkw on the 91.1 mph pass, given it weighs 1800 kg with me and the tow bar. 60fts piss poor 2.3 sec due to auto, the thing would run 14's if it were manual.  Couldnt stall it up any more as it would drag you through the lights.

Mods,  jaycar digital fuel adjuster, K&N panel filter in stock airbox, aquarium bleed valve and 8 psi boost (spikes to 10 psi on gear changes), split dump, high flow cat and 3 inch mild steel exhaust.  Tuned A/F ratios on the road using a wide band.  It cruises happily at 15.5:1 AF ratio and I have 12.5: 1 on boost until around 5800 rpm, after which it richens up into the 11.5:1 area.  Total cost of mods approx $700 (got the 3" cat back exhaust cheap off Lone).

 

I rigged up the digital fuel adjuster so I can turn it on and off while driving , which requires inserting a diode into the output signal line to stop the ECU getting feedback when the DFA is turned off.  Did one run with the DFA turned off at the drags for a 15.8 at 88 mph.  My calcs suggest the Jaycar unit improves fuel economy around 12% and gives 20 hp (approx + 9% ) at the wheels. Neat stuff

Well done Ben, 10's is damn impressive. Gotta get the exhaust on mine, work keeps getting in the way. And I have the adj exhaust camshaft pulley and new cambelt to go on as well. BTW, what fuel was it?

Launch technique, I used to be able to just use the left foot braking while the right foot was planted on the accelerator. But with the extra power from the intercooler it drives though the brakes, and wheelies up the rears like a line locker first. I found by adding the handbrake it stops the rear wheelspin and I can hold about 0.5 bar at launch. Flick the handbrake off with the left hand while sliding the left foot off the brake. As soon as I plant the right foot it jumps to 0.7 bar.

It feels to be around 140 to 145 4wkw now, so maybe the extra ~30 4wkw (from the exhaust and the pulley) will mean a change in the launch technique.

[OC]

10's is incredible, hope mine runs at that. Congrats!

[Ben D]

10's is incredible, hope mine runs at that. Congrats!

Sorry for the delay in replying - for some reason I forgot to hit the notify of reply button.

If you have the jaycar unit switched so you can turn it on and off, you can run leaner at idle and cruise because it needs less fuel when it is warm. I run the normal ECU programme when it is a cold or hot start, then switch over to the jaycar unit after a minute or so on a hot start, or after the temp gauge reads 1/4 of operating temperature for a hot start. Essentially, I use the stock ECU now only as a choke (they do tend to run like they have the choke on, don't they...) Chances are my fuel settings once the car is warmed up are leaner than, say, Sydneykid is using at idle and cruise, thus the additional fuel savings, though it seemed to like the exhaust too ...

You get a 3 way on/off toggle switch and run the signal wire which comes from the airflow meter to the middle pole of the switch. On one side of the switch run the wire to the Jaycar unit (for this example, a blue coloured wire). On the remaining side of the switch run the wire back to the ECU input (for this example, a green coloured wire). This gives you the ability to bypass the jaycar unit when you want (ie. on a cold or hot start)... However of course the output from the jaycar unit (lets say this wire is red) also has to connect to the ECU input. The jaycar output must splice into the green coloured wire and thats where you get your backfeed and that is why you need a diode in the red wire (signal output from the jaycar unit) before it gets spliced back into the green wire (ECU input). There is around 0.5 V drop through a diode, so if you've already leaned it out using the jaycar unit, you'll have to put some fuel back in to compensate for the diode. Its worth the effort though with the extra fuel saving at idle and cruise, where you can go leaner than 14.7:1 A/F ratio without hurting the motor.

With more stop start around town driving on the next tank, we got "only" 520 km out of 57 L, still 10.9L/100 km. The main problem no matter what we do is these things weigh a tonne and accelerating that mass uses fuel.

[Ben D]

sorry, its a 1997 RS4, I guess series 1

[Sydneykid]

Sorry for the delay in replying - for some reason I forgot to hit the notify of reply button.

If you have the jaycar unit switched so you can turn it on and off, you can run leaner at idle and cruise because it needs less fuel when it is warm.  I run the normal ECU programme when it is a cold or hot start, then switch over to the jaycar unit after a minute or so on a hot start, or after the temp gauge reads 1/4 of operating temperature for a hot start.  Essentially, I use the stock ECU now only as a choke (they do tend to run like they have the choke on, don't they...)  Chances are my fuel settings once the car is warmed up are leaner than, say, Sydneykid is using at idle and cruise, thus the additional fuel savings, though it seemed to like the exhaust too ...

You get a 3 way on/off toggle switch and run the signal wire which comes from the airflow meter to the middle pole of the switch.  On one side of the switch run the wire to the Jaycar unit (for this example, a blue coloured wire).  On the remaining side of the switch run the wire back to the ECU input (for this example, a green coloured wire).  This gives you the ability to bypass the jaycar unit when you want (ie. on a cold or hot start)...  However of course the output from the jaycar unit (lets say this wire is red) also has to connect to the ECU input.  The jaycar output must splice into the green coloured wire and thats where you get your backfeed  and that is why you need a diode in the red wire (signal output from the jaycar unit) before it gets spliced back into the green wire (ECU input).  There is around 0.5 V drop through a diode, so if you've already leaned it out using the jaycar unit, you'll have to put some fuel back in to compensate for the diode.  Its worth the effort though with the extra fuel saving at idle and cruise, where you can go leaner than 14.7:1 A/F ratio without hurting the motor.

With more stop start around town driving on the next tank, we got "only" 520 km out of 57 L, still 10.9L/100 km.  The main problem no matter what we do is these things weigh a tonne and accelerating that mass uses fuel.

OK I'm confused, at idle and crusie mine runs closed loop, so it doesn't matter what the DFA is set to. The ECU will always aim for its target A/F ratio (ie; lambda voltage), changing the AFM voltage has no effect of the closed loop aim table. The standard ECU has water temp compensation (ie; when cold go richer X%) and it doesn't run closed loop until the engine gets up to normal operating temperature.

So if I lean it off at light throttle (open loop) then it will lean it out a bit at cold run, but I doubt that would be enough to cause it to run rough. It certainly wouldn't cause any damage as it is still in a rich running state. If I am merely compensatiing for increased efficiency (eg; exhaust) then it won't, in fact, be any leaner at cold run than it was standard.

So remain confused :confused:

[Ben D]

OK I'm confused, at idle and crusie mine runs closed loop, so it doesn't matter what the DFA is set to.  The ECU will always aim for its target A/F ratio (ie; lambda voltage), changing the AFM voltage has no effect of the closed loop aim table.  The standard ECU has water temp compensation (ie; when cold go richer X%) and it doesn't run closed loop until the engine gets up to normal operating temperature.

So if I lean it off at light throttle (open loop) then it will lean it out a bit at cold run, but I doubt that would be enough to cause it to run rough.  It certainly wouldn't cause any damage as it is still in a rich running state.  If I am merely compensatiing for increased efficiency (eg; exhaust) then it won't, in fact, be any leaner at cold run than it was standard.

So remain confused  :confused:

Yes, I ran around for a few days with the wideband on (I had another O2 sensor boss welded onto the split dump so I could run the stock O2 sensor as well as the wide band). With the DFA switched off it indeed runs at closed loop at cruise and idle, but runs rich on boost (as rich as 10.5:1) and also during throttle transients. With the DFA switched on (with its output running through the diode, remember, before it enters the ECU) it leans it off at cruise and idle, right through the rev range in fact. I can get a stable cruise at 16:1 and , would you believe, a stable idle too at that A/F ratio (once the stepper motor catches up), it begins to run rough at idle around 17: 1. A testimony to the combustion chamber design I think. Set up like this, you need to switch off the DFA for cold starts (and briefly for hot starts too). I placed the switch on one of those blank inserts on the dash to the right of the steering wheel, so its near the keys and hence easy to switch on and off as required during cold or hot starts. My guess is that the ECU can only trim so much fuel in or out to achieve stochiometric at closed loop.

I'm not making any of this up, I simply tuned as I always do, determined a baseline, gathered appropriate data using a reliable tool (a calibrated wide band O2) , then modified A/F ratios to suit the tuning aim at hand using the DFA. I was pleasantly surprised to see how much control the DFA gave me over fuelling set up as I have it. If you have access to a wide band and put an extra O2 boss in your dump pipe it might be worth checking what you car is doing on the road with the DFA - you might be surprised as if you got near 500 km out of a tank, you might be leaner than 14.7:1 at cruise too. If we can replicate this on another car, it may well be information worth having, though I'm sure some people won't want to revert to a manual "choke" switch on their stagea, even if turning the choke off gives them 20 hp.....

[Sydneykid]

OK, I am still confused.....more help required........

With the DFA switched on (with its output running through the diode, remember, before it enters the ECU) it leans it off at cruise and idle, right through the rev range in fact.  I can get a stable cruise at 16:1 and , would you believe, a stable idle too at that A/F ratio (once the stepper motor catches up), it begins to run rough at idle around 17: 1.

I can lean mine off as much as I like with the DFA, as soon as it goes closed loop (idle and cruise) it goes to 14.7. My understanding is that is the target in the aim table in the standard ECU.

My guess is that the ECU can only trim so much fuel in or out to achieve stochiometric at closed loop.

I haven't seen the Stagea closed loop aim table, but the R32 and R33's have no limit. The ECU can turn the injectors right off if necessary in an attempt to reach the target. I don't think that matters anyway, if the target is 14.7 it will richen it up (also unlimited) if necessary to reach that target.

As for idle, I unplug the AFM (zero voltage) and mine will still idle and start fine, hot or cold. I don't believe the ECU uses AFM signals at idle at all, it use engine rpm, water temp, throttle position, road speed and lambda when in closed loop. It is only when I attempt to get off idle that there is an issue, basically it stalls when I apply load. Since you have had some success, I must test lowering the voltage with the DFA to see whether that makes any difference on mine.

Over 15.5 there is a general warning about its effect on exhaust valve seats. Plus there is an argument that says you need more throttle opening to hold the cruise speed, so there may not in fact be any benefit. The test is injector duration (which can be read off the IEBC input), if the injector duration is longer (regardless of the lambda) then it is using more fuel.

Verrrrry interesting, sparked my interest to do some more fiddling, as if I don't already have enough to do.

Ps, even with a power FC and Datalogit software on the R32's and R33's, I can't change the closed loop aim table.

[BensDR30]

Interesting you mention the closed-loop use at idle. That gives my faulty O2 sensor theory more weight, as the idle on my car would hunt (indicating non-optimal mixtures) and there was occassionally a drop in idle speed to around 500rpm & a resulting flat-spot on take-off.

Now the O2 sensor has been replaced, all is VERY well in regards to the idle. It's smooth, consistent & the initial throttle response is excellent.

Oh, I've bought a DFA & controller too - and grabbed myself a handheld single channel CRO. Been meaning to get one for years....

[ian]

Oh, I've bought a DFA & controller too - and grabbed myself a handheld single channel CRO. Been meaning to get one for years....

Which CRO did you get? :-)

Ian

[sy300]

I have not yet done a long distance using a whole tank. I did a trip a while ago, used 1/2 a tank on the open road, the other 1/2 round town, and got 11.5 l/100km. Around town it's about 14-15 l/100km. I figure that a whole tank open road trip would be in the 10's. The car is standard everything, cruised at around 110 for the open road. It is colder here in NZ, lately driving to work in the mornings it's about 5degC, the Stagea loves the cold air.

[ian]

... all skylines love cold air!

[BensDR30]

Which CRO did you get? :-)

 

 Ian

The Velleman unit from Jaycar (plus soft case.). I've used one of these at work, and it's more than adequate for 'hobby 'use:

http://www1.jaycar.com.au/productView.asp?ID=QC1916

[ian]

The Velleman unit from Jaycar (plus soft case.). I've used one of these at work, and it's more than adequate for 'hobby 'use:

 http://www1.jaycar.com.au/productView.asp?ID=QC1916

Looks good..

If anyone wants to see the full tech, it is at http://www.velleman.be/common/product.Aspx...lan=1&id=348271

Ian