Frank's Cam Part 3

Last week we finished installing the cam in Frank the EF Falcon. Because Jim Mock Motorsport (JMM) provides a variable cam gear with the kit, cam timing is easily adjusted. We dialled-in the cam with 49-50 thou lift at Top Dead Centre – the advanced setting suggested by JMM to give more low-down power. With the cam at this timing and a plug-in ChipTorque chip installed, on the road the car had seemingly improved bottom-end torque but the top-end felt little changed.

So what would the car be like with the cam timing set to give a more retarded 42 thou lift – the setting suggested by JMM to give best overall results?

On the Road with Cam Timing Changes

After a failed attempt (see the ‘Doing it Wrongly’ breakout box below), we set the cam timing to 42 thou lift, measured on the inlet valve at TDC. And what was the car then like on the road? Well, a mixed story.

The engine response above 4500 rpm was improved, the idle was slightly worse, and the bottom-end and mid-range torque and throttle response noticeably dulled. The top-end response was improved (in that the engine revved more freely) but was it developing a heap more power up there? No it wasn’t. Against the stopwatch, the 0-100 remained much the same at around 7.5 seconds. Interestingly, the air/fuel ratio was richer at high revs than previously – implying that in fact less air was getting into the combustion chambers (the Falcon runs a MAP sensor, not an airflow meter).

We unplugged the chip and ran some more times. Without the chip, the air/fuel ratio was richer at full load (and over-rich at idle) and the snap throttle response much blunter. The 0-100 km/h times were about the same though...

These results led to an important decision needing to be made. Which of the two cam timing settings should be used when dyno-tuning the engine management system?

The car had not seen the dyno in either cam timing configuration. I was sure that peak power was not improved with the cam timing set at 49 thou lift, but I thought that, even though the 0-100 km/h time had not much changed, the top-end felt a little stronger with 42 thou lift. So from a point of view of gaining maximum possible power, the second cam setting gave the most potential.

But what about fuel economy? As described last week, with the cam timing set at 49 thou lift, 100 km/h freeway cruise had netted 7.5 litres/100km – the same as the standard car. But what would occur with the cam at the 42 thou lift setting? We did the fuel economy test again to find that this time, the economy was 8.1 litres/100km. That immediately appears to indicate that the 49 thou lift setting was 8 per cent better for economy – but all is not as it seems.

I’d noticed that in cruise with 49 thou cam timing, the air/fuel ratio (as displayed on a MoTeC wideband air/fuel ratio meter) had been sitting on about 17:1. (Yes, very lean but the car still ran beautifully.) With the 42 thou cam timing, the air/fuel ratio was richer by about 1 ratio – hovering around 16:1. That’s 6 per cent richer!

Hmmm, 49 thou lift cam timing gave fuel economy that was 8 per cent better than achieved with 42 thou timing, but with mixtures that were 6 per cent leaner. So the change in fuel economy of the different cam settings can in fact be mostly explained by the different air/fuel ratios that were occurring.

This implied that if engine management changes were used to lean out the mixtures in cruise, the cam timing that gave the best apparent potential for top-end power (42 thou lift at TDC) would also be able to deliver the same freeway fuel economy.

So before heading to the ChipTorque dyno for a full real-time remapping of the mixtures and ignition timing, which cam setting to use? It was a close-run decision but in the end we went for the cam timing that gave best top-end power potential – 42 thou lift at TDC.

Doing it Wrongly After watching Simon the mechanic install the cam and then dial it in to 49 thou lift, I figured I’d do further cam timing adjustments myself. This involves removing the tappet cover, removing the radiator fans (to get easy access to the crankshaft main pulley), and installing a dial gauge to measure the lift of No 1 intake valve at Top Dead Centre. In the instructions supplied with the cam, JMM suggest that the valve lift should be measured from the hole that’s in the rocker. However, if you do that, you may run into the trouble I had. The problem is simple: as the rocker moves with the valve, the tip of the dial indicator plunger can jam in the hole without this being noticeable, so giving incorrect results. Better to place the dial indicator so that the plunger makes contact to a smooth part of the rocker further along the line of the engine, either forwards or backwards from the hole. A check of your work can be made by looking at the degrees cam timing change shown on the adjustable gear. To go from fully advanced to fully retarded is only a tiny change on the wheel – far less than 1 degree and much closer to being just the thickness of the measuring lines. So if you end up with the cam (say) 3 degrees advanced as indicated by the cam gear markings, something is wrong.

Dyno Runs

We’d thought the on-road gains weren’t great but it took the dyno runs to really show how bad things were. With the cam set to 42 thou timing, the setting recommended by JMM, power was little or no better from 2000 – 5500 rpm. That’s right, there were only a few kilowatts in it anywhere. This is what the 0-100 km/h testing on the road had already shown, but it was sobering indeed to see it in colour on the dyno screen.

Concerned that I had made a mistake in cam timing, I got the ChipTorque mechanics to check the cam timing. It was at 42 thou lift at TDC – exactly what is specified by JMM. At the same time, ChipTorque also checked that the crankshaft damper Top Dead Centre mark was accurate – it hadn’t slipped or anything like that. And it was fine as well.

The lack of increased power wasn’t a blocked exhaust (power was down everywhere, not just at the top end); it wasn’t a misfire; it wasn’t a change in ignition timing or anything else identifiable.

So what to do now? Since at 50 thou timing (ie advanced timing) the cam had seemed to give better low-down performance on the road, I had ChipTorque set the cam timing to this figure. But a dyno run then showed that power had gone backwards everywhere from 2000 – 5500 rpm! But of the two cam timing settings, it was this one that was actually superior on the road.... (Another way of putting that is it was the better of two bad options.)

But perhaps it was just that the engine management wasn’t optimised for the cam? There was only one way to find out – do a full custom engine management tune on the dyno. But even after hours of tuning, peak power barely crept above that achieved with just the cold air intake, extractors and exhaust.

This dyno sheet shows the sorry tale. The red line shows how we finished up after the cold air intake, extractors and exhaust had been fitted. The blue line shows the results after installing the cam and setting it to 50 thou lift at TDC. (Note: as described above, the results with the cam timing at 42 thou lift at TDC was similarly poor.) The green line shows the results of real time dyno tuning the mixtures and ignition timing. The new cam, valve springs, 98 RON fuel and custom tune increased peak power by a pitiful 1.8 per cent. That’s a bloody expensive 2.5 kilowatts... Not to mention that power was in fact lost over most of the rev range!

I communicated with Brenden Mock of Jim Mock Motorsport and he was appalled and concerned at the lack of gain that his cam had provided. Amongst other statements, he said that the minimum gain they’d ever seen on the dyno with that cam was a 10kW at the wheels. But, perhaps significantly, that was in cars that usually had less power than mine had as standard...

Engine Management As indicated in the main text, despite the lack of power improvement with the cam, ChipTorque did a full engine management remap. One reason I wanted to persist with the engine management tune – even though the cam was clearly doing nothing for power - was that I was after a fuel economy gain. As described previously, the engine management changes to suit the mods were being done in two steps. Step 1 was to plug-in an off the shelf ChipTorque chip designed to suit a Falcon six cylinder with a warm cam. Then Step 2 was to fine-tune the program on the ChipTorque dyno. So what did we want improved in the real-time engine management tune - that is, what didn’t we like about the generic chip? Fuel continued to be injected on the over-run. This could be seen on the instantaneous fuel consumption display (instead of going to zero it stayed at numbers as high as 8 litres/100). We wanted as little over-run fuelling as possible. The car was slightly jerky on trailing throttle and we wanted this trait reduced or eliminated. With the off-the-shelf chip installed, we never heard the engine detonate even the slightest, implying that the ignition timing could probably be advanced throughout the load range. (That’s not surprising, since by now 98 octane was the fuel of choice.) The car ran sweetly in 100 km/h cruise with air/fuel ratio of 17:1. This implied that this air/fuel ratio could be more broadly used in cruise applications. Finally, by definition, a generic chip isn’t fine-tuned to the specific car, so we wanted that done as well. Rob Stewart did the tune. Areas tuned included the neutral and in-gear dashpot (ie how quickly revs fall when the throttle is closed), about four different ignition maps, closed and open loop fuel maps, lean cruise fuel maps and over-run fuelling maps.

On the Road

As expected from the dyno figures, on-road performance was unchanged. But throttle response (with the high octane fuel and ignition timing set to suit) was clearly sharper. The enhanced over-run fuel cut-off created the slightest of jerks when re-applying throttle, but the improvement in fuel economy was worth that trade-off. In fact, the fuel economy was clearly better than when the car was dead standard. Interestingly, the 100 km/h freeway cruise test instantaneous fuel consumption figures didn’t change, but overall economy in general driving improved by between 5 and 10 per cent – say 0.5 – 1 litre/100km.

Huh?

But hold on – the whole point of the cam installation was to gain power. And as the dyno graph shows, there was at the most only a piddling gain at the top end!

Brenden Mock of JMM suggested that I measure the cam lift and timing with the cam still in the engine – just in case there was something wrong with the cam manufacture. He also offered to supply another cam at no charge – either the same Dev 4 cam or a different grind.

But that put me in a quandary. Basically, I was sick of spending time and money. The installation of the cam – a process that grew to include maintenance extras like timing chain replacement, timing guide replacement, idler pulley replacements and others – had cost me $1200. Together with the cam (which cost $920, including new valve springs and the adjustable cam timing gear), I was already up for around $2120, more than it cost to turbo my Prius – and in fact, probably more than it would have cost to bolt onto the Falcon the twin ex-Supra sequential turbos and huge water/air intercooler that I have...

And then there were the costs associated with the engine management custom tune and cam re-timing. Lachlan Riddel of ChipTorque had offered to do the engine management tune gratis, but when the car was sitting on his dyno and needed the cam timing firstly checked and then changed, I asked him the going workshop rate – after all, this wasn’t the job he had agreed to. He had named the dollars, but then later when the hours ticked by, instead suggested that in return I install a small garden in the concrete opening at the front of his new workshop premises. (Which I later did.)

To do as Brenden Mock had suggested and measure the installed cam would need a few more hours of labour. That could be my labour or a paid mechanic, but it would still be labour. Then to install and dial-in another cam would need still more hours of labour. And after that, the engine management would again need to be real time tuned to suit the new cam – say another 2-3 hours on the dyno.

The original cam had unfortunately been thrown away (I’d forgotten to retrieve it from the workshop that did the new cam install) so going back to that wasn’t an option.

And while the Falcon may not have achieved a power increase from the cam and retune, its current modifications work together very well. The new cam decreases the exhaust resonant boom at around 2000 rpm; the engine management changes result in better fuel economy and much better mid-range throttle response; the bottom-end (say 1000 – 2000 rpm) is extremely tractable and strong; and when booted, and the on-road performance is pretty good.

Why spend more time and money, perhaps to achieve nothing better? Or even to go backwards?

I decided to do no more modification work on the engine.

Clearly, with the benefit of hindsight, I would have done things differently. In fact, I think that a better outcome could have been achieved at a substantially lower cost by simply fitting the cold air intake, the extractors and exhaust, retaining the standard cam, running high octane fuel, and doing the real time engine management retune.

In fact, in summary, here’s how I view the engine modifications, based solely on the results achieved on my Falcon:

1. JE intake system and installation – cheap, easy, effective, small (3kW) power gain on the dyno and clearly better response on the road

2. JMM extractors & Mercury exhaust and installation – not cheap but excellent results with a clear dyno power gain (8kW) and revolutionised bottom and top end on-road performance; downside of an exhaust drone

3. ChipTorque real-time engine management re-mapping (called by the company a ‘custom chip’) – not cheap but better throttle response, better fuel economy and a slight power gain (4kW)

4. JMM cam and installation – expensive flop

You live and learn...

Contacts: www.jimmockmotorsport.com www.chiptorque.com.au Simon’s Car Clinic - 07 5543 6155

Simon was paid at normal rates. The camshaft was supplied by Jim Mock Motorsport at commercial rates. The chip was supplied by ChipTorque free of charge. The real time engine management dyno tune was carried out by ChipTorque free of charge. The checking of the cam timing and then re-timing of the camshaft was carried out by ChipTorque in return for the establishment of a small garden at the front of their workshop.