In Part Two of our interview with HSV's Chief Engineer - John Clark - we discuss engines...
We've heard many reports of engine seizure with the LS1s - what do you believe is the cause?
Ahh, is that on the earlier engines?
I'm not sure - but there have been quite a few incidents.
Yeah, look, I suppose there have been enhancements that have gone through for the engine. There was, maybe, some low oil level scenarios at one stage and some concerns with oil pick-up. I'd be surprised if there have been failures that've occurred in a fair time.
If there's a low oil level scenario, does that mean the engines consume excess oil?
No, not consuming oil. Well, whether it's being used within the engine I wouldn't say. You need to keep a check on the oil. HSV run the synthetic Mobil 1 oil - we change all the original oil here at a hoist in our production facility. It's the same as what Corvette use.
So you're suggesting the seizure problem only applies to the earlier Gen 3s?
If there was something it was probably about the VT2 timeframe - I wasn't in this position at that stage, though. The big part was reviewing the oil pick-up and sumps and all this sort of stuff. I'd be intrigued to see what numbers there are - when there's a failure people say, "Oh, all the engines are failing". I'm guessing, there may be 150,000 engines out there and maybe 0.001 percent of these have had an issue.
How realistic is that 0.001 percent figure?
Well, you're the one saying there are all these failures - I'd be intrigued to see what the figures are. When there's a failure in a component, everyone says they're all doing it. I don't know. I think Holden produce 25,000 V8s a year - we produce about 3500 cars a year. I'd really be intrigued to see what the figures are.
How many engines has HSV had come back under warranty?
Well, our warranty goes through the Holden warranty - so we get feedback from that. We have a 3-year warranty, but - yeah - I don't know.
So there have been a few?
It's the same as anything on the car. Somebody might complain about the paint on the bumper bar.
Sure, but engine seizure is a bit different...
Look, I don't know - I've only been in this position for the last 18 months.
Have you heard of similar problems happening in America?
No. I suppose if you jump on a Corvette website I'm sure you'll be able to find information on it. There's probably a problem with the front bumper bar with a chip in it or something like that. I don't know.
Okay - moving on - the HSV 255kW engine picks up 30kW over the base Holden LS1 using extractors, exhaust, intake snorkel and an ECU re-map. How much of that gain comes from the intake?
One thing we hang our hats on from the VR timeframe is we always had an intake duct that came out from the engine bay area and into cold air. When you're sitting idling at the traffic lights and you're in hot air, you don't want a gulp of hot air - it reduces spark and you start getting knock and all the rest. The cold air intake is there to give stable performance under a range of temperatures and conditions. It's consistency.
All of those things you mentioned add up - when you put it all together it works. The management system has been calibrated with all of those things in place - remove one of those components and it'll be determinantal. I always talk about engineering integrity. HSV is not just an engine, an interior or a body kit - it's a package. At the top-end I'd say the intake might give a couple of kilowatts here or there.
When revising the intake, what are your main criteria?
Our big criteria is making sure there's enough airflow through there. It really starts from the throttle and everything else from there toward the airbox. With the 300kW GTS and SV300 engine we went for a bigger throttle body, so we needed a bigger air intake pipe into the air cleaner itself. As I said, we also want to take off and have cold air straight away - we've done a lot of testing and found the colder it is, the better it is.
In the current models that draw air from behind the headlight, is there any positive pressure built up through the intake at high road speed?
We've looked into whether it's beneficial, and I suppose the big thing with positive pressure is by the time the air enters the airbox, passes through the bottom portion of the airbox and then the filter, there's not any forced induction. We do all of our engine work on a dyno, which is stationary of course. It runs in a room with a cooling fan and all that, but there's no forced induction effect. We don't find any difference between an engine on the dyn and in the car. We run the engine with exactly the same full exhaust as on the car and we ensure it's run with all the ancillaries.
Is there any wind tunnel development involved when designing the intake?
No. In Australia, at the moment, there are no wind tunnels with chassis dyns - in the UK there is, but the cost of transporting cars and everything is quite prohibitive. There is a stage where we do wind tunnel development depending what stage the car is at - a new body or model shape we'll wind tunnel test. We also use some of the race team testing info, so we use some of that when we do styling work. With our front facias we reduce the airflow under the vehicle so high-speed stability is improved.
(More discussion of aerodynamics is coming in Part 3)
Does HSV take pressure measurements throughout the intake system?
We do - we have done pressure measurements in the past. We just tap into the airbox itself and put in a pressure transducer. I'll see if I can get some figures.
Later Supplied Information...
We have no current available reports on air pressure in manifold."
In the early '90s SV5000, an in-guard air pick-up was used - why was that location changed?
The big thing, I suppose, is people will change the car and do things inside the wheel arch - like take the lining out. Sometimes there'd be contact with bigger aftermarket wheels. Also, a lot of dirt gets thrown around in that area, so we try to get it to cleaner air at the front of the car.
Was water ingestion an issue with the relatively low air pick-up of the SV5000?
Not with the guard liner in place - water was not a problem. There is a water ingress test we do, which includes going through a bath at the proving grounds and making sure no water gets in there. The water is up around fifty centimetres deep, and you cruise through at about 20-odd kilometres an hour. There can be a small amount of water that can get into the bottom part of the airbox, but nothing on the clean side of the filter.
Getting back to the current intake layout, what sort of intake air temperatures are measured compared to ambient?
Umm, good question. I'll find that out. Roughly, when we look at ambient temperatures of about thirty-five degrees Celsius, I think we're about five degrees on top of that.
Later Supplied Information...
The air intake temp sensor (located in intake duct after filter) is usually 10 to 15 degrees Celsius higher than ambient. When idling at traffic lights, the air temp can rise up to 35 to 40 degrees above ambient. On take off, this is where the cold air intake works at its best as colder air from outside is quickly ingested into the engine (not hot air around engine bay). The air intake temp drops quickly.
What dust filtration testing does HSV perform?
We use the same air filter as the Holden car. We have looked at other filters that are around to see if there's any torque or power increase, but weighing that up with the filtration of dust. The test procedure for dust ingress, to me, is more important. Holden have tested their filter, and it goes through a parts-per-million dust particle test - which is very tough. The paper filter we use has been more than adequate.
Is there an induction noise test that you do?
Yes we do - we have the current ADR requirement of 28/01 pass-by noise that we have to pass. This isn't just some aftermarket manufacturer testing stationary noise - it's a full pass-by. We enter a speed trap at 50 kays and go wide-open throttle from there. There are noise meters on both sides of the car as you continue through the speed trap. We do this test at the proving ground on what they classify a 'noise road'. It's a very specific area for the requirements of the ADR where there is no noise reverberated back. Of course, it's important that we pass that and we're at the limit of those requirements.
That's another area where we hang out hats - that our cars meet full ADR requirements.
How much of the overall pass-by noise comes from the induction system?
A huge amount. I can find out the exact details of the pass-by test, but it's at the start where the noise meters take in induction noise from the front of the car; you go full throttle into the trap. Once you go past the noise meters, they pick up the exhaust noise. So you get the entry of the intake and the exit of the exhaust. You also get tyre noise, engine noise - it's the overall noise of the car. It's not like a stationary noise check.
Later Supplied Information...
The test vehicle enters a speed trap at 50 km/h (+5/-1 km/h), and throttle is fully opened as it passes through. The throttle is held fully open for 20 metres and is then fully closed. Automatic transmission vehicles are tested in Drive, while manual vehicles are tested in 2nd and 3rd or 3rd only.
A microphone is placed from 7.5m from either side of the vehicle's centre line, and exactly half way along the WOT strip (ie 10 metres from the start). The maximum allowable noise level for passenger cars is 77dB(A). Note, however, the reported noise level is not the actual number as recorded during the test, as adjustments are applied to the raw data.
The Editor has driven the standard Holden Monaro and commented on excessive induction noise; the GTO Coupe is much quieter in that area. What's HSV's policy on induction noise compared to Holden's?
I'm intrigued why there is a difference, I must admit, because there's no physical difference between the induction duct of a Monaro and the GTO. Only on our 300kW car we have a bigger air intake duct between the airbox and throttle body, giving it a throaty roar. There is the cold air induction that we use on the airbox, which is different to Holden, but - really - our car should give the same or a bit deeper induction noise. If our car's quieter than theirs I really am surprised.
We've mentioned HSV's ECU reprogramming - what sort of specific changes are made?
Many and varied.
Within the ECUs there's a huge amount of tables that can be accessed. It's an American ECU - the same as they use in the Corvette - and this is one area where we deal extremely closely with Holden. Our calibration guy goes out and spends about three days testing at the proving ground with his counterpart from Holden. They spend a lot of time data logging. They also do the hot and cold trips as well - the hot trips are where we try to get knock sensor activity.
What sort of air-fuel ratios and ignition timing do you run at high load compared to the Holden cars?
To be honest. I might have to come back to you on that.
Later Supplied Information...
Idle - 14.7:1
Wide Open Throttle (WOT) - 12.1:1
Cruising at constant speed 14.7:1
Tip In quickly goes to 13.5:1
(No ignition timing figures supplied.)
The good part with the current knock sensor system is that - because they're tuned so well - when it hears a small amount of knock it doesn't just ramp out all the timing and then put some back in again. It only pulls out enough to keep power going.
HSV recommends running premium unleaded instead of the normal unleaded that the Holden LS1 is happy with. How much scope for power does the extra octane give?
I'm not sure on that. I think the maximum power would be close, but - because it's the transient time where you get a lot of knock activity - that's when it could be different. One reason we recommend premium unleaded is because you can get it pretty readily around the whole country now. We set the cars up to run on premium unleaded - 95 octane - but, due to the fact we run knock sensors, it will run on standard unleaded. And that, to me, is a huge benefit.
We also look at fuel economy - I always quote the story of my wife's parents living in Mallacoota; I'll often cruise up there and get less than nine litres per hundred kilometres. It's about a 600 kilometres trip, with the cruise control set at 100 - 110 km/h.
So - given those conditions where the ECU will go into 'lean cruise' mode - that's an absolute best-case scenario for fuel consumption?
Yes - but that's not really trying. The criteria I give is cruising on the open road - you can get good figures. The thing is - for us - it's not a huge facet for our customers. Put it this way, the old Holden V8s with carburettors and all that, if you got lower figures it was fantastic. We keep improving calibration to improve drivability, performance, fuel economy and emissions.
So it's fair to say that fuel economy is a relatively low priority?
I wouldn't say it was lower - it's a blend of emissions and performance. You don't want to focus on one and everything else drops away.
Let's talk about the exhaust system - how do you design your extractors?
The process for the extractors is mainly dyn work, and we also have computer simulations. We have all this old data of what works on the old Holden 5.0-litre, and you can put that over to the new engine and a lot of it doesn't work. It was a trial and error scenario based on initial calculations. Sometimes on the dyno we use adjustable length tubes so we can find peak power and torque. We also deal with the manufacturers that build our extractors as production stuff. We get some of their thoughts and bring it all together on the dyn. Once you've got the optimum set up, you've got to look at clearances, how it fits into the car, how it can be manufactured and installed. We have System Management Team Groups that include production people and all that and they look into it as a whole.
How many different sets of extractors are typically tested?
If you welded them all together you'd have a damn big Christmas tree! We have heaps - sixty to eighty sets, something like that. And the thing is, once you change the extractors, you have to change the calibration to suit. You've got to do a fair bit of calibration work on the dyn. It's very labour intensive.
Do you use any heat resistant coatings?
No. We're always looking to see what's around - like with some of our concept cars - but it all comes down to how they go in testing. We go through a whole procedure to make sure the coating stays on and all this.
So you've tried them and they haven't stacked up?
We have looked at them in the past - and we'll continue to look at them.
I guess in the application we had, they didn't suit what we were trying to achieve. At one point we were looking at different emission standards - we used to run at US83 standard, we now run at Euro2 standards and are looking at Euro3 - and a lot of it came down to heat in the catalytic converter on start up. What you want is for the cat to heat as quickly as possible. We've had coatings, and had the pipes wrapped in insulation to see if it's a benefit - and it wasn't for what we were trying to chase.
All the HSV models we've tested have had quiet exhausts at light-load cruise. What are some of the design factors that come into play to achieve this?
We spend a lot of time achieving that - I don't like cars that drone. We spend a lot of time with noise meters and with the manufacturers - at the moment, Walker do the main construction of our mufflers, so we spend a bit of time with them. It all comes back to spending time. We have different rear mufflers across the 255 and 300kW engines - they've got different internals for the different power and backpressures we want to achieve. And, of course, there's noise as well - we find a car that puts out more power will put out more noise. That all comes back to the testing I mentioned before. The position of the mufflers and that are pretty much set. All we can do is change the volume and the internals - like baffles and pipes and all that. We do a lot of fiddling around.
What sort of internal designs do you use?
Very good ones; you're welcome to buy one and cut it apart with a bandsaw...[laughs]
What's the basic layout of the HSV exhaust system?
It's a symmetrical system where it goes from 4 into 1, down to a 1.8-litre catalytic converter, an intermediate and rear muffler. So there are two cats, two intermediates and one muffler.
Explain how the volume of the cat converter is important.
The biggest factor is the size of the brick you can get in there. The bigger the brick, the more surface area you've got and the better emissions you can get. But you don't want to be silly and have a 3-litre cat, because you've got to warm it up to get it to work quickly. Again, it's a process that needs a lot of time.
Tell us some of the background of the 300kW engine - how much of it is formulated by Callaway?
Well, it's manufactured in America and we've worked with Callaway (in the States) in the development. We did the testing in Australia with Callaway - we worked in conjunction. They have a lot of experience with their Corvettes and C12s, so we worked with them to do a lot of the development testing. We had a couple of the engineers come out here initially at our dyn stage - they ran them on their dyns, we ran them on our dyns, and then we put them in cars and ran all of our usual tests. HSV did all the mapping.
It was a fantastic relationship - works well for them, works well for us.
As you probably know, that engine's also got different heads, a cam, the throttle body is machined from an aluminium billet - so there are a lot of things that go into it. There's a lot that goes in to get 300kW. The Holden engine and the Corvette one are similar but there are a few differences in oil pick-ups, sumps and throttle bodies - so there are all these differences. They're a specific-built engine for Holden - it's not just a Corvette engine.
Next week: products, testing and planning.