Turbo F1 engines - How they started part 1
Turbo F1 engines - How they started part 2
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Motoiq-Eric Hsu wrote: 1987 Cosworth F1 GBA 1200+bhp 1.5L V-6 Engine
Back in 1977, Renault started to enter F1 races with a single turbo V6 engine. It didn't really shine in terms of performance, but in 1978 the car finished in the top 10 and scored its first points. Then in 1979 the turbo Renault got its first pole and its first win. Needless to say, other engine designers saw the light and Ferrari and BMW soon followed suit in 1981 with turbo engines of their own.
At the time Cosworth was still dominating F1 with the normally aspirated 3.0L DFV so Cosworth did not feel the urgency to develop a turbo engine immediately. It wasn't until their diminishing wins started to become apparent that Cosworth started to get off their high horse and start on a turbo engine. The rules at the time stated that an engine could have a maximum capacity of 3.0L if normally aspirated and 1.5L if supercharged. These displacement rules were written in 1966 when turbocharging automotive engines wasn't really even considered. Keith Duckworth (the "worth" in Cosworth) pretty much was against the entire idea of turbocharging in F1 because he believed it was technically against the rules. What Duckworth said was that a turbocharger was actually a second motor that shared the combustion chamber inside of the engine and of course two motors were not allowed in F1. To further his point, Ferrari was injecting fuel directly into the turbine section of the turbo (anti-lag) effectively converting a turbocharger into a gas turbine and turbine engines were not allowed in F1 either. While Duckworth's points are probably valid (you gotta remember that a turbocharger on a gasoline engine was a relatively new idea at the time) to some degree, the rulemakers in Paris still allowed turbochargers.
Cosworth's first attempt at a turbo F1 engine in 1983/84 was actually based on the Cosworth BD alloy 4 cylinder engine block. Duckworth decided the BD's alloy block would be ample for the original power goal of 650bhp. It was an elaborate setup with an exhaust driven turbo and a second turbo driven by a Ford CVT transmission via the crankshaft. The turbos were staged for big boost (5+ bar absolute). All of it was controlled via ECU which was super state of the art back in those days. It must have been a pretty damn big piece of hardware based on 1987 sized electronics to control all of those devices. The standard BD cylinder head had to be redesigned for boost and flow, but in the end the engine wasn't able to deliver since the horsepower targets kept increasing. Originally the turbo F1 engines from Renault, Ferrari, and BMW were running gasoline, but the rulemakers allowed "rocket fuel" which was actually gelled toluene.You know for damn sure it burnt super slow if it was gelled so it must have had some crazy high octane equivalent. With the new rocket fuel, the other engine manufacturers were already surpassing 800bhp in 1985. This 1.5L BD based 4 cylinder engine with staged turbos was bending crankshafts at 3.0 bar (absolute) boost @ 11,000rpm. Even with a redesigned crank and flywheel the complexity of the turbo setup and transmission was probably a complete clusterfcuk. I'm sure the engine only having 4 cylinders was probably another limitation for increasing power beyond 650bhp reliably. You have to remember that this was 1987 before the time of 3D modeling, FEA, simulations, etc. While Duckworth did redesign the clutch and flywheel to live at that power output, it was clear that it was going to be an uphill battle with a 4 banger. The good old boys in NASCAR back then probably weren't making 650bhp out of their 5.7L small blocks yet and here was the F1 crowd playing with 1.5L engines.
After securing financial support from Ford USA, Duckworth, Mike Costin (the "Cos" in Cosworth), and designer Geoff Goddard went back to the drawing board. What they whipped up was a 120 degree 1.5L V-6 with alloy block and heads with Ford badging. Duckworth was spending more time at home having cashed out by selling the company to UEI so Goddrd took the reins and designed the bulk of the GBA with weekly visits to Duckworth at home. The first component drawings were started in December 1984. By August 1985 the Cosworth GBA was first tested in a car. That's pretty damn fast for a clean sheet engine design isn't it? Initially there were some engine block issues, but after some revisions the engine became very reliable at 1000bhp and was run at more than 1200bhp in qualifying. How's 800+bhp/liter for strength? According to Cosworth lore, the engine ended up being more reliable than the Honda VTECs.
If you are an internal combustion engine nerd like myself, then you'll probably dig "Cosworth: the Search for Power" by Graham Robson. I believe the 5th edition is the latest. You probably don't want to read the 6th edition (it doesn't actually exist) because then you would just be reading about Cosworth's downsizing and diversification (read doing business outside of motor sport) and the decreasing size of the motorsports as a whole which blows big time. Anyhow it really is an excellent book filled with stories, interviews, famous quotes from Duckworth, and behind the scenes stories of many of Cosworth's historic race and production engines. Most of what I wrote above I got from Robson's book, mixed with some question asking at Cosworth and some of my own opinions. Chances are you won't find books like this on any of the other race engine manufacturers because...well because their histories probably just aren't that interesting. Their stories would all just read "...left Cosworth in 1988" or maybe "...left Cosworth in 1994", etc.
We have an actual GBA show engine in our conference room.
The two upper pulleys are probably crank driven by gears inside of the alloy front cover. The lower left pulley is the multi-stage oil pump and the lower right hand pulley is the water pump and alternator which are driven by a common shaft. Check out the old school 9 tooth crank position sensor.
At the back of the engine you can see the distributor, coil in the center of the valley, and the 7.25" clutch. I'm guessing that Magneti Marelli igntion coil is super heavy duty judging by its size and the fact that it has to ignite the cylinder pressures of a 800bhp/liter engine with extremely short dwell times at 12,000rpm through igntion wires, distributor cap, and rotor. I'm not sure if they are using a 7.25" clutch because it made too much power for a 4.5" racing clutch or if 4.5" racing clutches and modern friction materials did not exist yet.
Here's the LH exhaust cam position trigger. Or at least that's what I think it is. The pickup sensor isn't present, but it looks like that thing could lop off your finger if you weren't careful.
The turbos are Air Reseach units. For you young guys, we call them Garretts today. The compressor housing looks like it is just cast aluminum and pretty closely resembles a T04B in size. Perhaps they weren't casting magnesium yet for compressor housings. Khiem, why don't you look up that compressor cover part number? It's 444852-5. This is just a display engine so this turbo may not have been the final 1200+bhp qualifying spec turbo. For show engines, just about any version of a part or engine can be thrown together.
The compressor wheel has 12 blades and the inducer measures approximately 55mm. The shaft play tells me it's a journal bearing turbo, but the shaft play is definitely smaller than a standard T04 unit. The wheel to housing clearance is also extremely tight compared to a standard T04. In fact it appears to be closer than even at modern day ball bearing GT, but I am definite ball bearing turbo technology did not exist back then...or did it? The center housing does not look standard issue Garrett so I'm guessing there was some voodoo big money magic going on here to maximize compressor efficiency to the very extreme.
The turbine wheel is an 11 bladed deal and from the exducer doesn't look like anything too special. In fact it looks a lot like a Navistar TA34 wheel (you Turbonetics lingo people might call it a "stage 2") if you ask me, but I did not take the turbo apart to examine the turbine wheel's blade shape. Once again the wheel to housing clearance is looking tighter than a modern day GT so I'm guessing they were trying to squeeze every last ounce of efficiency out of the turbine stage also. The turbine housing outlet is very nice with a smoothly expanding inside diameter all the way to the back of the outlet.
A v-band turbine housing from back in 1985 beats HKS and TiAL by about 21 years. From the rear view, the compressor housing uses a T04E type clamp. The turbine housing A/R appears to be extremely small. I would estimate it to be in the .40-.50 range. After all it is a twin turbo 1.5L engine with 0.75L feeding each turbine stage. It is an extremely thin wall casting so it looks smaller than it actually is I'm sure.
The turbine housing inlet and wastegate connection is hand fabricated and is welded to the exotic looking material cast turbine housing. I am unsure of the header material, but I'm guessing they are made of inconel.
Here is the bespoke multi-stage dry sump oil pump. It just looks expensive.
On the other side of the engine is the bespoke water pump at the front of the engine and the bespoke Magneti Marelli alternator behind it. The alternator looks a lot like a small version of a mid 80's European car alternator doesn't it?
Here you can see two Bosch EV1 looking injectors per cylinder that actually fire upstream. I know absolutely nothing about gelled toluene so I'm not sure what benefit there was in firing the fuel upstream of the valve, but I'm sure the engineers designed it this way for a reason. At the base of the throttles you can see that they are bolted to the cylinder heads via a phenolic gasket for heat isolation. We use the same proprietary formulation of phenolic for our Subaru, Mitsu, and Nissan thermal guard gaskets today.
Here you can see the throttle castings and linkage for the individual throttle bodies. The vacuum hoses go to a vacuum/boost manifold...
...here. There are two of these manifolds: one per bank. Then a hose goes from each of the manifolds into that round device on the right.
This is a detailed view of an inlet to one of the two plenums. The two o-rings are for some kind of Wiggins type connection I'm sure. There is considerable hand blending at the joint of the o-ring flange to the fabricated tube which is made from two pieces of sheet. I am guessing it was shaped like this to clear some kind of body work. Even to this day at Cosworth, we still spend probably too much time with attention to detail on our inlet manifolds. In the case of the Subaru EJ and Nissan VQ plenums, each port is CNC matched and then hand blended to each individual runner.
This is what the hand fabricated piece looks like from the outside. The valve cover looks like it is all business with black wrinkle coat and Ford F1 signage.
Here's a bottom view of the engine assembly. While it doesn't look quite as high tech as the current F1 CA2010 engines, it still looks like a pretty damn serious piece of machinery.
This plaque on the show engine, which also looks like it is from the 80's, states that the engine was only ever raced one season. However Robson's book says that the enigne was raced in 1986 by Carl Hass' Haas/Lola new F1 team and in 1987 by Benetton. Apparently despite the fact that the GBA was originally designed for gasoline with a 6.5:1 compression ratio and all of the other turbo engines were significantly more powerful on rocket fuel, the new Haas/Lola team couldn't produce a reliable or fast car regardless. Switching to gelled toluene, Cosworth had slowly raised the compression up to 8:1 and was producing over 1000bhp by the end of the season, but the Haas/Lola cars weren't up to the challenge. Ford decided to switch the engines to the Benetton team. In 1987 Cosworth was at the FISA 4.0bar boost limit, the engine was reliable for 600 miles between rebuilds, and the Benetton B187 was regularly finishing on the podium. But by the end of 1987 the FISA was limiting the boost to 2.5bar. The plan was to eliminate turbos from F1 by 1988 and that was the end of the GBA. No bore and stroke specs were ever officially released on this engine or any other Cosworth clean sheet race engine for that matter.
There not much publicly available info about the use of gelled toluene in F1 and most of them point to Cosworth TEC (GBA). Note I've concentrated on gelled fuel not toluene benefits. Here is a short comment from the same source as above that mainly states the increased volume as a benefit.Tommy Cookers wrote:@Forza
interesting stuff !
regarding the rocket fuel or even 'rocket' fuel Toluene, you are party to mythification
gelled ?? (Napalm is/was gelled fuel also)
how would that work in a car ?
sincerely, do you have further information on this ?
Steve Mitchell wrote: Hi X,
Nice article on the engine. I have some of the specs on it in the XLS sheet I gave you. The fuel had a high amount of toluene to get around the gay FIA rules of 102 octane. It acted like it had much more octane because of the slow burn rate. The reason they talk about gelled fuel is because of the fuel tank limits. They were only allowed 150 liters for the whole race. If you freeze the fuel, it will contract about 30% allowing more fuel inside the tank. Of course as it warmed up it expanded. Renault and Honda both ran the fuel from the tank through a heat exchanger to bring it up to temp for atomization. I believe that this engine was also the first appearance of the IGV for Cosworth. Renault had the DPV system on their engines. I have a paper on it somewhere.
BESTCHEM Racing Fuel additive - Toluene (114 octane)-military specs: TT-T-548EBecause toluene is such an effective anti knock fuel it also means that it is more difficult to ignite at low temperatures. The Formula 1 cars that ran on 84% toluene needed to have hot radiator air diverted to heat its fuel tank to 70C to assist its vaporization. Thus too strong a concentration of toluene will lead to poor cold start and running characteristics. It’s recommended that the concentration of toluene used not to exceed 30% or what the engine is capable of utilizing. I.e. Experiment with small increases in concentration until you can no longer detect an improvement.Octane ratings can be very easily calculated by simple averaging Toluene has octane rating of 114. So use this formula to figure what octane you get when u mix toluene with gasoline:
Litres of gasoline x Octane (eg.95 or 98) + (Litres of toluene x 114)
Total Litres of Gasoline & Toluene
example The fuel tank capacity of an EVO 8MR is 55 litres. Based on a 30% toluene mixture, filling it with 16.5 litres of toluene and 38.5 litres of 98-octane gasoline will yield a fuel mix of:
(38.5 litres x 98) + (16.5 litres x 114) 55 litres= 102.8 octane
Notes: Common ingredient in Octane Boosters in a 12-16 ounces bottle will only raise octane by 0.2
- 0.3, i.e. from 98 to 98.3 octane.
and SAE technical paper - F1 Honda RA168E engineBestChem wrote:Aviation fuel verses Toluene?
Aviation gas is less dense than most racing gasoline. Instead of weighing about 6.1 to 6.3 pounds per gallon like racing gasoline, it weighs 5.8 to 5.9 pounds per gallon. The racer must compensate for this by changing to richer (larger) jets in the carburetor when changing from racing gasoline to avgas. Most types of aviation fuel have very high lead content, which would rule out cars equipped with catalytic converters. Most piston-engined aircraft burn leaded fuel. Also aviation fuel has a very different hydrocarbon mix to optimize volatility properties at high altitude. Avgas sometimes has a high level of aromatics, which can contribute to lazy throttle response.
The other major difference is octane quality. Avgas is short on octane compared to most racing gasolines. Many racing engines with "quick" spark advance curves or with no centrifugal advance have more spark advance at low rpm than avgas and some racing gasolines can handle. The result is detonation, especially during caution periods in circle track racing because all of the spark advance is "in", rpm is low, and part throttle air fuel ratios are too lean for the operating conditions.
If the driver does not "work" the throttle back and forth, pistons can be "burned" which melts away part of the aluminum piston material. Inadequate octane quality is one of the quickest ways to destroy an engine. Pistons can be severely damaged during acceleration where detonation is present and the racer may not know what is happening until it is too late.
Another interesting fact from McLaren Heritage ProgramJohn Lievesley, Former F1 engine designer wrote:
WAS the turbo era of the eighties really as memorable as the rose-tinted specs suggest? Having been deeply involved in competition engine design and development, I believe that I am well qualified to answer this question with an unequivocal, 'yes'. Here’s why…
In terms of the spectacle, which is surely what sells F1, they were heady days. I hold treasured memories of sitting on the banking during closed practice, on the inside of Copse, while watching Nelson Piquet powering the Brabham out of Woodcote on the old Silverstone GP circuit. The ground trembled. It really did. The car appeared out of a shimmering heat haze and three seconds later it was gone round the corner! That BMW engine boasted upwards of 1,250 bhp in qualifying trim.
If the sight, sound and smell of the turbos was awesome for the spectator, it was no less exciting for the engineers. In terms of both metallurgy and fuel, the turbo era broke new ground.
Almost all of the available turbochargers were derived from diesel applications designed to run with exhaust gas temperatures of below 750ºC, whereas our petrol-fuelled engines frequently saw 1000ºC or more. Hence metallurgical changes were needed for turbine wheel and housing reliability, and to stop the piston crowns melting. We already had oil cooling to our pistons but we were forced to become more sophisticated with this, when even more heat had to be removed.
Toleman Motorsport - Toleman TG181 - 1981 (Jarama)
Engine: Hart 415T
Type: 1.496 cm3 S4 T/C
Power output:
- 540hp @ 9.500 RPM/min (1981)
- 580hp @ 10.500 RPM/min (1982-1983)
- 600hp @ 10.750 RPM/min (1984)
- 750hp @ 11 000 RPM/min (1985)
Similarly, diesel engines were fuel-governed (there was no requirement for intake air throttling), unlike petrol engines which were essentially throttle-governed. This led to complications of turbine shaft oil sealing to counteract oil pull over on closed throttle, as well as lag when the driver hoping for rapid response to throttle opening, didn’t get it.
Ironically, the governing body of F1 had given tacit approval to reduced capacity, turbocharged engines long before any of the teams chose to use them. It was only Renault’s persistence with the ‘yellow teapot’ – so christened because of its propensity to boil over by the end of the race when it was first introduced in 1977 – that forced everybody to take turbos seriously.
Remember that in the days leading up to the RS01, computerised performance prediction for engines had been but a pipe dream. Any innovation came from inspiration, otherwise it had to be a product of mental toil followed by build and test.
Renault RS01 - 1977
Engine: Renault EF1
Type: 1.492 cm3 V6 T/C
Weight: 179 kg
Power output: 510hp @ 11.000 RPM/min (1977-1979)
As an engineer, I found it easiest to comprehend a turbocharged engine by reducing it to two separate modules: 1) the conventional non-turbocharged combustion and energy conversion module, integrally mounted with part of the pumping function; 2) an additional separate pumping module. The driving system for the additional pump uses a turbine taking its energy from the exhaust gases, hence a ‘turbocharger’.
The biggest problem, without a doubt, was ‘lag’. It was difficult to deliver the extreme boost in controlled fashion, which made some of the cars animals to drive. Other difficulties were ‘surge’ – particularly in the compressor rotor if the air flow + pressure ratio combination fell outside the design range of the rotor – or ‘over-speed’, when the required air flow could not be delivered without running above the maximum design speed of the rotor. Either condition could result in serious damage to the rotor and/or the shaft assembly.
Developments that have helped to reduce these problems are variable geometry vanes and more sophisticated wastegate control. To improve the speed of response (i.e. reduce the effects of lag), the inertia of the rotor assemblies was reduced. The turbocharger suppliers created designs known as “hybrids” by marrying compressors and compressor housings from one design, with turbine rotors and rotor housings from another. This technique has developed further into ‘clean sheet’ designs that better match the real performance of the assemblies to our ideal targets, a process that has been very interesting and educational.
Twin-turbo experiment
An unsuccessful series of tests that we tried early on at Hart was to replace our single, huge turbo assembly used on our inline 4, with a pair of smaller units akin to the ones arrived at by our V engine competitors. The logic was that the smaller lighter inertia turbos ought to ‘spool up’ more rapidly. We tried numerous exhaust arrangements but all suffered from the same problem of low or below 1 ΔP compared with our ‘huge’ single unit. My conclusions were two-fold: 1) I had failed to fully appreciate the apparently better gas flow efficiency of our bigger units, creating lower back pressure in the exhaust compared with the small twin units; 2) in purely practical terms, unless they chose to accept “Plumber’s nightmare” piping, the V engine designers had to use twin turbos and so had probably never considered anything else.
To explain our concern over ΔP: by definition, this is the ratio of inlet gas pressure compared with exhaust gas pressure. In principle, the higher our inlet gas pressure and the lower our exhaust gas pressure, if all else remains constant, then the greater will be the flow of working fluid (gas) through our engine and the greater will be the potential power output, so we like high ΔP.
Unfortunately, the achievement of a high inlet pressure will generally go hand-in-hand with a high exhaust pressure because as usual in this world we don’t get anything for nothing and the turbine has to supply the energy to drive the compressor. Depending on the characteristics of the two components, there can be a ‘sweet area’ on the turbo’s map where everything is in harmony and the compressor easily adds more intake boost than the turbine creates back pressure.
Another problem was the fuel. To appease the anti-motorsport lobby, it was supposed to conform (very loosely) to road fuel standards. Yeah, right! It became known as “rocket fuel” and consisted largely of toluene, a glue solvent, to suppress detonation. It resulted in streaming eyes, was rumoured to be carcinogenic and stank both before and after combustion. If used today, it would probably carry a public health warning if only to protect the spectators, but as racers we were blasé.
Toleman Motorsport - Toleman TG184 - Hart 415 -1984
The previous generation of modern day F1 engines, the V8s, were signed off for a life of 2,500 kilometres but only because they were effectively detuned. The turbo era, by contrast, was wild: we were lucky if our qualifying engines lasted six laps in total before they were reduced to a steaming pile of junk. Full throttle, high rpm and high boost is not a good combination. It was hard for drivers to catch an engine when it began to let go and with most of them being an idle bunch, loathe to park the car at the side of the track and walk back, it meant that our failures were often very spectacular and very public!
For all that, it was an exciting period. Particularly if you worked, as I did, for an outfit that wasn’t endowed with the biggest of budgets, because you had to be bright. For me personally, working for Brian Hart with the likes of Ayrton Senna, it was a steep learning curve but a satisfying one. And yes, I do remember that drive at Monaco in ’84. It was ‘our’ engine in the Toleman that day, but I really can’t claim the credit: all I had contributed to what was very much a team effort was my ability to add innovative design; it was the weather and Senna’s brilliance that made it all possible!
Q: It’s always a pleasure to walk down the Boulevard at the McLaren Technology Centre and see a different set of cars on display. Who chooses which models are rolled out for public gaze?
Support operations manager Emmanuel (Manu) Esnault: There’s input from lots of people. Often I’ll make a proposal to John Allert, the McLaren Group Brand Director, and also to Jonathan Neale, our CEO. Often it will be related to upcoming VIP visits or events because it’s good to have a talking point. For example, recently we had a Japanese Championship-winning F1 GTR on display because we had some Japanese guests.
The Boulevard is to promote the brand and the McLaren image. So we must use iconic cars – but of course, it is a bit frustrating that we can’t have them all on display! We have cars that are more exotic and more exclusive but it’s often difficult to justify showing them off. For example, we have a very rare 1983 Porsche 911 TAG-turbo. This car has less than 2,000 miles on the clock and is in absolutely mint condition. It was only ever used for engine-mapping the F1 TAG turbo engine. There is nothing else like it.
McLaren's TAG Turbo-engined Porsche 911
