Block Buster, Inside Ken Block's Monster Gymkhana Killer
By Mike Kojima, photos by Jeff Naeyaert
So you have made your fortune as a purveyor of an extremely popular shoe and clothing brand. You have torn it up on the rally circuit in the USA and made forays into the world of WRC. Now what? Ken Block is single handedly bringing the sport of Gymkhana back to the mainstream, first with his extremely popular series of Gymkhana viral videos and now with actual events, the first of which we witnessed last weekend at Irwindale raceway.
Perhaps Tanner is a Block Buster?
Gymkhana was popular in the United States in the 50's and early 60's but was overshadowed in this country by Autocross. Gymkhana is very similar to Autocross in the way that it requires maneuvering in tight low speed corners, usually defined by cones but it adds elements that require moves from rally racing and drifting as sliding is the fastest way through many of the turns and obstacles in a Gymkhana course. Gymkhana is cool because it uses elements of grip, dirt and drifting. Although it has disappeared in the USA, Gymkhana has stayed popular in Japan. Now Ken Block is bringing it back.
Car constructor OMSE and engine builder Ultra Motors worked together to develop the 2.0 liter Ford Duratec motor into a reliable and potent power maker. 750 hp and 700 lb/ft of torque @ 60 psi of boost with an 8000 rpm redline.
Not one to bring a knife to a gunfight, Ken has the ultimate weapon to bring to the show, his Ford Fiesta rallycross car. This car is a marvel of technology with a multitude of state of the art systems. It's something for the car nerd to drool over, drool for a long time. After facing this car in the first Gymkhana we know first hand that it is also an awesome weapon of mass destruction. The Fiesta was built for Block by Olsbergs Motor and Sport Evolution or OMSE for short. OMSE is a highly experienced builder of rally and rallycross machines located in Sweden.
The induction system has a bunch of expensive and very purple quick release Wiggins clamps and this huge Green Performance air filter which unfortunately hides the really trick turbo and manifold from view.
In line with the standard MotoIQ tradition, let's skip the pretty pictures and dig right into the heart of the car's guts starting with the engine. The team's PR
types were somewhat secretive about some of the carís specs so we have to make educated guesses about some of them but we will note that. The engine started as a 2 liter Ford Duratec production unit and was massaged by Ultra Motors in the UK. The Duratec is actually a highly developed engine being the basis of many racing systems ranging from Rally, to Touring cars and even the late Formula Atlantic series.
You can kinda see the rare and elusive Garrett TR30 motorsports turbo here. Only qualified race teams may buy this turbo for a huge price. The turbo was originally developed for WRC restricted engines. On this engine a bigger trim is used on the compressor and turbine. No restrictor need apply here.
The engine uses a Jenvey ITB intake system with an OMSE custom machined intake manifold plenum. ITB's offer superior throttle response and bottom end power. If you are wondering what all those braided steel lines do, they're a vacuum manifold. ITB's have the throttle plates in the intake runners instead of at the opening of the plenum. Thus there is no vacuum in the plenum only in the runners behind the throttle plates. So intake vacuum must be taken from each runner to feed things like fuel pressure regulators, MAP sensors and anti lag systems. This blow off valve is bypassed when the antilag is used. When the throttles close, the vacuum opens the anti lag valve which sends boost pressure straight to the exhaust manifold. The ECU then makes the injectors run rich and retards the timing. This causes fuel to ignite in the exhaust manifold which helps drive the turbo, pre spooling it, eliminating or reducing lag.
Ultra Motors modified the engine's block, enlarging the cooling and oiling passages for more flow. Most noticeably you can see the external water passages to help ensure a good amount of coolant flow in the cylinder head. A custom Arrow crankshaft with an 84mm stroke machined from billet was selected. Arrow is a supplier to many F1 teams and makes really high quality cranks. Carrillo rods and JE 88mm forged, lightweight strut type pistons were also used for a final displacement of 2044 cc. The JE pistons use a fairly high compression ratio of 10:1. ARP fasteners are used throughout the bottom end to ensure reliability.
This shot shows the 900cc shower type injectors. Shower injectors are often used on racing engines because of their superior atomization. Because shower injectors introduce the fuel a long way back by spraying into the bell of the intake stack, much of the fuel vaporizes when going down the runner. The fuel's latent heat of vaporization cools the intake charge causing it to shrink and increase in density. More charge can be ingested improving volumetric efficiency.
To ensure lubrication in the violent high G maneuvers that rallycross and Gymkhana create, a dry sump lubrication system is used. A custom OMSE casting is used for the cylinder head. The OMSE head has improved cooling and has a stiffer deck for improved sealing under extreme boost pressure. OMSE ported the head and fortified it with Ferrea valves, lightweight titanium on the intake and heat resisting inconel on the exhaust side. Ferrea valve springs and titanium retainers are used. Ultra Motors camshafts were chosen to activate the valves.
At 60 psi of boost there is not much margin for error so with the rev limiter pounding and anti lag popping going on a pop off valve is added for safety to the intake manifold plenum just in case you have a turbo sneeze and a hiccup at the same time if you know what we mean.
It was very difficult to get a good shot of the Garrett TR30 turbo due to all of the intricate plumbing around the engine compartment. Here you can see its not for public consumption thinwall magnesium compressor housing.
To seal the head to the block under extreme conditions, the block deck is grooved and exotic inconel gas filled o-rings are fitted. These work to provide an active seal against combustion pressure. An MLS gasket backs up the o-rings as does the thick deck OMSE head casting. ARP studs help keep the head from lifting.
A single Tial 44mm wastegate controls boost pressure. You can see the thin heat shielded investment cast stainless exhaust housing and big 90mm downpipe. The 90 degree wastegate discharge into the downpipe could be better as Jeff pointed out as over 40% of the exhaust flow comes thru the wastegate.
On the exhaust side a divided OMSE tubular manifold is used with one of Garrett's unobtanium TR30 turbos. A divided manifold pairs cylinders 1-4 and 2-3 together feeding them individually into a divided twin scroll turbine housing. This phases the exhaust pulses exactly 180 degrees apart and takes full advantage of the pulse energy to help spool the turbo. Divided systems improve turbine efficiency by about 15% which is significant as it can reduce turbo lag by over 20%. Divided systems usually have better volumetric efficiency as well by reducing reversion. Since turbo engines by nature have more backpressure, having a divided system helps reduce the amount of reversion or exhaust blow back into the cylinders. In a log manifold, an adjacent cylinder on the exhaust stroke can blow into a cylinder on the intake stroke contaminating and heating the charge. A divided system makes this much more difficult. This facilitates the use of more aggressive cam profiles.
Charge piping leading to and from the intercooler uses quick release aerospace Wiggins clamps allowing them to be removed in seconds.
The direct fire ignition system uses Denso coils and ignitors. We think these are Honda CBR parts.
The Garrett TR30 turbo is a Motorsports part that is generally not available to the general public. The TR30 is brimming with trick technology. It has a ball bearing center section. The center section is cast from thinwall stainless steel to reduce weight. The ported shroud (for more surge margin) compressor housing is cast of thin section magnesium and the twin scroll exhaust housing is thinwall stainless. The thinness of the housings are one of the reasons why these turbos are not available to the public. They cannot pass Garrett's burst testing. In burst testing the turbo is spun at ever increasing revs until it explodes from the centrifugal force. To pass the test, no part of the turbo can escape the housing in the explosion. All Garrett consumer and OEM turbos pass this test. The TR30 is designed to be light weight and is not burst tested, thus you have to be a confirmed legitimate high end Motorsports team to be allowed to purchase the turbo.
The dry carbon shrouded huge radiator helps keep things cool.
The TR30 also has interesting features like a titanium compressor wheel. The added strength of Ti allows the Garrett engineers to design the wheel with much thinner blades and a smaller very compact hub. This greatly improves the compressor's internal aerodynamics. Itís the same principal behind why a billet compressor wheel performs better but taken to an extreme with a much stronger exotic metal. The exhaust side uses a scaled up version of Garrettís super efficient 9 blade NS111 wheel profile that is normally only used in Garrettís small frame turbos. With its 56 trim 76.2 mm compressor wheel with a 57mm inducer and an 84 trim 60 mm turbine, the TR30 is much like a GT3076 turbo but with more exotic technology and lighter weight.
Note to all of you home built race car constructors. Every race and drift car should have a high mounted circulating surge tank to get all bubbles out of the cooling system.
A single Tial 44 mm wastegate is used to control boost and an HKS SSQV blow off valve vents surge causing back flow. The air to air intercooler features a UK made ultra efficient Pace heat exchanger core with OMSE fabricated end tanks. A huge 90mm downpipe extracts exhaust from the turbo to the side mounted exhaust in a big way.
The 90mm exhaust terminates into this famous side exit.
An off the shelf Jenvey ITB intake manifold is used. ITBís or individual throttle bodies have one throttle for each cylinder. ITBís are used on a car like this because they have superior low end power and throttle response. The Jenvey intake manifold is mated to an OMSE surge tank containing Bosch 900cc/min shower type injectors that spray across the plenum into the ITBís intake bells. Full race engines often use shower injectors for superior atomization and to use the latent heat of vaporization of the fuel to help cool the intake charge to improve volumetric efficiency. Shower injectors are terrible for emissions so donít expect to find them on a production car ever, but on a race car, who cares.
The dry sump system uses this rear mounted tank for better weight distribution.
The lightweight dry cell battery lives under the carbon passenger floor. You can see the easily accessible charger plug as well.
The functional carbon rear wing adds downforce with little additional drag.
The ATL fuel cell has an internal surge tank and two Bosch 044 motorsports fuel pumps. The filter is external for easy servicing.
The rest of the system consists of an ATL fuel cell and a surge tank for twin Bosch 044 Motorsports fuel pumps and regulators. The surge tank helps prevent fuel starvation in high G maneuvers. The ignition system is a high powered direct fire type using Denso coil packs firing Denso iridium plugs. The unusual engine management system is composed of an OEM SAAB ECU reprogrammed by Ultra Motors with boost and anti lag control. We are sort of puzzled by this choice in this day and age of advanced Pectel and Motec systems but that is what drives the motor. An AIM MXL electronic dash monitors the engine.
The AIM MXL dash is driven by the cars seemingly strange choice in engine management, a SAAB ECU. We figure the choice was made for OEM reliability with low price and some smart guy knows how to rewrite the ECU's data structure so it can control all sorts of things like the anti lag and center diff control.
Ken's office is all business, flocked low glare carbon dash, carbon Sparco steering wheel, easily accessible fuses, at hand sequential shifter by right side of steering wheel, turning brake lever, and AIM MXL dash.
Of course these switches control the window washer and wiper but they also seem to control the dampers, launch control and perhaps torque bias?
Other switches include brake bias, fuel, blower, more damper switches, an Ohlins labeled shock controller that looks sorta like a Tein EDFC and a few mysterious switches we do not understand.
This super engine puts out over 750 hp and 700 lb/ft of torque at an amazing 60 psi of boost with an 8000 rpm redline. It can do so for long periods of time with rally type reliability. You have probably witnessed the pounding it takes in Kenís videos and we have seen it firsthand. This engine is bulletproof. It is longitudinally mounted in the chassis instead of transversely like a stock Fiesta to allow the use of a sophisticated AWD drivetrain.
The elaborate all inclusive cage is both for protection and to stiffen the chassis for better handling.
The drivetrain is perhaps even tricker than the engine. OMSE and Maktrak collaborated by building a bespoke bullet proof, dog geared, six-speed, sequentially shifted in line transmission. The ultra strong six dog gears are machined from S135 grade steel with the case cast of RZ5 Magnesium alloy. The transmission is dry sump lubricated with an internal oil pump to ensure proper lubrication of the internals under all conditions and to reduce windage losses. When we took these pictures, the crew and PR
person were very secretive about letting us look under the car so we suspect that it may have exotic WRC type electronic controls of the torque split and front to rear slip.
The alloy pedal box contains dual brake master cylinders with a cable adjusted balance bar which adjusts mechanical proportioning. The carbon sub floor is cool as well!
The package reliably handles the Duratecís turbocharged fury and weighs less than 57 kg. We think the center differential is electronically controlled for torque distribution and to lock and unlock according to the engine control mapping to help the car turn. We believe that the plate type center diff also unlocks the diff when the parking brake is applied as the parking brake cylinder has many unidentifiable hydraulic lines coming from it. An Alcon triple disc modular clutch handles the power transfer with a low moment of inertia while withstanding brutal AWD 7000 rpm electronically controlled launches and clutch kicks. The front and rear differentials are also built by Maktrak with a 3.73 final drive ratio and we are pretty sure that they use Salisbury style clutch plates. The diffs are tunable by changing ramp angles and spring preload. We know that these diffs are available as clutch style and viscous or a combination of the two together. We think that the diffs on the Block car are both clutch type but tuned differently at the front and rear. They have magnesium cases and weigh less than 22 kg each.
The entire body is reskined in dry carbon or carbon Kevlar. Carbon Kevlar is used in high impact areas like bumpers and fenders. Here is the roof skin as seen from the inside of the car. Look at the cool adjustable roof vent!
Cool carbon door panels, this car has it all, so much attention to fine detail.
The front suspension features Ohlins 4-way adjustable thru shaft electronically controlled dampers. The car supposedly has a spring rate of only 70 inch pounds. If this is true we suspect that the dampers actively help give the body platform control. We suspect this spec is wrong and the springs are really 70 newton meters or around 400 inch pounds. Custom made suspension arms greatly widen the track width. The blade anti swaybar adjusters are set fairly stiff.
The car's suspension is a critical key to its performance. The suspension links, axles, hubs and uprights are bespoke units fabricated by OMSE to have correct geometry, articulation, greatly widen the track width and to accommodate the AWD system. Tubular antisway bars with blade type adjusters are used at both ends of the car.
Looking at the rear suspension tells us a lot. The rear geometry has a little bit of anti squat, not much negative camber gain and a surprisingly low amount of bump travel. Short toe links give a lot of toe in under roll. A tubular antisway bar has blade adjusters. The rear bar is set full stiff. You can see the Alcon 4 piston rear caliper and 355mm rear floating rotor.
The real jewels of the carís suspension are the Ohlins 4-way adjustable dampers at each corner of the car. The dampers are used with super light 70 in/lb springs and the car's platform is controlled hydraulically. The dampers are independently adjustable for high and low speed compression and rebound damping and are electronically controlled as well which is probably why such light springs can be used. These dampers in combination with the electronics probably cost more than most new cars!
The electronic control valve for the rear shock.
The brakes are Alcon with 6 piston forged monoblock calipers at the front with 4 piston rear calipers. The caliper's amorphous carbon Lorrane brake pads grip huge 340mm front and 355mm rear floating rotors. A billet floor mounted Alcon pedal box holds dual master cylinders with a mechanical balance bar for setting brake bias. A driver adjustable prop valve is also used for fine tuning of the brake's proportioning. A hydraulic turning brake is operated by a CNC machined lever.
The big Alcon six piston front caliper and 340mm floating front rotor. Cool light forged Volk TE37 wheels.
OMSE prepped the already strong Fiesta chassis by seam welding and installing an all inclusive cage that not only protects Ken in case of an accident but completely ties the chassis together, improving chassis rigidity, a critical factor to building a good handling car. An interesting note is that the Fiesta uses a lot of Ultra High Strength Steel or UHSS boron alloyed steel in its unibody. Boron steel has impressive yield strength of 190,000-200,000 psi which is about as high as nearly any steel alloy can get. The Fiesta isnít the only car to use boron steel (most cars made since 2004 use at least some of it) but it has one of the highest percentages of use in its chassis over any production car.
Grooved full floating rotor on a lightweight alloy hat peaks out behind the TE37 wheel.
Look at all of the lines coming off the master cylinder for the turning brake, could this be for center diff control?
The unibody's skin is removed and an OMSE fabbed dry carbon skin is bonded on in place of the steel for lightness. OMSE also fabbed up the carbon/kevlar wide fenders, doors, hood, wing, bumpers, interior panels and rear hatch. The composites are partly responsible for the car's light 2425 lb weight and amazing 50/50 weight distribution. Recaro FIA Profi race seats with Sabelt six point harnesses are used as well as a Sparco carbon WRC steering wheel. Finally, holding the car up are Volk Racing superlight forged TE37 wheels in an 18x9Ē size shod with 245/45-18 BFG KD tires.
Short wheelbase, wide track, light weight, AWD and lots of power are an unbeatable combination in Gymkhana, unless you are up against Tanner Foust in an almost identical car!
We are amazed by the level of technology that Kenís car exhibits as well as it mind numbing performance as witnessed at last weekís Gymkhana Grid event at Irwindale. Only Tanner Foust in a similar car could pose a threat to Ken. Will we see more of the car and sanctioned Gymkhana events in the future? We hope so as we really like Gymkhana's mix of grip and drift driving as well as the no nonsense race winner un-judged format.