PPP-106 - Peugeot 106 Rallye

The PPP-106 was the original EBD Racing sprint car, built from 2006 around a Peugeot 106 Rallye Series 1. The car was not a shopping exercise - every significant component was designed, modified, or fabricated in-house. The engine design intent was set from the outset: a free-revving 1400cc naturally aspirated unit using individual throttle bodies, with a cylinder head substantially reworked to match the induction system rather than the other way around.

This page is the retrospective engineering portfolio for the build. The original site at ppp-106.co.uk ran from 2006 through to around 2008 and documented the build in real time across fifteen or more individual pages. The content here consolidates that material into a single structured reference.

Key Specifications

The 1397cc Build

The engine concept started with a question: what combination of TU-series blocks achieves the right bore and stroke for a high-revving 1400cc class entry? The answer was to combine the TU2J2 (1296cc) and TU3 (1360cc) to arrive at a 76mm bore and 77mm stroke - 1397cc total swept volume. The geometry is near-square - bore and stroke differ by only 1mm, with the stroke fractionally longer at 77mm. The near-square configuration minimises mean piston speed at the target 8500 RPM while keeping the displacement within the 1400cc class limit.

The build involved pages of calculations, simulation work, and deliberate choices at every stage. This was not a parts-catalogue build. Material was removed where it reduced inertia, added where it reinforced critical stress paths, and balanced as a complete system rather than component by component.

Block preparation included full chemical stripping, special metals primer for the aluminium block, undercoat, and a Broom Yellow top coat on ancillaries including the water pump housing, thermostat housing, and oil cooler. The block itself was finished in Peugeot-themed blue, consistent with the Series 1 Rallye colour scheme of red, yellow, and blue. The rocker cover was stripped of its powder coat, polished, and chrome plated.

Valves and Springs

The valvetrain uses one-piece EN 214N austenitic stainless steel valves, waisted as part of the head flow work. Uprated single valve springs replace the standard items, with new retainers throughout. A bronze cam thrust plate was fitted. Valve guides were modified on the lathe to reduce overall length to suit the opened-out ports.

Induction System - R6 ITB Manifold

The induction system was one of the most complex design challenges in the build. The Yamaha R6 2004 throttle bodies were chosen for their individual throttle body arrangement and the quality of the throttle bore geometry. Fitting them to a Peugeot 106 TU2J2 head is not a bolt-on exercise.

The first step was to establish the available space. With the carbon fibre bonnet fitted, there was 150mm of available height at the manifold entry point on the head face. The distance from the manifold face to the bulkhead is approximately 210mm. The steering rack is a clearance constraint as the track rods move with the suspension, and the bulkhead shape dictates where the assembly can exit rearward. A cardboard model was made of the available space before any CAD work started.

The manifold design started from a 3mm thick PTFE inlet gasket, scanned 1:1 and imported into SolidWorks as a sketch reference. The gasket defines the port spacing on the head - and it was the mismatch between that spacing and the R6 TB bore spacing that drove the port re-pitch decision.

A MkI weld assembly manifold was designed with bosses for vacuum take-off and measurement points. The cross-section view of this design made the problem clear: with the original head port spacing, the flow path from TB to port was anything but ideal for the inner cylinders. The decision was taken to match the head port spacing to the R6 TB centres rather than accept a compromised flow path.

A MkII concept was developed around the re-pitched head (see Head Work section below). The revised manifold was checked with a cardboard prototype on the car before any aluminium was cut. First stage fitting used only ports 1 and 4 to verify angle and bulkhead clearance. Once confirmed, the assembly was tacked up to minimise distortion before full TIG welding.

Carbon Fibre Inlet Trumpets

Carbon fibre inlet trumpets were made specifically for the R6 throttle bodies using an EBD three-piece modular mould system. The modularity allows inlet tract length to be adjusted to tune the inlet resonance point. For the PPP-106, both 40mm and 50mm trumpet lengths were made to provide setup options at different circuits.

Injector Arrangement

The system uses 8 injectors: 4 in the original head positions and 4 upstream in the R6 throttle bodies. The Emerald M3DK engine management system maps all 8 injectors. Button control replaces the standard stalk controls.

Head Work - TU2J2 Port Re-pitch and Flow

The TU2J2 is a reasonably well-flowing head by the standards of its era and class. Getting the best from it requires a complete system approach - you cannot modify the ports in isolation without knowing what the inlet manifold, throttle bodies, exhaust, and cam profile are doing. The modifications here are purpose-built for the specific components in this engine.

The major constraint in the original TU2J2 head is the port spacing. The two centre ports (cylinders 2 and 3) are spaced further out from the head centreline than the equivalent spacing on the R6 throttle bodies would require. Ports 1 and 4 are already at the correct centres. Rather than accept a bent and compromised flow path through a conventional manifold, the decision was made to re-pitch the two centre ports.

Port Re-pitch Process

The two centre inlet ports were milled off the head entirely. This required approaching from multiple angles and set-ups on the mill. The casting material was then welded up to reinforce the water jacket and provide a sound base for the new port block. After welding and flushing, the ports were reinstated at the correct centres. The result is a head where all four inlet ports feed the throttle bodies with equal, straight flow paths.

Combustion Chamber Work

Before porting work began, the combustion chambers were TIG welded up to allow re-profiling. General reshaping removes valve shrouding and improves flow around the valve seats. Volume is checked against each cylinder to maintain balance between bores and to verify the target compression ratio. The head was skimmed in combination with the combustion chamber modifications to achieve 11.5:1 compression ratio.

Exhaust Port Work

The Raceland exhaust manifold was fitted to the PPP-106 with modifications to suit the re-pitched head. The original bore mismatch between the manifold and the unmodified exhaust ports was significant - which actually gave useful freedom for offset in the porting work. The exhaust ports were also gas flowed as part of the overall head treatment.

Head Classification

EBD classify this as a Stage 4 head - not an off-the-shelf modification. The full list of work includes: modified valve guides to suit opened ports; reprofiled combustion chambers; chambers matched to pistons; head skimmed to target compression ratio; bronze cam thrust plate; inlet ports re-pitched to match manifold and TB centres; valve seats re-cut; and all modifications oriented around maximising volumetric efficiency across the operating range.

Rotating Assembly

Pistons

The standard Peugeot 106 Series 1 8V pistons weigh 395g including gudgeon pin. The replacement Wossner 76mm forged slipper pistons with a smaller, lighter gudgeon pin come in at 315g - an 80g per cylinder saving at the small end before any con-rod work is done. Valve-to-piston clearance was checked using the plasticine squash method at TDC before the block was decked to the final compression ratio target.

Con-Rods

The con-rods were fettled to remove stress raisers - a manual process of blending and polishing the rod profile to eliminate machining marks and sharp transitions that can initiate fatigue cracks under high-cycle loading. Small-end bushes were replaced with bronze items machined with an oil way to maintain lubrication at the gudgeon pin. ARP con-rod bolts were fitted throughout.

Crankshaft

The crankshaft was lightened to 1.145 kg less than the standard item. Beyond the mass reduction, the crank was mirror polished to minimise oil-cling during rotation. The standard cast iron crank has a surface finish that holds a film of oil around it as it rotates - that oil adds to the effective rotating inertia and consumes power. A mirror finish breaks that film and reduces the moment of inertia further without removing structural material.

Flywheel

The 180mm Series 1 Rallye flywheel presented a challenge: the small diameter leaves very little material to remove without compromising structural integrity. The modifications were first calculated and checked using FEA before any machining took place. The lightened flywheel has a mass 400g less than standard. After machining, the ring gear was pinned to the flywheel body to prevent it spinning on the cast iron - always a real risk with a heavily lightened item of this type.

Balancing

Due to the extent of material removed from the rotating system, the complete assembly - crank, flywheel, rods, pistons, and OMP Group N clutch cover - was balanced externally as a unit. Only 5 grams had to be removed from the assembly to achieve the required balance. Given how radical the modifications were, that result validated the precision of the individual component work carried out beforehand. Flywheel phase one testing involved running the engine on the starter motor with the bellhousing fitted and no gearbox, verifying ring gear concentricity and flywheel runout with a DTI before further engine running.

Chassis and Body

Rollcage

An OMP AB/106/129AE rollcage was fitted - a type 129AE fully welded-in unit weighing 19 kg. The competition category did not permit front triangulation to the suspension turrets in the engine bay, so the front triangulation bars were repurposed as additional door bar strengthening. This required the dashboard to be cut to allow the cage to be fitted and the dashboard refitted afterwards - a consequence of the cage geometry and the wideboy Corbeau Revolution seats.

Sump Baffling

A sump baffle plate was fabricated and fitted. The design was based on the Peugeot Sport baffle geometry, without the trap door arrangement used in the official item. The purpose is not windage reduction - the mirror-polished crankshaft already addresses oil-cling. The baffle's primary function is to minimise oil surge during cornering and braking and to reduce the torque coupling effect of a mass of oil changing direction. The central orifice was left open to feed the oil pump. Flow holes were added and the baffle welded into position. The sump was powder coated for corrosion protection.

Carbon Fibre Bonnet

The standard Peugeot 106 Rallye bonnet weighs 12.4 kg including the catch mechanism, cable and hinges. The EBD carbon fibre replacement came in at under 3 kg - a saving of approximately 10 kg at the front of the car, ahead of the front axle, which also improves the front-to-rear balance.

The mould was taken directly from the original metal bonnet after preparation - all stone chips and surface imperfections were removed before the glass fibre mould was laid up. Carbon fibre was then laid into the mould paying attention to weave and weft orientation. The early version was lightweight but had deformation characteristics that needed addressing in a subsequent iteration - a consequence of going as light as possible on the first build.

The exhaust manifold insulation jacket - 12mm fibreglass wadding - was fitted partly to protect the carbon fibre bonnet from radiated heat and partly to maintain a cooler inlet charge temperature by reducing under-bonnet temperatures generally.

Gearbox

The gearbox was stripped and rebuilt around a Quaife ATB (automatic torque-biasing) differential. Unlike a plate-type LSD, the Quaife ATB uses gears rather than clutch plates. It does not lock harshly with a fixed pre-load - instead it automatically biases torque away from the spinning wheel to a continuously varying degree. For a front-wheel-drive sprint car this means better traction out of slow corners without the torque steer and snatch associated with plate-type units.

Fitting the Quaife ATB requires almost complete disassembly of the Peugeot MA gearbox. The OE crown wheel was machined to accept the Quaife retaining clip and anti-slip ball bearings - the crown wheel is case-hardened, which made the machining operation destructive on cutting tools. The hot crown wheel was then pressed over the Quaife unit with locking compound and the ball bearings located. The gearbox uses 75W80W oil.

Engineering Analysis

A full piston kinematics and dynamics study was carried out for the PPP-106 engine. The study covers piston acceleration and deceleration at speed, peak force on the small end, con-rod stress analysis under those peak loads, and calculated factor of safety for the modified rod geometry. This analysis was also used to validate the rocker mass reduction work, applying FEA to the modified rocker profile before any material was removed.

The kinematics page on this site includes an interactive calculator built around the actual PPP-106 engine dimensions - you can adjust RPM, bore, stroke, rod length, and piston mass to see the effect on peak forces and rod stress.

Build Photography

Build Timeline

EBD Racing was founded in 2006. The PPP-106 was the first car built under the EBD name, constructed around a Peugeot 106 Rallye Series 1 owned by Graham Pickard. The engineering and fabrication work was carried out by Gareth Knopp at EBD, with the build documented in real time on the original ppp-106.co.uk minisite.

The stripdown began in early 2007. Engine machining, head work, manifold design and fabrication, rotating assembly balancing, cage fitting, and body work were all documented through 2007 and into 2008. The car was running and mapped on the Emerald M3DK by late 2007, with run-in footage filmed at Brands Hatch on the start-finish straight early in 2008.

The car competed in sprint events across the South East. The engineering documentation from this build - particularly the head flow and port re-pitch work, the manifold fabrication process, and the rotating assembly treatment - informed later EBD projects and contributed to the analytical methods used in the kinematics and dynamics work linked above.

Common Questions