About the car

Saturday, 27 May 2023

About the car
XoomShift Solo


About the car

The car is a Westfield SEiW, originally built as a road car, but slowly making the transition to a racing machine.  The engine is a Vauxhall Redtop 2.0L 16V.  As we got it, this had Weber carbs and a Weber Alpha ignition system.  Power at this stage ought to have been around 170bhp, but the Alpha ignition never worked properly.  Originally SVAed at a rather portly 630kg, the car has shed somewhere around 125kg and now weighs in at 504kg.

Over the 6 years we've had the car, quite a lot has changed.  The following is just the things I can remember.

Wheels & Tyres

Compomotive CXR ultra light motorsport wheels
Avon crossply slick tyres (8.5" front, 9.2" rear)


All interior panels replaced with carbon sheet and carpets removed
Boot box removed and replaced with alloy panel.
Rear arches widened to accept 8" tyres
Front side panels flared at rear of engine bay to provide exit for engine bay air.
Windscreen removed and replaced by aeroscreens
Heating and ventilation system removed
Westfield Sports seats removed and replaced with a single glass fibre shell
Original seat supports removed and side mount brackets welded to the chassis
Scuttle and nosecone converted to quick release.
Carbon dashboard
Dashboard mounted on brackets welded to chassis rather than screwed to the scuttle
Original gauges replaced with digital dash and our own gear indicator/shift lights
Rear diffuser
4" headlights
Motorcycle indicators
Lightweight race mirrors
Lightweight scuttle
Lightweight front cycle wings


Extra chassis braces added inside the cockpit and around the front suspension and engine bay
Chassis alloy side panels removed
2 gallon alloy fuel tank fabricated and fitted
VW Polo alloy radiator
Alloy swirl pot
Full roll cage
Engine mounting moved 2" back in the chassis

Front suspension

Widened track
Fitted Protech dampers, new springs.
Added antiroll bar.
Alloy front hubs.
Solid Poly bushes.
Modified uprights to give improved Ackerman.

Rear suspension

Rear antiroll bar
Protech dampers.
A mixture of rose joints and solid poly bushes.


Front Wilwood alloy 4 pot calipers and lightened disks
Rear lightened disks and alloy calipers
Floor mounted pedal box incorporating remote adjustable balance bar.


At the end of 2011, our much respected Vx engine broke its crank.  The cost of replacing the steel crank and bespoke rods together with the rest of the likely repair bill meant that we decided to make the change to a Ford Duratec.

Saenz steel rods
Heavy duty ARP big end and main cap bolts
ARP head studs
Omega intruder HC pistons with deep valve pockets,
Extensively modified SBD head  but the standard valves are big enough
Dual concentric valve springs and titanium caps
Full race Kent cams
RaceLine Dry sump
54mm Jenvey taper direct to head throttle bodies.
ITG foam air filter
Raceline 4:1 exhaust manifold
Repackable Techcraft alloy exhaust can
SBD lightweight alternator
Alloy catch tank
Davies-Craig electric water pump
Aeroquipped fuel lines throughout
Good for 270bhp@8100rpm and 190lb.ft@5000rpm


Lightweight steel flywheel
7-1/4" Helix paddle clutch (single plate, sprung centre) with coaxial hydraulic slave clylinder
AP master cylinder fitted to modified Westfield pedal box.
Elite IL200 5 speed sequential gearbox
XoomBox based pneumatic shift system.
Ford XR4 differential case and 3.62:1 crown wheel/pinion, TranX limited slip diff


Lightweight race battery
Emerald ECU
Innovate LC1 wideband lambda sensor
XoomBox datalogger/traction control/launch control + 7 segment shift light
Datalogging channels := engine speed, 4 wheel speeds, throttle position, lambda, oil pressure, oil and water temperatures, x & y acceleration
Xtra Flat Shift X10der for XoomBox - semi-automatic pneumatic driven clutchless up/down shifts, gear display.
Water pump controller.  we didn't like the Davies-Craig supplied pump controller, so we built our own!  Much better.

Increased power, reduced weight and stickier tyres have had the expected effect on lap times.  A clockwise sprint run at Kames was around 98s the first time it ran there.  By the end of 2007, this was down to 87.5 - and that was before the fancy engine!  The first event in 2008 saw this reduced further to 85.5 and at the second it went under 85.  Mid 2009 saw both drivers dip below 84s, and in October, Stephen recorded out first sub 83s run.  The fastest runs we recorded in road legal trim were 82.53 for Stephen and 82.61 for David, both recorded in July 2011.

For 2012 along with the Duratec engine, we switched to modified class and changed the tyres for slicks and shed 25kg or so.  This allowed Stephen to reduce the Kames run to 80.8s with David recording 81.45.

At its first Autotest

A standard road going Westfield

David waiting to start an autotest run

David at Kames 04/2006

Stephen at Kames 04/2006

By the end of its first season sprinting

Windscreen has gone, sportseats replaced by shell, rear arches extended for fatter rubber, front lights replaced by lightweight items, RAC legal rollover hoop

2009 livery

On the way to the start at Golspie.


The roll cage is the biggest externally visible change for 2011. Underneath though, much more changed.



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This site was last updated 03/15/13