CPR prepare Race Car for 2010 Time Attack

Stay Tuned, we have some exciting improvements in plan!

CPR R35 GTR Stage 4-5 Tuning - Engineer's Notes

For our STAGE 4 tune the working brief was to achieve a strong and repeatable 600 hp 600 which from initial study of the stock turbo spec, would possibly be the most we could reliably find from them. Well this is when the tuning of the GTR became both interesting and more involved than basic breathing add ons. The HKS panel filters were finding 10 WHP (additional power at the wheels) in the lower tuning stages. It was an obvious thought to us that a good improvement of air intake design would result in reasonable gains over the stock air box, as peak power was influenced relatively well by the basic introduction these HKS panel filters we thought it may be a restrictive area and worth a rework.

From the advance of gaining the Cobb Tuning PRO-ACCESS TUNER Software we are now able to 'live access' the GTR ECU during tune on our Dyno Dynamics AWD dyno and therefore gain valuable data logs of critical input signals from our previous stage tuning packages that work so well repeatedly exceeding target performance claims. More specifically data logs from output 'injector duty' and input 'air flow meter' signal on our STAGE 3 (using cobb generic tune) offered concerns as to the 'head room' left in these components to enable safe power increase. With this STAGE 3 generic tune running out quite rich in A/F ratio to mid 10:1 there would be room in the injector to find 30 -35 hp over our 580hp STAGE 3 with a more realistic and leaner target A/F of low 11:1. Unfortunately the same could not be said for the air flow meter signal as they would already reach their 'full scale deflection' of 4.9-5v in the 580hp STAGE 3. Therefore ANY increase in air flow over them would NOT be seen by the ECU and an accurate tune would be severely compromised at high load and high rpm!!

To gain headroom we chose to remount the stock air flow meter cartridge sensors into a larger body, therefore lowering the sensor voltage for a given total volume of air measured (Grammes/sec). Obviously correctly sizing this housing to allow the higher air flow and still be 'future proof' in further package development of higher power was critical. As the stock housing is the actual air box moulding we combined the development of our larger body housing into a full replacement induction kit, drawing air from the preferred forward area front panel so as not to pull ANY air from the warmer engine bay itself. To filter the air thoroughly, a cone shaped filter element was chosen to optimise flow in that given are which is in fact is capable of more than twice the flow of the panel / flat stock alternative!

With both these component limitations addressed we wanted to drop the total exhaust back pressure to a minimum and so the development of our replacement 3”front turbo outlet elbows allowed the removal of the more restrictive forward catalysts.

Time to see what increase in performance would come from these mods on the dyno, but first the critical rescaling of the airflow meter bodies was necessary to correct the ecu's interpretation of the now respectively lower voltage. This became a VERY technical necessity as side effects of getting straight into the tune would be extended to gearbox clutch control and calculated torque changes!

In our opinion there is only ONE way to skin this cat and it took time to build the file to support these hardware changes but the results were absolutely perfect, offering scaling to modify to an estimated 800hp!

Alternatively to this it is possible to buy the HKS 570 / 600 R kit which comes with NO ECU TUNE but chooses to interrupt the input signal and corrupt or clip its appropriate value. In our view and with our understanding of the side effects this technique causes at the transmission control unit (TCU) the age of corrupter and interrupter boxes have gone and should be left in the 'Nauties'. We would NEVER fit a Fuel Cut Defender (F.C.D.) to an '97 evo 4 , so why are their equivalent appearing on GTR's???

Back to the tune and it soon became obvious that the induction kit and turbine elbows combined had released far more power than expected, achieving over 530 whp but leading us to severe leaning out above 6000rpm at 15psi which we could not support with the stock fuel delivery! Injectors were flat out after 5500rpm with 17psi boost held up to this rpm offering 630+ torque.

It became clear that this combination of hardware would need more fuel delivery on tap, so the introduction of larger 750cc/min RC injectors made safe this power level again with a comfortable amount of headroom in the injector for 800hp. Again the scaling of these injectors within the ECU is critical for its closed loop and target A/F ratio control to function accurately, amongst other side effects caused if this is not done correctly.

Alternatively, it is possible to use the same thought process as HKS used in their 600R kit and change the stock fuel reg to an adjustable unit to raise the fuel rail pressure and force more fuel through the stock injectors , which in turn, loads the stock pumps to the point they too must be changed for stronger units!! Again a very unprofessional approach in honest opinion!

This inadvertently became our STAGE 5 package but we found it necessary to add after market stronger sprung actuators to keep stable boost control. The lower exhaust back pressure limited the repeatable boost level at peak power and on back-to-back dyno runs the boost would fall dropping expected power at higher temperature. The after market actuators held consistent boost on repeated runs and deemed well worth the labour intensive fitments of them and earnt their place in this 630 hp / 630 CPR STAGE 5 package.

Our STAGE 4 tune saw the emittance of the turbine elbows and the forward cats replaced. This corrected the boost control inconsistency and dropped power to the desired level that could be SAFELY supported by the stock fuel injectors. So we found our 600hp/ torque package by essentially detuning the power found using hardware that is now our STAGE 5 630hp package!

Strange how things can work out!

Another 600hp+ R35 GTR - Stage 4 Tune from CPR

CPR finish another Stage 4 Tune on UKDM R35 GTR - Black Edition, resulting with 612hp (flywheel estimate) and over 600lbft.

CPR Stage 4 Conversion includes;
- CPR Full 3.5" Exhaust System
- CPR Front Y-Pipe De-Cat Section
- CPR Larger Air Flow Meter Housings & Induction Kit
- Cobb Tuning Access Port
- CPR Custom Cobb Tuning Map performed on our Dyno

Review our Tuning Programme for R35 GTR

New CPR Demo Car - '09 BMW M3 E92

CPR have recently received their new Demo / R&D Car, a 2009 BMW M3 E92, to mark their continual development of their European Sports Car Performance Tuning Programme.

The car will undergo development in aspects of Chassis, Braking and Power, where we will test our own products on the car in Track and Road environment, with a focus on offering customers a well researched tuning programme.

Please keep an eye on our blog for updates on this project

New Forgestar Rims arrive at CPR!

Our shipment from Forgestar arrived today from USA, with a very quick lead time, we are now ready to install our new Demo Car - 2009 Porsche 997 Carrera.

Introducing the Forgestar F14, 19 x 8.5" Front, 19 x 11" Rear in CUSTOM Offset spec'd to our requirements for the best possible stance.

Installed photos coming soon!!

New Forged Rim Range - 'Forgestar' - CPR Official UK Dealers

CPR are proud to announce that they are now the Official UK Dealer for a new exciting high-class forged wheel range, offering
the finest quality of Forged Rims to suit Porsche, Lamborghini, BMW, Mercedes and V.A.G.

The entire wheel range is available in ANY offset, meaning the perfect wheel stance can be achieved, and clearance for the biggest of brake kits.

Even better is the price, RRP on set of 4 Forged x 19" Rims in any Offset/Width/Finish is around £1300.00+VAT!

Incredible value for such a bespoke custom, lightweight and incredible strong wheel.
We are awaiting a set of very special F14 Rims in 19x8.5/11" for our new Demo '09 Porsche 997

Forgestar F14

18×8.5 offsets from +26 to +50
18×9.0 offsets from +20 to +55
18×9.5 offsets from +26 to +60
18×10 offsets from +16 to +42
18×11 offsets from +23 to +55
18×12 offsets from +36 to +68

19x8.5 offsets from +26 to +48
19x9.0 offsets from +20 to +55
19x10 offsets from +20 to +44
19x11 offsets from +23 to +55

20×8.5 offsets from +26 to +50
20×9.0 offsets from +18 to +56
20×9.5 offsets from +7 to +43
20×10 offsets from +31 to +69
20×10.5 offsets from +20 to +55
20×11 offsets from +48 to +81
20×12 offsets from +39 to +75

Forgestar F10

20x8.5 offsets from +30 to +50
20x9.0 offsets from +18 to +56
20x10.5 offsets from +20 to +45
20x12 offsets from +39 to +65

Forgestar F05

19x8.5 offsets from +32 to +47
19x9.0 offsets from +26 to +44
19x10 offsets from +26 to +44
19x11 offsets from +33 to +60

With over 30 years of combined experience in the automotive wheel industry Forgestar Performance Wheels has bridged the gap between forged wheels and cast wheels. Forgestar Performance Wheels is proud to introduce the world's first one piece lightweight custom flow formed wheel lineup.

Flow Forming is a production procedure that turns the wheel (or rim section) over a special mandrel and three hydraulic rollers using tremendous pressure. The pressure and turning then force the rim area to form against the mandrel, creating the shape and width of the rim. During Flow Forming, the rim actually "flows" down to create the full rim width. During Flow Forming, pressure applied to the cast rim actually changes its mechanical properties, so its strength and impact values become similar to those of a forged rim. That translates to up to 15% less weight when compared to a standard cast wheel. Our technological breakthroughs in heat treating allow us to increase dent resistance without having to make the wheel heavier.

Forgestar Performance Wheels proprietary Flow Forming technology allows the customers to choose between a range of offsets for every wheel width that is offered. The end consumer is able to choose a wheel that will perfectly fit their own individual vehicle. All Forgestar Performance Wheels are compatible with tire pressure sensor monitors and allow clearance for most high performance brake caliper upgrades.

Forgestar warrants that wheels manufactured by Forgestar will be free from structural failure as long as the original retail purchaser owns the product. Forgestar further warrants to the original purchaser that products manufactured by Forgestar will be free from defects in material and workmanship under normal and intended use for a period of one year from retail purchase.

To view the Forgestar Range go to

For more information and to purchase go to

Richard McDonald Evo 7 Circuit Car - Complete!

CPR complete another Full Race Car conversion project for Richard McDonald.
The car started life off as a mild tuned 500hp Evo 7 GT-A Automative, but Richard requested a conversion project to allow it to compete in the UK Time Attack Club Series for 2010.


CPR stripped the entire car down to a bareshell, and then built a Full FIA Weld-In Cage Cell, along with ligtening the car and RS Differential Conversion.

Autobahn Paintworks in Blackpool fitted a Carbon Roof Skin and repaired the original Chargespeed Aero Kit and Carbontrix Front Bumper, aswell as painting the entire interior and cage in black

Tein Super Racing Suspension (previously fitted to the CPR Orange Works Evo) was fitted, along with full Polybush kit to stiffen up the suspension links.

Whiteline and Cusco ARB's completed the suspension setup for the car.

The Motor was left at the original spec, which is 2.0L Forged with CPR500HP Full Turbine Kit.

CPR changed the Intake Plenum for the CPR Spec D.I. Intake Plenum and 75mm Boomba Racing Billet Throttle Body, along with Aeromotive Fuel Rail

A major upgrade required for preparing a car for serious work is the upgrade to the conventional Oil System, due to the fact that hard cornering can cause Oil starvation. One route is to go for a Full Dry Sump Kit, but a similar prevention system can be achieved by installing an Accusump System, as Rick chose.

The Accusump system accumulates oil in a reservoir, and then in the cause of low oil pressure being sensed, the system will blast oil into the motor under high pressure, to save the bearings/turbocharger.

Rick's car previously had a lethargic automatic transmission fitted as Rick is unable to drive conventional clutch vehicle to his disability, however, Rick decided that to ensure the car was competitive, an upgrade to the transmission would be required to reduce transmission losses. CPR have converted this car from Automatic, to a Manual 5 Speed Car, and have installed the Drenth Full Race Dog Gear Set into the new 5 speed housing, along with the Ikeya Sequential Shifter conversion, as fitted to our Time Attack Evo's.

CPR then had a specialist mobility company in Liverpool called 'Da Vinci Mobility' install an automatic clutch system, whereby a trigger operates a motor which control the clutch pedal. CPR then modified the system further to bring it up to a level where Rick could use the system in a racing application, along with Flappy Paddles and Pro-Shift Solenoid Operating the Ikeya Shifter. The original Handcontrols that Rick had previously on his Evo 7 were modifed and re-installed, so that throttle and brake can be operated by hand. The interior was finished off with a Flocked Dash, Suede Sparco Steering Wheel, and AIM Digital Dash Cluster, with custom wiring from CPR to enable Rick to monitor everything on the car from the digital dash.
To meet Time Attack regulations and for safety, a full FIA Lifeline Fire Extinguishing System was installed also.

Full Group N Brake Line Kit, modified ABS System, and Twin Bore Hydraulic Handbrake were then fabricated and installed by CPR, to compliment the AP Racing brake set up.

Massive amounts of weight saving have been achieved with this project, and now with a full sequential dogbox installed, the car has been totally transformed, where Rick has planned extensive track testing to become familiar with the new setup, before competing in Time Attack next season. CPR wishes Rick all the best in his first season of UK Motorsport.


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