Noble M400 Buyer's Guide

Some information on what to look for when buying the most powerful 6 cylinder Noble. We have experience with running the Noble M12 and M400 cars. Please get in contact if you have any specific questions for which you may not be able to find any technical answers.

Introduction

The Noble M400 was introduced at the 2004 Birmingham Motor Show for the more demanding customers who planned to take their car to the occasional track day and also to enjoy more performance on the road.

Key differences

The M400 differs to the GTO, GTO-3 and GTO-3R in the following areas:

• • seat type and position

  • dampers (Ohlins Single Adjustable Monotube Damper 36mm, S36DR1)

  • spring rates

  • fitment of front anti-roll bar

  • revised suspension pick-up points

  • high lift cams

  • water cooled Garrett T28 turbochargers

  • track-spec sump

  • Pirelli P-Zero Corsa tyres

  • improved throttle cable path

  • improved gear shift mechanism

  • interior oil temperature & pressure gauge

Engine bay

M400s have tendency to boast high under-bonnet temperatures. The turbochargers produce a large amount of heat that is not very quickly dissipate in the engine bay due to low levels of airflow through it. The issue should be solved not so much with complex shields but by a specialist such as Turbohoses in USA who can provide information about ECU changes and additional hardware to lower the ambient temperature.

Modifications for frequent track use

The M400 can be taken on track but will benefit from a number of small upgrades:

• • larger and more efficient intercooler

  • high flow exhaust (unlikely to pass the MOT)

  • dynamometer tuning depending on fuel and temperatures in the region where it is used

  • accurate engine oil and coolant temperature gauges (the standard ones are not particularly responsive)

  • modification to the brake ducting to allow high flow (typically) or reduced flow (very cold days)

  • exact geometry alignment (vitally, any toe settings on the rear suspension)

  • Garrett GT28RS Ball Bearing Turbochargers if you have the money (quicker spool time)

Fuelling

The M400 with the latest factory map should make approximately 330-350 horsepower at the wheels (many dynamometers read differently but Dyno Dynamics are taken to be a good repeatable and not over-estimating benchmark). As standard it has a higher fuel to air ratio than the M12 which allows for some power improvement if the owner is able to extract some better airflow. However, it is advised to check each modification on a rolling road dynamometer because a number of conditions may contribute to the engine running lean and causing catastrophic detonation.

A safe envelope of +50 is achievable with ECU recalibrating leaving parts unaltered. More power ideally requires upgraded parts and the gearbox is typically the weak link in its ability to cope with high torque for extended miles.

Turbochargers

The standard T28 turbochargers run out of thrust at approximately 6750 rpm. They can be upgraded with a 360 degree thrust bearing and larger (but still light) compressor wheel. The cost is approximately £600 each and this allows it to make approximately 500 HP at the crank shaft with approximately 1.4-1.5 bar of boost.

Two ball bearing GT2860RS turbochargers with 0.60 compressor housing A/R and 0.64 turbine housing A/R can produce up to 700 HP but require bigger induction, oil and coolant pipes. The turbochargers will not release their full potential without some engine work such as valves, springs and cams (pretty much the Mountune job). At this power level it is wise to uprate the gearbox internals (see below). Up to 3000 rpm the power level will be if anything slightly lower than the T28 but from 3500 they are identical and start diverging above that rpm. The GT2860RS will not run out of thrust at any point below 7500 rpm.

The GT2860RS compressor map shows the area of highest efficiency at a pressure ratio of 1.7 and a power level of approximately 550HP (combined for 2 turbos). This is where the compressed air will be coolest. However, running them in real life at this power level will make them a little less responsive than a smaller compressor, despite the temperature rise from a lower efficiency. Take for example the fact that the Nissan Silvia S15 uses the GT2860RS to produce approximately 250 HP in standard form (passing all emissions and calibrated for comfortable street use).

The boost can run up to ~ 1.4 bar at 4000 rpm and can tail off to 1.1 bar at 7500 rpm

Anyone considering a single turbo setup can look to the EFR series by Borg Warner. The range of turbos caters for anything from 500 to 700HP.

EFR 8374

EFR 8374 USA

Transmission

Many specialists take approximately 425 lb*ft as the safe limit for the gearbox to endure moderate mileages. With sensible power curves, this results in approximately 550-570 HP at the crankshaft and 470HP at the wheels. A vital aspect is to run a gearbox cooler and high grade lubricant.

There are no alternative gear sets and the gears can only be shot peened and microfinished. Any engine power above 650 HP at the crankshaft may begin to do damage to parts such as bearings in the gearbox or cause other effects on the light aluminium cast casing. After all the transmission is from a petrol Ford Mondeo, not a diesel so it was never designed for abrupt full-boost changes nor “step-off-the-clutch” launches.

Tuning example

Below is an example of a customer M400 and its upgrades

Performance (standard):

• weight 1065 kg

• 0-60: 3.17 s

• Quarter mile: 11.4 s, 120 mph

• Skidpad lateral acceleration: 1.05g

Performance (modified)

• 510 Wheel HP:

• twin Garrett GT28RS ball bearing turbos

• 3.5” thick RacePrecision bar & plate intercooler

• Relocated dual larger air intakes

• Ferrera custom super alloy valvetrain

• Ported & polished heads

• RacePrecision Custom ground cams

• Upgraded 6-speed transmission with microfinished gears, Mocal cooler, & Quaife LSD

• Kevlar/Kevlar clutch

• Fidanza lightweight aluminum flywheel

• Custom 3” mandrel dual exhaust, 3” Burns Stainless ultralight mufflers

• RacePrecision tune for MBE ECU

• Blitz Sequential Boost Controller i-D

• HKS racing bypass valve, Red Dot

• 75lb/hr injectors

• Bosch 044 fuel pump & relay & wiring upgrade

• Sard fuel pressure regulator

• RacePrecision water/oil cooler

• East-Penn Deka ETX20L 15.5lb AGM battery