Following on from our first trip to the guys at Redline Tuning in Essex, we were given a list of updates that were necessary to get the car up to speed.
There were some minor modifications to wiring loom to make full use of our ECU. Straightforward cutting and joining.
Our two high pressure fuel pumps were both putting out around 200 litres per hour, unfortunately the data from the first dyno runs showed that we were losing fuel pressure at high revolutions. As a result these were replaced by two more pumps both capable of 400 litres per hour.
In simple terms the engine is now using more than 3 1/2 litres of fuel per minute once running over 5500 rpm. As our peak is at 7000 rpm, with the current cost of fuel, huge power really doesn’t come cheap!
We also discovered that our turbocharger was undersize. Those of you that have seen this will find it slightly hard to believe as it is already huge by normal standards.
The image above is our old turbo next to a unit from an Audi TT.
The below image is old against new.
The main reason for fitting a turbocharger in the first place was to allow what is a slow and ‘lazy’ engine to spin at the 7000 rpm we need to reach our target speed.
The original turbo was actually causing a restriction above 5500 rpm and was not allowing enough air through to the engine.
So, with our new turbocharger, improved fuel pumps and corrected wiring off we went back to Redline tuning to try and complete our engine mapping and tune up.
As is always the way with these things, when you start to stress parts and mechanisms on what is a complicated system you do end up showing the next weakest part.
The day on the dyno was going well and as the tune was getting nearer to perfection both the measured BHP and torque were increasing rapidly.
We were running minimal boost from the turbo and once the base map was sorted we could start to up the pressure from the turbocharger.
Unfortunately this optimism was then followed by the all too familiar sudden noises and loss of power to the rear wheels.
The big difference this time was rather than wondering what had failed we had information to both point out what had happened and what we would need to prevent it.
It turns out a by-product of enlarging the engine was that the increase in power also causes an increase in torque.
Unfortunately torque is the enemy of gearboxes.
It turns out that whilst we were producing 600 bhp we are also producing 650 ft/lbs of torque.
After a bit research we discovered that our gearbox, from a ten cylinder Dodge Viper, whilst it is desgined to cope with 800 bhp is only desgined to cope with 425 ft/lbs of torque.
The difference in power requirements is highlighted in the next image.
The one on the left, is the first motion shaft from our (not up to it) gearbox, the one on the right is exactly the same part from a Reliant Robin. We appreciate the Reliant is not the most powerful but it certainly shows the difference.
The first motion shaft is the part that transfers the engine power to the gearbox.
As a result we now have a new and shiny gearbox that is designed to cope with a lot more torque.
Whilst we were organising the gearbox we also took the opportunity to double check the condition and strength of the remaining drive train parts.
As a result the rear axle, clutch assembly and propshaft were all removed stripped cleaned and treated to new lubrication.
We also stripped the engine to make sure all was well inside.
Unfortunately on start up, the engine still has a disquieting noise. We have since stripped the engine again to see if we can locate the errant part.
As this update is written we still do not know exactly where the noise is coming from.
The mystery deepens and we will try and keep you informed as and when the answer show itself.
A very frustrating time!
On a completely different note, we were really pleased to be contacted by one of our subscribers.
Mark made the following observations, thank you Mark we really appreciate your thoughts and agree with your sentiments.
Thanks again Mark. To us our project is not simply to see how much time we can spend in a cold cramped workshop, but what we really want to acheive is to inspire others.
If we can encourage someone else to get that old car or motorbike out of the shed or simply get up and do something they wouldn’t have done otherwise then we have succeeded.