SWR Web Site - NOS Questions and Answers

The only difference in the engines is the Cam Sensor which is fitted to the VR Engine.

If the VR Loom is fitted to a VP engine it will log a fault code of no Cam Sensor but it will operate normally and not go into Limp Home Mode, if the Diagnostic Light is fitted it will be on when the engine is operating showing a code has been logged, if this is annoying simply disconnect the light until it is required.

The only difference in the engines is the Cam Sensor which is fitted to the VR Engine.

If the VP Loom is fitted to a VR engine it will operate normally and will not log any fault codes.

The TPS or Throttle Position Switch is fitted on the side of the Throttle body and Sensors the Position of the throttle plate.

This Switch operates on 0 to 5 volts with 3 wires (or as close to 5 Volts as you can get it)

This switch when changed is often incorrectly fitted, the only way it can be set up is with a multimeter, the signal out is 0 volts at closed throttle (or as close as you can get it) and 5 volts and Wide open Throttle (WOT) (or as close as you can get it)

If incorrectly fitted or faulty will create flat spots and incorrect fuel and ignition settings.

The fitment of an aftermarket low Profile sump in most cases involves the removal of the hump on the centre of the rear Main Bearing Cap.

The VP and VR engines from the factory had a problem with the alignment of the cam bearings, many engines spat out a cam bearing under warrantee and they are still doing it today.

To ensure your engine will not do this use the race cam bearings and pin the centre two cam bearings, this was even done in all of the Formula Braham engines using that block.

When a new cam is fitted it is important to make sure the cam is easy to rotate before any of the engine is assembled.

these engine usually run around 75 lbs oil Pressure if the pressure drops to 45 to 50 lbs it is usually one cam bearing has been spat out, if oil pressure goes down to 10 lbs it usually means two bearing have gone.

If the cam bearing are not pinned it is very common for them to move slightly and block off the oil gallery and engine failure will occur very soon after this.

The original set up with the factory reservoir uses the 1510 Series belt so the reservoir is flat.

If using a remote reservoir you can use the shorter belt being the 1500 series, this will allow the fittment of aftermarket rocket covers without the power steering pressure hose fouling.

Point to note the 1500 series while the same brand as the 1510 does seem to stretch a bit when first ran so dont forget to check the tension, the latest version of the alloy power steering bracket has been modified to allow for easy adjustment.

The 1500 Series and new powersteering bracket are the way go if you can for the following:

shorter belt so less chance of coming off
Greater clearance on the Power Steering Pump outlet line
Greater clearance to the bonnet on some cars this is a problem with the 1510 series
New Alloy Power Steering bracket is very easy to adjust

There have now been two cases where the NOS computer and chip has failed the Max RPM test when tested by officials with the engine not running.

All of the NOS chips are sent out with the same Rev Limit, all chips are tested before being sent out.

Some people think that a faulty chip may increase the rev limit but this is not the case, if the chip is faulty for what ever reason (welding on the car, jumper leads, wrong wiring loom, broken solder, etc) the engine will not run very well at all, and we will replace the chip at no cost even if you broke it.

If an official tests your computer with their on car max rev tester and it does not pass get them to:

Up to now Chips that have failed the official test have had nothing wrong with them.

Fuel Pressure and fuel flow are two different tests but both must be correct for the system to work.

Fuel Pressure is check with the engine idling and taped into the pressure side from the fuel pump prior to the fuel rail

Typical fuel pressure for a VP to VT commodore is 350 KPA (50 PSI) without the vac line fitted

Increaseing the fuel pressure by modifying the pressure regulator or using restrictors is dangerious and illegal.

To test the fuel make sure the tank is full, take off the return line put it into a 20 litre container and time how long it take to fill with the engine idling.

Do not just do half the test, if there is a proble with the system it will usually show up after 15 litres have been flowed.

If you are running a fuel filter prior to a typical 044 EFI pump the filter must be at least 100 microns as the pump does not have the ability to suck in an on road situation there is usually a pusher pump in the tank to ensure supply.

If you have a filter after the pump you must make sure it is designed to handle the pressure and is replaced or cleaned regularly. Most Petrol EFI filters are not suitable as the glue in the filter is not designed to handle methanol, the ideal set up is a stainless filter with a rating of 10 microns, but this must be cleaned every meeting.

We now have NOS filters to suit the High Pressure side of the fuel system these should definately be used when running any modern injector

With any of the modern Injectors you must run the baskets, it is recomended to change them each meeting

Some classes insist you have fitted a ignition cut off, this is not the same as a battery isolator

A battery isolator is fitted beteen the battery positive and the starter with all other positive wires coming from the starter, this will not not stop the motor if it is running as the alternator is feeding the system, but this is what you want on a wingless to save the battery and make it safe to change the injectors, or have kids in the car for a pic.

An ignition cut off has to be in the feed to the ignition, with the power wire from the alternator going to the battery side of this switch, this will not stop battery power to the starter and alternator.

See what temp the exhaust is, you can do that by feeling close to the pipe or using a temp probe.
this information will tell you if all cylinders are playing up so look for fuel or coil pack or fouled plugs
If just one look for injector or spark plug

do a fuel pressure test I recomend all cars run a pressure guage (see process on this page)
Do a fuel flow test.
Ensure you have a 100 Micron Stainless filter before the pump
Ensure you have a 10 Micron Stainless filter after the pump

Check with engine running that if you wriggle a wire the engine does not stumble
Make sure all screws and earths are tight
Always make sure you tie up the wires so they dont dangle and loosen a connection
Check the Crank Angle sensor connection it is common to damage the terminals I now use a heavy duty "farmer" terminal to reduce this

Remove each connection and check for damaged terminals and corrision
Use a Circuit cleaner or special Terminal Cleaner to ensure good connection

Check the volage is between 13 and 14.8 V out of this range the computer will go to limp home mode.
If the alternator has a faulty diode it can still work ok but will spike Computer and send to Limp Home Mode

Having heaps of drama's from New coil packs would not recomend fitting one
Always make sure you use a heat paste on the back of the coil pack to ensure the heat if transfered from the coil to the engine
If the coil over heats it will never recover and will need to be replaced
When selecting a second hand coil pack ensure
- the spark plug terminals have not been corroded
- None of the coils have been replaced (if a coil needs replacing the base will to)

As these engines are standard and low in power you do not want a heavy valve spring as this will cost you HP
Engines miss firing at high revs can be caused by weak valve springs
I note that it is often said you can tell this by free reving the engine, well my experience tells me you cannot without some load on it
A simple way to check the springs is to put the one fitted in a vice with the std one and close the vice the weakest one will collapse first
Note not all the valve retainers and spring listed on the recomended parts list are the same do your home work