Postby fras » October 6th, 2014, 9:36 am
These are in order that will typically give you best 'bang for the buck' as you go and get progressively more expensive. As with everything in life, you do tend to get what you pay for although a very expensive part may provide only a marginal improvement over a cheaper alternative. Generally you shouldn't start mods in the next stage until you'd done everything in the stage before.
STAGE ONE Basic upgrades
Free Flowing Rear Muffler box
The brand is not important but a good design is not overly 'loud' while still providing good flow. I good trick is to use a 2 1/2 in/out muffler box on a 2 1/4 system.
Pod Filter with Improved Cold Air Intake
Brand is not that important as any pod filter will outflow the factory panel filter. Popular choices are K&N and Simota. Cold air intakes can made from a large diameter pipe ducted to the front or by fitting a bonnet scoop.
Exhaust System 2 1/4" or (2 1/2 for 2L V6)
Mandrel Bent system is best but is a more expensive option than press bent. If going press bent, increasing pipe size to 2 1/2 is an option, but a mandrel bent 2 1/4" system is optimal for road driven cars.
Headers
Aftermarket headers will improve performance, especially on gen1 models which have a heavy cast iron exhaust manifold. Generally speaking, 4-1 designs will give very good top end performance, 4-2-1 will give good mid range performance.
Adjustable Camgears
Dialing in the camshafts eliminates manufacturing variations and gets the best possible performance from the camshafts.
Rechiped factory ECU
Available for 1G owners only, but gives good gains down low when combined with the mods listed above. PM me if interested.
STAGE TWO Advanced bolt on upgrades
Piggyback ECU
The stock ECU can only be tricked so far, your going to need extra fueling by now so some kind of piggyback ecu is required. VFAC or Emanage type devices are popular.
63mm Throttle Body
The stock 60mm throttle can be bored to 63 very easily and gives very good gains
Cylinder head porting
Cleaning up the castings on the head, especially the valve pockets which can have bad castings and match port the inlet manifold to the head.
Injector Upgrade
Particularly 1Gs because the have very small factory injectors and will probably be operating well beyond the normal maximum 80% duty cycle so its time to upgrade them to something larger. Will need to have at least piggy back ECU.
Exhaust system 2.5"
To get the most out of the next stage you will need to free up the exhaust even more. This may result in a reduction in low rpm performance, but by now your probably going racing and gains up top will be worth it.
STAGE THREE Engine Internals
ECU
A programmable aftermarket ECU will get the most out of the modifications done so far, and will be required if you want to go all the way.
Cylinder head porting
Further improvements to the shape and dimensions of the runners. Consult an experienced cylinder head tuner.
Increase Compression Ratio 12:1
Required to get the most out of aftermarket camshafts.
Camshafts
Increasing duration and lift will improve top end performance.
Pistons and Rods
Lightweight pistons and rods will potentially allow higher RPM. Not much off the shelf, so they will have to be custom made, luckily most piston and manufactures will do custom ones.
Crankshaft
Knife edging, and fine balancing all the moving components will reduce parasitic losses and increase reliability at sustained high RPM
