Recommended mods to RB30E
It costs a lot of money to get big power out of a NA motor, so if there's any chance that you're going to want more than "just a little bit" more power in the near future, start saving your money for a turbo conversion. A turbo conversion will ultimately cost less per kw.
Things like a pod filter and PULP will help your car in the meantime
If you want to get more power out of your RB30E, here is a list of things you should start with.
In no particular order.....
- 2 1/4 or 2 1/2 inch exhaust system (mandrel bends)
- High flow cat
- Advance the timing to 20 degrees
- Pod filter
- Camshaft and chip
- Port and polish head
- Extractors - cost: around $250-$350 + fitting
- PULP - cost: about 20c per tank more than regular fuel
- Enlarged or XF Throttle body
General consensus on the R31 Skyline Club forums in regards to R31 N/A modifications appears to be:
Pod Filter[edit]
This is the first modification that most people perform. It is a simple, quick and cheap mod to perform on the RB30E, CA20E, or any engine. Installing a pod filter will allow your car to breathe, without the restrictions it suffers with the air box. Laws on pod filters vary between states. Oiled filters are not legal for road use in most states. Oiled filters are not recommended, due to their ability to foul the AFM. Cooler air molecules will result in better power from your engine - so the cooler you can get the air the better. If you want to keep the warm air from the engine away from the pod filter, you can make a heat shield.
Exhaust System[edit]
- 2.25" exhaust if automatic and not planning on upgrading camshaft later on
- 2.5" exhaust if manual or planning to upgrade camshaft
Mandrel bent as opposed to press bent will result in better flow. Remember the most restriction is at the smallest diamter in the exhaust pipe.
Advancing the timing[edit]
The timing can be advanced manually by turning the distributor past manufactors specs (15±2 Before Top Dead Centre) when running on PULP but this will advance your entire iginition maps also which can result in pinging during high load and rpm combinations on bad fuel or hot conditions. To advance the timing properly you will need a timing light. (A good inductive one which clips on to the plug lead) Run the car up to normal temp, and then with it idling in neutral with all accessories and lights off, put the light on the plug lead for number one cylinder. Loosen the bolt which locks the distributor and turn it till you get about 18 degrees, the marks have an orange one for top dead centre, and the marks are at 5 degree intervals, if you set it just before the fourth mark from TDC that will be about 18-19 degrees which is a good starting point. Listen for pinging, particularly on hot days, and if it does, retard it till it stops.
Extractors[edit]
Various types of extractors on the market for the RB30E. It should be noted that the R31 Skyline extractors are a different length to the VL commodore extractors which should make the buyer beware. The extractors generally should be slightly larger than the same diameter as the exhaust, depending on the size. This is since the exhaust usually restricts the actual gases coming out of the engine through bends (where mandrel bends will provide less restriction than pressed bends). The GTS1 and GTS2 model Skylines have 2" extractors to 2.25" catylitic converter to 2.25" exhaust. The price in extractors is usually dependent on their quality (like build materials such as stainless steel and the welding) as well as the accuracy of the turing in the bends of the pipes. Better tuned length extractors will generally flow better than ones where the lengths are slightly off. Prices begin at around $250.
High Flow Catalytic Converter[edit]
Next you could spend the money to increase the flow in your catalytic converter by getting a high flow system, which will improve for those running 2.5" exhausts going to a larger size. How effective a high flow cat is against a system without one is something I haven't completely determined myself. Gutting a catalytic converter is highly illegal, polluting, dangerous (contains heavy metals such as cadmium in the honeycomb) and will result in turbulence due to the gases hitting the back of the cat as they try to escape.
Camshaft and Lifters[edit]
After this you can perform modifications to the engine itself through changing the camshaft over. There are various types, such as the Nizpro ones which are meant to be very good as well as other types like AVO. Camshafts which are still fairly mild (stage 1 or 2) are able to be run by the existing computer (ECCS) without any modifications. Other types will require some kind of computer modification by either replacing the program chip with a reprogrammed type for that camshaft or replacing the whole computer itself with an aftermarket. Obviously the second option is going to be more expensive but gives you the option to retune your system. Note that when replacing your camshaft you will either need to replace the lifters of which there are 12 (costing upto $70 each from Nissan) or get them reground due to the different wearing with the old camshaft. This can increase costs significantly on top of a cam and chip package.
Porting and Polishing[edit]
Other options after this can include porting and polishing which will can better flow through the inlet and outlet ports. The GTS2 engines had mild head work performed to the exhaust ports and the GTS1 exhaust ports also look slightly larger on my currently engine than stock. These will increase the amount of flow that your engine can suck in as well as breath out and will take advantage of a good induction and exhaust system. I believe the amount of power from this modification is mainly noticeable in the high revs (prob around 5500rpm - 6000rpm) when the air intake / expelling will take advantage of the larger ports.
Aftermarket Chips[edit]
There is also aftermarket chips (if you dont upgrade your camshaft) but I believe they are fairly expensive for the amount of changes in software. They bascially do what they state in the brochures - increase the timing of your engine (the company will ask if you will run PULP all the time or very often) as well as modify both the igntion and fuel maps.