I have a 509 bhp nissan skyline with 400lbft of torque , what is the best way to increase the torque ?

Put some 14" wheels on it. that will change everything lol.

The max torque in an engine is reached when the engine is at a point where there are no restrictions and doesn’t have to overcome any other forces. The variable timing for the cams was invented to extend that point by helping the valves to stay at their best point at different RPMs and is used by most engines today. To increase torque (and as a direct result, power or HP) you have to increase the air and fuel mix and be able to maximize the flow (intake and exhaust flow). Based on those simple statements, most aftermarket performance parts are created to accommodate more air, more fuel, and better air flow for your engine. The best way to increase torque is by increasing the volume of your engine. But because we can’t do that, at least not without taking it apart and rebuilding it almost completely, we have the “blessing” of force induction, AKA turbos and superchargers. If you don’t want to increase the boost in your turbo(s), then you have to increase their volume. That requires to upgrade the turbo(s) for something bigger. Of course, you will have to trade the power gain for something (nothing comes free) so you will loose spool speed, or as usually referred too, you will gain turbo lag. Turbo lag can be compensated today by using innovating materials and technologies. You can upgrade to ball bearing turbos that use light weight fans to virtually avoid most turbo lag. Of course, you will need to match your new turbo(s) with the corresponding parts for the engine. Pistons, valves, injectors, intake size, exhaust size, etc. All those need to be adjusted for maximum performance. Now, before you go and buy new turbo(s), you should analyze what you have. In most cases, you should be able to get more power by studying your current setup and fixing any problems. A better intake that matches your air requirements and a good exhaust are key parts on this play. If you don’t have performance exhaust manifolds, you should look into those before upgrading any turbo. A good performance exhaust manifold will help the turbo by “sucking” the air out of the turbine (using aero dynamics and fluid dynamics basic theories) giving you more torque as a direct result. You should also measure the boost at the turbine level. It should be the same or lower than the intake boost, otherwise you are “clogging” your turbos and overheating the entire setup as air flow is restricted. Most people think that just going to ebay and buying cheap “performance” parts will do magic. Well, it will give you some extra power, but in reality, you will be wasting your money. You need a real expert to analyze your setup, and give you real solutions so each penny you invest will be going towards power and performance, and not to a cheap copycat machine shop in China that did not make sure to duplicate for real each part they made (so you just got a “nice looking” piece of metal that is worth nothing). Good luck.

An r34 gtr engine will give you more from stock to play with else trying asking on http://www.skylineowners.com/forum/index.php Plenty of owners on there giving free advice aimed directly for this car.

Take the hand brake off.

Have the ECU unit digitally reprogrammed .

Nice wheels. Think of your drive train! Putting that amount of torque to the road. Apart from re-mapping the ECU you could try changing camshafts for something 'less peaky', boring out, changing turbo's, etc but you could lose the magic 509 bhp. That is the nature of petrol (gasoline) engines, high bhp, but lower torque .There has to be a 'trade off' somewhere. If you really need the extra torque go, dare I say,--- diesel!!! sorry if I upset you. (A Volvo 12 litre produces up to 480bhp, but over 1800 ft/lb of grunt from 1200 rpm!!!) I know its a truck engine, but you cant beat overall cubic capacity. The more swept volume the more potential power output you will get. Good luck in your search for the 'Holy Grail'!!

Stick a VW 5 litre V10 diesel engine in it. 554 lbft. @ 2000rpm.

replying to comment about ECU I doubt he has a stock ECU in a skyline with 509 bhp.. ..not much you can do with that beast.. You'd have to list your mods for someone to help you b/c someone's bound to tell you to do something you might have already done.

If you have 509bhp it sounds as though there is nothing else you can do to add to the torque unless you want to consider and enigne conversion and have an r34 gtr enigne as they have more bhp stock than an r32 and have great tuning ability and can also be moddified to over 1000bhp easily