Jaguar XJ8 4.0 Supercharged tuning.
Discussion
Supercharger upgrade pulleys claim power improvements however many say that this is only a change to more power lower down the rev band rather than a true improvement. Induction upgrades seem only to increase/improve the sound rather than the power. What works is an exhaust upgrade from the crushed standard pipe and methanol injection systems might help. Latest mods appear to imply that changing the supercharger might give the best improvement but at a greater cost than £1k
I'd say that the cheapest most effective means of tuning would be to have the ECU re-mapped (it's a bit like chipping, only better!). It'll take a 370BHP V8 upto around 400BHP and will also bring the power in at much lower revs, loads more torque too! Will be a bit more than £750 though (not sure how much it is now as had mine done a few years ago. Give Chas a bell at Racing Green, they send the ECU's off to France for re-mapping (same people that do electronics for Ligier). You could get a new washable fast flow air filter (around £40-£50 and about 5BHP I think, also available from RG). The S/S exhaust is also a good mod (around 15BHP for rear section and 20BHP for the front I think, a lot more dosh than £750 though! I'd do the ECU first if I was you, cos I did when I was me... If that makes sense......
To be hounest I am not sure what will give you more bang for your buck, it is either a pulley or a (good designed, not just any) exhaust.
My experience is that the larger pulley will give you much more torque/power in the low to mid rpm range, and this is what you use most of the time, therefore most people seem happy with it. I did not however gain anything at top end, as checked with before and after dynos, so I am not happy about that.
I have not changed my exhaust yet, nor done anything to the ECU, though I do know that some tuners admit not much is to be gained. If you want to go this route, than first demand a dyno example (Before and After). If they cannot provide one you could wonder about their claims.
XJR420, do you have a before and after dyno? I would be interested in seeing that, at least the after one.
My experience is that the larger pulley will give you much more torque/power in the low to mid rpm range, and this is what you use most of the time, therefore most people seem happy with it. I did not however gain anything at top end, as checked with before and after dynos, so I am not happy about that.
I have not changed my exhaust yet, nor done anything to the ECU, though I do know that some tuners admit not much is to be gained. If you want to go this route, than first demand a dyno example (Before and After). If they cannot provide one you could wonder about their claims.
XJR420, do you have a before and after dyno? I would be interested in seeing that, at least the after one.
I really don't think you need to chip the car, run it on 98 octane and it will liberate a lot of performance that is already programmed into the ECU.
The intercoolers benefit from pushing as much water through them as possible, so firstly bleed the system (sounds easy, but isn't) and consider adding a separate intercooler circuit and pump to make one per bank.
That will cost you very little but make a HUGE difference, and to be honest without the cooling the engine is going to be power limited even if you do play with the pulley ratios.
The intercoolers benefit from pushing as much water through them as possible, so firstly bleed the system (sounds easy, but isn't) and consider adding a separate intercooler circuit and pump to make one per bank.
That will cost you very little but make a HUGE difference, and to be honest without the cooling the engine is going to be power limited even if you do play with the pulley ratios.
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