Anyone running this? Good option?

 

To use the crank pulley you need the tune too.

 

How does the supercharger know which pulley is spinning it faster? And is anyone running either, or both, pulley(ies) only? Good option? Other supercharged cars have no need for a tune to change pulleys, is the jag tune requirement just up-selling?

 

There was a thread about this a while back and I separately asked VAP about using a pulley w/o a tune and they said your performance wouldn't be optimal and I also seem to remember your ECU could throw a CEL. I would imagine this would happen because the boost, MAF output or IAT don't match an expected value vs rpm and engine load.

 

I understand, but I still wonder if it's up-selling. Other supercharged cars run fine with a pulley only upgrade.

I also understand there may be boost limits imposed by software, but that doesn't mean a pulley wouldn't still be beneficial for cheap power down low.

Anyone actually running a pulley only with or without problems? I've yet to read a report.

 

I believe Unhingd ran an upper pulley before a tune was available. He has previously discussed this, though there are an awful lot of tune/pulley threads.

 

Link please?

 

 

This forum was so nice, polite and even funny when I first joined a few short months ago. Of late, it has gotten snarky and mean spirited. What (or who) happened?

 

Calm down. Lots of cars' supercharger pulley upgrades do not require an ECU tune. I already said I understand the limits an ECU may impose so that's not important to the question.

Questions:

Does a pulley only work without engine damage?

What's the bang for the buck business case?

Personal experiences please?

IMO +10hp at low RPM would justify the low cost.

 

I think the answere to that question is rather clear...(and it's not "what"...)

 

Upper pulley: Fine without tune, you will gain mid-range torque. But the ECU/Valve will bleed off additional boost it creates at top-end, a remap will stop this and gain you extra power up top.
Lower pulley: Unwise without a tune, will absolutely throw a cel and maybe limp mode. Tune will unlock a lot of power.

On a V8S a rough expectation is as follows at crank:
Stock: 495HP
Tune only: 605HP
Tune + Upper Pulley: 620HP but even great gains mid-range
Tune + Lower Pulley: 640HP and big gains through out rev range
Tune + both pulleys: 670HP but make sure injectors, plugs are in tip top condition as your at peak supercharger efficiency and pushing the injector duty cycle hard, normally the tuner will pull spark timing up top to cope with both pulleys, its not really worth it.

A V8S for ultimate power is best with crank pulley, 200 cel exhaust and tune, you run cooler and a lot more power, about 660HP.

 

Thank you, very helpful! Is there an upper pulley only dyno floating around? I'd also like to see a readable VAP dyno, the ones on the website are pretty gross. At least they pulled down the old one that compared VAP to stock, where neither crossed anywhere close to 5250. Someone must have pointed out the fake. Not confidence inspiring.

I'd prefer to keep the boost limit stock. The tune numbers above would be too aggressive for the long haul Imo. Peak hp isn't very important to me, I'm looking to raise the low end torque curve for maximum acceleration without peak stress. I'm also V8 RWD.

 

Not to hand, but just changing the upper pulley will see you around 30-40lb/ft improvement in the mid-range and around 20-25HP in the mid-range. At the top-end there is no improvement because as already has been said the factory ECU map bleeds boost off at a pre-determined PSI limit which on the SVR is 13PSI, whereas the stock factory pulley is 15PSI.

The V8S, V8R, SVR and Project 8 all run the same identical engine, supercharger and upper pulley yet they all have different power outputs:
V8S: 500PS
V8R: 550PS
SVR: 575PS
P8: 600PS

All they change is the mapping, this is why a regular V8S gains the most from a remap as the map allows the full 15PSI the stock upper pulley is capable of delivering, but on the lower powered cars the boost is simply bled off earlier and I know on the P8 its around 14.5PSI and the SVR is 13PSI, the less models will of course be less.

As such this is why fitting a smaller upper pulley without tuning has little to no impact on top-end power due to boost been bled off pass the max boost PSI set in the factory map, as such you only get mid-range gains and quicker throttle response due to the supercharger spinning faster.

 

 

Sounds like the upper pulley without a tune is what I want. Thank you.
​​​​​
​​​​It seems a tune would only increase peak psi by lifting limits without lower end gains as the sc doesn't spin any faster per rpm. That is the opposite of what I want.

A tune plus pulley is another option to get the low end torque rise and a higher limit, but a pulley will do fine here.

​​​​​​Thanks again for clarifying that the need for a tune to use only a pulley is in fact just a phony fear-based upsell.

 

Why not listen to someone with lots of experience? Gibbo has put lots of time and effort into modding his car, I think it would be wise to take advantage of all the experience and free advice he is offering you.

My question to you is - you have a RWD V8 and you don't have enough low/mid torque? The old adage is that torque gets you going, HP keeps you moving. I find that at speeds below 50 mph, with my car the acceleration is only limited by traction, so increasing low end torque wouldn't be very helpful. Beyond 50MPH, at least at WOT, you should be in the higher RPM ranges, hence you likely would want top end power. I opted for a tune only, and can tell you from experience the butt dyno notices a difference. Given that on sale it can be well under $1000 for a tune, I think it is clearly a great performance bargain.

As for safety, running a VAP tune at 605 hp doesn't seem significantly different from the SVR or project 8 tunes, so I am banking on minimal longevity impact. Alternatively, increasing boost at low RPM's often leads to detonation, which is obviously a bad thing for forced induction engines.

Its your money, do what you want, but why try to reinvent the wheel?

 

How do you come to conclusion its phony when the tune will gain you 100HP on a V8S!

Pulley only will simply only give you more low/mid range power/torque, you will still have 500PS. If you want 600PS then you need the tune and to gain 100PS from a tune is not phony at all, infact it is bloody amazing value for money and VAP should be your first port of call.

You are either a troll, have a very strange and unique way of thinking or are not the sharpest tool in the box......

 

This as Jaguar tested this platform under extreme stress at around 700PS and on the test track and there was no issues and the maximum factory tune is 600PS which is the Project 8 and a car designed by Jaguar to be driven extremely hard, its a track focused car.
Another example the SVR at 575PS, there is a ring taxi and I know the owner (Dale Lomas) and he has around 14,000 miles which are pure track miles on his SVR and the only issue was a cracked radiator, no doubt from a stone from track use, zero engine, trans or SC issues and he drives it flat out all the time.

So if you want best bang of buck and are out of warranty a tune gives you the biggest gains and best value for money and the favourite combination is an upper pulley and tune due to upper pulleys costing not much and been fairly easy to swap out, just don't heat the supercharger snout too much when fitting the new pulley, otherwise you can damage the SC bearings. This is why some prefer to pay more and get the crank pulley, it is even easier to fit and you gain even more power and torque, but this does require the tune otherwise the stock ECU mapping cannot handle the additional air flow and the car will go into LIMP mode.

 

^^ +1, and I'm leaning towards troll.