The expected V6 boost matches with the 1320, it would be way above 20 psi on a stock car if they would have the 1900.

So I find it hard to be the case, unless the air is massively bled where I take it that would be electronically controlled, and that would mean there is still a lot on the table via a tune on the V6.

 

It has been my understanding that the V6 and V8 SCs are identical. Here is documentation of what's in the V8S:


I would welcome any concrete evidence the V6 uses the R1320

 

You can plug in the numbers to the formula and see which makes sense:

Theoretical Boost = (((Supercharger size in liters x Pully Ratio) / (Engine L / 2)) x 14.7) -14.7

It would be poor engineering to have the same sized supercharger for significantly different engine displacement.

But then again, Jaguar designed their V6 to be identical in size to their V8 so all logic goes out the window.

 

Fully agree, the boost values will already show that there is a different supercharger as mentioned, and that is only logical as you need to size the supercharger to the engines volume to sit within the optimal performance range.

If there was a electronically controlled way, the tuners would have found that by now already.

Now there is still an interesting option for the V6 owners, and that is as far as I know the engine block dimensions are the same with the V8 ones, and that means that most likely it will be easy (ie maybe with some small mods) to place the V8 1900 supercharger on it. You may need to get even bigger upper pulleys to reduce boost somewhat ;-)

 

What boost number are you referring to?

 

Yours for instance (ie 1st post), but that wasn't even needed considering the boost calculations.

I just used the theoretical calculation (with small mod to come close to more realistic levels), and I guess the table below speaks for itself, but don't take these as exact values, its still just a ballpark.

Edit: As I don't see any expected jump in boost on your car with the pulley change, are you sure all limiters have been removed?

 

The part numbers for the 5.0 and 3.0 super chargers are different, if that counts for anything.

There also appears to be a "resonator" and "pressure sensor" bolted to both...

 

Digging into it deeper, I believe you are correct. The 1900 would be hugely over-sized for a 3 liter application. In fact, even the 1320 should be more than adequate to produce substantially more pressure for the 3.0L, but tuning will be needed to take advantage. The torque management we are seeing on the V6 is extremely limiting, preventing full factory peak torque (339 lb-ft) from occurring across a broad range of engine speeds.

 

I originally thought that was accounted for by the difference in pulley (which is not a separately listed part, but the SCs now appear to be a totally different.

 

Even your 2.5% pulley should have already added about 1.5 psi, so clearly there are still torque limiters active which should be removed, its now up to the tuners to get rid of these.

 

Hope it's one of these ones....

 

The Denso one is already cracked (/copied) by most tuners, and to be honest, anyone with experience of the Bosch ecu should be able to crack this one as well I guess.

 

It's unlikely that increasing the SC rpm from 15,360 to 15,740 rpm (@6000 engine rpm) will produce anywhere near an additional 1.5 psi. I believe it works out to about 1/3psi.

+1. Scheduled to have another go at it on Monday.

 

I had incorrectly the V8 66mm as stock (instead of the V6 62mm), but even then its almost 1 psi more.

 

We just didn't see that. Perhaps the ecm is controlling a by-pass valve. I'm still not clear how you would expect close to a 10% increase in boost from a 2.5% increase in SC speed. The increase should be some number less than 2.5%.

 

I don't know the new Bosch setup, but on the Densos it was purely throttle control by the ECU to reduce boost. Maybe with the Bosch it is also with the bypass valve as iirc there it is electronically controlled. But I think its easier for the ECU to keep the torque control via the throttle, as the control is not based on boost but on calculated torque.

 

I concur with you on this. I'm still wondering how you figure a 9% reduction results in a 1.5psi boost and a mere 2.5% reduction in gearing still results in a 1psi boost.

 

maybe didn't read it right (am in a denial phase that I need glasses ;-)), it would have been about 2.5 difference from the 66 pulley size.

Attached now only the V6 pulley sizes, so you see the values I get.

 

I am assuming the final column is showing boost. The -2.5% is showing a 0.73psi boost increase of 4.6%. I would have expected less than that given the lower isentropic efficiency at those SC speeds (~65%).

 

...has been found. I worked with VMax Tuning to send a number of tune files back and forth over the past 2 days. There is still a bit of fine tuning that could be done but the results as they currently stand are astounding. We now have before/after dyno runs that are independent of the tuner (VMax), and my local tuner has verified that he sees no conditions in the current tune that might jeopardize the engine. As a result of this, I will be abandoning (at least for now until free-flowing headers are available) the notion of installing a crank pulley. Also,until the clutch problem is solved, additional torque and power beyond what I now have, will do nothing for the 0-60 times. I will leave it to VMax to release the results.