Any advice on the pulley offered from Mina for the V6 S engine for the F-Type Coupe? I have contacted Mina and they swear that an ECU or any other upgrade is not required with the pulley swap. Even going as far as saying the pulley is fairly stealth in design as it is very similar to OEM. Any thoughts or opinions are appreciated.

 

Welcome to the forum, i've moved your post out of the X351 XJ section into the F-Type section.

When you get a moment stop by our new members area and introduce yourself.

 

Do yourself a big favor & don't put a pulley on a V6.

 

Why, so? We'll need to put a pulley and/or tune on the V6S Manual just to keep up with V6 base Automatic.

 

I believe Mina is saying that just because they don't have a tune. Despite the fact that the stock tuning may (or may not) be able to adjust the Air/Fuel ratio to fully compensate for the additional 1.5 psi boost, it will not be maximizing the ignition mapping to get the full benefit of that additional boost. A good tune will also help to ensure that the additional boost doesn't over-lean the mixture (detonation).

 

Just speculating, but it could be that the V6S is already pretty close to the ragged edge...

For example;

The 5.0L in the Project 7 is at 575hp, that's 115hp / litre
The tuned 5.0L cars with pulleys are up around 630hp, that's 126hp / litre

The 3.0L V6S is 380hp, that's 126.6hp / litre or pretty much the same hp/litre as the fully tuned 5.0L

Rica, for example, says they get 398hp without a pulley, or 132.6hp / litre, and Rica says do not put a pulley on the V6. Could be that the limit is close.

I don't know, as I said just speculation, but it does seem that the V6S already punches above the V8 in output, there has to be a limit somewhere.

 

It's not the displacement that's critical, but more so the specific equipment. My understanding is that components such as bearing and rod dimensions are similar between the two engines. The Project 7 is generating 72hp / cyl. where the V6S is only generating 63 hp / cylinder. 3 liter formula engines have generated over 1000 horses, but of course, those have massive journals. The V6 should be able to handle in the 415 hp range just fine. Also consider, the primary purpose of the pulley isn't to increase the hp, but rather the torque. Given a shorter crankshaft of the same cross section, the V6 should actually be able to handle more torque than the V8.

 

V6 = 84.5 x 89.0 x 6
V8 = 92.5 x 93.0 x 8

You are still suggesting that a 499cc cylinder (V6) should put out more power per volume than a 625cc cylinder (V8). I just don't buy the concept of output per cylinder when the cylinders are not the same volume.

Or to put it another way, the V6 should put out more from less?

The V8 is damn close to being a square engine (equal bore & stroke) and the V6 is oversquare (less stroke than bore)

Square engines are said to be the ideal, oversquare is for high revs & torque/power higher in the rev range.

If we talk about torque then I don't see how it's possible to get that much more out of the V6 either, in stock form the V6S is already kicking the V8's ****.

3.0L is 460Nm, or 153.3Nm/L, the 5.0L is 680Nm, or 136Nm/L

Tuned is a little harder to put numbers on, but let's say

3.0L is ~495Nm, or 165Nm/L. The 5.0L would have to be making 825Nm to match that performance, and they aren't making nearly that much, 750Nm on a good day.

The V6S is well & truly punching above it's weight already.

 

That is exactly the conclusion I've reached absent any better info. I'm not messing with the OEM engine set-up, but would consider bringing my base V6 up to V6S specs. It does appear the V6S has been punched out to essentially it's max safe output.

 

I am not suggesting that, all else being even, the displacement doesn't determine the limits of power output. What I am stating without reservation is that the total power output that an engine can reliably handle is based on what's there (Crank, rods, bearings, etc.), not what isn't (volumetric displacement). (This is the zen of mechanical engineering) If the crank for both engines are of similar construction and cross section, the same rods and bearing are used, the V6 should be able to handle the same power (I didn't say deliver) as the V8 on a per cylinder basis. With a shorter stroke, it may actually be able to handle (not deliver) more power and torque per cylinder. (just thinking out loud).

 

Keep in mind the V6 engines have a 10.5:1 compression ratio while the V8 only has a 9.5:1 ratio. The V6 engine is under a lot more stress than the V8 in stock form. Upping the boost only intensifies this.

 

That's not really that much. We used to run crappy BMC engines at up to 14:1 compression (albeit on 130 octane leaded racing fuel).

 

Lance,

You're gonna do the pulley and tune come hell, high-water, and no matter what else, aren't you? That works for me. It's always good to have someone else jump in first to check for sharks.

 

Happy to oblige. I'll be collecting A/F ratio and power data at various stages of the project: baseline, pulley, and then with tune. Still trying to determine the best tuner.

 

Irrelevant comparison. That's an n/a engine with extremely high octane compared to a FI engine with pump gas.

9.5:1 compression at 23.75psi of boost is much much less physical stress and combustion pressure than 10.5:1 compression at 27.6psi. Thats a 65 psi difference prior to combustion.

 

I have read that the 5.0l engine during testing a and development has been pushing out 750-800hp.

As for anybody wanting to tune the Jag EC should spend the time reading in the XK thread. At this point I would not trust any tuner to provide a successful tune. I would only even consider one were I have the OBCDII tool and can reload the flash. It has turned out that most flashes do not stick and that the EC falls back to one of the default maps on the ECU. So you may have a nice tune and dyno run and two weeks later after a spirited drive you are back to were you started from.

 

Agreed, and yet another reason to stay away from current offerings. None of them seem to be willing or able to provide any substantive documentation.

 

I won't be messing with mine, but if I were to consider it, I would price a new engine and assure myself that I was prepared to fork out that much if something went wrong. And under warranty this applies whether or not the failure was due to the tune and mods, from long experience with the Land Rover side of JLR I can say they are very quick to deny warranty for modified cars even it it is patently unrelated.

 

Getting back to the OP's question.

On the 5.0L V8's the pulley & tune go hand-in-hand, fitting a pulley without a tune results in very little because the ECU is limiting power output, I would expect the same for the V6S.

 

Please let us all know when you finally put a rod thru the side of the block.