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If anyone is interested, here is the baseline engine performance on a stock V6S engine along with commentary by my tuner:
"Here's the baseline dyno data. It's about what I expected power wise as well as being very rich in the higher rpms. One bar of boost, 14.6 psi....
I calibrated the speed output so the indicated road speed is accurate. This run was done in 4th gear so you can see why road tuning is pretty much out of the question at the speeds necessary to get a wot lambda reading."
The boost numbers are the most telling here. Where the 5.0L runs 9 or 11 psi depending on the factory tune, and 13psi on a number of the pulley+tune cars, the V6S is making 14.6psi straight out of the box.
Makes a strong case as to why it cranks in hp/litre compared to it's big brother.
AFR's are a little rich in the top end, I would have expected 11-11.5:1 but I don't think 10.5 is too crazy, rich is safe and probably helps a little with the high cylinder pressures/temps. If you lean it out a little you might pick up 10-15hp or so, worth the effort? I wouldn't think so but that's not my call.
375hp at the crank to 318hp at the wheels, about 15% which is inline with the 15% we saw with a V8S that was on the dyno recently.
Thanks very much for sharing the information, much appreciated.
The boost numbers are the most telling here. Where the 5.0L runs 9 or 11 psi depending on the factory tune, and 13psi on a number of the pulley+tune cars, the V6S is making 14.6psi straight out of the box.
Makes a strong case as to why it cranks in hp/litre compared to it's big brother.
AFR's are a little rich in the top end, I would have expected 11-11.5:1 but I don't think 10.5 is too crazy, rich is safe and probably helps a little with the high cylinder pressures/temps. If you lean it out a little you might pick up 10-15hp or so, worth the effort? I wouldn't think so but that's not my call.
375hp at the crank to 318hp at the wheels, about 15% which is inline with the 15% we saw with a V8S that was on the dyno recently.
Thanks very much for sharing the information, much appreciated.
Doesn't it also make a strong case for being VERY careful about trying to extract more out of the V6?
375hp at the crank to 318hp at the wheels, about 15% which is inline with the 15% we saw with a V8S that was on the dyno recently.
15% loss through the drive train is fairly typical, but that is what I would have expected on the 1:1 gearing in fifth gear. I am surprised the loss was not greater in 4th gear.
Doesn't it also make a strong case for being VERY careful about trying to extract more out of the V6?
Well I didn't want to come right out and say it so directly, but yes I would agree with you.
Originally Posted by lhoboy
15% loss through the drive train is fairly typical, but that is what I would have expected on the 1:1 gearing in fifth gear. I am surprised the loss was not greater in 4th gear.
It slipped my mind for a second that you have the manual transmission.
Manual's don't lose as much through the drivetrain as automatics so 15% in 4th maybe would be closer to 10% in 5th?
Also when we dyno'd the V8S it was in 5th on the 8-speed if I remember correctly so also not in the 1:1 gear.
Also when we dyno'd the V8S it was in 5th on the 8-speed if I remember correctly so also not in the 1:1 gear.
That would make sense since the 4th gear MT ratio is close to the 5th gear AT ratio (1:3.9 vs 1:4.0 final ratios). No sense burning up tires on the rollers at 170+ mph.
That chart is very enlightening. After looking at it more carefully, it also quantifies my butt dyno perception that the engine stops trying harder shortly after crossing 5K rpm. I've mentioned that here several times before.
- 3K to 4.5K you pick up a little over 100HP
- 4.5K to 5.5K you get an additional 30HP
- over 5.5K, add 15HP before it maxes out at 6K, then falls off a bit until redline
- torque peaks at 4.2K, then falls off continuously until redline
Thanks for the graphs, yes it makes it even clearer.
What's strange to me is seeing all three values (boost, hp and torque) drop away from 5800-6000rpm
Other engines with TVS blowers just keep going & going with no drop off.
Which makes me wonder if a) the blower has really been way overdriven and reaches it's efficiency limit, or b) this characteristic is part of the tune (a throttle pull-back)
Not sure how to prove or disprove either theory right now.
a) the blower has really been way overdriven and reaches it's efficiency limit, or.....
That curve certainly looks like a typical SC at the peak of its range. Looking at this, a reduction pulley probably won't improve top end performance, and probably would not enhance the peak hp and torque, but might lower the engine speed at which those peaks occur.
You mentioned this was 4th gear only? There might be some useful data in other gears if so. I suspect that there is a significant amount of software interaction in the manual between the gearbox, the engine and the blower. I don't have any data yet, but to me, the drive train does seem to do things differently based on what it has been doing in the past few minutes, and what gear it's in.
Here's a news flash: If any one claims to have a reduction pulley for a V6, they're lying or stretching the truth, to say the least. The 12% pulley I ordered from one vendor was a 2.5%. There is no possibility a smaller pulley will fit, since, in the case of the 2.5% pulley, a bit of polishing was needed on the nose of the SC housing to ensure adequate clearance where the pulley slides over. For a true 12% or 15 % difference, an over-sized crankshaft pulley will be needed.
For reference, the stock pulley measures 62mm.
That said, here are the dyno results for the 2.5% pulley along with a comparison to baseline.
Looking at these charts, and after tapping into the ECU, my tuner is convinced that there is substantial performance improvement that can be expected with a good tune by producing a flat torque curve (providing more torque below 4000 rpm and above 4500 rpm) without significantly increasing the peak torque. He hopes to have the checksum digits needed by the end of the month when I'll take the car in for the tune.
Well, even the air/air Intercooler on your Mini makes surprising numbers.
The GP intercooler I have on the MINI is even more impressive, but not nearly as impressive as this water/air exchanger.
Originally Posted by F-typical
Just need to smooth out some of those torque-curve 'canyons' next...
Precisely. That's what we'll be working on next. The factory tune is all about torque management, the purpose of which is more to save the driver from self destruction than the engine.
Precisely. That's what we'll be working on next. The factory tune is all about torque management, the purpose of which is more to save the driver from self destruction than the engine.
I think you may be on to something here after looking at those torque curve peaks and valleys. You could get a substantial performance improvement without pushing things much past factory peaks.
I think you may be on to something here after looking at those torque curve peaks and valleys. You could get a substantial performance improvement without pushing things much past factory peaks.
That's was we will be aiming for. I'll keep you posted.
11-10-2015, 12:43 PM
V6S Tune
