It's just another calculation the program is doing which doesn't help. The program needs to guestimate driveline losses, 5%, 9%, 25%. It has no idea but it multiplies some percentage to increase the numbers. Stating power at the wheels keeps it more honest.

 

Did you get your AFR ratio when measured? What year is your car?
What Dyno machine was this? Different Dyno require a different conversion ratio to crank hp

 

Thanks! Results are pretty good I must say!
Just came back from Vegas

Thanks! Results are pretty good I must say!
Just came back from Vegas
re dyno: Depending on the Dyno type correction factors are different to calculate crank
I was expecting to hit 12.4 but what I didn't calculate for is Vegas horrible track, first off turnes out i it's up the hill so track speed are down, plus head winds that day and DA density altitute around 2200 . All of the cars in our race group including the RS3 which was the fastest in our group ran slower than expected. Around 600-700 cars in total that night which was nuts, there was maybe 7, 8 accidents that night I assume partially because of poor track prep.. We waited from 7pm to 11:30 pm to get just two runs in that was really frustrating.
Rs3 which normally runs just under 12 and traps 115 could only run 12.5 , 12.35 and best of 12.15 with highest trap of 112.
Q50 red sports with intake , exhaust and jb4 tune pushing 500 hp could only do best of 13.0 and 110 trap
Na Camero SS at 14.5, SRT8 at 14.1
I was lucky at end of the night it was 12:30 at night and just ran my third time and they let a few cars including mine hot lap back to back runs before closing the track, surprisingly the more I ran the faster car got 12.7 , 12.67, 12.61 with consistent trap of 110mph, then they shut the track down. Best 60ft on best run was only at 1.92 . Over all car did good for the crappy track conditions in Vegas, should be at least 2 tenth faster at other track here home in Cali.

 

Thanks! Results are pretty good I must say!
Just came back from Vegas
re dyno: Depending on the Dyno type correction factors are different to calculate crank
I was expecting to hit 12.4 but what I didn't calculate for is Vegas horrible track, first off turnes out i it's up the hill so track speed are down, plus head winds that day and DA density altitute around 2200 . All of the cars in our race group including the RS3 which was the fastest in our group ran slower than expected. Around 600-700 cars in total that night which was nuts, there was maybe 7, 8 accidents that night I assume partially because of poor track prep.. We waited from 7pm to 11:30 pm to get just two runs in that was really frustrating.
Rs3 which normally runs just under 12 and traps 115 could only run 12.5 , 12.35 and best of 12.15 with highest trap of 112.
Q50 red sports with intake , exhaust and jb4 tune pushing 500 hp could only do best of 13.0 and 110 trap
Na Camero SS at 14.5, SRT8 at 14.1
I was lucky at end of the night it was 12:30 at night and just ran my third time and they let a few cars including mine hot lap back to back runs before closing the track, surprisingly the more I ran the faster car got 12.7 , 12.67, 12.61 with consistent trap of 110mph, then they shut the track down. Best 60ft on best run was only at 1.92 . Over all car did good for the crappy track conditions in Vegas, should be at least 2 tenth faster at other track here home in Cali.

 

Can you please enlighten me as to what the bit in bold is?

 

​Quote:
Originally Posted by Ranchero50

WThe key thing is your curve is stable unlike Alex's. Your tune is stable and pretty happy. Without the positive displacement bloweradding air the torque curve would be much more inclined similar to the HP one.​​​​​​Sounds like nonsense but seems to be a common thing coming from Ranchero , but please enlighten me too o wise one , and please enlighten me how my curve is not stable

By the way , how do I delete my double post? Cant find delete anywhere

 

Wow, 6-700 cars is nuts! I would love to be able to run that late at night though. The cooler air makes a huge difference to the supercharger. Using an OBD2 app on my mobile, my 1/4 mile terminal speeds differed by 2-3 mph in my '10 XKR when running at night on the street in 8-9 degrees C compared to 20 deg C on the track. They tend to pack up at around 4pm on our track, just as things are starting to cool down and only race in the warmer months!

I also found that back to back runs makes a difference and I assume that is because of heat soak. My inlet temperature is over 70 degrees while waiting to start a run and 50 degrees by the end of the track so going straight out again seems to be good for the supercharger.

Your 60 times sound like they are still very good. The best I ever did in my '07 was 2.22 and they averaged 2.44 over the 19 runs I did while I had the car which is why I never broke in to the 12's. Doing decent burnouts is making a difference in my '10 so I would have liked to try again with my '07.

Shame about the track though. It sounds like you would be doing 112-113mph in the right conditions which is similar to what my '07 was doing so I suspect 511bhp is optimistic. I would have put my '07 at around the 460-470bhp mark and as a comparison my '10 XKR when stock did 115.73mph. Very good effort for a DIY tune though!

 

I barely do a burnout at all , just a brief spin enough to shake some dirt or rocks stuck to tires, also avoid the water box completely.
On Hp and torque numbers , I think they are close to being correct. Stock 4.2 XkR Dyno from 340-360 rwh from what's I have seen , and mine did 359 with the pulley upgrade , this was on the same Dyno which is now at 426 rwhp. By the way so I actually have a time slip from my first run in Vegas 2 years ago running against a same XLR Cadillac I ran this time. Had pulley upgrade mod only and
I did 13.4 at 105mph trap and XLR did 13.7 that time , and now I shaved the time by .8 of a sec in ans gained 5mph quarter mile on this track, which is a lot. XLR did 13.8 this time by the way. He is at 450hp stock, he ran his car at sea level and gotten 13.0 before. Keep in mind that I have a convertible which weights 100lb more over coupe. Normally you shave 1/10 of sec in querter mile for each 100lb drop of weight. So I think 511 crank is accurate, maybe gear ratios and power band curve are different in the 5.0 thus a little lower trap. I will be going to Bakersfield track in Jan which is at near see level , so we will see what car traps at.

 

Gear ratio different in the 5.0 ???

The final drive is identical in the 4.2 & 5.0 and the xf6hp also has the same ratio

Nevertheless would love to see how your vehicle performs closer to sea level good work

 

Just an FYI, the kick into the lower gear is an extra trigger under your right foot that is past full throttle.

If you hit the soft stop in manual mode and do not lead foot the pedal this won't happen.

Just relax, find the full throttle point. Don't hold the pedal down past full throttle.

Not sure if it can be disabled or not.

Give it a try, get the feel for the extra switch past full throttle that if held for a certain amount of seconds causes the kickdown.

 

A positive displacement blower is one that displaces a certain volume of air per revolution. Roots (Eaton) types use a pair of lobed shafts where the lobes intertwine forming a seal between the shafts and the air is forced to the outside. Other designs use a pair of screws that literally screw the volume of air into a smaller space from front to back. The other style blower uses a finned wheel and uses centrifugal force to accelerate the mass of air from the inside out where it piles up in a pipe and builds boost similar to how a turbo works except crankshaft driven. A centrifugal blower requires a lot of RPM to build boost where a positive displacement is pretty good at low speeds. That's why our cars perform very well for the engine displacement.

Google it or check the Wiki for a more in depth description.

 

Dont think we needed a lesson on what positive displacement blower is ,but on you comment quote . "Without the positive displacement bloweradding air the torque curve would be much more inclined similar to the HP one." You could have a similar power torque curve on all types of engines , NA, turbo , and so on...

 

Yes, but you would need to play with the intake runner length and cam profiles much more which usually loses power up top. Blower is a great thing, IMHO better than a turbo, especially without the heat issues.

RE: your original curve, does the car feel like it lost power at 4400 rpm on the street? Pity you couldn't post up the video.

 

Scroll up for updated dynograph I posted just in 4th gear ,so your not confused with the first one. Why in the heck would I loose power at 4400rpm ? I gained over 67rwh on top end and probably more through the power curve. See my time slips before tune and after , on same Las Vegas track, I picked up 5mph trap speed and gained from 13.4 to 12.6...