Supercharged Versus Normally Aspirated for MPG

[Joseph Garcia]

I had the opportunity to take a 900 mile trip, virtually all highway, with my supercharged 07 Yukon XL Denali, the first long distance trip with my new setup. I drove conservatively for the most part, with the cruise control set to 72 mph and the engine speed averaged 1800 rpm. There were altitude changes of approximately 3000 feet on the trip.

For context, with my normally aspirated setup, I averaged 11-12 mpg in the city and 15-16 miles on the highway. In the city, when I drive like, using @Doubeleive 's famous saying, 'Drive it like you stole it' , I averaged 10-11 mpg.

With the supercharged setup, I average 10-11 mpg in the city under normal situations, and 9-10 mpg when I drive aggressively. On the recent highway trip, I averaged 15.4 mpg.

As such, I am very happy with the mpg's with the supercharger setup, and it appears to support Whipple's claim that the supercharger's drain on mpg's, is miniscule, when not pushing the supercharger.

 

[Doubeleive]

Probably work out to about 7-8 for me

 

[j91z28d1]

what kind of supercharger set up?

 

[Marky Dissod]

what kind of supercharger set up?

2007 Yukon XL Denali, 6.2L, L92, 3.42:1 (not 3:42), Z55, 6L80
2.3L Whipple Supercharger with Intercooler

I had the opportunity to take a 900 mile trip, virtually all highway, with my supercharged 07 Yukon XL Denali, the first long distance trip with my new setup.
I drove conservatively for the most part, with the cruise control set to 72MpH and the engine speed averaged 1800RpM.
There were altitude changes of approximately 3000 feet on the trip.

For context, with my normally aspirated setup, I averaged 11-12MpG in the city and 15-16MpG on the highway.
In the city, when I drive like, using @Doubeleive 's famous saying, 'Drive it like you stole it' , I averaged 10-11MpG.
With the supercharged setup, I average 10-11MpG in the city under normal situations, and 9-10MpG when I drive aggressively.
On the recent highway trip, I averaged 15.4MpG.

As such, I am very happy with the MpG with the supercharger setup, and it appears to support Whipple's claim that the supercharger's drain on MpG, is minuscule,
when not pushing the supercharger.

I'd not be surprised if the supercharger was not supercharging or barely supercharging at 1800RpM, depending on altitude.
@Joseph Garcia, what is your supercharged L92's static compression ratio?
Where the altitude changes mostly descending, mostly ascending, or roughly equally up&down?

 

[Joseph Garcia]

I'd not be surprised if the supercharger was not supercharging or barely supercharging at 1800RpM, depending on altitude.
@Joseph Garcia, what is your supercharged L92's static compression ratio?
Where the altitude changes mostly descending, mostly ascending, or roughly equally up&down?

Agreed on the 1800 rpm statement.
10.5 -1 compression ratio.
The altitude change was both up and down twice, as I crossed the mountain range on both legs of the trip. I did notice far fewer gear downshifts with the supercharger setup when climbing, versus when I did this same trip with the normally aspirated setup.

 

[Charlie207]

Did they list how much power is needed to drive the supercharger?

 

[Joseph Garcia]

Did they list how much power is needed to drive the supercharger?

Whipple says that the power draw for the supercharger is 1HP while cruising.

 

[j91z28d1]

Whipple says that the power draw for the supercharger is 1HP while cruising.

I have always read that the bypass on the screw type blowers work much better than say a big centrifugal.

one of the big reasons the oem goes with them.

 

[petethepug]

The more hp/tq, the less difficulty the vehicle has attaining its end speed goal. This can also be cheated with more efficient gearing. All that is based on driving habits identical to the owners previous non s/c motor.

Typically a long cruise with the cc switched on makes a good comparison for before & after adding the s/c.

Obviously after a s/c is added owners take quite a while, if ever, to drive like they used to. What’s even more scary is the cheat factor of a 10SP 2019+ 10L80 can now be easily paired with a blown 6.2L. Even more scary is that all that performance is not on the fringe and more serviceable and reliable than a $150k 682/653tq Escalade V

 

[j91z28d1]

tuning with boost for good fuel mileage can be hard. if your truck gets enough rpm for boost at cruise, say towing or going up a hill, most ecm's that are na engines with boost added, anytime over a 100kpa will go into PE mode, meaning closer to 11:1 a/f vs a NA engine that can stay at 14.7 much longer, and even in PE can run high 12 a/f when worked hard.

there's a tons of tuning strategies and lots or times different tables in oem ecm's that came with boost to try and run clean and not just default to boost a/f under any load.



on a side note, I see there's adapter plates to put stock hellcat superchargers on ls engines now. guess stock ones were cheap when they upgraded to larger. and stock being much larger blower than the lsa supercharger is.

 

[Joseph Garcia]

I took these measurements because I was just curious about the mpg change before and after supercharging, more of a mental exercise than anything else. Obviously, I could not care less about my truck's mpg, as it is my fun and dog riding vehicle. If I ever had any interest, or need, in pursuing better mpg, I'd pull my Honda Fit out of the garage. It has not been out of my garage since before last Thanksgiving.

 

[fozzi58]

I didn't notice much of a change when I went from NA to boost on my truck either - at highway cruising speeds. (5.3, whipple 2.9, 6L80)

Hard to keep from burying your foot into the throttle with all that power but when I kept the fun under control, it was pretty mild mannered and MPG did not change much.

Biggest MPG drop was going from the factory 3.08s to 4.10s Highway driving is dead to me now. 2250rpm at 75 MPH with my 24's and its more like 2700rpm when I have my 22" race wheels on. But the fun factor has increased.

I put a worked 528i in my rear view at a stop light last week. Another driver surprised by the Burb.

 

[norcalboon]

What tipped the scales for your decision on a Whipple? Did you install it yourself?

I'm looking at SC options options for my 6.0 LQ4 in my '05 K2500 and Whipple, Mangnuson and Edelbrock E-Force are on the table. Whipple has largest volume at 2.3 vs. 1.9 for others. Mostly interested in improved towing performance.

 

[Joseph Garcia]

What tipped the scales for your decision on a Whipple? Did you install it yourself?

I'm looking at SC options options for my 6.0 LQ4 in my '05 K2500 and Whipple, Mangnuson and Edelbrock E-Force are on the table. Whipple has largest volume at 2.3 vs. 1.9 for others. Mostly interested in improved towing performance.

I talked to 3 Mechanics from different repair shops and asked for their opinion/recommendation for a shop with performance/racing expertise in GM LS motors and supercharging. All 3 Mechanics recommended the same shop without hesitation. I met with the shop owner and outlined my supercharger project wants, as I had already decided to let someone with deep knowledge of supercharger tuning install and tune the supercharger. This shop highly recommended the Whipple brand, as they found this to be the most reliable equipment for the non-racing enthusiast, and thus, the choice of the Whipple brand was made.

Then, an expert tuner with deep knowledge of towing tuning for superchargers is a must for you.