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Stock Challenger Hellcat: Legmaker vs. Stock Intake

88K views 199 replies 70 participants last post by  Himmelkat 
#1 · (Edited)
Vehicle Car Engine Auto part Automotive design



Stock 2016 (White) vs. Stock 2015 w/ Legmaker (Red) Hellcats.
144.56 mph vs. 147.54 mph in the 1/2 mile.

Summary:
Stock 2015 Challenger SRT Hellcat, automatic. Independent test of the Legmaker vs. Stock Intake. 93 octane, 10% ethanol.

5th gear dyno from 2590 to 6100 rpm
Average total power under curve gain of 9.1 rwhp / 8.7 rwtq

Your Goals
The decision to purchase the modification depends on your goals:
  • to pursue quicker 1/4mi times (+1 mph, 0.1 sec), 1/2mi speed (+3 mph)
  • to increase engine power (at least average +9 rwhp across the total RPM)
  • to hear a louder whine from the engine
  • to draw attention to your Hellcat (impressively loud on acceleration)
  • to improve underhood appearance
  • to subdue the "mod bug" bite

Smoothing 0
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Smoothing 5

Text Line Slope Design Diagram


Stock with lower intake temperatures and higher coolant temperatures than Legmaker

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Calculated estimations:
1st-5th gear (calculated 1/4mi to ~125mph)
3.70% increase total rwhp / 3.25% increase total rwtq
Average total power under curve gain of 9.5 rwhp / 9.5 rwtq

Inlet Temperature Considerations (calculated stock to 95.0 deg F)
Average gain of the LMI could be calculated as 16.8 rwhp / 13.7 rwtq.
If the stock dyno inlet temperature was the same 95 deg F as the LMI testing temperature, the average gain of the LMI would be higher. The two dynos for stock show that, for every 3.6 deg F change in inlet temp, there is an average 5.2 rwhp / 3.3 rwtq difference.

This also shows that it only takes a 12.6 deg F difference to have a negative effect over stock.

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Testing Standard Conditions (at the start of each dyno run):
  • J1349 standard reference (1.1684 kg/m^3 air density; 29.53 inHg - 100 kPa; 77 deg F)
  • J1349 standard reference Inlet Air Temp at 77 deg F with variance between 56 - 95 deg F
  • J1349 standard reference coolant temp between 165.6 and 240.4 deg F (+/- 37.4 deg F of 203 deg F operating temperature value)
  • Inlet Air Temperature (MAF sensor reading) was 89.6 deg F (stock) and 95.0 deg F (Legmaker)
  • Coolant Temperature was 204.8 deg F (stock) and 203.0 deg F (Legmaker)
  • Air Charge Temperature was 134.6 deg F (stock) and 132.8 deg F (Legmaker)
  • Intercooler Temperature was 78 deg F for stock and 80 deg F (Legmaker)
  • Oil Temperature was between 180-185 deg F.
  • 5th gear for automatic Hellcat transmission (6th 1:1 runs the dyno too high)
  • 0 graph smoothing for most accurate raw data results.
  • SAE correction value applied to results.

Total Horsepower/torque area under the curve with gearing applied:
5th Gear:

HP Total Area under curve: 2.9% increase
Stock 1710.584 vs. LMI HP Area: 1761.782 (+51.198)
TQ Total Area under curve: 2.5% increase
Stock 2094.184 vs. LMI TQ Area: 2148.579 (+54.395)
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1st-5th gear (calculated 1/4mi to 125mph)
3.70% increase total RWHP / 3.25% increase total RWTQ
Increase total 9.48 RWHP / 9.54 RWTQ

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Baseline drivetrain loss estimations:
HP to rwhp 0.9038; TQ to rwtq 0.9415

Dyno Measured / Rated Stock output
639 rwhp @ 6000 rpm / 707 hp @ 6000 rpm (0.9038 drivetrain loss)
612 rwtq @ 4800 rpm / 650 tq @ 4800 rpm (0.9415 drivetrain loss)

Legmaker Product:

2015-2016 Legmaker Hellcat Intake. The pre-filter was not used during testing.

Engine Auto part Vehicle Car Automotive exterior


References
Kenne Bell Air Temperature Testing - IAT's Air Temperature Testing Supercharger Kits. The 13 Variables | Kenne Bell
 

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#13 ·
What does, "The pre-filter was not used during testing". What's a pre-filter?
Thank you
LMI supplies a water repellent pre-filter "sock" that goes over the filter to keep any moisture off the filter pleats when driving in inclement weather. The rain shield that is also supplied with the kit keeps water from hitting the filter from the open hood vent, but when driving in the rain, water can still enter from the front inlet area. The pre filter will be a bit of a restriction that may or may not alter the data.
 
#21 ·
Ray, something seems conspicuous about the stock filter graph. There are 2 distinct dips in the HP curve where the LMI has the significant gains (>10 HP delta). Did you by chance monitor A/F and spark timing perhaps with a wideband or a Trinity logger? Were these runs an average of 3 each or just single runs? I just can't get past the fact the stock intake appears to make the same HP as the LMI at 6000 rpm but just 200-300 rpm lower it's more than 20 HP different.

If a HP gain is from less pressure drop across an induction system the HP curves should be very similar to each other with the LMI gradually pulling away as the air flow demand of the engine increases. This doesn't look like that. Perhaps there is some data smoothing needed as well to better see the trend?
 
#22 · (Edited)
Were these runs an average of 3 each or just single runs?
A total of 2 stock and 3 legmaker runs were conducted based upon the testing conditions mentioned in post #1. The most similar temperature conditions for stock vs. legmaker dynos were used in the comparison.

There are 2 distinct dips in the HP curve where the LMI has the significant gains (>10 HP delta). Did you by chance monitor A/F and spark timing perhaps with a wideband or a Trinity logger? I just can't get past the fact the stock intake appears to make the same HP as the LMI at 6000 rpm but just 200-300 rpm lower it's more than 20 HP different.
I was only able to log command A/F which kept pegging for ~ 13.8. I did not log spark. It appears that Legmaker causes the torque curve to shift to the right. The dips in the stock HP curve also occur with the Legmaker, however, at different RPMs: stock @ ~ 4100 rpm; 5200 rpm and Legmaker @ ~ 4550 rpm; 5900 rpm. This matches closely to the torque dips that occur on stock @ ~ 4100 rpm; 5200 rpm and Legmaker @ ~ 4550 rpm; 5800-5900 rpm. I suspect torque management or spark trim, but without recording spark it's hard to tell the root cause. It also occurred on the other stock and LMI dyno runs.

Perhaps there is some data smoothing needed as well to better see the trend?
Here is the graph with smoothing 5 applied, however, it just averages the raw data.

Text Line Slope Design Diagram
 
#24 · (Edited)
No problem. It's definitely interested how much smoothing can skew the raw data.

It's a good thing "area under the curve" was mentioned because that really tells the tale instead of the peak numbers.

It goes back to the discussion of "peak numbers are great for marketing" but the real story is what is happening across the entire RPM band. I'll post up the total power comparison of stock vs LMI with gearing applied shortly.
 
#30 ·
I just installed my LMI Intake last night on my 2016 Challenger and took it out today.

Besides the prominent whine, the other thing I really noticed was the throttle response has improved.

I cannot wait until temperatures warm up enough to really test out my new 3.09 gears + LMI intake. :D
 
#32 · (Edited)
TrackDay Here is the other baseline dyno vs Legmaker. In this case, the stock inlet air temperature is cooler and coolant temp is higher vs. the other dyno comparison. It suggests the engine likes hotter coolant temps (pulling away more heat) and lower intake temps which should not be any surprise.

Judging by the other LMI graphs, it very well could be pulled timing due to higher inlet air temp readings. The inlet temp on those graphs were 98.6 deg (outside of the testing standard) and there were several more dips around the 3500, 4600, and 5500 rpm points.


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#33 ·
So in both comparisons the stock and LMI come back together at 6000 rpm. Strange.
Still, it's obvious to me the LMI makes gains over the stock. I'd really love to see this done on a 750 RWHP or so car running some good fuel.
 
#34 ·
So in both comparisons the stock and LMI come back together at 6000 rpm. Strange.
Yeah, possibly something to do with pressure drop vs. stock. I imagine, once on the road, this will likely be different because of the air being forced into that area from the headlamp. I'll still need to test that out...and will likely require me to buy another DS InTune...to datalog and run it on the TTDyno software.

As mentioned, peak numbers always get focused on by the consumer in marketing, but the largest takeaway should be the total power being made in comparable testing conditions.

Average total gain of 9.1 rwhp / 8.4 rwtq from 2590 to 6100 rpm

Horsepower/torque area under the curve:
5th gear
Stock HP Area: 1710.584 vs. LMI HP Area: 1761.782 (2.9% increase; 51.198)
Stock TQ Area: 2094.184 vs. LMI TQ Area: 2148.579 (2.5% increase; 54.395)

Total Horsepower/torque area under the curve with gearing applied:
1-5th gear to 5000 rpm (simulated 1/4mi to 125mph) / 1-5th gear to 6000 rpm
HP Area: 3.70% increase; 194.68 / 3.25% increase; 187.15
TQ Area: 4.46% increase; 262.37 / 4.06% increase; 257.44
 
#40 · (Edited)
Ray - As always your testing and follow up analysis is spot on and well laid out for people to see.

I can tell you there have been a number of positive comments come back to me after reading your unbiased test and honest feedback. Kudos to you.
That's great news. Btw, the intake makes the engine sound ridiculous at WOT. It's hard to keep my foot out of the go-pedal.
 
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