Jeep Aero mods testing - with results

[AdrianD]

Hello everyone!

With very limited time I managed to get some testing done on my Jeep. My scan tool displays and logs a ton of ECU parameters and I chose actual injection quantity and mass air flow. Instant MPG resolution is 1L/100km, which is not exactly accurate

Control test was done with this lip installed:


Mod #2 was installing front tire deflectors:


Mod #3 was installing a big plastic panel over the lower grille


The test was done on the flattest stretch of road I could find, in a, luckily, free of traffic interval and I've removed from the data log entries when I was accelerating or coasting. Speed was set with cruise control to 60mph.

Control test (only lip):
Average injection quantity: 21.40 mg/stroke
Average MAF: 619.4 mg/s

Front tire deflectors:
Average injection quantity: 21.48 mg/stroke (0.37% worse)
Average MAF: 617.0 mg/s (0.38% better)

Front tire deflectors and lower grille block:
Average injection quantity: 20.89 mg/stroke (2.4% better)
Average MAF: 610.2 mg/s (1.49% better)

It's a short stretch of road, 4.5 miles total.

Just looking at the instant MPG, I was in the 6L/100km range three times with the front tire deflectors and the lower grille block, while during the other tests I was in that range only once.

Thoughts? Should I still keep the front tire deflectors?

I have the panels for blocking the upper grille ready, I just did not have time to install them today when testing.

[freebeard]

I'd say insufficient sample. Results < 1% are down in the noise. How many passes for each of the three scenarios? Did you control for temperatures and wind speed/direction?

The deflector [apparently] leaves 2" of the tires tread exposed.

[kach22i]

Keep it on, it looks cool.

Tell us more about the material used.

Is there anyway you can make it more of a gentle radius verses a 90 degree bend?

[oldtamiyaphile]

Testing is nice, but frankly we have a pretty good archive to know what works based on previous user experience.

If you can't reliably test fuel economy, use coast down tests. If you notice more speed at the bottom of a hill you always drive, then your mod is working. I've always found that this is noticeable in the airdams I've done.

I've also found there's a lot less noise coming up from under the floor.

The actual fuel savings are harder to measure, but if it does the above then it's got to be helping.

[Frank Lee]

Please post bigger pics next time. Thanx

[AdrianD]

Originally Posted by freebeard

I'd say insufficient sample. Results < 1% are down in the noise. How many passes for each of the three scenarios? Did you control for temperatures and wind speed/direction?

The deflector [apparently] leaves 2" of the tires tread exposed.

4.5 miles was round-trip, between 2 roundabouts. All tests done in the span of 30 minutes.

Almost 2 inches of the tire was exposed, it's less now with the new tires. Image updated in the first post.

Originally Posted by oldtamiyaphile

Testing is nice, but frankly we have a pretty good archive to know what works based on previous user experience.

If you can't reliably test fuel economy, use coast down tests. If you notice more speed at the bottom of a hill you always drive, then your mod is working. I've always found that this is noticeable in the airdams I've done.

I've also found there's a lot less noise coming up from under the floor.

The actual fuel savings are harder to measure, but if it does the above then it's got to be helping.

I agree on the archive part, I've went through a lot of topics with aero mod results but nothing for a Jeep and all the trucks I could see had the wheels more tucked in.

The airdam worked, I'm sure of that, I've went through a few fuel tanks with it installed.
As for coastdown, the hills around here are all twisty or have a 30mph speed limit at the bottom

Originally Posted by Frank Lee

Please post bigger pics next time. Thanx

Heck, I even edited the current ones to comply

Originally Posted by kach22i

Keep it on, it looks cool.

Tell us more about the material used.

Is there anyway you can make it more of a gentle radius verses a 90 degree bend?

Thanks!
It's some 3 mm plastic board from a local home improvement shop. Soft surface, bendy when heated up but brittle when cold.
I've tried a soft bend on the grille block, couldn't do it, maybe I need to heat it up differently, a heat gun is too focused.

[kach22i]

Originally Posted by AdrianD

Thanks!
It's some 3 mm plastic board from a local home improvement shop. Soft surface, bendy when heated up but brittle when cold.
I've tried a soft bend on the grille block, couldn't do it, maybe I need to heat it up differently, a heat gun is too focused.

Is this a plastic laminated foam core board?

Please post a close up photo of an edge or provide a link to the material.

In my experience, chin spoilers greatly enhance stability in cross winds, and that reason alone makes them worth doing.

[AdrianD]

The results here are all only with the chin spoiler:
https://ecomodder.com/forum/showthre...l-35650-2.html

It's homogeneous in structure, I'll try to find the sticker on the board to get more info.

[kach22i]

Looks like ABS plastic not PVC plastic, but I'm far from being sure about it.

ABS is stiffer and lighter than PVC if I recall correctly.

Plus ABS is typically black, and PVC typically white.

However, ABS is typically much stiffer and less prone to bending than fresh PVC.

[AdrianD]

It's in different colors, even yellow. Sticker not found, I will get it next time I go to the home improvement shop

Anyway, here is the upper grille block:


I set off to Austria for the yearly skiing holiday and used only 3 out of 5 blocking plates out of fear of overheating. When giving it the beans uphill, the water temperature went up a few degrees. Going steady uphill on the highway, no problems what-so-ever.
Running all 5 blocking plates here but it still takes about 5 miles to get up to full temperature.

Over the usual test section of highway (600 km) the trip computer showed 35.1 MPG and the calculated fuel consumption was 31.65 MPG. Exact same as the summer fuel consumption and 3 years ago when I had snow tires and just the chin spoiler. Traffic however was not the same, lots of trucks to pass, and passing on the highway in Europe means going 70-80mph. I'm pretty happy given that. Trip computer shows 28 MPG going 75mph, which is awesome.

The lower corners of the tire deflectors are now rounded off...I guess they are not stiff enough to maintain their position going 80mph.

The whole chin spoiler was wet from road spray all the way until the bend in the deflectors. Does that mean that the bend is too sharp?

On the return trip there should be less traffic.