AeroMod Me! (1997 Acura CL)
 

Alright, after doing some fine tuning on the VAFC, ive made a record 36mpg tank, and I believe I am about to break that one with this next tank that I'll be filling on Friday (I'm at 36.4 avg according to my torque app)... So I am now ready to dive into the aero mods! Just looking for advice that will help with the biggest gains.

Goals:
-Lighter engine load at cruise speed;
-Longer coast downs.

I cannot do a boat tail because it won't fit in my garage if I do, but any other mods are on the table (other than mirror delete, for safety reasons)

I've done lots of research through this site and have some ideas in mind, but am more interested to hear your thoughts for my particular car's shape rather then just throw on mods.

Current mods: antenna delete, lowered suspension, CAI (though I will likely make it just a short ram in the future for warmer engine bay air)

I am guessing my spoiler doesn't help with aero but it def looks better with one on, though I would not object to taking it off.

What about a plexi Kamm back, would that help?

I could def use some cleaning of the underbelly in terms of airflow...

And a partial grill block is def in the future too (though I may end up glassing a new more aero front bumper if I can find a design that I know will work and still look half decent)

What are your thoughts???

http://ecomodder.com/forum/attachmen...1&d=1353006697

Kamm back would help. Rear wheel skirts, wheel covers. You can add a little convex mirror on the inside in place of the exterior mirror. Works great.

Also, get a front lip/spoiler to push air around the sides instead of under the car. Then you won't really need to make a belly pan.

I would do a kamm for sure and plexiglass would work just fine. Depending how far back you bring it if you would either break it into pieces or hinge it at the very top to keep access to the trunk.

The spoiler is probably not hurting anything considering it sits pretty low. The spoilers you have to watch out for are more of the ricer styled ones that increase drag and down force, but down force is not needed at hypermiling speeds

Another thing to consider is smooth wheel covers. I gained about 1mpg consistent tank to tank over having open steel wheels. I can still check fuel pressure and remove the wheels without removing the covers. http://ecomodder.com/forum/showthrea...tml#post330171

Thanks for the responses, I've had a hard time finding a good Kamm design thread. Several attempts even netted negative results...

Yes I am planning on wheel covers and possibly skirts for the rear as well.

Just pumped my tires up to 42 psi (max sidewall is 44) up from 30 so we'll see how that helps on the way home today.

Design the Kammback just like a boat tail, but cut it off at the back of the trunk. You should use all the same angles as a full boat tail would. If you're not sure just do a cardboard mockup with 10-15 degrees on all sides and ABA coastdown test it. (and tuft test too)

If you can get a straight and level photo of the car (or better, a blueprint-I had no luck) then just input it here to overlay the template. That will give you the ideal profile.

I'm not so sure a Kamm would help much without it being meticulously designed and built, and even then you might only get 5-7%. Reason I say that is your roof to rear glass transition area radius is freakin huge, there are papers done on this that show a big rear radius improves Cd a lot.

The rear spoiler is almost certainly helping you some, and very unlikely to be hurting you. It isn't a lot, but If you like it, keep it.

Have you pumped up the pressure on your tires? That's 5% right there if you have them at 30psi currently. Also, blocking any kind of upper front grill area would help for making you more aero and it will also raise the intake temperature since this is generally where the air going to your intake comes from. Forcing the air through the radiator first heats it. (news flash, right?)

Plug that puppies nose!!

http://i49.tinypic.com/sb31nq.jpg

Kammback construction (on a sedan) example:

http://ecomodder.com/forum/showthrea...ods-20741.html

would duct tape suffice for holding on a coro kamm? i'm not ready to drill holes in my roof quite yet:D

My boat tail's structure is aluminum drilled to the body but its skin seams are duct taped. You just have to manage the rough ends (where you rip it off the roll) so the air doesn't catch them. It helps to cut curves into the ends with a razor. Also, if you're layering, put down the rear-most tape first and work forward.

tape is more than sufficient!

http://ecomodder.com/forum/showthrea...tml#post320868

My own renditions of a Kamm was/still held onto with duck tape/Clear Packing tape. As I too have not figured another way yet to mount them to my car semi-permanently(still new). But i have tried a few diff ways, and materials. maybe get an idea. Me and Neon above, wound up with similar pivoting kamms, just coinsidence. good luck.

You don't need to design your kamm using rocket science just a common sense, aero template and remember to taper it to the back. And you can get good numbers from that Berta kamm coastdown test

Grill blocks
Smooth wheel covers
Side mirror delete. I have had mine off for 2 years and the inside mirror works great!
Belly pan
Kamback. Leaving room for a boat tail ( you might not have space now but you will want one someday)
Take the tires right to max side wall.

Different cars have different aero characteristics to begin with, Andrzej & Weather had cars ideally suited for a Kamm, there was essentially nothing aero about where the air left the backs of their cars. This Acura has quite a bit going for it in that the top of rear glass area has a large radius, and I've seen papers that show this is great for reducing the Cd. I'm not saying it's ideal, but, without knowing what the air is doing, a half-baked attempt to "Fill the Wake" in the case of this Acura CL will end up hurting the Cd. A very well executed Kamm going all the way back to the tail lights and having the sides shaped correctly would be the only way a Kamm would be an improvement on what is already a fairly aero car. The sides would be key to getting it right. We all know how to do the top part.

I pretty much gave up on making a Kamm for my Civic due to this reasoning.

I think Chaz is right here. If nothing else the rear of the Acura is pretty different than the BMW, WS's matrix, the fiesta or even my Neon. All the basic stuff would still apply though as you said, especially for the top.

If you're thinking of a kammback, I would suggest leaving it towards the end and do the other mods first like air damn, grill block, etc. The time and effort involved in building an effective kammback could easily be spent other places first.

Good point. It is definitely time to do some front end mods, intake temps in the low 50s just isn't cutting it for FE, I had to P&G much more to maintain a reasonable average.

Anyone have a good reference for front nose cone designs?

I think there is definitely area for improvement at the back of the car

http://ecomodder.com/forum/attachmen...1&d=1353103655

Nose cone may net you less improvement than the Kamm, actually. Block off those holes up front, get the wheels taken care of, then think about the rear end.

BUT BEFORE YOU DO ANY KAMM STUFF make sure you tuft test the rear window. If it has attached flow, as Chaz said, you may not even bother. It will not be ideal, but if it's there it may get you by. Depends how much you like to tinker.

For highway FE, I saw about 25% MPG increase without a boat tail, and 46% increase with one. With all we've mentioned in this thread you may be able to top ~35mpg on the highway at 60mph.

I saw a CL up close yesterday while walking on the street, I feel like the rear is probably slipperier than most cars out there...The sides taper in more than a lot of cars (especially from that time period), the rear window has some nice big radius turns on the C pillars and slightly tapers in. Maybe some tuft testing first to see how the air is behaving? Just eyeballing it I would suspect that the air reattaches at the end of the trunk.

I think CLs are extremely pretty cars, if it were me I'd go for areas that don't impact aesthetics first, especially since your mpg is not that bad to begin with. I would cover the bottom up and block the grille first. The rear bumper has a nice angle to begin with. You could also put some subtle fairings behind the rear wheels.

looking at it now with the template, doesnt look bad as i thought. I didnt have much time to look before with my kamm response. Maybe a few inch extention to your spoiler could make a small improvement.

Agreed with others on buttoning up the front, and front/rear belly pans. haven't seen what it looks like under the boot area, but if like other hondas i've seen, its a parachute. still not as big as mine.

With your CL lowered, i assume you've also made a roll bar change, and aligned everything properly. How is your chamber?

I would leave the spoiler as is. You could extend it or whatever but I dought it will be worth it. If anything just block off the gap between the spoiler and the trunk to help keep that pocket of air in place.

Go with the grill block, and wheel covers.

Already netting 37mpg avg hwy :D looking to break 40!

There is quite a bit that can be done to the underside, especially the rear, its got a huge parachute!

The car was lowered by the PO, no clue as to whether the stabilizer bar has been changed, or what alignment adjustments (if any) have been made, though it has some serious negative camber. Tax season will net me a camber adjustment kit (if needed) along with some LRRs.

I've been hoping to stumble across some light 15in wheels since there are a lot more options at a better price point. I don't believe 14's will clear due to the disc brakes.

Thanks for all the suggestions! Still looking for a decent front airdam design template if anyone comes across one! :D

Attach Al bar at one wheel well, bend, bend, bend, attach at other wheel well. Remove, drill holes every 10". Drill holes in lawn edging. Zip tie together. Attach to bumper. I used body screws on the ends and zip ties on the rest.

http://ecomodder.com/forum/showthrea...tml#post335804