not sure if I introduced myself

[philip1]

The wheel dams ahead of the tires have Cd1.10,not quite as bad as a parachute but close.They need some radius of curvature or its total separated flow and much interference drag downstream.

Interesting so why does the insight have flat wheeldams? yah they curve from top to bottom but not side to side.


------------- The center of the belly must be squeaky clean or diffuser is a wash.------------

My car is pretty flat and clean in the center of the car


Are you air-tight under the nose,between the fascia and radiator bulkhead?

under the nose is not completely air tight but it is way better than stock where tehre was nothing between the airdam and rad bulkhead... BTW I extended the front tray back to the oil pan (this is how the European car is done)

-------------- You already have a Kamm-back.

I am aware of this and it's surprisingly clean aerodynamically .32cd stock I'm not sure if that's cdA or not.



------------- The "basjoos" stuff is the only thing that's really going to show up at the pump.The existing rear overhang of the body makes a boat-tail problematic due to length issues,whereas basjoos Civic didn't have a rear to begin with.Wagons,vans,and SUVs with existing rear overhang makes real drag reduction an extra special challenge

I have no real intention of going that extreme with this car. My plan is to have it still look more or less factory but get great milage. Subtle is the plan.

I am toying with a splitter just to see if it will work but that will be after rear skirts.

[philip1]

I loaded up a silhouette into flow illustrator. I was surprised how good it was.

YouTube - Saturn wagon on flow illustrator

[cfg83]

philip1 -

Welcome to EM! I like the haircut. I have the same frontal wheel dams, so I may have to change that depending on aerohead's response. I think that the flow illustrator implies an "invisible" kamm-back :



My SW2 has a similar "invisible" kamm-back :



I also think the flow illustrator works better without the wheels. As you can see, I fill in the wheel-wells so that it looks like a hovercar.

CarloSW2

.

[Otto]

Originally Posted by philip1

went to the local home store and bought some foam and got to filling gaps

the light grey you see is the foam and yes the gaps were that big.










I ran a 100mile test loop to see what if any difference these made and road noise is reduced significantly. I set my trip report on my scan gauge outbound 37.1mpg inbound 36.9mpg for an average of 37mpg. this was on a 55mph road with many hills I am not sure if these improved milage at all but the quiet is nice

Phillip, did you happen to notice difference in noise before and after the addition of the foam to the gaps? Or, was that done all at once with the belly pans, etc.? In other words, I'm curious about how much noise reduction you may have gotten just from the foam-in-cracks trick. (I hate noise.)

PS: An indelible felt tip Magic Marker with black ink would camouflage those foam strips such that they'd not be noticeable. Do they stay in place well, or do you have to keep messing with them?

[philip1]

the foam cut noise substantially unfortunately the front doors pulled off the foam between them and the fenders but even after removing that it was much quieter than without.

I have been doing one mod at a time and running a test run after each.

[cfg83]

philip1 -

Originally Posted by philip1

the foam cut noise substantially unfortunately the front doors pulled off the foam between them and the fenders but even after removing that it was much quieter than without.

I have been doing one mod at a time and running a test run after each.

That's exactly what happened to me. I put foam strip on the back of the front door (I thought that concave would be better for keeping it secured). I think I will try it again, but instead put foam strip on the front of the back door, because the way the door opens should reduce the rubbing. Mine lasted a while because I was careful and I used a different strip that was more sticky and had more surface area to stick.

CarloSW2

[aerohead]

Originally Posted by philip1

The wheel dams ahead of the tires have Cd1.10,not quite as bad as a parachute but close.They need some radius of curvature or its total separated flow and much interference drag downstream.

Interesting so why does the insight have flat wheeldams? yah they curve from top to bottom but not side to side.


------------- The center of the belly must be squeaky clean or diffuser is a wash.------------

My car is pretty flat and clean in the center of the car


Are you air-tight under the nose,between the fascia and radiator bulkhead?

under the nose is not completely air tight but it is way better than stock where tehre was nothing between the airdam and rad bulkhead... BTW I extended the front tray back to the oil pan (this is how the European car is done)

-------------- You already have a Kamm-back.

I am aware of this and it's surprisingly clean aerodynamically .32cd stock I'm not sure if that's cdA or not.



------------- The "basjoos" stuff is the only thing that's really going to show up at the pump.The existing rear overhang of the body makes a boat-tail problematic due to length issues,whereas basjoos Civic didn't have a rear to begin with.Wagons,vans,and SUVs with existing rear overhang makes real drag reduction an extra special challenge

I have no real intention of going that extreme with this car. My plan is to have it still look more or less factory but get great milage. Subtle is the plan.

I am toying with a splitter just to see if it will work but that will be after rear skirts.

Philip,Honda has a windtunnel at their disposal for fine-tuning components.I think you'd be surprised at the disturbance a flat panel can cause to the airstream.These panels are to move the air away from the tire face,which is descending at the velocity of the car(an aerodynamic torture-chamber).The wake created by a flat panel is very large with respect to its physical area.You may be able to reduce the size of your dams,and still have the tires fully "hidden" within their wake.------------ With respect to the belly,going way back to the 1970s,with bellypan research published by Skybor and Rylski,the first 2/3rds of the bellypan is the critical part and it doesn't matter how good the back is unless the front and middle is really clean.------------ With respect to the nose,if you can create an air-tight duct between the grille and radiator,you can get away with the most blocking,as you'll have the best ram-air pressure available for cooling.------------- The extended tray is good as you're moving useable kinetic energy towards the tail.------------- Cd 0.32 is your coefficient of aerodynamic drag.Multiplied by the cars frontal area will get you your drag-factor (CdA).-------------- My comment about basjoos stems from the fact,that if you're looking for significant drag reduction and increased fuel economy,it cannot happen with "subtle" changes.For your car's body style,virtually all your drag is in the wake behind the car.To really cut it's drag without adding length,you'd have to cut away the body behind the A-pillar,then re-construct like the body of the EV-1 electric car,with teardrop taper to roof and sides,while narrowing the rear track.Short of that,and you're looking at some sort of boattail device.And like I mentioned,you already have quite an overhang.Quite a challenge! There are some materials in the Stickys that will help you evaluate the potential benefits of various mods.The data is derived from real life and should be able to be used with a high degree of confidence.Happy fabricating!

[philip1]

My wheel dams are not 90* to the road they are angled back at the bottom I will think about cutting them down or completely removing them. they only stick down just about .5 inch below the air dam. On that note I am rolling around the idea of a front splitter that would create a true flat front tray. As the car is now the air dam bottom is even with the bottom of the engine sump.

the back of the car has been cleaned up a bit with the removal of the roof rack and some ineffective VG's. the car is also designed with a taper front to back both top and sides. I may consider one or two things to create more of a virtual boat tail.

BTW refer to the flow illustrator it gives the indication that the car creates a virtual boat tail. I am aware that it is more of a guess than anything else but it is encouraging.

YouTube - Saturn wagon on flow illustrator