91 Dodge airocap

[aerohead]

I got into Hucho's book and located the material I mentioned.It wasn't what I thought.
It had to do with the EPA Composite Cycle:
*Lowering drag from Cd 0.46,to Cd 0.30 (a 34.78% drag reduction) would provide:
*a 14% fuel consumption reduction for a gasoline vehicle.
*a 17% '' for a Diesel vehicle.
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*It doesn't parse out a steady-speed,level road relationship.
*And it has more to do with the higher thermal efficiency of the Diesel in Urban driving than aerodynamic effects on the highway.
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*We might default to the earlier GM metric of a 5% mpg improvement for any 10% drag reduction at 55-mph.
*And a 6% mpg improvement for any 10% drag reduction at 70-mph.
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*The aerodynamic fraction of total load/power does increase with velocity,but as the drag comes lower and lower,there is a diminishing return.
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*What we're interested in,is the reduced power load,which directly affects mpg,based upon a constant BSFC for the engine which undergoes gear-matching to keep the new top speed rpm equal to the non-streamlined top speed rpm.Without gear-matching,we can lose up to 50% of the streamlining benefit,as the engine falls into an island of inefficient operation.
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*This makes it very difficult to predict things when we're not presented with a BSFC map for our vehicle's engine.
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*And this is aggravated by the fact that even if we get a top speed from say CAR and Driver,Road &Track,etc.,it won't actually represent the vehicle's actual potential,since top speeds are gear-limited perhaps in mid-gear,with 2-additional overdrive gears provided to slow the engine, at a constant top speed (at sometimes,much lower horsepower than rated power,but full torque),to reduce engine wear.

[slowmover]

Sorry I missed this before now. Too many hours and days on the road. Will be looking to see how it works out. And the spell checker cracks me up.

As to BSFC map,'check Diesel Daves comments. Nearly any automotive diesel is close for GP work. The VW TDI, for instance. The rest is more intuitive, granted, but there is room to mess around at or barely above 60-mph in terms of gearing.

Above 65 (which doesn't save time) the increased wear on tires and the decrease in braking/handling safety closes the door to that.

My impression after nine years is that the truck is set to do its best work from 55-65/mph (on my third gen). Really, 58-63 with my gears and trans ratios. This is where to look.

[gumby79]

https://youtu.be/VgUJAnXGeKk

https://youtu.be/s-a_qy47zhk

[gumby79]

Had the worst FE ever to day.
From fuel log:
Had to run to the ER 90-102mph for 72mi 33mi at 65mp
Ran 8-900Egt. 750 on 7%down grade to maintain 90-102mph
Pulled to 1100EGT on 7%up grade at 80. Had to stay below 98%throttle to stay in OD dam truck would lose 5-15 mph instantaneously on a down shift as I back pedaled to try and cetch 4th.
14.51mpg
Alls well sliped wile sharpening mu chainsaw. Wouldhave been 5-8 stitchesbut alass thanks to Durmabond (aka food grade supper glue) none.and no tendons.
should be 25-29mpg going home.at 60-65.

[deejaaa]

hate that. i've had my share of cuts and none i'd like to repeat.

[gumby79]

I have moved my average stock 29xxmi at 18.237mpg .to 23mpg with my Aero Tonto cover. (My new name as it dusen't fit the cap description, non opening) this improvement is including a move to Montana from Portland, OR +2 round trips, high speed, normal, loaded, mostly empty, several 1xxxmi with 1200lbs of tools(including rollaway tool box +tools) in the back under the Tonto waiting for my house to close.

9896mi@22.7 (it dropped my average by.3mpg to drive 80-102mph for 72mi) I'll try to recover some of that when home bound tomarow. Decided to spend the night and weight for Costco to open in the morning as they have my motor oil for 38$$/3gal. As compaired to $5/qt.
10,000mi jun1-September 30,2016 4482mi in the month of September alone.saved 102$$in 3 months.

Plans are a go for DARCO wind tunnel with Aerohead in September so we all get to see if the air moves as I see it . Won't get an accurate CDa number. As my small full size truck (compaired to todays 3/4 ,1ton trucks) has just a little bit more frontal area than is ideal for the test section. I had a conversation with DARCO back in March and they said no go to big . During one of Aerohead's calls he talked to the staff about squeezing the Wale in . Well the answer was yes with one caveat . Because of % blockage in the test section we would not get CDa pinned down but an ABA is doable.
Would like to reskin the Tonto as a few spots reacted badly to the mylars slightly lower melting point and the foam boards lower yet melt point. Causing dimples as the foam shrank/ bonding/ pulling the heat shrink, making the skin and foam bord 1 pice in many places. Cant be to adverse as I've seen 29.3mpg as a high compaired with23.01mpg naked

Dreem big chisel down to reality.
DARCO was a big dream now its reality.

9.25 days till DARCO getting excited.
Ps maby we can answer the old A/C or window down questions.
Time for sleep.

[gumby79]

Well sleep is not forthcoming...so
Future plans are...
After the dust settles from DARCO. I'll be working on more aero modds the goal is 40mpg before messing with the factory sealed Injection pump ( this is a fully macanical diesel)
I may try to put a 12^cm wastegated exhaust housing on my H1C turbo-charger from a HX35 . Stock was 21^cm when I rebuilt the H1C(at about 250,000miat 280,095now) I added a 16^cm housing +exhaust wrap on manifold/ turbo as well as a turbo blanket. The 16and wrap improved efficiency of the motor as it took 100°f less waste heat to spool any given psi.(100°f drop across the boord. Aka 600°f =1psi stock 500° f =1psi modded ect ect)
---
I have some led trailer lights so maby a tail cone to accentuate the Aero Tonto cover.
-----
I am 6'3" tall so my head is just below the roof , my line of sight is in the upper 1/3 of the wind screen . This was a problem with my 79 Chevrolet pu 4x4 back just after high school. Back then I was told that I was crazy as a bed bug in the psych word for wanting to do a hood blister like Aerohead has on the t-100. The biggest hold back is my truck has an almost perfect body(less the shi♧¥stock paint falling off paint, bad primer requires stripping to bair metal to fix) and that makes it difficult to cut into this 25year old ultra clean rig.

Stock CDa is estimated at .45-.55
Aero Tonto cover =estimate/ prediction .203-.253 =57% reduction

My goal of 40mpg is 31%above my current max of 29.3 this will take some time and looking outside the box. As with my Tonto. (Witch has miles of improvements available some compromise. Form over function.
---
I'll try pulling the Headache rack , sliding the AeroTonto up to the cab . For the trip home.
This will have several effects.
1 close the cab cover gap .
2 remove of the horns .(ladder rack).
3 smooth the transition from cab to cap.
4 delete the opening ability (making it like the other fixed position caps.)
Wind providing the taire down should take 10min (I'll time ) and reattachment of the floating cap (with some ingenuity) up to 1/2 hr.

--- ive had the rear closing attachment come undone at 60mph ... yikes... this was before the lift struts . It lifted aproxamitly 9-15" above the tailgate... Indicating the angle may be too steep (DARCO will anwser) there is definitely lift .(as apposed to down force).
---
I need to redesign the hinges, to include a retainer/safty cetch . On bad roads, aka dirt roads with washboard. The front slid over off the hinges...yikes ... the wight part was only attached at the rear by 1 ratchet strap . The front dropped down about 6"and rested.this has happened 3 times in 30,000mi once at70mph and 2 on dirt roads at 35-40mph (As aposed to catastrophic lifting and by by) the redesign will include an alignment guild for the hinges to make installation less problematic in windy conditions.
Well 4:00am a nother try at sleep.
Dreem big chisel down to reality.

[aerohead]

Originally Posted by gumby79

Had the worst FE ever to day.
From fuel log:
Had to run to the ER 90-102mph for 72mi 33mi at 65mp
Ran 8-900Egt. 750 on 7%down grade to maintain 90-102mph
Pulled to 1100EGT on 7%up grade at 80. Had to stay below 98%throttle to stay in OD dam truck would lose 5-15 mph instantaneously on a down shift as I back pedaled to try and cetch 4th.
14.51mpg
Alls well sliped wile sharpening mu chainsaw. Wouldhave been 5-8 stitchesbut alass thanks to Durmabond (aka food grade supper glue) none.and no tendons.
should be 25-29mpg going home.at 60-65.

One of the Blues Brothers band was cutting a tree limb from a ladder.The branch broke,swung down,knocking the ladder from out from under him,and he landed on top of the running chainsaw.
He was okay,but boy was that close.
Glad all your internal parts are still inside!

[aerohead]

Originally Posted by gumby79

Well sleep is not forthcoming...so
Future plans are...
After the dust settles from DARCO. I'll be working on more aero modds the goal is 40mpg before messing with the factory sealed Injection pump ( this is a fully macanical diesel)
I may try to put a 12^cm wastegated exhaust housing on my H1C turbo-charger from a HX35 . Stock was 21^cm when I rebuilt the H1C(at about 250,000miat 280,095now) I added a 16^cm housing +exhaust wrap on manifold/ turbo as well as a turbo blanket. The 16and wrap improved efficiency of the motor as it took 100°f less waste heat to spool any given psi.(100°f drop across the boord. Aka 600°f =1psi stock 500° f =1psi modded ect ect)
---
I have some led trailer lights so maby a tail cone to accentuate the Aero Tonto cover.
-----
I am 6'3" tall so my head is just below the roof , my line of sight is in the upper 1/3 of the wind screen . This was a problem with my 79 Chevrolet pu 4x4 back just after high school. Back then I was told that I was crazy as a bed bug in the psych word for wanting to do a hood blister like Aerohead has on the t-100. The biggest hold back is my truck has an almost perfect body(less the shi♧¥stock paint falling off paint, bad primer requires stripping to bair metal to fix) and that makes it difficult to cut into this 25year old ultra clean rig.

Stock CDa is estimated at .45-.55
Aero Tonto cover =estimate/ prediction .203-.253 =57% reduction

My goal of 40mpg is 31%above my current max of 29.3 this will take some time and looking outside the box. As with my Tonto. (Witch has miles of improvements available some compromise. Form over function.
---
I'll try pulling the Headache rack , sliding the AeroTonto up to the cab . For the trip home.
This will have several effects.
1 close the cab cover gap .
2 remove of the horns .(ladder rack).
3 smooth the transition from cab to cap.
4 delete the opening ability (making it like the other fixed position caps.)
Wind providing the taire down should take 10min (I'll time ) and reattachment of the floating cap (with some ingenuity) up to 1/2 hr.

--- ive had the rear closing attachment come undone at 60mph ... yikes... this was before the lift struts . It lifted aproxamitly 9-15" above the tailgate... Indicating the angle may be too steep (DARCO will anwser) there is definitely lift .(as apposed to down force).
---
I need to redesign the hinges, to include a retainer/safty cetch . On bad roads, aka dirt roads with washboard. The front slid over off the hinges...yikes ... the wight part was only attached at the rear by 1 ratchet strap . The front dropped down about 6"and rested.this has happened 3 times in 30,000mi once at70mph and 2 on dirt roads at 35-40mph (As aposed to catastrophic lifting and by by) the redesign will include an alignment guild for the hinges to make installation less problematic in windy conditions.
Well 4:00am a nother try at sleep.
Dreem big chisel down to reality.

Gumby,not to drop a bomb,but I've re-scheduled the DARKO test session for one week later,Sept. 16th,at 1:00 PM.
I just got to thinking that I was cutting things to close.I didn't get to sleep until after 5:00 AM this morning (a new record).
I hope this doesn't wreck you and your friends schedules.
I'll be fabricating up to the departure date 'n hopefully have something significant to share.
Hope you can still make it.

[gumby79]

Can do thank you for the week lead much appreciated.. starting to thrum with excitement. .. looking for to talking about a v2 AeroTonto.