Aero mods lower drag

[ClintJ]

Always modifying!! I read on a another website about a guy modifying his NWH10 prius with an underbody diffuser mounted under engine/front of the car to improve his highway MPG..
His import Prius reads in 5min intervals his fuel consumption in km/lt and in standard form he was getting 5.6lt/100km.
So he made up a temporary underbody diffuser so that there was less turbulance created from the bumper back to the engine crossmember.
His mileage improved from the previous 5.6lt/100km to around 5lt/100km becoming the average and high 4s being the best result..
Here is the link: Browser Warning

So armed with this knowledge I thought that I would attack my vans front end and makeup a diffuser.
I made a cardmoard template that covered the whole bumper and tapered back to the front differential crossmember. I then traced that onto a 1mm sheet of aluminium and then cut it out and fitted it up and temporarilly mounted it. (just needs more screws fixing it to the leading edge. It is however bolted at each corner of the bumper and one screw in the center with it bolted onto the crossmember at the rear, so it not going to fall off but could use some more crews at the front to get a better finish)
Anyhow my best previous record was 9.3lt/100Km or 30.3MPG imp(highwaycycle) but tonight with my barely running motor(low compression and no intercooler) I got with my diffuser mounted 8.58lt/100Km or 32.92MPG.
I will note that there was no diffuser on my previous best run, I did have 5 passengers on board, 5cases of beer, 5 snowboards and my engine was healthy at the time and intercooled and that was my best in comparison to any previous results on long journeys.
So to say that I had made an improvement from 2 afternoons of work(3& 1/2hrs) and maybe $60 worth of material to improve my highway mileage like that would be worth it!!
I do have more plans but I think that I will remove the diffuser and run the car on the same road and conditions to proove that it is an improvement..
I can also add some diffusers like in the link to divert airflow around the tyre. Im also going to lower the car in the future and maybe make some wheel covers on the rear so that the body is more streamline like the older citreons that have the wheel covered by a panel.
I really want to get down to 6lt/100Km or better on the highway!
Oh and my Van is a 4WD Auto in case you ask!

ClintJ

[ClintJ]

Well I added some skirts onto the front bumper to deflect the air away from the tyre both on the wall and on the underside.
My skirt isnt completely filled in behind it so a pocket of air or another drag surface is created.. I need to fill it in so that drag is reduce there plus the air is also diverted around the insde of the tyre as well..
Testing tonight with the original diffuser panel plus the skirts improve economy by 3.2%. This could easily just be my driving but I tried to replicate the same speeds as last time...
My test gets me on a quiet piece of freeway where I follow the posted speeds ranging from 80km/hr to 110km/hr.
My record tonight was 8.31lt/100km or 12.03Km/lt or 33.99MPG.
Still on my tired non intercooled needs to be repaired engine.
Tomorrow I will look at completely filling in the back of the skirts so that drag is reduced around the skirt and the front wheels.
I will then look at making another panel to go from the front differential crossmember to tthe engine. And later on a rear diffuser that will have me cut out the boot where the spare tyre hides to make a box that can mount the tyre inside the car that is also the diffuser to allow under car air to spill up nicely to the back of the car and reduce drag.
Im hoping that all of these mods will get the van running 7lt/100Km or better or 40.33MPG or better....
If I get this far then my engine that I am building should improve the mileage again.
This will include water methanol injection for intercooling and Hydrogen assistance which should see 15% or so improvement just from the hydrogen...

[Father Ted]

Pics..we need pics of these mods

[owenmall]

Yes pics for us illiterate poms.

[ClintJ]

Ok pics..









I think that explains whats been done...
My plan will be to fill in behind the wheel deflectors so that there is no void and the airflow is also deflected to the inside of the tyre.
So far the work has taken me about 5hrs to do all of that.
Must say that the deflectors dont look the prettiest at the moment and I wish that I had time to take up fibreglassing.. Too many things to do and not enough time..
ClintJ

[owenmall]

Now I can see what youre up to. sorted, There are a couple of guys on here that are doing some fibreglassing and you could be giving them some food for thought.

[ClintJ]

Ok done a big road trip last night to look for my spare conrods that cant be found anywhere, so I went down at my parents farm to have a look. Its a 800km round trip.
The run was on 100Km/hr country road and 110Km/hr freeway.
Both roads have many ups and downs so this road would account for everyday driving.
I had a gerry can that I put 16lt of diesel into incase of running empty whilst trying to go for gold.
I already had some 50km already up the clock from city driving as well and to say that I could hold a constant 100 or 110 speed is impossible with 100~130 being in the boundaries.
I done 870Km on 76.39 lt of fuel.
8.78lt/100km
11.39km/lt
32.17MPG
I still havent fixed my engine and its still not intercooled(no water injection as yet)
Had I stayed on a 100Km/hr the whole way then maybe the result would be 8.3lt/100km or better but this was realistic driving so I cant complain much but would like it to be better...
Still havent filled in behind the deflectors but will do so shortly.. Dont know whats going to come first. The hydrogen generator, water/methonal injection or more aero mods.....

ClintJ

[ClintJ]

Been doing some more work.. I removed my rear roof mounted spoiler the other day and I also made up some foam blocks and filled in behind the deflectors so that there was less drag from the deflector and more air being diverted around the tyre...
Same course and driving style.
7.98lt/100Km
12.53Km/lt
35.4MPG
This is highway kms and as stated before 90~115km/hr
I have a city cycle reading as well
10.5lt/100Km
9.52lt/km
26.9MPG

After all of this and seeing how easy it is to shape and form polystyrene foam, Im going to make up shortly some plugs for a fibreglass mould for the left and right deflectors for this van.
The front can be widened a little to cover more of the tyre wall so that the verticle access is covered and underneath shaped a lot nicer than the current faom and racetape setup...
Just goes to show that making aero mods can make a difference in both city cycle and highway cycle economy. Never thought Id break into the 7's in lt/100km..
Next up 7.5lt/100!!!
Im only 3lt/100km off a toyota prius 5lt/100, and I m driving a pasenger van.

[ClintJ]

Hey everyone, how you doing?
Dont mind me if If I hijack my own thread.
I really like to post my trials and triblulations up here for you guys to judge the outcome.
And when I do get replies then I really find it encouraging to continue with my work.
Im sure that like the rest of you that when I get home there is nothing better than jumping in front of the computer to numb out after a days work.
I love it but I also have my wants to improve performance whilst improving fuel economy.
Im by no means a engineer or the sharpest tool in the shed but what I really look foreward to is feedback on what Im doing.
I do really hope that what I have to offer the group helps out.
Otherwise I dont think that Id post anything on here or .org
Its just like Happy Gilmore, cheer me on and I will do the hard work to help you guys...

ClintJ

[Father Ted]

That is EXTREMELY interesting!!!!!

I might just have a go myself. When I can find the time