UK RV streamline a brick challenge. (Aero + other mods)

[cRiPpLe_rOoStEr]

The fuel-efficiency benefits from a higher power may also apply to your motorhome, it's all about how the engine is tuned. Injection timing, injector nozzles, camshaft, boost, there are many things that can be tricked to improve it for both power and fuel-efficiency.

Originally Posted by guyd

how do other people with turbo-diesels with intercoolers fare with grille blocking? Surely blocking the air to the intercooler reduces efficiency, or does the rad get moved? My intercooler is directly in front of the main coolant rad, so one or t'other would have to be moved - I suspect the coolant would be easier / better to move as pipe length doesnt matter on water, but does on air.

It's more reasonable to move the radiator. I'd only move an intercooler if it was top-mounted like in my grandpa's Toyota Hilux - a front-mounted intercooler is always more effective due to the better air flow and lesser effects of the hot air convection inside the engine bay. But that leads to another question: where to move the radiator?

[guyd]

Yes, where indeed to move the rad. I have however fitted a duct to try to make most of the air go through the rad, rather than round it. Its pretty miserable here, so a partial grille block should be liveable with.

Got a mobile alignment company out, and for 60 quid ($97) he found a misalignment of 4 and 5 degrees, toe out. Wow. Set back to zero now. That should help.

6" front air dam in place, with about 5" showing under the front bumper.

[flying kurmaster]

Hi Guyd I have a similar shaped brick only smaller. It is an all alluminium kurbmaster camper with a 6cyl 292 petrol engine. So far I have installed a camback, a partial boat tail if you can call it that, wings down the sides at the back about 150mm angled in at 15% forming a box shape, a grill block, a small air dam, fender skirts.I have found no noticeble improvement in mpg after testing for around 1000 kms I am still on or around 16 mpg (imp) there has been improvement in the stability of the van and I find myself driving 10% faster. I am in the process of installing a full belly pan and skirts down the side which I have not tested as of yet as it is not quite finished. I plan on changing the front bumper and scooping the air under in a smoother fashion. From my experience so far, I have a feeling that my gains will be minimum. I also plan on replacing the clutch fan for an electric one and removing the air polution pump this is where I think I will see some gains. All these aeros have made it quieter and nicer to drive but have done little so far to improve my fuel economy. I think you are looking in the right direction focusing on the engine and drive train. someone pointed me to a TExas study that said by installing a 140mm radius above the windshield on busses like yours would reduce drag substantially, how that will reflect on you fe with your roof is anyones guess. Good luck

[guyd]

Right, i know its not scientific aba testing, the traffic in the uk precludues that most of the time, but a several hundred mile drive reveals a new mpg - 14.75uk mpg which is about 12.2 usmpg from a uk 11.5, so an immediate 28% improvement from the last run.

Anyone know about allison at545 gearboxes, im sure mine isnt right, as i can do 50 to 65mph in fourth, at 2200rpm without the engine changing revs at all. Sure, theres going to be a bit of slip, but that much? 50 mph up hill, 65 on the flat, more than that downhill.

Edited to correct way round conversion, after 5 hours drive im tired.

[samwichse]

I think you're going the wrong way with that conversion. 14.7 MPG UK is ~12.2 MPG US.

Still respectable for such a huge brick though.

Sam

[freebeard]

Originally Posted by flying kurmaster

I have found no noticeble improvement in mpg after testing for around 1000 kms I am still on or around 16 mpg (imp) ... and I find myself driving 10% faster.

There's your problem.

[btracing]

If your speed goes up while the RPM stays the same, it seems to me the clutch needs some work. Maybe take a look at it and try to find a new one?

[guyd]

Thanks btracing, but its an auto, not a manual.

[btracing]

Ok, that changes a lot, haha. Maybe a transmission flush can do some nice improvements than?

The weather is now pretty bad too, I guess no updates for the next two weeks or so. It's snowing right now here in The Netherlands, but you should be getting the motherload.

[guyd]

Its pretty miserable here too.

The tranny is supposedly reconditioned - well I should hope so - it cost me two and a half thousand pounds, plus a thousand to fit. eek.