I need a bigger engine....

Other than fixing my kids' bikes I have had bugger all to do with push bikes since I was a teenager. I have spec'd up plenty of motor trucks though. Total Horsepower Requirement is the sum of Rolling Resistance Horsepower, Grade Resistance Horsepower, Air Resistance Horsepower. I calculated that at 10,000 lbs GCM, first class concrete highway, 64 sq. ft. frontal area (8' x 8' van), 1% Grade, to be 111 horsepower plus accessory losses (fan, pumps, alternator, compressors).

Having established your horsepower requirement, the next step is to create a gear split chart and compare it to the manufacturers literature to see if the engine is producing sufficient power at the desired road speed. You may need to change your final drive ratio or gearbox to achieve this.

The heavy transport industry generally accepts that aerodynamic aids have little effect below highway speeds.

Horsepower requires fuel. If you are not fed then you won't work well either.

sounds like you need a bigger fuel tank:cool::cool:

sounds like something is wrong with your Isuzu JC. Plenty of Tdi owners on here are towing 2.5t with ease @ 110km/h and no where near the fuel consumption of yours ;)

Quote:

---

Originally Posted by Brian Hjelm

The heavy transport industry generally accepts that aerodynamic aids have little effect below highway speeds.

---

Highway speeds for trucks are 90km/h in NZ and 80km/h throughout Europe. Even at those speeds truck makers and freight companies have invested heavily in aerodynamic devices to reduce drag and fuel consumption.

And they continue to spend and research.

Truck at 80km/h
4mx2.5m frontal area.
Cd of 0.6
velocity of 22.2m/s

Drag Force = 0.6x10x0.5x1.2x22.2^2
Drag Force = 1778N.
Power = force x velocity.
Power = 1778 x 22.2
Power = 39.5kw

Diesel burnt to provide 39.5kw in a 220 g/kwh diesel engine.
10 litres/hour or 12.5 litres/100km.

If you can drop the drag coefficient from 0.6 to 0.48 (20% saving) then you'll save 2.5 litres/100km.
Over a 1,000,000km truck life that's 25,000 litres of diesel.

At 90km/h it's 2250N, 56.25kw and 14.6 litres/hour, 16.2 l/100km.
At 100km/h it's 2777N, 77kw and 20 litres/hour, 20 l/100km.

Quote:

---

Originally Posted by Dougal

Almost but not quite.
Compound turbo and heavier flywheel.

Light flywheels are complete **** on a diesel. When you double the torque, you need to double the flywheel to keep torsional vibrations the same.

---

Mmmmm, I'll agree to disagree there.. Had friend with a 4 pot Perkins in a RRC in the UK.. Was forever wrecking the box and running out of go at 2200 rpm.. We ripped it out, halved the flywheel weight, added a turbo, intercooler and pump of a later 4236 and the thing flew! Transformed the motor, made the thing drivable and the box survived.... Half the torque, twice the power and nearly twice the speed. Yeah, granted trucks and tractors need torque, but Land Rovers with the marzipan shafts and older gearboxes don't like it. The 5.9 Nissan in my 101 was the same... We shaved a massive amount of the flywheel, drilled and bolted the original pressure plate onto the thinner flywheel and stood back!! Bugger all torque, but get to 2000 rpm and the thing came to life and then pulled all the way to around 3500 rpm. Never broke a shaft, or the gearbox and I drove it like I'd stolen it... everywhere! (The overdrive's were a different story:twisted:)!!!

Quote:

---

Originally Posted by Sitec

Mmmmm, I'll agree to disagree there.. Had friend with a 4 pot Perkins in a RRC in the UK.. Was forever wrecking the box and running out of go at 2200 rpm.. We ripped it out, halved the flywheel weight, added a turbo, intercooler and pump of a later 4236 and the thing flew!

---

Of course it was better. Turbo, intercooler, more fuel. All good things. But you'd have a much better result with a heavier flywheel than lighter.

A lighter flywheel puts more torque pulse through to the gearbox. A heavier flywheel protects the gearbox.

JC, my worst consumption was worse than yours... I my case it was between canberra and ADL towing a 5m boat at ~120km/h into a HUGE headwind.
I normally get ~11-13 l/100 however in that case I think it was closer to 24!!! :o

Quote:

---

Originally Posted by Dougal

...Even at those speeds truck makers and freight companies have invested heavily in aerodynamic devices to reduce drag and fuel consumption.

And they continue to spend and research.

...

---

However, that said, a lot of the "devices" freight companies spend money on are snake oil...

Quote:

---

Originally Posted by isuzurover

However, that said, a lot of the "devices" freight companies spend money on are snake oil...

---

No argument there. A brewing company has what looks like F1 spoilers on top of their curtain siders.:(

Must have been a good product testing meeting when they came up with that one. They were claiming 10% fuel reduction. I call bollocks.

Quote:

---

Originally Posted by Vern

Just buy a land cruiser, it will complete your grey nomad look you are going for with that massive caravan thingy:p

---

Jealousy is a curse. Caravanning is a wonderful way of life. If I hold you up on your breakneck trip towards oblivion? Tough. I'll get out of your way as soon as I can. The question was asked towards caravaners on this forum and I don't think you qualify. Sorry but I'm a bit fed up of the caravan bashers. I'm 39, two young kids who love getting away with the van and I hope we will do this for many years to come. :):):cool:
Regards
Robbo

Quote:

---

Originally Posted by uninformed

sounds like something is wrong with your Isuzu JC. Plenty of Tdi owners on here are towing 2.5t with ease @ 110km/h and no where near the fuel consumption of yours ;)

---

Are you talking about the 300tdi's??:eek: If so, I'm trading the TD5 tomorrow!!.:wasntme:
Regards
Robbo