Diesel Advice

[theothersean]

I am new to this site, but I wanted to share a plan I have for this summer, and get any advise that'll help.

First of all, after looking at several threads I noticed that I am ignorant to many of the terms everyone has been using. So, I ask that nobody use acronyms. I need terms that I can search for if I don't know the meaning.

Okay, I have been planning for a while to buy a lightweight car to put a small diesel engine in it with two turbochargers, and probably a manual transmission I could pull from some broken down car.
My goal is to take from the Opel Eco Speedster. I figured aerodynamics won't play a huge role because I won't be travelling at 150mph, so weight would be the most important thing, especially for city mpg. I had my eye on two Austin Healey bug eyed sprites that have been rusting into the ground in a storage place. The weight is almost exactly the same as the Eco Speedster.

What I need most input on is how to best reduce the weight, whether or not a smaller engine would be better for mpg (I still want plenty of power), and anything else I may be missing, or could otherwise help me.

Thanks a bunch!

[groar]

Hi theothersean, welcome on-board.

Originally Posted by theothersean

I figured aerodynamics won't play a huge role because I won't be travelling at 150mph, so weight would be the most important thing, especially for city mpg.

Never reached 150 km/h, but I did feel a difference with the rear wheel skirts on our megane. I usually drive at 70-80 km/h (44-50 mph). May be is it only my wishes, but I feel that with wipers removed and passenger mirror folded the car coasts a little more. With lengthy coast in neutral with engine on, better aerodynamic will help.

On our scenic a simple wiper cover did a measurable difference : 2 km/h at the bottom of a small hill.

Upper front grill block do works (be careful in city), as pumping tires at max sidewall.

Have fun,

Denis.

[AJI]

The Sprite? Nice idea. Though which model are you thinking of starting off with, the Mk1 or later ones? The MkI is the familiar "bug eye"...

And the MkII onwards had a more conventional (and possibly more aerodynamic) look:

With regard to removing weight, I'd think you'd struggle given how light the cars are in the first place and how they aren't really filled with all the stuff that weighs down modern cars, like electrical equipment, thick carpets and insulation, power-everything, safety equipment... the only way you'd realistically save weight is by dumping the passenger seat, removing all carpets and most of the interior trim, and doing the extreme by replacing all the metal panels with glassfibre, polycarbonate or something similar. Which would also be expensive.

You could probably make aerodynamic improvements by removing the chrome bumpers and wing-mirrors and maybe making a rudimentary flat floor under the car, as older cars aren't known for their ground-hugging stance.

Lastly, what diesel engine are you planning on running? If you wanted a big project something like an engine transplant from a smart fortwo CDI would be entertaining.

[theunchosen]

IF you're goal is lightweight. . .then find something else.

No car even comes close to as light as you can get it, except maybe the citroen 2CV.

If you are honestly out for lightweight. . .Find a small aluminum chassis(think Go-kartesque)(no more than 500 lbs) with space for a car sized engine. Find the smallest diesel you can and on a wrecked car and buy the engine trans CV joints and steering assemblies. Put the engine in the back and tool the steering if you need to(the chassis might come with it) for the front.

You'll have a vehicle at under 1000#s with plenty of power and you can cruise at idle around 30-45 mph. coroplast, fiberglass, whatever as a body and you could easily do 80-90 mpg with a passenger and tons of play if you wanted it.

existing cars are very heavy because they are designed to be ridden, not save fuel. If the chassis weighs more than the engine you're kidding yourself that its all about the weight. A small kubota with revamped pistons and rods with a turbo could do all the power you'd need and its only going to weigh. . .maybe 200 lbs.

An aluminum(if you are loaded and can pay someone to manufacture a carbon fiber or fiberglass monocoque platform do that) chassis with no body carbon fiber racing seats steering and wheels ought to be under 400-500 lbs.