Project MMPG ~Slow build thread

[dodger21]

I have been lurking for awhile and have asked a few questions. I have been thinking about what it is I want to build this car for. Well, recently (as we all have seen) gas and diesel have jumped over a country who supplies less than 5% of our oil consumption. I am sitting back chuckling to myself as some guys are complaining over filling there oversized SUV's for their family. Family meaning guy+girl+1 CHILD= Need for a rather large vehicle. Complaining how it takes $70 to fill up for them to get to work each week. Yada, yada, yada, poop.

So, Project MMPG (Maximum Miles Per Gallon) starts now. What I have is a 85 VW 2dr Golf with a 1.6L NA diesel coupled to a 5spd transmission, ACH code. A good start but needs more. Currently done to it:

Larger than stock tires :laugh:

I get 35mpg around town and 52 on the highway because of said tires. I am wanting something more uniform.

Here are the plans to the car:

13" Steel to replace the 14" aluminum with smaller tires (Less rotating weight. Know of any mileage savers? Donuts maybe  )
Lowering a inch or 2 (less under car turbulence)
Custom front and rear roll pan/valence (Help direct air flow)
Lose additional weight from the interior (Back seat is not even remotely used, yet. Keeping a spare and less tools)
Front/rear spacers to get rid of the tuck (Make the wheels flush with fenders for less turbulence)
Windshield high pressure area vented down and around car (Have ideas...)

Engine mods are:

Fresh head with a P&P
Custom intake POST filter
Custom intake PRE filter
Larger exhaust
Rebuilt injection pump
Rebuilt stock injectors
Timing advance bump
Inline electric lift pump
Regasket to rid of any leaks


All oils will be replaced by synthetic fluids. Everything will be grease and aligned. Tires might be hyper-inflated to seek out best MPG at times. Not all the time, just after I get a good baseline.

Will post up results and builds.

Peace

[JGWarner]

I'll be watching!

Do you know the gear ratios on that transmission? I'm putting a 5M (0.600 5th gear) in my TD Fox purely for MPG.

I assume you've already deleted A/C, power steering and considered un-belting the alternator?

[dodger21]

I do not have power steering or A/C 

I actually need the alternator to work. The lift/pusher pump I will be installing needs 12v power. Might look into a magnetically clutched thing to only cycle when juice gets below 10v. Solar panel anyone?

I didn't know there was a taller 5th gear... I may put that in my AOP tranny so I have basically 2 OD, 1 at .91 and the other at .6

http://www.4crawler.com/Diesel/VW_020_transmission.shtml

I notice almost all thing being equal, they say the AOP gets 10mph more in 5th than the ACH but they have the same final drive/5th gear ratios....

[coke]

http://www.scirocco.org/gears/

All the gear ratio information you could ever want. I found another site that actually listed speedo gear colors and what transmissions were compatible with what gears, but I can't find the link to it.

The ACH / AGS is what I'm looking for to replace my crappy AWY. I think its a major contributing factor to my exceedingly crappy highway mileage

[coke]

Ah here it is. Found it.

http://www.a2resource.com/eandt/ratios.html

[JGWarner]

Neato.

Check out the Ecomodder forums

Some cool stuff going on there. Including this...

[nathan_b]

They are talking on that top gear forum about 70mpg being crazy....

umm... a stock tdi polo has gotten over 94mpg UN MODIFIED...

they are rated at like 70mpg.




as for your build. get some 13 inch tires on there, a front spoiler, lower it 2 in. you are on the right track!
If you turbo it and use an td pump you can get better mileage because the fueling is based more on boost readings and therefore is more precise. It's not just a flat line increasing like a std pump. This also allows you to turn the fuel way down.

In my caddy I made it from athens ohio, to chicago, to wisconsin, back to chicago on one tank of fuel (including creeping through chicago rush hour). 50mpg.. oh yeah, loaded down with about 1500lbs, and the gf, and bags for the weekend. 740miles is my record for a tank, but after the gov mod I have made about 5mpg better. (and driving it harder). It lowered egts on the highway too. 60mph=575egt.

I think that unloaded, at 55mph, 45psi in tires I could break 60mpg. in a pickup truck

I think it says so much about america that vw said here is a comfy truck, with a real truck payload, with the maintenance of a car, that got 50mpg, made great heat, it's cheap and easy to maintain, oh, and it lasts like 40+years if you take care of it: and the Public said :NO THANKS. What a bunch of douches.

[mystery3]

In my caddy I made it from athens ohio, to chicago, to wisconsin, back to chicago on one tank of fuel (including creeping through chicago rush hour). 50mpg.. oh yeah, loaded down with about 1500lbs, and the gf, and bags for the weekend.

What the hell kind of suspension are you running under the back of this thing? And what about brakes?
I've done a lot of hauling in my caddy over the last year and basically 1180lbs + me (140lbs) and it was absolutely on the bumpstops and completely unsafe as far as stopping distance was concerned.

OP, don't forget wheel bearings. Also I'd look for weight in a wheel/tire combo and not worry about diameter. Kosei K1's are really light and can be found fairly inexpensively but I don't think I've seen them narrower than 7". The Compomotive CXR 1355 on top of the page is only 4kg in 13x5.5" that's not bad!

[Bugsy_malone 666]

Im just looking through this and thought it seems like a massive amount of mechanical work to achieve probably alot less gain than looking at the areo dynamics.

I mean something that I do have to remember is a US gallon(3.78l) is less than a british gallon(4.5l) so 50mpg is actually a higher mpg on my side of the pond!

ok that aside the thing thats using fuel is wind resistance, vw have spent years amking their cars heavier and at the same time keeping mpg stats about the same despite the weight increase, if you were to get the 1.4tdi polo motor in something that weighs as much as a mk1 golf you'd probably get 80-90mpg all the time.

I do think messing about with wheels and tyres to much may lead to no much more than hard work rather than extra economy compared to sitting down and looking at the aerodynamics. If you gear it up too much it will put more strain in the engine and just use more fuel, rather than less, which is counter productive.

So to start with, lightening what you can of the vehicle will help, its what they do with race cars to get better 1/4 mile times so obviously weight is an enemy. Look at replacing steel/cast parts with aluminium components where possible. Carbon Fibre interior panels or thin aluminium sheets? Look at panel gaps, making sure all your panels fit the best they can to minimise disturbance in the airflow.

I think you might have to weigh your wheels to see if there is actually a massive advantage or not to changing them, because if the wheels get smaller and tyres get bigger chances are you may not save anything in weight.

Engine wise I would say probably put a really low pressure turbo on of 4-7psi to make the engine just a bit more efficient as opposed to the normal 9-20psi diesels seem to run at, intercool it to improve futher. With the inlet you want to keep the stock idea in mind of having a system that works to draw the right temperature air in to get the best from the engine.

I think probably your biggest gains will be looking to see what you can do in the way of aerodynamic improvement, these articles may be of interest/use:

http://autospeed.com/cms/A_2159/article.html

http://autospeed.com/cms/A_2160/article.html

http://autospeed.com/cms/A_2162/article.html

Might help you with your quest a little, when it mentions about undertrays, you might be able to get one from something like a mk3 golf/jetta diesel, hopefully food for thought anyway

Thats my 2 cents worth

[erice1984]

Bugsy, interesting for getting air to flow through critical parts of the car.  I wonder how those would affect fuel economy.

Maybe if he tried to achieve increased airflow characteristics throughout the entire engine bay?  So that the air in had an exit out.  Maybe it doesn't matter for fuel economy, but only for engine performance (i.e. getting more power out of the engine).

I would conclude that get your radiator enough flow to keep the engine cool, but frontal cross section and air flow AROUND the car would be the most critical in achieving that increase in mileage.

[GEE-BEE]

15 X 6 OR 14 X6 LE CASLETS are the lightest wheel

Forged alloy , not cast

Lowered two with a kamei air dam sounds good

3.32 R & P with a .71 with a TD would b the best

radiator with good sealing is better flow, my 675 mm wide prevents most air from blowing to the side and I make a P seal for the top of the radiatot for better flow

need some, let me know

GB

[Bugsy_malone 666]

Bugsy, interesting for getting air to flow through critical parts of the car.  I wonder how those would affect fuel economy.

Maybe if he tried to achieve increased airflow characteristics throughout the entire engine bay?  So that the air in had an exit out.  Maybe it doesn't matter for fuel economy, but only for engine performance (i.e. getting more power out of the engine).

I would conclude that get your radiator enough flow to keep the engine cool, but frontal cross section and air flow AROUND the car would be the most critical in achieving that increase in mileage.

Well I think the article brings up some interesting points about how subtle changes to aerodynamics can make a big difference to the way something works so it maybe that for example where vents are cut in the bonnet behind the radiator in a low pressure zone means you can make the system more efficent to the point where you can start sealing some of the bottom of the engine bay.

Or say working out where the pressure area of the bonnet starts to rise nearing the windscreen, then you could maybe mount a very small deflector accross the bonnet to change the direction of airflow so it hits the windscreen further up and causes less pressure.

Change the shape of your mirrors for more bulleted ones, that sort of thing.

All things to be considered

on the new polo bluemotion vw changed the grill design to help air flow over the car so not much went into the engine bay like a big scoop, instead they opted to use air from a lower part of the car (under the bumpers middle) where aero dynamic gains were harder to achieve because of the general shape of the car. It maybe because of the shape of the old golf grills and under the bumper area with it curving under the body that you take the opposite idea with reverse naca ducts in the bonnet to draw air out without disturbing aerodynamics to much on top, meaning you can panel out the lower area to make air flow under the car better.

I'm sure theres tons that can be done interested to see what you achieve!

[dodger21]

Thanks Bugsy! I will be reading it up!

Also, I need to change a brake cylinder as it is leaking... 

[erice1984]

Good points Bugsy.  I like the way you are thinking.

[TDsamurai]

Ive read alot of opinions on making more flow through your radiator, personally i think you will lose fuel economy if you try and make the engine run cooler. Cooler intake air will increase flow because of a denser charge thus increasing power. But cooling the engine water temperature will probably provide a more incomplete burn. From my understanding these engines are built to run at 195. And to try and run it cooler than that would be counter productive.