Stock 21 mpg getting 29.8 mpg ... room for improvement

[b1gmoose]

Greetings,

I am new here, but I have been on a quest over the last few years to get my car to be as fuel efficient as possible. Little by little, car by car (have gone through 3 in the last 5 years, 1 rusted, 1 got t-boned, and driving current car)

I have an 89 BMW 325iX All-wheel-drive with manual transmission and inline 6 cyl engine.

I run Amsoil 10W-30 engine oil, Amsoil ATF in the transmission & transfercase, and Amsoil 75w-90 gear lube in the front & rear differentials. I also have the bypass oil filter for 25,000 mile oil changes. I will be going to 0W-30 oil in 8,000 miles. We'll see if that will generate an improvement. I just bought the car 17,000 miles ago, so I had to start somewhere with it. And I had 10W-30 on hand from my last car and the bypass filter assembly.

I would have an Amsoil Ea Air filter, but they don't make them for my car :-(. So I'm stuck with a K&N panel filter.

Tornado fuel saver
Denso Iridium Spark plugs
Bavarian Autosport 8mm plug wires (removes resistors)
MSD Blaster 3 High vibration coil
Ignition Solutions PlasmaBooster (multi spark box)
SUN Automotive Hyper Grounding Cables (super low impedence 99.99.......% pure copper with gold plated connectors). I have a trunk mounted battery and ran a HG cable from the trunk to the engine bay. I used HG cables and grounded the block, head, intake manifold, fuse box, ECU, ICV, AFM, and all engine bay grounds to the cable from the trunk. Also grounded the battery to it's stock location in the trunk with a HG cable.

Anyways, I am still trying to figure out how to increase my fuel economy.

I came across a few threads reference the Zemco Fuel Saver. I bought one, it came from Great Britian, Under $40 shipped. There is another one on eBay right now. I don't do much stop and go driving but it can help. As with all of the parts, as long as I stay with a cap/rotor based gasoline engine, it is a 1 time investment I can take from car to car.

I did have some concerns about the fuel saver, but got over them after thinking them over. I know there is more wear and tear on an engine when it starts. Well I got to thinkin', if the car is starting and stopping all the time it'll wear my engine out pretty damn quick. Well I also realized that Amsoil sells a precharger to prevent engine wear. So my conclusion is engine wear happens when it is a cold dry start. So as long as your car can maintain oil pressure for the 3-5 mins it may be off in stop and go traffic, then you'll be all set and won't wear it out. You'll wear your starter out faster, but those can be rebuilt easier. So my next project is to mount the Zemco and see how it goes. I don't do much stop and go driving, but every little bit counts and this will pay for itself pretty quick.

I have some additional questions for increasing fuel economy.

Headers? They will help with scavanging and make the pulses timed better, resulting in a little less backpressure & loss of low end torque, but will I get better fuel economy at 65mph in 5th gear at 3200 rpms (redline is 6500 rpms).

Crank Scrapers. Less roating mass of oil, better fuel economy? They claim increased HP/Tq so fuel eco should go up too right?

Anything else? I do all the typical stuff with higher inflated tires (within reasonalbe pressures), easy stop and go, no a/c, no windows, acetone in the gas tank, etc etc.

Any more tips or projects? I try to keep the price of new parts down around the 150$ at most range. A lot of stuff I pulled off of other cars in junk yards (tornado fuel saver for 1).

I tune the car up regularly & run fuel system cleaners every 5K miles. I rotate my tires & check spark plugs every filter change at 12,500 miles, etc etc. I keep the car tuned up.


Electrocharger anybody? www.sigmaautomotive.com/electrocharger/electrocharger.php

Thanks,

~ryan

[SVOboy]

I dunno about how BMW does its transmissions but mehbe you could swap a 5th gear from something a little bit longer to take your 5th gear;s place, that's so high in the rpm range. I'm only at 3k at 65 and I have a 4 speed auto tranny. In any case, that would help a lot just to swap that, if possible. I dunno about the headers, it seems that in the hp versus mpg thread we decided more low end torque is good for mpg, but I can see how a header would help on the highway giving you more power for the same fuel at that rpm range. I'm excited also to see how the zemco goes, I'll go look at that one on ebay now.

[b1gmoose]

The car I have is a rather rare BMW. They did not import many AWD cars to the states in the body style from 1982-1992. All other BMW's are RWD.

I have the same internals for my engine, transmission, and rear diff. However, the oil pan for the engine is a special one. It has a hole through the center so the front axle can work in the small area. Also, the transmission I have has a special housing so it can connect up to the transfer case.

I have contacted the Metric Mechanic and am condisering going from a 2.5 liter engine to their 3.0 or 3.2 liter stroker. Also, they modify the transmissions for racing and 5th gear ratio is also modified. At 65 mph I would be running about 2700 rpms vs. 3200 rpms. But they need both the block & transmission as good cores to do what I want. And the price isn't the best. But I do plan on keeping the car for quite a while, so once I get an extra car (maybe an 80's diesel ford escort) I'll send my car down to get worked on.

I have 225K miles on the engine now without a rebuild so it's doing pretty good.

Every other BMW is extreemly interchangeable. The baby 6 can be swapped out for a big 6, a DOCH 6, A V8, a V12, but not in my car :-(, but I do love the AWD which is why i bought it.

~ryan

[SVOboy]

I spose then the 5th would not just be an easy swap for another 5th. I'd do this to my honda but I plan on getting the longest tranny period, so all the gears will already be the longest, ;-), hopefully I can learn some interesting stuff about bmws now. My dad has a 1st gen 7 series, but he never drives it.

[b1gmoose]

These cars are meant to be driven. I've found for every day not driven, $25 (exageration) needs to be done in maintenance. So if it has sat around for a month, something expensive is broken.

Best place for 7 series parts is www.stevehaygood.com I have dealt with Steve in the past and his is honest & knows how to run his business.
Best place for used BMW parts is www.theeurodepot.com BMW only salvage yard. They are just down the road from me and they have the best prices in the US.

~ryan

[SVOboy]

By not drive it I meant for since I've been able to remember things (I'm 17 now), so damn, it's got work to beeee done. The reason he never fixed it was cuz he needed to buy some tool, still never bought it...

[SVOboy]

Tried out the damn zemco fuel saver yet, by the way?

And have you ever explored chipping for fuel economy? I know a lot of bmws came with stock removable eproms.