Closer to Coveted 50mpg What More to Do?

[Davo53209@yahoo.com]

Originally Posted by some_other_dave

Making sure the car is current on maintenance can't hurt, and can only help. That said, if everything is in good shape already those changes won't have any noticeable effect on fuel economy.

-soD

I've toyed with the notion of removing the intake manifold from the top of the engine, while letting it sit in a bucket of mineral spirits, so oil as to dissolve the carbon deposits. Then following up with a pressure washer. After all, the car has 234,700 miles on the odometer....it couldn't hurt.

I've even seen suggestions that involve using oven cleaner or Amsoil Profoam. What does everyone think of those products?

[aerohead]

Originally Posted by Davo53209@yahoo.com

I've toyed with the notion of removing the intake manifold from the top of the engine, while letting it sit in a bucket of mineral spirits, so oil as to dissolve the carbon deposits. Then following up with a pressure washer. After all, the car has 234,700 miles on the odometer....it couldn't hurt.

I've even seen suggestions that involve using oven cleaner or Amsoil Profoam. What does everyone think of those products?

Carburetor/Choke cleaner will remove everything from the manifold.It's designed for this.I recently did this with the CRX.You could eat off the insides.

[Davo53209@yahoo.com]

Originally Posted by aerohead

Carburetor/Choke cleaner will remove everything from the manifold.It's designed for this.I recently did this with the CRX.You could eat off the insides.

If nothing else, I think that cleaning the inside of the manifold would allow the engine to breath better.

[wmjinman]

I'm going to guess that with 234,700 miles on it, things like cleaning the intake manifold will do nothing more than - - - make it clean. If you want to focus on the mechanicals, I suspect you'll do better by checking compression & depending on the results, maybe getting an engine rebuild.

Assuming the engine is fine and not needing a rebuild, having the latest and greatest coolant, battery acid, brake fuid, etc. probably won't get you anything, either. Having the lowest weight synthetic motor oil and transmission fluid CAN help, though.

Otherwise, make sure the tires are pumped up as high as you dare (I run mine up to 60, although anything above 50 is probably a waste).

Have you done any sort of grille block? I picked up a couple mpg by doing that, and since my front bumper cover/grille was black, just did it with black "gorilla tape" and it doesn't stand out too much.

After high pressure in the tires and a grill block, I'd say you can get the rest of it with your driving habits. Looks like your car is too old for a ScanGauge, which is too bad - those things are worth their weight in gold when it comes to the things you can learn about your car's "best efficiency spots."

Some general rules of thumb, though:

Eliminate as much high speed driving as you can. You mentioned thinking you did better at 55 than 60. I'll bet you do even better at 50!

Try to avoid idling like the plague. Doing things like rolling into the parking spot with the engine already off, and not starting it until you see the traffic is clear so you can immediately pull out onto the road will add up over the long run if you make a habit out of it. Also get in the habit of coasting (either engine off or just in neutral) as far as you can up to stoplights and stop signs. Make a game out of looking ahead to stop lights turning yellow up ahead & going into "coast mode" as soon as possible. It's amazing how far you can coast with the tires pumped up high - 1/2 a block is nothing. Sometimes I'll be taking off, going through the gears, from one light & then see the next one turn yellow. I'll just stop accelerating and start coasting before I've even gotten up to the speed limit on the street, and still make it to the next light before it turns green.

Finally, don't be intimidated by the impatient people behind you. If they want to switch lanes & "gun it" to pass you just so they can slam on the brakes for that same light you're coasting to, let 'em - - - even if they swerve back in front of you to rub it in your face they "won". They didn't win - they just burned a bunch of extra gas being an idiot. When you start getting those 50 mpg tanks, then YOU win!!!

[user removed]

You need to make sure the egr passageways are functionally clean. Probably nothing wrong with pulling the manifold, replacing the lower injector seals (vacuum leak potential). Clean the connectors on the injectors. Make sure everything is in good shape, if you have the talent and determination. You might blow past 50 MPG.

regards
Mech

[Superfuelgero]

The easy stuff: Clean the injectors, HAI, grill block, lighter oils, make sure the t-stat is the right temp, align to 0 toe/camber.

[bobdbilder]

Have you ever done a Port and Polish of your intake and exhaust ports? You probably can do it DIY with a dremel to delete casting imperfections. But my advice would be to go to a proper shop that knows what they're doing. This is especially true with working on the valves. What it does is make the engine breathe a bit smoother, reduce restrictions and if they are really good, cause air to swirl into the compression chamber. What you would get is an increase in engine efficiency. The added advantage is getting more power out of that engine.

Additionally, with an engine as old as yours it's worthwhile to bring engine tolerances back as it was before. Blueprinting of the engine helps to bring back the efficiency. This definitely need a professional to do it. And it may cost you a bit compared to where I come from. Its old skool tweeking of NA engines that really pays off.

Just a thought.

[wmjinman]

I think he started another post saying he finally hit 50 mpg (wish he had a fuel log on here, though)

But with as many miles as he has, a complete engine rebuild or even a valve job might show results. I don't know if the extra port & polish work would transfer to extra mpg, but it shouldn't hurt. And if it gives more power, which you'd expect, it might allow less downshifting on hills, which could possibly translate to more mpg

[Superfuelgero]

Originally Posted by bobdbilder

Have you ever done a Port and Polish of your intake and exhaust ports? .

If we operated at full throttle or had diesels this would help. On a throttle controlled engine, this would be a bad idea. It would slow the velocities of the air (this is a form of engergy). It is like sipping on a drink with a large straw verses a small one. The samll one will take less work, and be more controllable.

[bobdbilder]

I understand the car is a small engine car. The port and polish work that people do on these small engines are typically:-

a) Valve stem work
b) Valve lips and seat
c) Exhaust ports enlargement to meet the exhaust manifold bore.

There difference in terms of size of the ports is probably in microns. Measurement of flow is balanced to all cylinders using a pipet tube. In the end, you get less restrictions to flow. And if this was as old as I think it is, it would be good to do dynamic balancing of the whole piston-rods-cranks.