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Ways to improve gas mileage during a tune-up/intake manifold replacement?

5K views 17 replies 7 participants last post by  scott_s 
#1 ·
This is a question for folks like MPGMike who are interested in maximum fuel efficiency.

I am going to be replacing my intake manifold gasket soon, which I understand also involves pulling the cylinder head. I will also be performing an oil change and general tune-up at the same time.

What parts/oil should I use to improve mileage, and what things can I do to the head/manifolds/anything else while I have it apart to improve mileage? I want to try some of those Somender Singh "Power Grooves" as well as some lightweight synthetic oil, and I will also be adding an oil cooler. I will be getting a K&N air filter as well.

Any other tips or things i should do? I might try porting my exhaust manifold, but I don't have the skills to do much to the head besides maybe the power grooves.

Anytips or suggestions would be greatly appreciated.
 
#2 ·
Sounds like you already have some ideas. Make the intake ports on the head rough. A 40 grit sanding roll will make an improvement. The Singh groove will allow higher boost and more ignition timing without detonation. More timing may or may not improve mileage. For oil I use 1 quart Mobile 1 5w-30 and the rest Motorcraft 5w-30. Use the largest filter you can fit behind the radiator.

Drill a small hole in the distributor cap opposite the vent, the hole about the size of the plastic emissions hose. Epoxy a piece of plastic vacuum line into the hole, and run that line to the throttle body. This will draw the ozone from the cap to the engine where it can enhance combustion.

On the exhaust manifold, there is a big protrusion in cyl #3 that is your biggest enemy. Your second biggest obstacles are the bumps in the back of cyls #3&4. Other than that, gasket match the ports and it will work well for you.

While you have the head off, round off all of the sharp edges in the combustion chamber. Don't just take the sharp edge off, actually radius these edges. The smoother the transition, the more power you make. If working with a 782 head, open up the double hump a bit to allow more flow past the valves.

Though not related to having the head off, inflating tires to about 40 psi can make a noticeable difference without compromising handling too much.

If you contact me, we can chat on the phone. I seem to remember stuff better with somebody live talking to me. You can also jump on the www.mpgResearch.com forum for more ideas.

Mike
 
#3 ·
In addition to what Mike mentioned, Metric Mechanic can modify the valves to help reduce detonation and increase mileage as well. They are a national BMW speed shop in Richland MO.

A tuned cal can help as well. They usually tune for emissions and not for mileage. IE. a little extra fuel to keep the heat down. That is not a problem with the grooves. A little extra reading on the grooves with turbos search turbobricks.com

Here is a paper by Shell about oil etc. and mileage.

http://www.iantaylor.org.uk/papers/IMechEFE2000.pdf

* lower viscosity oils can increase mileage and power
* friction modifiers can increase mileage
* durability not reduced?
 
#7 · (Edited)
Air is a fluid. The air touching the surfaces of the walls is actually not moving. This extends out a short distance. There are layers of air where the flow is at different rates, with the center flowing the fastest. This is Lamiar flow. Fuel can fall out at the boundary layer. A rougher surface keeps the air swirling more. Something like what Mike does to the intake runners creates turbulence, which can actually increase the flow rate over that of the smooth surface. This also causes the air/fuel to mix more and better. Which is where an increase in mileage can come from.
 
#8 ·
I thought it was generally a rule of thumb to decrease turbulence in the intake. That's why those tornado thingys don't work.

Also, wouldn't a screen have a similar effect in the intake?

And I had another question. Sorry, I know this isn't my thread, but I'm still curious. So, if I bought a 327 crate motor and built it up with a sort of vapor injection: wouldn't I run into problems with excessively high exhaust temps because it burns so well? Or would I expect more power and COOLER temps because the burn is "exploding" rather than "burning"? I just want to see if I read this right.

Cause I had a moped that would lift up the front wheel off the ground and still get 230 mpg. (I leaned out the carb and modified the intake) BUT, I toasted the tranny 2 months later and burned a hole in the engine shortly after.
 
#12 · (Edited)
the extra TB gasket gave me seat of the pants faster, and it was part of the mileage coctail I threw at my horizon to get it from an 18mpg in disrepair, to 23-24mpg after a tune up, and 29-30mpg after all the goodies.

Experiment with plugs. Too hot and you'll ping, not a huge deal on an N/A engine, just take it back a plug range. I'd say starters go 2 heat ranges up, I like NGK's, some people like other brands. In my 2.3 volvo I opened up the gaps pretty wide (.005 over) to give it better low end. The overdrive was such that on the highway it was in very low RPM's, so it felt like it pulled better on the freeway and I was pushing 30mpg in that brick too. Do some reading about plug gapping and heat range theory, it's fairly simple stuff and the best part is it's free/nearly free!

Also, from what I understand a good burn is a complete burn, not a necissarily hotter one. I'd need someone who knew more chemestry to explain why. You won't burn up the chevy with a more complete burn, they burn up by themselves... oops! :D
 
#14 ·
I believe the type of turblance would determine if it is good or not. A surface that is rough with no thought, could cause things to be worse than the smooth surface, as far a flow. The turbulence would be every which way even fighting the direction you want the air to flow. But a surface with lines in it at a certain pitch can create an effect that will be like moving the air on rollers. Both the random rough surface and the lined surface will help mix the mixture more, with the lined surface mixing better, but the random rough surface would loose flow. Mike calls his intake lines Powre Lynz.
 
#15 ·
Hmmm. I have a couple extra Mopar smallblock oi lfilters in my garage, and if I read the oil filter comparison page those should fit.

Here is kind of a newbie question- when I go to the parts store to get the hotter spark plugs, what number should I ask for? I am going to get regula rold Champions, but I don't have a clue what to tell the counter guy to make sure I get a two step hotter plug.
 
#16 ·
Here are some links to pics of the Metric Mechanic valves I mentioned. With these valves they tune their engines for ~ 20% less fuel. They also help with detonation. The BMW heads he works with are prone to cracking, with these valves he said they have not had a head come back cracked in the 16 years they have been using them. Except from a few people that super over heated their engines and kept on running them.

www.sheenconsulting.com/car/pics/ValveTopST.JPG
www.sheenconsulting.com/car/pics/STValves.JPG
www.sheenconsulting.com/car/pics/IntakeSTtop.JPG
www.sheenconsulting.com/car/pics/ValveBottomST.JPG
www.sheenconsulting.com/car/pics/IntakeSTbottom.JPG
 
#18 ·
It is on the FET site Prepping Larry's Valves I believe.

These valves are different as the intake and exhaust are done on the bottom and the intake on the top. These are actually stepped as you can see from the one side picture. There is a science to the size of the steps. Mike's are grooved on the top of the intake valve.
 
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