SuperSubaru

Thanks for all the input, I will give an update in a couple weeks. When every single tank for 7-8 months reads 25-26.5 MPG, 2-3MPG (10%) is significant. But I will say the new clutch engagement did take a little gettin' used too. I had some O2 sensors laying around (brand new) so I will probably do that over the coming holiday weekend as well. I was hoping to see numbers approaching 30 all said and done.

Okay here's the dilly-yo (97 OBW 5SPD 136,000 miles): New clutch New head gaskets New timing belt/pulleys New water pump New oil pump New cam/crank seals New front wheel bearings All together $4000 Prior to the maintenance I was getting a solid 25-26.5 MPG, every tank - I check every tank religiously. As all my car is used for is back-and-forth to work (90miles/day). First two tanks after everything was replaced, 20 and 23 MPG. I was hoping to bump it up a bit with all of this, not go down!!! Any suggestions - I have no CEL. What would cause a sudden significant drop like this? Since they had to work on all sides of the engine, it was pulled from the vehicle.

I don't know how, but I know why, and don't like it.... Outback is now classified as a "light truck" so it doesn't have to meet the same gas mileage ratings.

My wipers simply stopped working one day in a salty-sloppy-wintery drive home. They wouldn't go up... I made it home. When I got home, I popped the wiper arm caps, tightened them up good - no worries since.

If I did one run or thirty runs, I saw a slight difference in HC and NOx, but when added together - they cancelled each other out. And the slight difference was within experimental error anyway. Had I seen something more significant, I would have ran with it and investigated further. I already know if I adjust the timing, things will change, I could have done that without cutting the head. I took one engine one head, ran it. Removed the head (takes a little bit of time) ground a groove, and reinstalled it, and ran again. It's not worth my time to continue. One side note - Oxygen numbers dropped measurably, so something was happening inside that was different, but at the end, it didn't matter. I was cautiously optimistic, but now I have proof. Subaru 2.5L need head gaskets replaced often - if some of you wish to try it for yourselves, stop by your mechanic with a dremel during the operation and try for yourself.

I did a CARB/EPA 6-mode test run 100,75,50,25,10,0% loading on the dyno. I carved one groove opposite the spark plug on a 6HP engine, here are my before and after final results - kind of what I expected: Baseline 6.41 HP 12.76 g/kW-hr HC+NOx 286 g/kW-hr CO w/ Groove 6.36 HP 12.72 g/kW-hr HC+NOx 287 g/kW-hr CO Overall, what was gained in NOx was lost in HC hence the nearly identical numbers for the additive standard. I would say both are within the experimental testing error - so no change. And for Nipper's sake: baseline: Drybulb 68.0 degF Wetbulb 63.3 degF RH 79.2% Groove: DB 70.2 WB 65.7 RH 76.0% Barometric Pressure 738.05 mm Hg (I only measured once as it doesn't change that fast on a constant overcast day).

First off, save all receipts for everything including the tire itself. Then I would in a Dodge owners manual... it would probably have a warning about just this somewhere in it. Or contact Dodge directly and see if they can provide something in print stating that what we all know. Don't mix and match sizes. You should be able to recover this one, I don't know how much your total bill was, but if worse comes to worse paying an attorney $500 to recover $2000-3000 might actually be worth it as well. Just my $0.02

Of course, humidity and temp are used in the calculations for a correction factor. So we are always comparing apples to apples - hope to have the testing done by the end of the week.

Well I got the rubber stamp from my boss to go ahead and give it a try - it really won't cost us anything but time. But I will be gathering actual data: -HP -Fuel Flow (which I can't believe would change much as the jetting isn't going to change and manifold vacuum is going to be the same) -Emissions (CO,HC,NOx,CO2,O2) If fuel and HP don't change (which will probably be the case), the emissions will give a much better reading as to what is actually happening during combustion. If combustion efficiency goes up, HC,CO, and O2 will go down, and CO2 and NOx will go up. I have to agree with Nipper that a 4-valve engine probably has little room for improvement in head design. But most 2-valves have substantial squish area. My test engine is an overhead 2-valve, gasoline, air-cooled, carburated single cylinder, rated at 6HP. Here will be my test method: Run the engine - record data remove head - carve groove - install head run the engine - record data same head, same valve lash, same everything, only change will be the groove. If there is any measurable improvement beyond normal run-to-run variances, then the experiment will continue. I will post the results. I did look up the patent number on the USPTO website, it does exist.

I am not stealing anything, I just want to test it to see if it works. If it does live up to the lofty claims, then I would probably forward the data to Mr. Singh and see if I could use it in production. I brought it up here, in this forum, because with all the 2.5L headgasket issues, there is a lot of people that remove there heads. This would be a great opportunity to see if someone else wanted to try it, one their own vehicle. I would be trying it on a small air-cooled engine. The grooves do point at the spark plug, allegedly so the turbulance created can accelerate the flame front (which starts there).

The cutting lines in the intakes (perpendicular to flow) works, that has been done for years. They help with the vaporization and turbulance of the intake charge. They claim the cuts in the chamber reduce tendency to detonate and engines run cooler, so theoretically you could increase compression ratio - which would make your engine more efficient. You should also be able to lean out the mixture more, since you are getting better mixing of the charge. If I can get approval from my manager, or wait until he takes a week off (probably between Christmas and New Year's), I will run a side-by-side HP, Torque, Fuel Flow, and Emissions run. The fuel flow I don't think would change as engine vacuum isn't going to change much, so without rejetting the carb - there shouldn't be much difference.

In my quest to improve emissions on the engines that I build at work, I came across this mechanism for improving everything (power, emissions, and economy). I am an engineer, and most items that claim to do these things all at the same time are (for lack of a better word) - crap. The only way to do this is to improve efficiency or reduce losses (mainly friction). This Indian inventor carves grooves in the heads and claims to greatly improve the turbulance inside the combustion chamber, thereby letting your engine to run more efficiently on the fuel you provide. My intuition says it makes sense, but he doesn't have any reputable hard numbers for comparison. The US patent office thought it was worthy enough to grant his patent application. http://www.somender-singh.com Since the heads we run are only about $15, I will probably try this and do a side-by-side comparison in the coming winter months (the slow period). The engine I will test is a 6HP air-cooled gasoline - if it works, I will let you all know for the next time your have to do your head gaskets, you can get out your Dremel tool as well. There is no shortage of people that admit to it working, race engines and stock alike. He even had an article in a Popular Mechanics magazine.

I took my cross members off, if nothing else road noise went down on the highway (which means it is cutting through the air more efficiently). I change plugs and air filter at the same time, so I don't know what did what, but end result was +3-4MPG (it was a pretty dirty air filter). Now, nearly all highway with 97OBW 5MT 26.5 MPG religiously - tank after tank after tank - I check it every time. You would be surprised how much a difference 2-3 lbs of air more in the tires can do as well.

On the most basic level, a knock sensor "feels" the harsh harmonic of engine knocking. As with today's engines, not all knocking is detectable to the human ear. Then it retards the timing automatically so you don't have to worry about causing excessive damage. On a smarter car, this is how the ECU knows what octane fuel you are running so you can get the most out of your engine. It looks like a little hockey puck (about 1.5" in diameter) with an electrical connection - and is usually bolted to the block, one per cylinder bank. That's the norm, I don't know how Subaru handles it.

I installed one in my wife's Ford Explorer. If you are at all handy, and don't mind removing the headliner (fiberglass is annoying), it really wasn't that bad of an install - maybe 4-6 hours with a buddy. Take your time, hide all the wires under the molding, I mounted the player under the back seat in the Explorer. I don't know what kind of unit your are getting, the player might mount with it - if not... under the passenger seat might work. I wouldn't decide on where to put it until the headliner is out.... make sure you have enough to mount too....