Cam for fuel economy

[TylerDurden]

The flag mirrors could be ditched entirely and replaced by video cameras.

[R.O.R-2.0]

the BIGGEST cam you can safely fit in the engine is going to be the one that gets you best economy.. not the smallest cam.

go ahead and change out your cam for the smaller one, report back with the results..

you want to get as much air into the cylinder as possible, as easy as possible..

low valve lift is not going to get the air in the cylinder very fast or easy..

[wolf_walker]

I found my bone stock 86 8v gasser Scirocco would do 38mpg combined in normal driving consistently with a very healthy and well tuned stock motor.
This is quite a bit better than most Caddys and Rabbits and Jetta's with that motor and the same gearing seem to get.  I attribute this to aerodynamics.
If I was shooting for big MPG, it'd be a TD in a Scirocco body and go from there, it isn't perfect but it's a hell of a lot slicker than anything else from VW
in that era.  If I ever move out of freaking CA I intend to do just that.

An early 924 is another interesting candidate for a high MPG "neat" diesel swap, but it'd be a little more work.  It's been done in Europe but I don't believe MPG
was the goal.

[scrounger]

Ror
What references do you have on fuel economy with this type of cam? There seems to be almost no information that I can reference.

Wolf. changing bodies is not an option for me. The door is open for you to do it.

[Blownoiler]

There is info on diesel performance around, but generally you have to pay for it, here's a link to one source: http://www.amazon.com/High-Performance-Diesel-Builders-Guide-Pettitt/dp/1613250622
The authors focus is on direct injection engines so there is limited info on IDI mods, still it's an interesting read with some helpful tips!  Reducing engine friction/pumping losses should get you better mileage, I can give you some energy saving ideas to ponder if you are interested!

[scrounger]

My plan is to map both cams. Determine the profile and lobe centers.

My take on this is that the industrial cam is for high efficiency at lower rpm than the road cam. My fuel rack seldom goes past half throttle with this car. I can appreciate if you are trying to make 50 hp having a road cam is the tits. My engine cruises at what 15 hp? That is where I want my peak torque.

I hear a lot of discussion about what builders don't like but no real data yet.

[theman53]

My guess: The industrial cam will have a very narrow power band and at an RPM of about 2,800-3,000 RPM as that is where most guys use the engine for work. It maybe better maybe worse, you let us know either way.

[scrounger]

I got my used cam today:
 
The weather is beyond crap at present. I am going to get a new timing belt and figure out how to install it correctly.

[Blownoiler]

It's good to see your experiment going somewhere, don't forget to post the end result, it will be interesting to see what happens to mileage.

[scrounger]

A preliminary measurement: Using a caliper across the peak and then 90deg away I get 8.9 mm (.35") of lift. So I would expect a bit more when done correctly.

[scrounger]

I had a bit of  time to put the new cam in my lathe to check out some of the specifications.
The cam has a molded in CME and Audi ooooo symbols on it. It was described as a 1.9 industrial cam.

Lobe centers 113°.
Intake max lift of .325" Exhaust max lift .340"
Duration (@ .039") intake     150° (crankshaft°)
                                   exhaust 164°

Duration total  intake     230° These are hard to measure.
                           exhaust  264°

As far as timing I don't have it in the car but probably should be close to splitting the lobe centers. Most cams are close to that.  The notch looks to be at the peak of the exhaust lobe.

[mzak88]

My .02... A powerful engine is an efficient engine. I am doing similar project but with MILD performance upgrades. Free flowing exhaust - strait pipe. Have installed 02A CTN trans with 3.164 r&p, then swapped .75 5th for a .658. This will net a 100km/h cruise at 2000ish. Efficiency should naturally improve, with any luck. 

[scrounger]

I calculate my rpm at 60 at 2600. You have a nice gear ratios for economy. Being able to cruise at max torque at 2000 would be nice. What kind of mileage are you getting?

[scrounger]

As the weather slowly gets better I am thinking of putting in the new cam.

I assume that I will need a new cam cover gasket, cam drive seal, cam timing belt, adjustable roller. Probably some type of extension for my dial gauge to measure fuel timing?

Will have to time the new cam with a bar through the slot on the opposite end.


Test by rolling the motor over by hand twice. Then go.

[8v-of-fury]

I suggest the rubber upgrade that comes with the shoulder-less studs. Worth the money. I have had my rubber AHU one off easily 100 times since new, and it still goes back on and provides a perfect seal.

Any flat bar at the back that fits will do, just something that holds the cam straight is all you need. I have eyeballed it in the past when timing tools weren't there (parking lot pump change-out to get it home ).

Timing belt and tensioner would be a good idea to replace right now for sure while you got it apart.

Timing gauge is not imperative.. Prothe has a full set.. pump lock, cam lock and dial gauge plus the right adapter. Good money, and excellent quality. I have had mine since 2008. Used it over 200+ times, no issue. (I don't even touch the gauge anymore.. :/ lol)