Fuel Efficient Cam Regrinds : General Info

[TestDrive]

Originally Posted by Tygen1

Have you considered asking this question of adjustable cam gears on a ford eskort forum. I thinks it's FEOA or something like that??? There ought to be plenty of knowledge over there.
So what's with the ZX2 being the third string bench rider? They are a plenty fine car, although I see your getting 50+ mpg with your wonder wagon...ZX2 adjustable cam gears are easy to find and relatively afordable...TeamZX2.com...

No, I haven't considered asking on those forums.
Googled them and found numerous posts indicating current unavailability of NEW adjustable timing gears for SOHC (Single Overhead Cam) engines. - The performance tuners all want DOHC (Dual Overhead Cam) engines like came in the ZX2s.

I'm glad you posted though, think I'll give them a try for a USED adjustable timing gear for SOHC.

[rkcarguy]

Unless you have milled your head and wish to re-align your timing with an adj. cam pulley, adding one to a SOHC is pretty pointless. Advancing the pulley means all your valves will open sooner but also close sooner, which basically does the same thing as just tweaking your timing instead. On a dohc engine the pulleys can be adjusted to open the intake valves earlier and open the exh. valves later for some gains in HP(or other way for more efficiency).
Most anyone I know of that has tried a SOHC adj pulley on the dyno has found -0- to the be the sweet spot, except on engines with a shaved head obviously.

[TestDrive]

Originally Posted by rkcarguy

Unless you have milled your head and wish to re-align your timing with an adj. cam pulley, adding one to a SOHC is pretty pointless. Advancing the pulley means all your valves will open sooner but also close sooner, which basically does the same thing as just tweaking your timing instead.

Does it do the basically same thing?
Won't the first affect the amount of air flow at given engine speed and throttle opening - (causing the ECU to adjust timing as well?).
While the second only changes raw timing - which may or may not result in the ECU adjusting timing? (My '99 2.0L has anti-knock sensors. My '93 & '94 1.9Ls don't.)

Originally Posted by rkcarguy

On a dohc engine the pulleys can be adjusted to open the intake valves earlier and open the exh. valves later for some gains in HP(or other way for more efficiency).
Most anyone I know of that has tried a SOHC adj pulley on the dyno has found -0- to the be the sweet spot, except on engines with a shaved head obviously.

No shaved head, but the engine has 160K on it; presumably tolerances are no longer OEM.
Were those people tuning for: performance, fuel economy, both?
My primary concern is fuel economy - not sure my sweet spot would be their sweet spot.

[rkcarguy]

Thats a tough one because we were tuning for HP.
I guess in theory if you retarded the timing so the intake valves opened later, the engine would draw in a little less fuel/air mixture on the downstroke PROVIDING your intake valves already close well before the piston hits bottom. This could have adverse effects of running hot however due to the also now retarded exhaust cam lobes which now also open and close "late". Gonna have to leave that one to someone more knowledgable of cam timing.....

I've generally found that most of my cars have gotten better mileage and performance by doing upgraded plugs, wires, cold air intake, and exhaust. I also slam the timing as far advanced as I can get and back it off a little once it starts to ping a little.
I'm one that believes a WAI is for those who can't restrain their gas pedal foot, as less air can be delivered by either less dense warm air or a throttle that is a little less open passing cold air, but the car drawing cold air will have the ability to make more HP at WOT than the one drawing in hot air.
Energy theory in general states that the more temperature difference there is the more energy is released, so I would think that cold air/fuel would provide a slightly more efficient burn, where as warm air could actually cause knock in some engines requiring a richer mixture/less timing and therefore worse mpg.

[Tygen1]

[QUOTE=TestDrive;96390](My '99 2.0L has anti-knock sensors. My '93 & '94 1.9Ls don't.)QUOTE]

Pull that knock sensor plug off the sensor of the ZX2. It doesn't work righ and will randomly pull timing when you don't need it. It will pull 6 degrees without any incremental change and goes off all the time. It may not add mpg's or hp but it smooths out the power curve considerably and makes it a much more enjoyable car to drive. This is one of the first things I did to mine and the surge that I had been trying to find for years disappeared
BTW, there's lots of free type mods you can do to the ZX2 to make it more fun and enjoyable to drive. Of course I'm a ZX2 nut, so take what I say with a grain of salt Of course you could wander over to Gassavers and see COZX2's ZX2 get over 100mpg to get some real bad ideas

[Tygen1]

Also, the ZX2 intake timing gear is not on a keyway so it is fully adustable as is

[Christ]

TestDrive - if you have a DOHC and a SOHC, you should count the teeth on both.

One of the DOHC's gears may interchange with the SOHC. (The DOHC will have 2 gears that are both a 2:1 ratio to the crank, for those who would argue otherwise.)

So if the SOHC and the DOHC both have a 18 tooth crank gear, then they'll both have 36 tooth cam gears, the only difference is the DOHC has 2 of them.

[metromizer]

In general, cam profiles for power and performance will have more lift and more duration... cams for better FE, less duration but usually about the same lift as stock. I base this on several race cam profiles I've played with, my Geo's Xfi cam, and a 1975 Ed Iskenderian "Mile-A-More" grind for a 327cu in Chevy V8 I stuffed into a Vega back in 1978. Less duration seems to net mpg gains in most engines is the trend, but I'm sure their are exceptions.

I'll also add that cam profiles are not just guessed upon, but the process for developing a new profile for a given application is done in itterations. Engine sofware like "Engine Analyzer" are a good place to start, you can run simulations from your PC, which had been very helpful for me in choosing a better profile for a race engine. But you need specifics, I had all of the data at my figertips from which to work, like intake runner volume and most important cylinderhead flow table for those particular sets of heads I was building an engine around. Not having meaningful REAL information and plugging it into software would likely be and excersize in "GIGO" or "Gabarge In, Garbage Out".

I had worked with cam grinders late Babe Erson in Anaheim, Ca and more recently, Dema Elgin now in Santa Rosa, Ca.

My advice to anyone serious about having a custom cam ground for any purpose, is to read up on cams at http://www.elgincams.com/ to become familiar with the terminology at least, then keep an open mind and talk with veteran Dema (or some other gray haired old timer cam grinder near you) about your goals to see if he can help you. Unless you are trying to set some world record, you will get very close to optimal in one try. Trying to figure out what blank to start from, how far to advance or retard the cam timing is way premature, my advice is to find an expert and give him your business.

Dema has taken cast cams and built up the lobes with hard weld, so we could change lobe centers adn increase lift, has built me a couple billet 8620 steel cams from my supplied blanks, but the knowledge base from which cam grinders work is increadible. BTW, he has my Xfi cam that I need to pick up.

[TestDrive]

Originally Posted by Christ

TestDrive - if you have a DOHC and a SOHC, you should count the teeth on both.

One of the DOHC's gears may interchange with the SOHC. (The DOHC will have 2 gears that are both a 2:1 ratio to the crank, for those who would argue otherwise.)

So if the SOHC and the DOHC both have a 18 tooth crank gear, then they'll both have 36 tooth cam gears, the only difference is the DOHC has 2 of them.

Good thought, it's conceivable that the DOHC application may fit and work just fine on the SOHC, but based on different part numbers for each application (both OEM non-adjustable and aftermarket adjustable) it almost for sure won't work the other way around. (Maybe a wider timing belt or something??) I'll have to look into it, but ...

What I have is two running cars, one resurrectable (close encounter with a deer) car and one spare engine that fits the resurrectable. Only one of the cars has a 2.0L DOHC engine - the running 1999 Escort ZX2 2dr 4sp Automatic. Only one of the cars has a 2.0L SOHC engine - the running 1999 Escort SE 4dr 5sp MT. The resurrectable 1994 Escort LX Wagon 5sp MT and spare 5sp MT transaxle are both 1.9L SOHC (same as 2.0L but different bore and emissions). I hardly drive the ZX2 - just enough to keep the battery charged and the seals wet. It's my insurance against the daily driver (me or the car) suddenly needing serious repair. In the case of the car it means I still have something to drive every night while I do the repairs myself. In the case of myself, it means a broken or badly sprained leg, arm, wrist doesn't put me temporarily out of a job. The short and sweet is I'm not tearing into the engine of the ZX2 to count teeth, until the Wagon is backup and running.

[TestDrive]

Originally Posted by Tygen1

Also, the ZX2 intake timing gear is not on a keyway so it is fully adustable as is

Thanks for the info, but see just above about why I won't be digging into the ZX2 real soon.