[65CrewCabPW]

I understand why the CVT eats a few mpg, as CVT's are very inefficent due to hydraulic pump losses, but why does the FDII do worse than the FDI?

Is the overall gearing different? Does the CVT use a different program? Does it run the engine faster for a given speed? Or is it something else?

Been thinking about getting a Patriot, and would like the offroad capabilities of the FDII, but the economy loss would be a hard one to swallow, as I drive a LOT of miles each year. If only...if ONLY we could have an FDII W/5 speed. I drove the 5 speed Patriot, and 1st gear is VERY tall for offroad crawling...too tall. Idle gets you like 5 or 6 MPH, which is wayyyy too tall for getting over real rough stuff.

Anyway, any explanation would be helpful...

Since my reply is held up waiting for a moderator... I'm posting this, so you can understand my comments. Apparently, being a complete technology geek gets me in trouble with people who don't dig as deep...
The following is an academic discussion of the CVT and it inherent inefficiency at low speeds.

http://www.lib.ucdavis.edu/dept/pse/resources/cvt04/papers/04CVT-49.pdf

Hope this helps...

[Gramps]

http://www.jeepforum.com/forum/f98/ratios-cvt2-vs-5-speed-395153/

CVT's are more efficient than standard automatics. Different final drive ratio in the FDII and more than likely have different shift points because of that.

I wish the CRD was available in N.A.

[65CrewCabPW]

Originally Posted by Gramps

http://www.jeepforum.com/forum/f98/ratios-cvt2-vs-5-speed-395153/

CVT's are more efficient than standard automatics. Different final drive ratio in the FDII and more than likely have different shift points because of that.

I wish the CRD was available in N.A.

The final drive wouldn't matter, unless the CVT hasn't enough range to get the engine rpm back to the "right" speed for economy.

And yes, CVT's, as in the belt mechanism are somewhat more efficent than a torque converter and planetaries, but since the CVT requires thousands of PSI in order to operate, it has considerable loss to run the hydraulic pump that supplies the hydraulic pressure to operate the CVT itself. It is less efficient, as in power in vs power out, than a standard lockup auto trans, but makes up some of that, in its ability to manage engine rpm.

Regardless, there's a lot less losses for a manual or DCT or standard automatic, because they don't have to generate several thousand PSI of hydraulic pressure.

[Gramps]

The programming for the FDII is different than the programming for the FDI and may have different shift points as determined by the factory. I have not been able to find out what the programmed ratios are on any of them so I am speculating on that.

The efficiency comes in because it can select a "better" ratio for the conditions.

Final drive ratio does matter. If with the FDI will run 60 mph @ 2300 rpm and the FDII runs 60 mph @ 2800 rpm. At any given speed the CVT2L requires more RPM compared to the CVT2, more rpm = more fuel consumption.

It's a very informative article that you've linked to. It appears that the next generation of the CVT is coming soon.

[65CrewCabPW]

Originally Posted by Gramps

The programming for the FDII is different than the programming for the FDI and may have different **** points as determined by the factory. I have not been able to find out what the programmed ratios are on any of them so I am speculating on that.

The efficiency comes in because it can select a "better" ratio for the conditions.

Final drive ratio does matter. If with the FDI will run 60 mph @ 2300 rpm and the FDII runs 60 mph @ 2800 rpm. At any given speed the CVT2L requires more RPM compared to the CVT2, more rpm = more fuel consumption.

It's a very informative article that you've linked to. It appears that the next generation of the CVT is coming soon.

I guess I wasn't clear... Highway fuel economy is mostly a sum of the following factors...

OVERALL top gear ratio (running engine in max efficiency speed for power needed)
Drag (air resistance)
friction (tires, drive train, etc)
How fast you're going.

What I'm not understanding, is if the final drive is changed, and the overall top gear ratio is changed and that affects the EPA rating, or if the CVT is programmed different, or if there's a friction or other loss factor that doesn't exist in the other CVT or setup.

I've very carefully read through every comment I can find. What NOBODY is clear about, because they don't address OTG ratio, is whether the CVT has the same range, but the final's changed...Or the CVT has a mechanical gear reduction set of planetaries (or otherwise), or if the CVT just has a much wider range of ratios than the standard one. It could be, for instance, that the CVT gear ratio range is just slid up or down a little, but has the same amount of adjustment... giving us a lower first, but less 'tall' gearing at speed. Or a combination of all this stuff.

I've read a bunch of threads on economy, for this forum and others I could find, and have yet to locate the key information. Jeep's been real cagey on revealing just what it is they've done. Because they changed the name of the CVT to CVT2L, I'm thinking that the ring and pinion in the differentials for front and back are NOT changed and that the difference is solely in the CVT itself.

Again, that's just speculation, because nobody's pumping out the data to tell us what cleverness they did.

If, however, the overall top gear (OTG) effective ratios are unchanged, then the EPA rating is mostly due to what would apparently be CVT programming changes that affect the EPA economy cycle testing. Since none of us drive using that cycle, it becomes a lot less relevant.

It would be nice if some people could run some FD1 and FD2's over equivalent runs and compare. Real world economy differences may be minimal.

[Gramps]

I guess that I do not understand how my first link http://www.jeepforum.com/forum/f98/ratios-cvt2-vs-5-speed-395153/ did not answer your question.

The Gear Ratios for the CVT2 FD I are:

anywhere between 2.349 - 0.394 depending on the Variator position.
Transaxle Ratio - 6.12

This calculates out to 14.37 in low and 2.41 in high.

I have not found out what the electronic settings are for the other four positions of the variator.

Update:The CVT2L also has 2.349 - 0.394 range and a Transaxle ratio of 8.15; low is 19.14 and high is 3.21

The CVT DOES have different programming, at least for the Off-Road mode that ups the rpm at idle and hill descent, but still has the same amount of variation for normal driving. I believe the shift points are determined by engine rpm and not road speed. Other than the Transaxle, half shaft and hill descent control unit the two CVT's are virtually identical mechanically. The rear differential assemblies do have different part numbers but I don't have a break down for the parts used.

The final drive ratio, what you call OTG, is 2.41 for the CVT2 vs 3.21 for the CVT2L, is the major difference for the drop in mpg, all else being equal.

Manually going into the Off-Road mode is the only time when the "L" aspect of the CVT2L really comes into play, other than the overall lower, mechanical, gearing of the final drive ratio.

Did this help of hinder what you're trying to figure out?

[65CrewCabPW]

Originally Posted by Gramps

Did this help of hinder what you're trying to figure out?

It helps. Now all I have to do is figure out where I read the information that conflicts with that...

I read that the final ratio is actually in the low 4's, not 6 or 8... Cripes... Now I'd like to know who said it.

Ok, depending on where you go... The Patriot axle ratios are listed as 4.12, 6.12, and 8.12

Google jeep patriot axle ratios, and you'll get a number of hits for each number.

Using the gear ratios and tire size, etc, the posted speed vs rpm do not match up well at all, especially for the 4.12 ratio.

[Gramps]

My info came partly from a Re-builders site that now has a dead link and extrapolating the info from the 2007 Patriot sales brochure confirmed these ratios at the time that I was working on it.

[65CrewCabPW]

Partial mystery solved. The 5 speed manual DOES have 4.12 gears. The CVT's have the 6.x or 8.x ratios. Since the CVT is made to do roughly equal under/over 1.0:1 in the range, the very tall OD cvt ratio has be backed up with 6.12 gears to get anything reasonable at the wheel and engine rpms.

Ok, here's how it works out. The absolute tallest possible ratio in the CVT2L is 7.8% shorter than 5th gear in the 5 speed. Wandering the 'net and other forums found me a post that says that their FDII normally runs 2900 at 65 mph. That's not the highest OD ratio possible. Would be nice if someone could confirm the "flat ground, no wind" rpm @ 65 mph with their FDII.

Leads me to think the MPG is lost in the programming. Apparently, no autostick in the FDII, which is too bad, because if you could force it to full overdrive, I doubt your fuel economy would be much different at all from the FD1 CVT. Less than 8% change in engine rpm just isn't worth diddly, for a dual VVT engine, as it concerns fuel economy.

On the other hand, an FDI CVT has a theoretical 1950 rpm @65 mph... All these numbers are approximate, given the assumption of a 27 inch diameter tire - I know some of you use slightly larger sizes, which change your gear ratio. A 28 inch tall tire works out to 1910 theoretical tallest gear.

Ok, I realize I left some info out...

FDI, rpm @65 theoretical highest OD, is 1950
FDII rpm @65 theoretical highest OD, is 2600
5sp rpm @65 in 5th gear: 2400
Caveat... Some specs give 5th at .81 which is:
5sp rpm @65 in 5th gear: 2700


Assumptions: 27 inch tall tire, using calculator found here:

http://www.angelfire.com/fl/procrastination/rear.html

If your FDII does not use the tallest gearing @ 65, then owners need to get on Chrysler's case big-time and tell them to alter the programming, and save you some gas money...

[Gramps]

OK, I saw the 6.12 pretty consistently, that's for the CVT2.

The 8.14 and 8.15 are pretty close depending on how you round it out. I didn't see the 8.12 but I have no doubt that I didn't look far enough. It's still with in the range of what we've been talking about for the CVT2L.

The 4.12 is the axle ratio for the 5 speed (x the 0.81 5th gear) gives the 3.34 final drive for the 5 speed. I also recall a 3.77 listed at one time as a possible early production unit for these.

[65CrewCabPW]

one source of info here...

Jeep Patriot Specs: 2009 Jeep Patriot Specifications and Options

Oh, and now I see that the 5th gear ratio is in dispute... source above says .72 and others say .81...

[Gramps]

We seem to be posting about the same time.

The standard CVT2 ratio, I figure, is calculated with the 27.3 tires; the CVT2L is calculated with the 28" tires that come standard for the FDII. Small differences but they are there.

We have tried to convert a CVT2L to AutoStick but there is no programing available for it and we even worked with the Jeep Engineers who TRIED but weren't able to come up with anything. The CVT2L needs the "L" gate to switch on electrically the Off-Road mode. Any programing has to be done using the VIN code which will tell the computer if it's FDI, FDII, 5 spped or AutoStick. We have no work around for this or batch file that we can run to fool it into thinking any thing else.

[Gramps]

Originally Posted by 65CrewCabPW

one source of info here...

Jeep Patriot Specs: 2009 Jeep Patriot Specifications and Options

Yes, that's one of the ones that I looked at. Their specs correlate to the brochures that I have or are fairly close. I always wonder about typos and just put the stuff that's close in the same bucket.

[65CrewCabPW]

Originally Posted by Gramps

We seem to be posting about the same time.

The standard CVT2 ratio, I figure, is calculated with the 27.3 tires; the CVT2L is calculated with the 28" tires that come standard for the FDII. Small differences but they are there.

We have tried to convert a CVT2L to AutoStick but there is no programing available for it and we even worked with the Jeep Engineers who TRIED but weren't able to come up with anything. The CVT2L needs the "L" gate to switch on electrically the Off-Road mode. Any programing has to be done using the VIN code which will tell the computer if it's FDI, FDII, 5 spped or AutoStick. We have no work around for this or batch file that we can run to fool it into thinking any thing else.

You and I both know it can be done, but would require additional wiring... I'd put the "L" mode on its own switch and use the shifter toggle for autostick - but I'm not an engineer, I'm just a car nut and computer geek . The trans controller has the capability and the routines are probably still there - it is highly unlikely the code was deleted and rewritten completely for the FDII. However, given the vehicle's electrical interface, there may be no means of accomplishing what you want to do - in that the input "line" has probably been re-pointed to the FDII code. Toggling high and low on that pin is now redirected elsewhere in the code and it would require the use of another couple of lines to implement the autostick.

Instead of that, perhaps we could ask for a "econ" and "sport" mode, where the econ mode is agressive at keeping the rpm's down and the sport mode lets you have a little more ratio especially at lower speeds, for more "snap" when you're driving.

Or, maybe we could pray the Mopar gods and ask them for an 8 speed DCT, with ratios from 5 to .5, so we can have economy AND a crawl mode, too. Oops, typo'd that.

Hmmm...got to thinking about that DCT thing... I like it. Gears 3-8 for normal driving, and gears 1 and 2 be in the 6 and 9 range... In "crawl" mode it starts off in 1 and can can be changed to 2. Otherwise, the gears ratios in the t rans would be about 4.2 to 3.9 for 3rd and end up about .65 to .7 in 8th. Economy, crawl mode... all in one. And no milage robbing CVT. Now, normally, a DCT engages the clutch when you push the go pedal a bit. This could be made with a "creep mode" where the brakes apply and lock the vehicle in place until the DCT begins to engage the clutch, whereupon it drops the brakes and engages the clutch... let off and the brakes instantly lock and clutch disengages. Lets you inch over stuff and move the vehicle without having to work the brake pedal manually. Easy as pie to do in an ABS and traction control equipped rig.

So, start hounding. Chrysler's already designed, and so has Fiat, DCT's for use in a wide array of rigs. The only odd thing about this would be the extra low 1st and 2nd gears.

[Gramps]

This should make for some interesting "geeky" reading for you. Just some background info on what we ran into when trying to convert an FDII to an AutoStick. http://www.jeepforum.com/forum/f98/autostick-conversion-511547/

The OBDII scanner can read the codes and reset them but it can't re-program the computer, that takes a StarScan, very expensive! Even with that it's all menu driven and won't let you enter non-compatible programs but does let you enter add on accessories. We'd have to find a way to override the system and that's way beyond my expertise!

They could also find a way to run a transfer case and give us everything we want too, but that adds more weight. Their sales philosophy is probably if the FDII won't handle your needs it's time to move up the food chain to a Liberty or beyond.