RokkTech Sensor - Long Term Consequences of Use

[jacqnbill]

Basically think of increasing the timing (2 degrees) as equivalent to removing the catalytic converter. No effect on durability, positive effect on power/efficiency, negative effect on emissions.

I have looked for the procedure to advance the timing 2 deg and cannot find it. Could someone point me to the info. What tools and test equipment are needed?

Thanks

Bill Davis

 

[DHerzog]

I have read so many positive posts regarding the sensor, I opted to buy one for myself... . This is my 1st diesel and I am not sure about any mods at all... .



Anyway, I'll give it a try and hope there are no problems.....

 

[Sled Dog]

I have read so many positive posts regarding the sensor, I opted to buy one for myself... . This is my 1st diesel and I am not sure about any mods at all... .



Anyway, I'll give it a try and hope there are no problems.....

Good Choice

 

[MMead]

Haven't seen much about the RokkTech Sensors in a while. Does anyone have any comments, positive or negative, about these devices after using them for several months?

 

[CumminsBu]

I'm still happy with mine.

 

[RKerner]

15K miles and no problems, just a little better mileage most of the time. 2 degrees is like stacking all the tolerances in the crank timing sensor system favorably - not a reliability issue in my eyes. You guys worry too much. :-laf

 

[WhiteSheep]

I've been running the Rokktech for about 5,000 miles with no problems. I noticed an immediate 1 mpg increase in mileage along with more diesel noise at idle. As for power increase, I would like to think there is more spunk off idle, but this could be wishful thinking. I searched my CD ROM shop manual for timing and found nothing by references to the gas engines.

 

[Buffalo]

White Sheep,



I did the "Tone Ring Mod", which, essentially does the same thing as the Rocktek Sensor.



I noticed the same things, as you. A little more rattle at idle & a very slight improvement in acceleration. Not real sure about the mileage, though. However, I don't think it was hurt.



At pretty much the same time as I did the tone ring mod, I installed a VA-C 3. 2 box. I took a ride to the sand dunes (Glamis, CA. ) & got 21. 47 mpg, hand calculated, (quite windy, that day. Strong head wind. ) I was driving 62-65 mph with the idea of trying to get good mileage.



I noticed you are in Phoenix. So am I. Around Bell Rd. & I-17, area.



Joe F. (Buffalo)

 

[Bow66tie]

I thought I read in our newest edition of TDR that you'd have to have at least a 6 degree change in the timing to notice any difference in mileage. I have thought long and hard on this accessory, but after reading the article I think I'll have save my $60. 00 for something else and pass on this one.



Michael

 

[betterthanstock]

I thought I read in our newest edition of TDR that you'd have to have at least a 6 degree change in the timing to notice any difference in mileage. I have thought long and hard on this accessory, but after reading the article I think I'll have save my $60. 00 for something else and pass on this one.



Michael

I emailed Robert Patton about that article, but got no answer, except from his secretary.

COmbustion has a fixed time delay of a few microseconds, and at 750 rpm one degree of timing will produce three times the interval (microseconds) that it does at 2250 rpm. SO, if you can use 6 degrees max on top of the factory timing advance (without busting the head gasket, as described in the article), then at idle it has to be dialed back to more like 1. 5-2 degrees.

Since the TST uses the signals from the stock crank/cam sensors, rather than re-program the ECM, keep in mind that they have to delay the signals from the sensors to the ECM by 2 full engine revolutions (for a 4-stroke engine, or at least one rev, if you cross the signals to the injectors), minus a few degrees (3 or 6 or 9 degrees). There is no way to electronically advance timing, just to delay it. So with that box on, you will have to crank longer by 2 turns, and the response will be delayed by two turns, minus whatever degrees of "advance", which can make the engine slightly prone to surging on cruise control, etc.



If you move the sensors (advance timing) physicaly, and then use an rpm and load-proportional time delay, then you get better response. (That's how the ECM does it, and a downloader can take advantage of that, but that may cost you your warranty)



I agree that advancing a fixed amount has the largest benefits at low to mid rpm, and the gains decrease at higher rpm, but most people do not care about improving their 3000 rpm efiiciency, but rather idle to 2000 rpm.



Also, the efficiency (and power) vs. timing changes, is not linear, but rather it follows a parabolic curve. This means that if your factory timing at 1800 rpm is delayed by 3 or 4 degrees from the theoretical peak (most efficient timing point) due to emissions, it is not necessary to bring it back the full 3 or 4 degrees. Why? Because the loss is not linear, and there is hardly any measurable loss for the first degree (1% or less) but then for every successive degree of retard it gets bigger. So when you advance a retarded timing engine, the first degree of advance will give the biggest gain (lets say from 4 to 3 degrees may give you 3% improvement, the next degree from 3 to 2, a 2% improvement, the next one is closer to 1. 5%, and the final degree only about 0. 7%).

So if you want to throw good money chasing the last 1-2 degrees, it does not pay as much as the first 1-2 degrees did. Also, once you cross past that peak, your efficiency will drop (and stresses rise) slowly for the first degree, and then more and more rapidly for every successive degreee of overadvanced timing. (the law of diminishing returns)



On top of that, cetane and outside temperature makes that theoretical peak a "moving target", which means that it's best to err on the side of being 1-2 degrees retarded, that 1-2 degrees over-advanced (both of which lose power, but one damages your engine as well)



So if a fixed timing advance of 2 degrees will give you a one mpg real-world gain, at $3/gallon, improving from 16 to 17 mpg will save you $551 over 50K miles, from a sensor that costs about $70.

A very sophisticated box or downloader, may double those savings, but you will have to pay for those savings upfront in the form of an extra $600 or so, and the potential for more problems, and warranty denial.

 

[betterthanstock]

On the subject of improving mileage and efficiency, adding this sensor to larger (honed or EDM) injectors of about 70-90 hp will improve your mileage even further.

Larger injectors shorten the injection duration, in effect advancing the timing of the center of the powerstroke. They also fool the ECM into thinking that you are driving less hard than you really are, which does the following:

1. it lowers the injection (rail) pressure, which increases the life of all injection parts

2. it causes the ECM to allow a slightly less retarded timing

3. your mpg gauge will be off 2 mpg, (as with a fueling box)

Their drawback is smoke at low boost levels. Adding this sensor cuts that smoke in half, and makes for very fast spool-up.

And of course, more fun to drive. If you already have a box, you can keep it turned off, except when racing, which will avoid problems of cracked injectors and leaky fuel seals.

The combination of larger injectors and this sensor, will produce about as good a fuel savings as you can get with any "MPG box" in a stock truck, while letting you have lots of fun, and reliability too.

 

[Buffalo]

Timing Rattle?

Betterthanstock,



For those of us that have tried the Rocktek Sensor or done the tone ring mod & have noticed a "Timing Rattle" at low rpm's & idle, are we doing any damage to our engines because of these mods? Is the "rattle" hard on our engines?



Thanks for your, very, informative posts. I always enjoy reading them. I'm sure you've forgotten more than I will ever know about these engines.



Thanks, again.



Joe F. (Buffalo)

 

[betterthanstock]

Betterthanstock,



For those of us that have tried the Rocktek Sensor or done the tone ring mod & have noticed a "Timing Rattle" at low rpm's & idle, are we doing any damage to our engines because of these mods? Is the "rattle" hard on our engines?



Thanks for your, very, informative posts. I always enjoy reading them. I'm sure you've forgotten more than I will ever know about these engines.



Thanks, again.



Joe F. (Buffalo)

I can't speak of the tone ring, since people have it all over the place. Most of those that thought 2 deg was good, then went for 4, have ended up backing it up over the winter due to timing rattle.



Two degrees is safe. At idle you have no boost, so how much damage can you do? The 12 valvers are over-advanced at idle by more than that, and they go a million miles.

I think with 2 degrees it is timed perfectly for cruising at 1500-1800 rpm. I said cruising. Accelerating, it could use a little more, 1-2 deg, and at higher rpm over 2000, it could use another 1-2.

But if you time how many seconds per day you spend under hard acceleration, as opposed to idling, and cruising, you will see that you cannot squeeze out a whole lot more MPG.

 

[Buffalo]

Betterthanstock,



Thanks, again, for your suggestions.



Joe F. (Buffalo)

 

[DPKetchum]

I put one on my neighbors 05 Dually 4x4 48re 3. 73 gears. He's got mid 80k on his truck. I installed his sensor with 30 odd k on it. He pulls 8500 lbs give or take all over and gets in the high 14 to low 16 mpg. The other day we went somewhere in his truck and I noticed very slight rattle(like a spark Knock in a gasser low rpm backing and turning on a grade. He's never comminted about the noise to me. His truck runs good. Only mod on it is the sensor mod.

 

[Bow66tie]

Thanks for the response betterthanstock. I definitely feel more informed now.



DPKetchum, I know your an informed Cummins owner, I've read many of your posts, but why haven't you installed the Rocktek sensor on your rig?



Michael

 

[DPKetchum]

I did before I installed my neighbors. Better cold start and smoother idle. Little bit more bottom end. I only have 21k on my truck. My sig won't take any more! Oo.

 

[JRD]

So now I have to go out and buy some "heavier" injectors just so I can get better fuel mileage... Gee thanks alot! :-laf



I would also like to thank betterthanstock for his very informative posts. You da man.

 

[Walker]

How would the use of something like propane (which advances timing depending on the amount used I believe) coincide with the use of the Roktech? Would you be over advanced?



What other things in terms of potential future power upgrades would need to be considered with use of an advanced timing sensor?

 

[betterthanstock]

How would the use of something like propane (which advances timing depending on the amount used I believe) coincide with the use of the Roktech? Would you be over advanced?



What other things in terms of potential future power upgrades would need to be considered with use of an advanced timing sensor?

Do a search on propane for the 3rd gen trucks. I only found 4-5 threads on the subject, about a year old.

It seems there may just be a handful that have tried it. Seems to be too risky.



Other boxes, people use it with just about any box out there, but the ones you really have to be cautious with are the downloaders, and TST,( though now TST offers adjustable timing, so I don't know how that will stack. ) The feedback with the older TST was that they only begin to add timing at about 1800 rpm, and adding the sensor really made the low end stronger, and the transition to boost fueling a lot smoother.