VENDOR RESPONSE TO THE NEED FOR TEST DATA
Realizing that there was limited data to substantiate the timing cause-and-effect, I sent a letter to several vendors that were listed in Issue 47’s and 48’s articles on performance for the ’03-’07 HPCR engine. The articles were authored by writer Doug Leno and Doug provided a comparison matrix that showed vendor products that effected timing.
Doug’s write-up (Issue 47 and 48) was done in mid-2005. Since that time there have been numerous other products introduced to the market that effect timing. I was remiss in not asking those vendors to respond. Admittedly, I am belated in keeping tabs on the performance marketplace.
The following is the letter that was sent to those vendors of record in mid-2005 whose products effected timing and the responses that were received:
In Issue 61 the obvious topic for the TDR will be, “It’s the (Fuel) Economy, Stupid!” We are planning a story on fuel economy and we would like to include your input in this article.
I plan to poke fun at myself with an exaggerated story about out-of-stock fuel magnets and the Tornado-thingee that does not fit our diameter air intake.
The serious stuff starts with this disclaimer: “Numerous times I have been cited for not including a legal disclaimer prior to an article that discusses a performance gadget, gizmo, or modification. Make no mistake: changing the timing of fuel delivery is a modification that can put your rights to warranty consideration into serious jeopardy. Additionally, timing changes must not adversely affect emissions according to the Clean Air Act, Section 203(a) and EPA Memorandum 1A.”
This disclaimer will be followed by Joe Donnelly’s “How-To” material on fuel pump timing for better fuel economy. Joe covers the mechanical VE and P700 fuel pumps, taking us up to the advent of electronics.
At this point it becomes subjective with comments from writers, “I think…
”So, I will jump on the band wagon. I think timing (either mechanical advance or electrical) is the magic bullet for Dodge/Cummins owners to consider in their quest for cost-effective mile-per-gallon gains. Have I missed the mark?
Thus, the purpose of this correspondence is to allow you and your company a forum to present any fuel economy data you may have on your VP44 and HPCR boxes. To keep the correspondence on track, I have provided a Question & Answer format below. I would appreciate your responses to these questions.
I received a response from TST Products’ Mark Chapple and MADS Electronics’ (Smarty) Marco Castano. Their answers make up the balance of this article.
Is fuel injection timing a “magic bullet” or is the editor off-his rocker?
TST Products’ response: I don’t see it as a magic bullet, but I believe there is a definite trend. As emission laws get tougher, manufacturers retard timing to reduce NOX. The reduced NOX comes from lower cylinder pressures and temperatures, but this is the opposite condition one would want for best fuel efficiency.
But this is the opposite condition one
would want for best
fuel efficiency.
MADS Electronics’ (Smarty) response: I’m sorry to say, timing alone is not the “magic bullet.”
Let me expand.
The mechanical VE and P-7100 injection pumps have a preset and fixed value for the “beginning of the injection stroke.” This means that the preset timing is optimal only for a rather narrow RPM/load range of the engine.
Since the introduction of the first “real” emissions regulations (NOX, HC and PM emissions) all engine manufacturers were forced to introduce electronic engine management. The introduction of electronic control modules provided a much more refined control over the injection timing. Electronic engine management provides the ability for dynamic timing changes throughout the RPM band. Therefore not only RPM, but parameters like engine temperature, boost pressure, intake air temperature, etc., can now be taken into account to adjust the timing of the engine. Were there no such thing as emissions regulations the electronics could provide the “perfect” timing for the engine.
Thus the best possible mileage? Unfortunately, the world is not a perfect place…
Were
there no such thing as emissions regulations
the electronics could provide
the “perfect” timing for the engine.
Thus the best possible mileage?
In order to reduce the combustion temperature thus NOX and PM emissions one simple way is to retard the timing. Furthermore, for the emissions test(s) the low load/low RPM range is weighted more than, let’s say, wide open throttle. That means the high load/RPM range is less important from an emissions point of view.
This leads to what’s under our eyes or should I say right foot? Detuned/sluggish engines in the 600-2000 RPM range. Range where we use them most! Detuned because of the emissions. Sigh!
This is of course counterproductive from the mileage point of view in a Diesel engine! As you surely know, the diesel engine is most fuel efficient in the lower RPM range; typically the best BSFC is yielded, which happens to be around peak torque.
Then faster the engine gets into the peak torque range then better its fuel efficiency in the real world. This is where the timing really comes into the picture! Correct timing means an engine that’s more willing to gain the revs. Thus we get sooner to the best fuel efficiency range.
This is the real reason why most customers report
mileage gains with their power modules.
Although, the timing is retarded typically only 1-2 degrees for the emissions (also Cummins has to make sure to deliver the best possible mileage. What about a new word? Emissions possible mileage?) which leads from my findings to a 1.5-2% mileage loss.
To come to a conclusion. The timing alone gains about 2% mileage. This nets out to nothing that could be measured in the real world! Yet, the timing (engine responsiveness) combined with increased fueling in order to get into the best BSFC range as soon as possible is what really gains mileage!
This is the real reason why most customers report mileage gains with their power modules. They get to the RPM range sooner and can stay longer where the diesel engine is most fuel efficient.
Do you have a mechanical timing recommendations(s) for ’89-’93 VE fuel pumps? The expected mpg benefit?
TST: The ’89-’03 engines didn’t have to meet as strict emissions rules thus the timing was left in a position for fairly high in cylinder temperatures and pressures. Timing changes would have very little effect on mpg.
MADS: No.
Do you have a mechanical timing recommendations(s) for the ’94-’98 P7100 fuel pump? The expected mpg benefit? Data?
TST: Timing was retarded more in ’94 to meet the NOX laws thus advancing timing had more effect on mileage. Though we didn’t make dyno runs at constant horsepower to measure fuel economy on our 12-valve truck, my log-book mileage appeared to improve by 3 to 5% once we advanced timing from about 12.5 to 15.5 degrees BTDC. This lowered exhaust temperature a bit at a constant power, and made the engine rattle more.
MADS: No.
Please share your timing experiences with the ’98-’02 VP44 fuel system and your performance module. The expected mpg benefit? Part number to be used? Settings for best mpg? Data?
TST: The ’98.5-’02 trucks with the VP44 pump had even more retarded timing than the ’94-’98 trucks to meet an even lower NOX standard. We used computer tools to change the numbers in the ECM timing tables and again lowered exhaust temperatures and picked up 3-5% fuel economy in our log-books.
MADS: Reported mileage gains with the Smarty S-03 are in the 1 to 3 mpg range. And, although I would like to believe in a 3mpg gain…I have never experienced it personally in my daily driver(s)! I’ve found that a 1 to 1.5mpg increase sounds more reasonable. There is no such thing as “best” setting for mileage. Everything depends upon driving style and conditions. This is why we strive to deliver to most flexible tuning system possible. “One size fits all” just can not do the trick.
Please share your timing experiences with the ’03-’07 5.9-liter HPCR fuel system and your performance module. The expected mpg benefit? Part number to be used? Settings for best mpg? Data?
TST: We ran dyno tests with various timing on our ’03 Ram and gained about a 4% improvement in fuel economy at 55mph, up to a 10% gain at 75mph. Book mileage jumped 2-3 miles per gallon on this truck for a 10-15% gain.
MADS: The answer is the same as my response to the question about the VP44 fuel system. The product that should be used in HPCR applications is the Smarty S-06 or SJ.
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