Cummins ISL Performance

[rockcj]

http://www.vehiclefx.com/index.asp?P...ROD&ProdID=100

What do you think?

David
05 Alpine

[rockcj]

http://www.vehiclefx.com/index.asp?P...ROD&ProdID=100

What do you think?

David
05 Alpine

[SteveS]

It seems they are making unsubstanciated claims to me. I couldn't find anything on how it worked or laboratory tests conducted. Also, I question their claim about adding more heat by adding more fuel alone (as the chip programming does". Typically, the engine runs hotter if it is lean...has more oxygen that required for complete combustion. As an example, for those who have experience with gas welding, when is the torch the hottest? Answer: when it is "rich" in oxygen. I also don't understand the claim of a flat torque curve. I believe torque is related to the physical properties of the engine and I am not convinced that fuel control can flatten the torque curve out while increasing the RPM (increasing the horsepower). If RPM is limited then the claim of a flat torque curve can certainly envisioned, but the description claims increasing to max horsepower with a flat (maximum) torque curve...doesn't make sense to me. It is certainly interesting but I would need a lot more information on how it really works and see some testing results.

[EngineerMike]

I'd agree w/Steve- not enough info to make any kind of sound judgement.
Diesel combustion is fairly simple- inject fuel into cylinder w/air in it, & compress till it ignites. You can inject sooner or later. Or you can "shape" the injection charge by doing a multi-step injection, or you could inject from more than one injector, or you can swirl the charge... All these affect timing BTDC.
Or you can vary the air, via turbo-charging.
More fuel = more heat. More air compression, absent compensation, = more heat (compensation is via inter-cooling or charge-air cooling).
Everything Cat or Cummins has done in the last 10 years, to my knowledge, is a variation on the above. Variable turbo boost, super-ultra-fancy injectors (Cat has some that are individually programmable & have to be "flashed" furgoodnez sake), higher injection pressure for better spray pattern, reworked fuel/air/timing tables, etc.
Other than the vague claim of "optimization," the website says nothing about what they do to improve power/efficiency. Not that Cummins has the perfect control system, but they have to mess w/something & I'd want to examine exactly what before hooking their gizmo up to my expensive hot rod. Just my $0.02.

[EngineerMike]

BTW, Steve- I've got gauges on my GM 6.5 turbo diesel coach, & it is true that adding more fuel beyond the point of the engine's ability to convert it to power, yields nothing but heat (OK, more smog too). I can hit a hill & jump to 1100 degrees EGT, then stomp on it adding no more boost but adding fuel- all I get is 1275 EGT (ouch) & no more GO-GO. Those who have this engine but "thought" big-block gas, frequently made the mistake of dropping down a gear to "pump more fresh air thru the block to keep things cool." That too was counter-intuitive; higher rev's put the computer higher in the boost curve, sending more compressed air to the cylinders (w/out inter-cooling on our model). If you've had an air compressor, you know that compressing air causes heat; for a turbo it's somehwere ~+300 degrees for heavy boost demand, so if you don't cool that down before entering the cylinder, it comes straight out in ~+300 added EGT (& head temps, which can cause cracked castings it you let it get outa control). The "gas" thinkers, who would have been correct for naturally aspirated gasoline, were jumping their EGT's & head temps by 150-250 degrees w/no benefit.
The diesel control & output variables are different than gas to sufficient extent, that some seat of the pants reactions are counter-intuitive. That reinforces the conclusion that more info is needed to evaluate the claims by this after-market outfit. My guess is that their main market is pick-up owners who are less concerned w/warranties on their rigs than we are (despite the rather bold claim that the package won't void warranty).