So we have been talking about more HP on these things in all these threads but does anybody know what we are up against to make more power at higher rpms?
Let's just stick to the facts here, no smack talk or BS....
Who can answer these two questions properly:
1. Why can a gasoline engine make more and more power as you add airflow (while keeping the air/fuel ratio good of course) but a diesel engine may not?
2. Why is a diesel engine better able to make power at lower rpms compared to a gasoline engine but the gas motor makes better power at higher rpms (explain the combustion dynamics here)?
As far as I've been able yo learn it has to do w/fuel atomnization (spelled that wrong) and pulse width. At the higher RPM's you lose the window at which the Injector delivers the fuel. I think this is what HRT is working on. May be wrong, please jump in without the smack if I am.
The gas motor makes more HP because of the formula for calculating HP. RPMXtorque divided by 5252 (I believe). Because the gasser can spin 6000+ it makes more power...
As far as air flow goes this is what I have learned: I was in a diesel class and this is what they tought me. Gas engines gain power by adding air, this is why you use a throttle plate to control power. Diesel makes power from adding fuel, which is why your throttle controls timing and PW, and there is no throttle plate, it takes in a full volume of air every stroke.
Common rail injection system with lots of injection pressure for one thing which gives you more than just good atomization (there's your 25%).... getting warmer.......
There is an illustration of a diesel injection/combustion event at the end of this video. This video illustrates 2 injection events similar to a "split-shot" injection like the stock injection configuration of a stock 7.3 super duty. This will help you understand what has to happen to make a diesel work.
Notice when and where the fuel hits in relationship to overall time.
There is an illustration of a diesel injection/combustion event at the end of this video. This video illustrates 2 injection events similar to a "split-shot" injection like the stock injection configuration of a stock 7.3 super duty. This will help you understand what has to happen to make a diesel work.
Notice when and where the fuel hits in relationship to overall time.
[/QUOTE] 2. Why is a diesel engine better able to make power at lower rpms compared to a gasoline engine but the gas motor makes better power at higher rpms (explain the combustion dynamics here)?[/QUOTE]
I'm far from an expert on the subject however, what i've always heard is that diesel combustion is a much longer burn than gasoline. The energy from combustion acts on the piston's longer, making torque. Since this process takes longer, you have less time to burn the required amount of fuel to build power as the rpm's increase. The atomization available from common rail helps, but too a point.
I'm far from an expert on the subject however, what i've always heard is that diesel combustion is a much longer burn than gasoline. The energy from combustion acts on the piston's longer, making torque. Since this process takes longer, you have less time to burn the required amount of fuel to build power as the rpm's increase. The atomization available from common rail helps, but too a point.
Getting hot..... when can you inject fuel on a gasoline engine? Remember that on gas motors the fuel is injected before the intake valve. You can inject fuel before the intake valve actually opens so you aren't held to the same "fuel timing" constraints as a diesel engine.
Since gasoline requires an actual ignition source, i guess technically you can inject whenever you want to suit your requirements; economy, power, heat... Generally injection occurs right before ignition and combustion is more explosive than diesel's slow burn. Since it burns faster you can keep adding air and fuel to increase power-rpm basically until you meet the mechanical limit of the parts.
The gas engine also gets all the fuel and air it needs on the intake stroke. the only real "timing" to worry about is ignition, which is pretty much instant. Also, the more arflow you get in a gas engine, the more air/fuel mix you get. Even if the rpm's are stupid high, you're still able to pull in an ideal mix of fuel and air and ignite it exactly when you need to.
1. Why can a gasoline engine make more and more power as you add airflow (while keeping the air/fuel ratio good of course) but a diesel engine may not?
2. Why is a diesel engine better able to make power at lower rpms compared to a gasoline engine but the gas motor makes better power at higher rpms (explain the combustion dynamics here)?
1. Just because you are giving a diesel the proper air/fuel ratio doesn't mean that the fuel is actually being injected in a time that it can actually be used for power generation.
2. The characteristics of a diesel engine are much better suited for overall power production when compared to gasoline. However, the time window to inject fuel in a diesel gets smaller as RPMs increase, usually giving the advantage to a gasoline engine.
So if we're dealing w/burn rate and event timing how do the non-alcohal diesels turn 7000rpm. I've watched 1st hand how they rev, they sound terrible until the mixture equalizes then ZOOOM! This isn't a test but a legit ? I know they're mech pumps and are most likely under more fuel PSI but how are they getting a clean burn @ that high of an rpm? Could the burn rate be answered by the speed and PSI of the inj event? I know some of the answers here but would like a clear complete exlpanation if there is 1 to be had. I'm not asking for diesel 101 just the high perf aspect.
Well HEUI is a handicapped system for extreme performance. The 7.3 has been given up on by the big guys and they have called it a dead platform.
Mechanical pumps get the fuel in the right amount of time; the crap you hear before it gets up in the RPMs is the locked injection timing being too much for the lower rpms (mechanical runs the same timing all the time).
Common rail can get the fuel in fast too because of the 25,000 PSI of fuel pressure....
HEUI hasn't been made to do it YET......
The rate of injection on a mechanical pump is directly related to engine speed, therefore keeping the injection rate = to that of the engines desired fuel at the desired rate.
The mech pumps are positive displcement, the fuel either goes in in that amount of time or blows the head off the pump, breaks the shaft or blows the tip off an injector.
Our system is limited by HPOP, speed of the injection event and flow rate of the HPO system. We do have an advantage in that we can control the fuel delivery more precisely than a mech, but a severe disadvantage of high performance fueling.
On the right track for sure...... so is everyone starting to see why a 500cc injector with a stock nozzle doesn't help you make much power at 3500 RPMs?
So with the HPOP HEUI system on our trucks, how can you increase the HPOP side to allow more fuel faster into the cylinder? I know you can double up the HPOP to increase pressure, but is that all any one knows?
The dual hpop isn't for more pressure it is to keep up with flow (volume) demands..... That is why there is a pressure drop with a single HPOP, you need more volume. I like to keep things below 3000 PSI (for now anyway).
With the after market fuel system w/regulators, what PSI do the power strokes like to see, and is to much bad? I have mine set at 70 and it seems to be running good with on;y one HPOP but my ICP code is always flashing.
65 psi is a good place to be. If you have a regulated return I'd actually use a boost reference to the regulator with a mechanical boost fooler that pops off at around 20 psi. This allows you to set the base fuel pressure around 45 so your pump lives a happier life and gets to full 65 psi once you need it.
My regulator does have a line that hooks to the boost line but I am not sure how that all works. ?? I had the pressure turned down a month ago to around 50-55 then turned it up to 70 and noticed a difference on how the truck ran, but the ICP code comes on more.
With what I have had to pay for to get this truck back on the road I can't afford to get the dual HPOP setup at the moment. Are their any other options to help out for now?
you should boost reference the regulator with a 20lb max pressure so that it runs 40-45 psi at 0 boost but will gain I psi of fuel pressure per 1lb of boost until it hits 65psi.
The injectors need 60-65 psi of pressure to work at full tilt, they just don't need that much during less than full demand conditions.
I know up til now we've been talking mostly hard mods (mech) but how about 10K 140v IDM and this Bigg Boost? I know you guys don't like the YouTube Powerstroke help guy but claims it does produce. Any ideas?
The 10K and 140v IDM mod make more power on a stock truck but not necessary on something with a chip on it. IMO a burned up IDM from not resealing it properly and allowing water to enter is expensive. If you want a modded IDM I'd just go have one modded by Swamps.
And the big boost mod is a joke.... a stock turbo doesn't last long at much above 25psi for very long in most cases. You can just disconnect your wastegate and watch boost on a gauge.
The only way that's gonna happen is if you possibly try to "time" the engine by running just the right amount of boost for a given compression ratio, and at a pre-determined rpm start injecting fuel directly into the intake runners.....
Just sit back and control IAT with water and boost with gates so that the fuel just happens to "pop" at the right time....
For instance, at 10,000rpm you only have 6ms per rev. Say you planned to inject the fuel within a 30 degree window. That would leave you a whopping half a millisecond to inject the full fuel load. A Heui for instance, wouldn't have even flinched in .5ms. Problem number 2. If you somehow managed to get an injector to deliver say 200cc in .5ms, how on earth do you idle it?
idk.... maybe lots of injection pressure, short stroke and a bunch of cylinders never thought about it really
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