Fan for fuel cooler?

[GMCTRUCK]

Once we got into the warm summer weather my truck developed the "bursting" issues others had been talking about with some of the high hp boxes. I hadn't had problems in cooler weather but, the warmer the temps got (especially above 80 degrees) the worse the bursting got at higher and I would have to turn down my TST lower and lower as the temps got hotter. Now that it's getting cooler out I can turn my box back up. Today for example was low 60s and I could crank up the power with no bursting. So perhaps a bigger fuel cooler, double coolers, or an aux. fan blowing on the fuel cooler could help avoid adding a pump? Maybe?

[mackin]

Tomac mentioned he only had bursting based on tank fuel level not to long ago .... Did you see that post ??

Mac :confused:

[dmaxalliTech]

I thought the bursting was in the programming in the box, something that needed to be fine tuned, I dont remember it being from heat or lack of fuel, He has a nice lift pump set up ready to go but we are holding off now that it was found to be in the box itself...thought he was running out of fuel.

[a64pilot]

I haven't experienced it yet, tranny won't hold. However with the 140 hp tune I could run 9&9 with no bursting, didn't have the 140 hp tune in hot weather though.
dmaxalliTech,
Are you sure it isn't running out of fuel? TST isn't fixing their bursting by turning down the fuel to stay inside the pumps capacity are they?

[Kennedy]

Talk to Greg @ TST and have him set it back a bit. If it is bursting, the rail psi is going wild and THIS is a potential sign of cavitation...

[a64pilot]

John,
If it's cavitating, then the low pressure pumps flow capacity has been exceeded, right? Then it is running out of fuel if I understand what you are saying. Wouldn't a low pressure / high volume boost pump help?
Or do I just not understand what is happening?
On Edit,
This would explain why GMCTruck has to turn his box down in higher temps. Higher temps = lower vapor pressure = fuel vapor in the fuel lines = Bursting, which is apparently also pump cavitation.
So as he says either cool the fuel or pressurize it. How hot is the fuel in the tank when you experience bursting? I am wondering how much cooling you could do with 100 deg.+ ambient air with an air to liquid heat exchanger.

[mtomac]

At first the TST comp didn't burst on me with a full tank of fuel during a few 0-100+ bursts on the highway. On a different day it made one pass down the track (13.16) at 9&9 without bursting with a 1/4 tank of fuel. Then after that pass I couldn't run it any higher than 8&7 and ran 13.2's. So on the way home from the track I filled the tank and it still bursted like it did at the track on any settings above 8&7. I don't remember the temps on those days but the bursting COULD be temp not fuel level related. Although if the bursting was temp related a full tank of fresh cool fuel should have cured bursting but it didn't.

However, the Quad stealth doesn't burst and it is more HP than the TST. I don't think the injection pump is starving for fuel because Quad himself is running his 03 Duramax with the same tuning I am with a big set of injectors and he is laying a cloud the whole way down the track. I think we are reaching the limit of the stock injectors, I don't think there is any problem with the stock fuel system not supplying the injection pump enough fuel. The stock injectors can only put so much fuel into the cylinder in the time they have to get it in there. The tuning box that gets closest (to the injectors capacity) without going over (bursting) wins. That doesn't sound too much like Bob Barker explaining the rules of a game to a contestant on the Price is Right does it?

My fuel pump, plumbing, ect will still be sitting here until I get some more concrete evidence it is needed for anything other than adding extra filtration.

[ 09-03-2003, 10:44 AM: Message edited by: Micheal Tomac ]

[Manfred]

a64pilot -
If memory serves me right, we learned in combustion engineering that the water temperature in the radiator reduces the coolant temperature about 15 deg.C. Radiators usually are finned and have quite a large surface area for the air. I'd not expect much of a reduction of the fuel temperature of our oil cooler, from what we get now while driving, unless the cooler is modified.

[Kennedy]

Originally posted by a64pilot:
John,
If it's cavitating, then the low pressure pumps flow capacity has been exceeded, right? Then it is running out of fuel if I understand what you are saying. Wouldn't a low pressure / high volume boost pump help?
Or do I just not understand what is happening?
On Edit,
This would explain why GMCTruck has to turn his box down in higher temps. Higher temps = lower vapor pressure = fuel vapor in the fuel lines = Bursting, which is apparently also pump cavitation.
So as he says either cool the fuel or pressurize it. How hot is the fuel in the tank when you experience bursting? I am wondering how much cooling you could do with 100 deg.+ ambient air with an air to liquid heat exchanger. Possible. Nothing is certain, but from waht I have observed, the rail pressure was spiking and dipping all over the place.

I've seen a couple of thing recently that have me scratching my head, and I guess I need to see one of these pumps dissected to formulate any educated guesses.

I have seen:

Lift psi will hold SOMEWHAT at shutdown, but will gradually drop to a negative.

Excessive lift psi will not allow the RPCV to keep rail pressure in line.

30"+ hg suction head will still allow the Dmax engine to run/drive etc.

Excessive lift psi SEEMS to cure the TST bursting issue, but IMHO, the pump is NOT happy in this state as it has trouble modulating pressure. Additionally, 5 psi is not sufficient.

The new TST Comp programming has eliminated most, if not all bursting by setting the fueling increases at a more modest level.

Lift psi is being overcome by inertial (g force) load under hard acceleration.

Some stacking combos are making moreHP that the TST Comp w/o bursting issues which also makes a guy scratch his head.


OK, that said, from an outside perspective (this is where I need to dissect a pump), it seems that one could equate the transfer side of the Bosch pump to an oil pump. It has a fixed displacement in a manner of speaking. Minimal gains in flow will come when changing over from a suction to a pressure feed pickup.


Lunch time!!!

[a64pilot]

Michael,
I think I understand your premise, basically if you can pour more fuel through bigger injectors and not starve the pump, then the pump has more than enough capacity for stock injectors. But what do you mean by exceeding the limit of the stock injectors ? Exceeding duty cycles and overheating the coils? As I understand it the only way to get more fuel through a stock injector at stock pressure is to increase the pulse width. Start too early and it detonates, end too late and you should get excessive smoke.

[a64pilot]

John,
I didn't read your post until after I posted the last one. I doubt that inertial forces are great enough to overcome 5 psi, were are only talking on the magnitude of 1.2 G or so and that for only a sec or two. If you are going negative on fuel pressure I think it more likely you are exceeding the boost pumps capacity.
Maybe the injectors or the electronics are overheating from long pulse widths?
Erratic rail pressures are exactly what I think you'd see from injesting vapor bubbles.
Is it possible that some of these stacking combos are increaseing rail pressure thereby allowing more fuel flow with a shorter pulse width than the TST alone? (has to do with overheated electronics theory)
Manfred,
I agree I don't think it could do that much really either as designed in high ambient air temperatures. With the radiator there is about a 100 deg temp differential,a fan from Hell, and we apparently get only about a 15 deg C drop, I accept your figure as I really have no idea myself ;) With the fuel I wouldn't think the temp differental could be more than 10 or 20 deg so even a fan from Hell wouldn't help much I wouldn't think.
Remember the cool cans from when we were kids at the drag strip? Just coffee cans with a coil of copper tubing in it, filled with ice to provide cold fuel to the carburator, there by increasing charge density we hoped. Anyway such a thing would be good just for trouble shooting to see if fuel temp is really a culprit or not. I would plumb one into the supply side if it seemed I had temp related problems to see what would happen.

[mtomac]

But what do you mean by exceeding the limit of the stock injectors ? You can only push so much fuel thru the holes in the stock injectors.

As far as I know the Quad and the non pressure VA stacker I'm using do not increase fuel rail pressure.

[a64pilot]

Michael,

You can only push so much fuel thru the holes in the stock injectors I agree, that I believe is why someone said a while back why the comp boxes all made about the same power was because "you can only pulse a stock injector for so long", so if we are at the max flow of the injectors then we should be at the max power output of stock injectors and nothing should make more power, but apparently some stacks will. So it follows that we either are not at the stock injectors max or these stacks are increasing pressure, or I' confused again :eek:
I think John hit on the bursting problem by finding that rail pressure was fluctuating. Problem is I believe is finding out why rail pressure is fluctuating.

[SoCalDMAX]

Here's a theory, just a guess.

The fuel sloshes in the tank as one accelerates - it can actually end up against the back wall and top portion of the tank. If a person were at the track with less than say, 1/2 tank of fuel, the pickup may be uncovered.

I've never seen the fuel pickup so, someone who has would have to comment on how plausible this scenario might be. It obviously doesn't cover all situations.

Regards, Steve

[Kyle03D]

Just wanted to throw in that under load (pulling) my tst comp will cut out in 5te & 6 settings or higher (no egt limit), but when empty just accelerating 0 to 100 fast as possible it won't cut out in any settings(tranny issues aside). Load on the engine does something different to make it cut out. I'll be sending it back for update whenever I can do without it.

Kyle

[mackin]

Originally posted by Micheal Tomac:
</font><blockquote>quote:</font><hr /> But what do you mean by exceeding the limit of the stock injectors ? You can only push so much fuel thru the holes in the stock injectors.

As far as I know the Quad and the non pressure VA stacker I'm using do not increase fuel rail pressure. </font>[/QUOTE]Mike

So your stacking pulse on pulse ???
Assuming Quad has the limit in his grasp of the injector capibilities as you posted earlier,Are you doing it for the timing ?? Just trying to figure what your gaining ... I would think you would want to add some pressure...

Mac :confused:

[Kennedy]

Originally posted by a64pilot:
Start too early and it detonates... This is another DISTINCT possibility. I have had sporatic "bursting" with a couple of different stacking combos, but too hard to reproduce.

[Kennedy]

Additionally, it can be difficult to regulate pressure in an aerated/exploding fluid...

The pressure was bouncing off of 26,000 psi and dropping well below desired in somewhat rapid succession. It could be that the RPCV and/or programming are not liking the duty cycle range required also. Also, the FICM or EDU has to send the pulses which makes a lot of HEAT and could cause extreme outgassing and tons of air, cavitation etc...

[chuntag95]

Note, I am not advicating this in any way, but providing a different solution to cooling fuel other than a fan. You can get 12V thermoelectric coolers and apply them to a surface to make a cool can without ice. Reverse the polarity and they are now heaters. Marlow Industries makes them and I think they have a catalogue that you can order from. You can also have a custom design done based on your heat load and other specifics, but that will be very expensive.

[GMCTRUCK]

I should have mentioned my TST competition box is the aggressive version and never neutered to cure the bursting since I never had bursting till this summer. For example level 7 added over 180hp to my baseline. TST is making their power without fuel pressure though. Maybe being pulse width only the injector can't fill up quick enough at the big levels. Where as bursting doesn't seem to be an issue on softer boxes combined with pressure stackers. Quad's 215hp level is using some pressure to reach that number. If I stack in the Predator (which I haven't tried in cooler weather) it starts to burst with the TST on level 4. I might try adding the Predator again now that it's cooler out just for comparison sake. I try not to use the Predator too much because even with the TST off, driveability with the Predator is garbage. With the stick anyways, but, that's a different story. As far as the fuel level in my tank goes it doesn't seem to make a difference as I was running in level 8/9 yesterday with 3/8 tank and big smooth power with no bursting. Truck had been running all day but, outside temp was about 60. Same circumstances on a 90 degree day and the sumbitch will burst at level 6 sometimes even 5. So in my case I'm 100% positive it's fuel temp related. Perhaps a vapor or foaming issue. How about a cooler on the return and feed fuel lines? That might help. Of my 4 diesel pickups this is the first one to come with a fuel cooler. GM might have ran into this issue during testing and the cooler was probably an after thought. Maybe I'll just tape ice packs to my fuel filter. ;)

[ 09-03-2003, 06:39 PM: Message edited by: GMCTRUCK ]

[mtomac]

The 215 Quad Stealth must be soft in timing or pulse width because the big VA box I'm stacking makes a difference on the track although the stack only makes an extra 20 hp on a Dynojet. I also need the stacker box to protect the boost signal because the boost maping on the Stealth still needs some work and will cause a defuel between 60&70 mph when run by itself. I didn't know the Stealth had any added pressure.

[mackin]

Originally posted by Micheal Tomac:
The 215 Quad Stealth must be soft in timing or pulse width because the big VA box I'm stacking makes a difference on the track although the stack only makes an extra 20 hp on a Dynojet. I also need the stacker box to protect the boost signal because the boost maping on the Stealth still needs some work and will cause a defuel between 60&70 mph when run by itself. I didn't know the Stealth had any added pressure. Kinda figured something like that ... ;)

At some point you have to figure Rail Pressure will have to come into play to pruduce More Power in these boxes .... Lets face it to much timing ,grenade .... Duty cycle of solenoid is already at question,and has it's limits .... FRP will have to be bumped IMO ....



Mac
;)

[a64pilot]

So,
It would seem that most of us agree that this bursting is basically the injectors running out of fuel, whether it be from the injectors not having enough dwell time to build up to pressure or fuel flow and temp being so high that the fuel is basically boiling due to the low pressures and high temps creating some aeration (cavitation), or likely both at the same time.
It would appear that pressurizing and possibly additional cooling of the fuel should help. It would take a pump with a large enough flow rate to keep the fuel under pressure at all times, a pump that lets the fuel depressurize at WOT and higher RPM's isn't enough IMHO as that is precisely where the problem is.
I don't know of a pump that would work, I don't have enough practical experience. The John Deere tractors we work on heah at Goober's filling station are all gravity fed :D

[hoot]

Originally posted by a64pilot:
The John Deere tractors we work on heah at Goober's filling station are all gravity fed :D Goobers..... LOL

[Kennedy]

I haven't fully instrumented my truck yet, but I CAN say that I do not accumulate any air in the filter. Now keep in mind it takes TIME for the outgassing to occur as well.

My only point of measure is at the factory port which lies between my Mega filter and the injection pump.

There is quite a wide variance in pressure and pressure drop which is VERY closely related to rate of acceleration. I've even found that in a non-lift system, moderate braking (especially downhill will swing the negative pressure to a positive at this same point of measure...


I've been talking with a guy who sets up fuel systems for drag cars and gaining some interesting insight. They typically run 6 psi more when going from a front cell to a rear cell, and will add 3 psi when the car goes from a 1.40 to 1.30 60' time...


Once I get on the dyno and test w/o inertia, I'll know more...