ofelas

You know, its actually a valid point. Never mind case pressure, 2-3 psi is where it's at.

I'm wondering if I should leave my rad cap off, running zero pressure should help cooling.

Only problem is water exposed to air will corrode the insides of the rad.

Any thoughts on this?

nascar mark

You know you can eat that lettuce too, right.

93flatbed

My suggestion would be to run 100% antifreeze OR if you're at the track often, run 100% distilled water with some water wetter additive. Get a bigger over flow tank to catch. Billit catch tank!

edwinsmith

The reason for pressurizing the radiator is to increase the boiling point of the coolant. If you can run the engine hotter the thermodynamic efficiency of your engine will be increased and your fuel mileage will also go up. Leave the cap on and use at least a 190 deg thermostat. I won't go into the ratio of anti-freeze you should use for reasons of my own.

Edwin

Dan s

Change your spark plugs and check your headlight fluid. It's gonna be ooook

nascar mark

That’s hilarious. Ofelas is just yanking your chains and making a point that went over all your heads.

Dan s

RoflMao

93flatbed

OFELAS , physically cannot go over my head. I stand 6'2", he'd get a nose bleed up here....

boeingguy

Which coolant to use MS 9769 or may 88 vintage John Deere coolant be superior ...

ofelas

I would personally use 100% MS9769 as its mixed with 50% heavy water & has added lubricants for correct OEM water pump seals and heater core tube braze.

However, '88 JD coolant is rare stuff. It use Chernobyl heavy water to bring it up to 122.5% antifreeze spec, and proofs head gaskets against ether shots.

IDK which is better for optimal fuel system cooling.

1972RedNeck

Negative. The more pressure your oil pump puts out, the more that will flow through the bearings. This tends to be a good thing.

From my limited understanding, increasing pressure supply to a VE pump has no affect on max fuel rate. Please correct me if I'm wrong, but if more pressure equaled more fuel, someone would have figured out how to run 50 or 100 PSI of inlet pressure and would have been able to crack the 500 HP mark with a 12mm pump.

Can I ask you this, what are the advantages of slightly higher case pressure? It is often said that it helps "cooling", but how?

As for the increase in fuel pressure creating heat, this is why:

Increasing the fuel pressure from 5 psi to 15 psi does not increase fuel flow, correct?

Since we are not increasing the volume of liquid being pressurized but yet we are increasing the pressure, the temperature of the pressurized medium increases. Is this not so?

Also, the higher the pressure, the more fuel will leak past the piston and check valve in the lift pump. To quote resources much smarter than me, "Hydraulic fluid heats when flowing through a restriction as the pressure energy upstream of the restriction is converted into thermal energy." Is this not true as well?

So if you aren't increasing flow by increasing pressure, your fuel system is building more heat when you increase the pressure. It may be minuscule, but when you're splitting hairs with your hardwood pumps, it may make or break it.

edwinsmith

Everything you said is essentially correct except for the pressure increasing the temperature of the fuel. Liquids are incompressible so the Ideal Gas Rule doesn't apply.

93flatbed

Before I tore my truck apart I had an air dog 165 set at 21 psi at idle, under "Max effort" I could pull it down to 4-5 psi with my little 12mm pump. I don't want to comment what my 14mm pump did, kinda scary at just "normal" load. This was with a fuel cooler and fuel only, no drugs. Case pressure with my 12mm dropped off in the 60psi range. My 14mm is a bit if a freak with a custom vein pump it held case pressie but was dropping.

I've pushed 40-45 psi at a ve with only positive effects (12mm). My 14 wants more but I tore the truck apart, no real feedback at this time. I plan on shoving 40 at idle and boost reference 1:1 up to 70 or so once/if I get done with current build.

So no your point holds no weight with me. My truck has a fuel cooler on supply and return, fuel cell has cooling coils in it. I want my fuel at 60~°F as diesel breaks down around that temp point. I've spent more money on my supply fuel system than I bet 90% of this forum members individually has in their injectors and VE. I'd hate to admit what I've spent on my VE's and sets of injectors.

My toy is just that, a toy. I don't need it to take me to work and I don't need it to make me money. It's purely just to make a smile on my face. I understand most of the members on this forum need their trucks, so my build/info has no bearing on their trucks. BUT there is no instance that a VE pump doesn't like more case pressure and cool fuel. I don't know of anyone besides myself that has a custom vein pump. I know of a few that have feed extra case pressure threw the FSS hole to supplement dropping case pressures (some of the highest HP ve owners out there). The stock vein pump can only do so much, cram extra pressure at it and try to help it as much as possible. If it creates heat then cool that down.

MrFusion

I may be incorrect but here goes:
Pressure is a consequence of volume and space. For instance: pumping a liquid at 5 gallons per minute (GPM) through a 3" diameter pipe will have much lower pressure than the same GPM through 1/2" pipe. The same volume of fluid is being forced through a smaller space and since it can't compress it must go faster hence more pressure.
I installed a low pressure (15 PSI) piston pump on my rig. ALL of the fuel lines are stock. Therefore, since it is pushing non-compressable fuel through the same amount of space at a higher pressure then it must be pushing more volume. More volume allows the injection pump to have more fuel supplied than it typically needs so more fuel is returned to the tank. My understanding is that the excess fuel lubricates the IP and scavenges heat away from the IP and into the tank. As I understand it more volume is better until you create enough pressure to blow the front seal out of the pump unless you secure it with screws.
I wouldn't worry too much about more pressure creating more heat in our fuel systems since the pressure is relatively low. Comparing it to a hydraulic system is apples to oranges. Our fuel systems run 5 psi stock up to 50 PSI extreme. Most are under 20 PSI. Hydraulic systems operate from 500 to 3000 PSI through comparatively tiny passage ways (space).
Oh and OFELAS forgot to mention muffler bearing backlash!

ofelas

Well summarized.

That is exactly what I said in my first post #8 to this thread; best to read the message, rather than castigate the messenger.

Unfortunately, post #14 was a bit snippety.

Not sure where I initiated a reference to maple wood or 100% antifreeze...though it certainly was fun to play along after the factual answers to the initial OP questions were given