Vapor Lock & Hydro Lock

An explanation about the nature and causes of vapor & hydro lock

[groundshakersociety]

I don't know what I would do without your channel good stuff

[arthurfricchione]

‘Pete, you are a walking book of knowledge experienced it often in our hot rodding days in high school. Yes we knew it was vapor lock but we weren’t scientists we worked it out and off we went.magic. just a 327Cu In with two four barrel carbs and off we went. But I do remember it happening on my dads car we would just put a hand over the carburetor throat and actually pull it out. Oh the simple joys of life. Wish I had those cars now. Pete stay healthy and well Artie 😊

[QuantumWrench]

Thanks, Pete. Now I comprehend how hydrostatic pressure can be so damaging. I had not thought about that effect, until you put the picture together. Like a gallon of water from five miles under the ocean surface will occupy the same volume as a gallon at sea level, even though it is subject to well over 11, 000psi, it does not compress. No matter how much titanium is in your engine, it cannot compress a cylinder full of fuel. Seizure and/or busted parts will probably result.

Rapid expansion of gasses from a high pressure system into a low pressure environment due to evaporation is a state transition that has an endothermic chilling effect of cooling down. Much like the workings of an air conditioner or heat-pump home heating/cooling system or sweating and a breeze hits your skin. Expanding gasses as the result of combustion, that's a different problem of a chemical reaction. In both cases energy is conserved, so sayeth everyone. Figuring out how and where, can be a challenge.  Kinda fun remembering problems from some 40+ years ago.

[sctte-]

Great video...the fuel system is something I've never really messed around with when it comes to cars so I found this vid interesting!

[tjhamer]

Good vid. Pete. Last year a friend came by with a 65 chevy truck 6 cylinder that he just bought that kept stalling on him. when i opened the hood there was old tin foil thin on the fuel line. LOL. Then the new carb with just a paper base gasket.Got rid of foil and put thicker gasket under the car. FIXED

[satamanschmidt]

Pete you forgot one detail. Fuel injected cars are far less likely to experience vapor lock due to the high pressure in the fuel lines. Physics dictates that the higher the pressure the higher the boiling point.

[planeflyer]

Howdy Pete! Thanks for the great explanation.

Question: Back in the day, old timers used to pour cool water on the outside of a carburetor to cool it when encountering vapor lock; will this work with an EFI system?

[shoominati]

Thats why with an injection system or even a carby system, it's a good idea to run one of the types of regulators with the return line on in. and mount it on the firewall, or even under the car, away from the exhaust so you're not passing heated fuel back into the tank, which will eventually give you a tank full of hot gas, and a car that will no longer run - I've seen it happen.

[jonathanbosco]

Great video, Your video lectures are much appreciated.

[johnmckamy]

the little hold down bolt on the fuel rail looks loose.  great video .   I had an old charger that used to vapor lock all the time

[trailblazer]

Novice here but where does the spark plugs go on the engine you built 427. Love the videos by the way. I learned a lot.

[patwpb]

With all due respect, I seriously doubt that a running gasoline engine will have the conditions conducive for cryogenic thermal expansion to occur internally. Cryogenic thermal expansion typically occurs at temperatures around or below -238 F (-150 C). Would you please explain further?

Hydro-lock occurs in an internal combustion engine when there is a volume of incompressible fluid in the cylinder on the compression stroke that is near equal to or greater in volume than the effective volume of the combustion chamber.

I also don't believe that a running engine experiencing a fuel (boil) vapor-lock condition and or a cylinder experiencing no ignition/combustion events can experience hydro-lock from the fuel being injected.
On a running engine the cylinder/combustion chamber is completely swept (cleared) every 2 revolutions and there is not enough fuel being being injected to cause hydro-lock.

Here is why, let's do the math:
Assume Ford FE 4 stroke gasoline fueled 427 CI (7L) V8 11.5 CR with 76 cc combustion chamber, Multi Port EFI with (8) 1000 cc/min, 95.2 lbs/hr (43.181 kg/hr) fuel injectors good for more than 1000HP, most decimal values rounded to 3 places.
A 1000 cc/min, 95.2 lbs/hr (43.181 kg/hr) fuel injector delivers ~16.667 cc/sec at ~85% duty cycle.

The reference engine at 1000 RPM = 16.667 RPS, the time period for 1 revolution = 0.060 second.
Theoretical maximum fuel delivery would be ~1.00002 cc/revolution.
Total theoretical maximum fuel delivery per 4 strokes (2 revolutions) would be ~2.00004 cc.

Same engine at 5000 RPM = 83.333 RPS, the time period for 1 revolution = 0.012 second.
Theoretical maximum fuel delivery would be ~0.200004 cc/revolution.
Total theoretical maximum fuel delivery per 4 strokes (2 revolutions) would be ~0.400008 cc.

With a 72 cc combustion chamber it would be practically impossible to hydro-lock the reference engine with injected fuel due to vapor-lock or no ignition/combustion events since the injectors are incapable of delivering the necessary fuel volume in the allowed time periods.

However a defective or leaking fuel injector could result in hydro-lock, but only if multiple conditions are met.
Those conditions would be:
1) Hydro-lock occurring only on startup.
2) A defective leaking MPI fuel injector.
3) A residual fuel pressure system.
4) Prior to startup the intake valve on the cylinder with the defective leaking injector must be open.
5) The volume of fuel leaked by the defective injector must be greater than ~90 percent of the effective combustion chamber volume.
With the engine not running the defective fuel injector bleeds off the residual fuel rail pressure by leak-down into the intake runner and into the cylinder with sufficient volume resulting in hydro-lock upon startup.
The leaked fuel volume to result in hydro-lock in the reference 76 cc combustion chamber engine would have to be greater than ~2.332 fluid ounces (~69 cc).

Regarding vapor-lock, when the fuel boils and changes state from liquid to vapor (gaseous) you state air is then in the fuel lines/rail, how is air being introduced in the fuel line/rail?

Also fuel vapor-lock is detrimental because gasoline fuel systems, pumps and fuel injectors are designed to operate and precisely meter the fuel using liquid fuel and not a gaseous vapor. Boiling fuel in carburetor systems have similar but different issues where the fuel vapors vent into the intake air stream altering the effective air-fuel mixture. Engine mounted mechanical fuel pump fuel systems typically experience vapor lock on the suction side of the pump where the boiling is exacerbated by the negative pressure required to suck the fuel from the tank to the pump affecting the fuel vapor pressure.

Modern gasoline is not a pure substance, but a complex composition of petroleum distillate fractions that vary greatly from batch to batch. No two batches of gasoline are ever exactly alike.
The boiling point of gasoline varies greatly from ~90 F to ~300 F with the lighter fractions boiling at the lower temperatures and the heavier fractions boiling at the higher temperatures.
Some gasoline batches will more readily experience vapor-lock than other batches of similar brand and grade.
Fuel line vapor lock can usually be mitigated by employing the gas laws and raising the pressure of the fuel in the lines/rails and locating the fuel pump close to or in the fuel tank and by continually circulating the fuel in a closed circuit from and to the tank using separate fuel supply and return lines to/from the engine.

How is your doctorate progressing?
Your lighting, audio, color and video production is looking especially good lately, did you get a new camera?
Thank you for sharing and taking the time and expense to record, edit, produce and upload these videos.

[dannylarsen]

Can i ask what your opinion is of engine from what ive learned from this video i feel it is a bad idea....is that correct?

[bassmetalheadbang]

Please correct me if I am wrong, When you were speaking about vapor lock in a FIE could that lead to premature detonation in the cylinder causing a con rod to twist and possible seize the entire engine?

[pnslive]

Sorry if I sound inappropriate but I'm going to ask you a personal question. What school did you attend? And/or do you have any degree in mechanical/chemical engineering? Because it seems that you know your stuff.

[suvijakengr]

Vapor lock is occur only in gravitate fluid system not under pressure.

[ziggassedup]

I see the angle in your pitch Pete but how many EFI engines have you seen come in with a non functioning spark plug that resulted in a hydro lock.?...Me either...Just sayin'

[odetowny]

hi pete, i see this video is a few years old, but i just wondered if you could answer my dilemma. i have a 5litre v10 bmw m6 which went to my local bmw dealer for 2 sensor to be replaced and a new fuel sender gauge, all under warranty. now this is my awful situation. the mechanic has admitted to taking the car out for a test drive. in turn hes run out of petrol and the engine has hydro locked. is this possible ?? at the moment bmw are blaming a faulty injector, due to it coming to the end of its life (67, 000) and making me foot the £30, 000 bill. i personally think running the fuel that low, its dragged crap through the system and caused the injector to lock open causing the damage. would i be correct in my explanation . im just trying to get together as much ammo as possible for when my case probably goes down the legal route. cheers paul

[dieselfuel]

Question I drive a diesel truck now I’ve heard of hydro lock on a diesel But I’ve never come across it and wished I knew how to explain it also I’ve heard of a run away diesel. Never had it happen but is it possible for a diesel to hydro lock and why and how please let me know

[shoominati]

What models do you fly? (just noticed the Tx's in the background)