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Smokey Yunick's 2 banger turbo engine 1

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trucksmart

trucksmart

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Jul 27, 2012
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I think after reading the threads about Smokey's VW Rabbit 2 cylinder high mileage engine, everyone seems to be missing the main process that makes the engine so efficient. I thought the engine used two turbo chargers when I read about it in the 1970's. The whole idea was to homogenize the fuel air mixture so the lighter ends of the carbon were mixed up with all the other fractions of carbon and because it was so hot and moving under pressure it didn't have time to separate and ignite before the rest of the mixture burned. It was just a nice controlled continuous burn similar to that of a diesel engine combustion. This is why the engine never pinged or knocked even when starting from a dead start and slamming the throttle to the floor. That was the secret everyone is asking for.
I believe the fuel/air mixture went through two turbos before going into the combustion chambers. Because the mixture was completely homogenized and it was under high boost pressure it couldn't pre-ignite. The whole intake system was plastered with asbestos insulation so very little of the heat energy escaped from going out the tail pipe. You could probably hold your hand on the surface of the insulation without burning your hand. Look at how much money Mercedes Benz spent on their steam recovery hybrid (which never made it to production) and Smokey did it better and for very little money. (he actually stuffed a potato up tail pipes to diagnose the health of engines. He had and used common sense while it was still common.

The only problem to me seemed to be that it wasn't very quick off the starting line and they couldn't seem to find a way to file the patent but was had very smooth acceleration. What was amazing was he achieved 150 horse power from a two cylinder engine. Just think what he could have achieved from a heavy duty truck V-8 engine with this technology? Remember; with the homogenized vapor at several hundred degrees F. the molecules aren't very close together so it would take a lot of boost to fuel the engine at high power demands.
I think Smokey Yunick was just trying to prove a point and that is to find a way to more completely burn the fuel making the engine more efficient. I think he succeeded.
 
So then Pat, we then have no need for O2 sensors then, since you say the fuel is already completly burned in all ICR engines? That is how I read your reply.
 
"with the homogenized vapor at several hundred degrees F. the molecules aren't very close together"

I'm not familiar with Smokey's design- did he increase the intake volume so the molecules could be further apart? In most fixed volume systems (like a conventional intake) vaporized molecules will be as far apart as possible at all Ts and only speed up their movement at higher T.
 
Smokey's Hot Vapor Cycle engines come up from time to time on this forum. Here's a blow-by-blow from a few years back:


The big recurring themes from these posts and some others I've read throughout the years:
-The actual performance of Smokey's engines is in doubt, especially when compared to some of his more, ah, optimistic claims
-The temperatures involved require high-dollar, high-temperature turbine oil for lubrication, something that was allegedly admitted by Smokey himself.
-NOx emissions were likely extremely high due to combustion chamber temps.

Mixed in with these are allegations and claims of manufacturers wanting the design then backing out at the last minute, etc. Fascinating reading and fun to run some napkin calculations.
 
I didn't know about this engine and curiosity just got the hold of me and I checked it out. This engine makes absolutely no sense to me.

I read this article (and others) and rely what I understand on this image from the article:
dia1.png


I understand the concept of using the wasted heat to re-heat the mixture, but in any thermodynamic cycle I've seen, you do that AFTER the compression, not before. I would like to assume it produces some power by pushing on the piston during the intake stroke, but it says that there is no pressure increase in the manifold; the turbocharger, or homogenizer, is only making 1 psi positive pressure. Which I do not doubt because the turbine is spun by exhaust gases AFTER it has been cooled down, hence no energy left in the exhaust gases.

Even assuming the pressure was high between the homogenizer and the engine (which I believe could increase the efficiency), the tuning to prevent surging (hence pressure loss) at every rpm and under any load condition, would probably be a very difficult task to do.

But the worst, assuming the previously mentioned steps do increase efficiency somehow, is the pre-heat by the coolant. Back in the days, cars actually had similar systems to heat up the fuel mixture of a cold engine with either coolant or exhaust gases, with the exact same goal as this engine (better fuel atomization). As soon as the engine has reached its operating temperature, a valve was closed to shut off this heating process. Look at that, engineers of the time seem so ignorant as they chose to complicate the system by adding an extra valve to cancel what Smokey is actually doing with this engine! Worst, when racers used these Detroit engines and had to use the OEM intake, they actually blocked that exhaust gas passage; How foolish were they!

With this heating step, this is like running the car on an extremely hot day, which everyone knows actually decreases power. Not only does this expands the air (meaning that for a given displacement, less air will enter the engine), but if you heat up the fuel enough such that it becomes a gas instead of a liquid, the increased volume taken by the gas will take the place of the incoming air and, again, reduce the quantity of air that goes into the engine.

So, even assuming the engine is more efficient, there is no way it would produce more power. Maybe the same, maybe slightly more, but never 2 or 3 times more!

Furthermore, this how-much-fuel-evaporation-is-needed thing (called volatility) is so touchy, that there is actually winter and summer fuels and it varies from country to country because of ambient air temperature. Now, we should believe that this guy just takes any fuel, heats it up to maximum evaporation and bingo, he makes some magic happens?
 
Efficiency is a very broad term and to be considered should be preceded by a term like volumetric or thermal or mechanical or fuel.

The design above does not pretend to improve VE I think, but aims to improve TE at the cost of VE.

You are correct in that preheating manifolds to improve vaporisation is a very old technique.

I am not a Smokey supporter. I think he was far to fond of smoke and mirrors, but he also had quite some success at times.

The concept above I believe was intended to get extremely good vaporisation and mixing to maximise burn rate so the ignition could be fired later and still get peak cylinder pressure by about 12 deg ATDC. That way the engine does less work, compressing the already burning charge but still gets it burned in time to extract a virtually full power stroke.

Any modern engine, while in slightly lean mode burns virtually all the fuel before the exhaust valve opens so the unburned fuel argument is pretty much moot. The only maybe valid argument is burning all the fuel before the piston has really started moving down very much and not burning much while the piston is moving up much.

Good injector spray pattern and fine drop size and good air speed and swirl and squish and a hot cylinder wall and chamber all contribute a lot toward this, but to much swirl can separate fuel like a centrifuge and to much squish can leave unburned fuel in the extreme edges of the chamber leaving unburned hydrocarbons and to hot a charge can create nitrous oxides. Everything about it is a complex mix of multiple compromises between fuel economy, engine durability, drive-ability or response, power density, safety and emissions and in all likely environments with variable fuel quality.



Regards
Pat
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Capturing waste exhaust heat and applying it to the intake is a good idea in concept. The Chrysler turbine car of the early '60s had clever heat exchangers that did a pretty good job of it. But, the heat was applied after compression while in this engine it is before cylinder compression as already pointed out. Another huge difference between heating the charge in a turbine and a piston engine is the problem of detonation which makes it an extremely counter-productive thing to do. The more you heat the charge, the lower the CR has to be. But, this might not be a problem if this were a diesel.
 
There are various articles about Smokey's vapor engines. At the bottom of this page are more examples. Smokey claimed to have made several versions-- the 2 cylinder version described at the top of this post, the Iron Duke 4-banger in the Fiero, a Mopar 2.2, a prototype V6 converted to a 3-cylinder, a design created for the DeLorean, etc. Based on what's been published, it is difficult to pin down exactly what he did, either because the prototypes changed often or because of Smokey's slipperiness or both.
 
"Capturing waste exhaust heat and applying it to the intake is a good idea in concept."

Actually, it is a terrible idea in concept. It seems there may have been some good effect in spite of itself.
Turbine recuperation is different - that's transferring heat from the expanded exhaust flow to the part of the cycle where you're going to add heat anyway, (between the compressor stage and the power turbine/expansion stage).
To accomplish that in a piston engine, you'd need to do some trickiness like compress in one cylinder and expand in another.
oh, well - where's that dead horse icon?


Jay Maechtlen
 
Jay, to say recycling exhaust heat is a terrible idea in concept and then say it is good in turbine engines is a contradiction. If it is good in turbine engines, it's a good idea in concept.
The problem in reciprocating engines is where and how can you apply exhaust heat. With a turbocharger it is applied to the intake (in the forms of heat and pressure) and that seems to be a good idea in concept. Exhaust heat is put to the pumping work of charging the engine and can even supercharge the engine and can even provide a net positive cylinder pressure (pressure in the intake manifold greater than in the exhaust manifold). Good idea in concept.
In Smokey's engine it looks like a problem. Simply heating the intake charge is an obvious problem. Even heating the charge after compression would increase the tendency to detonate.
 
Smokey's engine was steam injected. Can be simply done by a water separator like the one i'm working on. No tank too fill or freeze.
 
trucksmart, I believe Smokey would be disappointed in you from calling his homogenizer a turbocharger. He said it was designed to keep a consistant pressure in the intake tract at all rpms levels acting as a check valve along with mixing the gasoline into the hot air to promote vaporization asap. He had mentioned that he noticed the quicker you vaporize the gasoline you have a more stable fuel that can resist ignition prior to the spark for ignition if done at a slower rate.

Too bad the engine wasn't around when the use of UREA was introduced in the mainstream because I think his engine would have worked out, however, like everyone says there isn't much out there that can be set in stone as far as Smokey's engine design, therefore thats why not many give credit. But I guess thats what happens when some decide to break barriers in technology and have been known from rule bending in a world famous racing circuit. If we can duplicate, I say Smokey deserves the credit on what he developed.

Has anyone even tried to duplicate his engine exactly?

Nothing is impossible, it just needs more time for development.

I think the one Smokey did for Chrysler was taken back by Chrysler, though Smokey kept the engine. I can't remember on that one exactly from his book. Propane & gasoline, Pat you brought up something I will make a side note on to study. A great forum to be a part of!
 
FahlinRacing, in the '70s the concern for better fuel atomization and mixture distribution made the idea of an "homogenizer" quite appealing. There were any number of viable ideas proposed and worthless gizmos sold on the promise that they would better homogenize the fuel/air mixture. However, it has already been pointed out that this is no longer a problem in modern engines. So, the value of this "homogenizer" feature is nil today. His other big idea seems to be the two methods of heating the intake charge. The concept here is anathema for piston engines. It would not be surprising if no one has tried to duplicate Smokey's engine.
It also been pointed out that Smokey was as good at obfuscating (at least in tech inspection) as inventing, so I would take his claims with a grain of salt.
 
Yeah, he did spend around 30 years on the side do this project. Some things work and others don't, life keeps on rolling.
 
This idea looks much better suited to diesel. There are no problems with detonation there. The diagram shows an intake charge temperature of 230 C increasing to an in-cylinder charge temperature at 820 C which indicates a compression ratio of about 9.5:1 and which is way over the preignition temperature of gasoline/air mixtures of about 565 C. The only way to beat this would be to drastically lower the CR.
 
I think Gale Banks tried this, not sure if he suceeded though with the hot induction charge. Wouldn't the diesel fuel need to be vaporized in the manifold/port prior to the entrance to the chamber? If we run too high of a boost, or too small of a turbo the heat created doesn't do much besides plateau power production and sometimes goes down. I think the fuel would have to be injected prior ot the intake valves or valve to begin vaporization IMO if a heated induction charge, or non cooled system were used.
 
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