Hey guys, I had some thoughts regarding the reliablity of the TT V35. Let me know what you think.

Often many people simply say that forced induction is bad for an engine out of ignorance or group think. As a former aircraft mechanic, I can tell you EXACTLY what is bad for an engine. I have seen some engines go 4000 hours between overhauls (and then, only valves replaced) and others make it less than 300. The key component of these, regardless of forced induction, was fuel management, more precicely, EGT and CHT. As you may or may not know, detonation causes the cylinder head temperature (a thermal barrier between the cylinder and the exhaust gasses) to become disrupted. This can destroy and engine in seconds because the very hot EGT is transfered directly to the cylinder, and the resulting metalurgy is affected (IE, holes in the cylinder, skuffs in the walls, etc) The best solution to this issue in aviation up until recently is been to run pig rich, where the excess fuel causes lower EGTS and lower CHT's. The negative aspect to this is fouled plugs, valve deposits, and much higher fuel consumption.
Up until recently (not including the big radials of WW2), the only way to run a fuel injected a/c engine was on the rich side of the EGT graph

due to the poorly distributed air and fuel (remember, one **** for fuel and non aerodynamic intake manifold) A company devoloped injectors for Lycoming engines which, through a bunch of techno mumbo jumbo, evens the distribution. This allows one to run on the lean side of the EGT curve, where the excess air, not fuel, cools the EGT and the resulting CHT. What occurs is a cleaner burn, lower fuel consumption, and longer engine life.
Well, what does all this mean for the V35. I think that the knowledge from aviation can certainly carry over to the automotive applications in that, if we can monitor each CHT and each cylinders EGT, we can adjust the a/f ratio of each cylinder and not just the engine (keep in mind that some distributions of a/f are so lousy that an engine is essentially 6 small engines running in parrallel) With this technology, we can encorportate a "cruise mode" that will run on the lean side of the curve, resulting in lower emmissions, lower fuel consumptions, and longer engine life. By altering the a/f of each cylinder, we can make reliablity of forced induction applications a reality. Let me know what you think

 

are you posting this in every forum?

 

Per the advice of someone, I thought itd be better suited for the tech forum

 

Yes, there is a FI forum as a subforum of this one. Try that.

 

haha, ill just leave it here so as to not bother anyone with a triple post! Mods feel free to move it

 

Your method seems to essentially describe the work already done on lean burning, direct injection, gasoline engines (though not specific to forced induction). From what I’ve read, low RPM cruising can be accomplished with very lean burns. However, this over taxes the exhaust catalysts and effectively poisons them (from too much NOx emissions I believe). Because of emissions, lean burning cannot be used in gas-powered American automobiles unless you can clean up the exhaust.

There is a solution however. The catalysts can be “washed” with a brief, really rich injector session. The unburned gasoline will remove the NOx through some chemical process if you don’t let the NOx sit too long. An extra sequence of catalyst may be required beyond what is typical to then catalyze the wash, I can’t remember.

Unfortunately this technique can only work in the absence of sulfur (don’t remember why, but some kind of catalyst poisoning I assume). Unfortunately USA gasoline has too much of sulfur, which I believe is scheduled to be rectified by new fuel standards around 2007. Around then, expect a few direct injection gasoline cars capable of ultra-lean burn cruising.

So there you go. If I remembered this stuff correctly, we can’t have cars that do this unless:

A-Emissions standards are lowered
Or
B-Sulfur is almost completely eliminated in gasoline

Sulfur is also being phased out of diesel too, which will be great. It might even become cool to have diesel engine (or turbine) sports cars.

--
Jeff

 

Actually, the leaner mixture burns less harmfully emissions I believe (my experience with fouled valves and cleaning the undersides of A/C burning rich mixtures. It is interesting to hear that the sulfur is a large component in the lean burning mix, however, dont most tuning guys simply take cats out anyway? Every conversation that I have read or heard of describing the lean mix almost always mentions the increase EGT as a result, but never the other side of the curve. Just curious if any of this has been accomplished in automotive technology

 

I think the NOx emissions are clean looking, but in fact are dangerous for the environment (not dangerous for the engine). Most of the carbon goes towards making carbon dioxide rather than sooty deposits during a lean burn. However the NOx family of emissions contributes to acid rain, even if it’s just an invisible gas in the exhaust. That’s why car manufactures go for stoichiometric burns. My guess is that airplane regulations are more lax compared to cars in terms of emissions since the margin of safety is much smaller relative to the danger of mechanical failure. Again, this is all coming from my vague recollection of engine technology stuff that I’ve read.

Now if you’re talking about tuning a car, that’s a completely different story as emissions laws are thrown out the window by most modders. However, it’s hard to build a business model around a technology that is not street legal. I think there would need to be a fair amount of research to develop a lean burning, FI, gasoline engine mod that is not concerned with emissions. And research costs money.

--
Jeff

 

Scorch

Good post, I was thinking of doing the same myself. You got those pics from John Deakin's articles on engine management. I am avid pilot myself ad strong proponenet of running LOP (lean of peak). John Deaking is God to me when it comes to experienced pilots and true understanding of the engine operation. I am also a big fan of George Braly's injectors, a great $800 upgrade! can't wait for his upcoming ignition system to finally bring the aircraft engines into the new age from the old-age of fixed timings/etc.

However, as far as car engines are concerned, they all operate ROP (rich of peak), especially in open-loop mode. There is no escaping it. The whole idea is to control EGT's, but in this case we can only do it via ROP operation, and just need to make sure the CHTs are low enough. Heat dissipation is not ofthe same concern as it is in airplane engines, as we have a far more efficient water cooling system rather than air-cooling. Neither is fuel economy, as we do not operate it at WOT like we do with plane engines.

Enjoyed your post. Miss flying (no money now). Miss my J35 Bonanza (lost in an accident in Vegas - engine failure).

Gurgen

 

Ah! Good to see a fellow pilot! Deakin is a great guy! really shifting some paridigms around the av world! I would think that the cooling issue could be controlled especially if the LOP mode was used in highway cruise. I fly a F33 bonanza, sorry to hear about your loss, if youre ever on the east coast, lets go flying!

 

Great! I would love to. I am hardly ever on the east coast, but would love to see your plane sometime!!!! Cheers

Gurgen

 

I dug up an old post I wrote on another newsgroup a long time ago that discussed direct injection. Turns out I described to you the catalyst tech. slightly wrong, but the sulfur issue remains.

Here's the old post. FYI, this post deals with a silly rumor that was going around back during the pre-order days that the 350z might have direct injection.


====BEGIN ANCIENT POST==========

I did some research into direct injection. This post is long and boring so I’ll go ahead and drop the punch line for those that want to know what the heck I’m trying to say without reading the whole thing:

The 350Z could conceivably have direct injection in the US even with our high sulfur content fuel. It just wouldn’t have as good a fuel efficiency as a Japanese or European spec (lean burning) direct injection car. (This is total speculation and I doubt the Z will actually have direct injection.)


Now for the long, boring stuff:

Basically, direct injection can provide 2 benefits:

1.) Improved intake and combustion
2.) Improved efficiency


I won’t dwell on benefit number 1 since it’s well covered on the following website:

http://www.mitsubishi-motors.co.jp/i...GDI/page1.html


However, I will point out that from a performance standpoint one of the best parts about the improved combustion is that the possibility that detonation (knock) would be reduced.


Now benefit number 2 relies on the fact that you can run the engine incredibly lean without stalling or running rough. Running lean essentially means that you have way more air in the cylinder than you need. You basically burn every last drop of fuel when you run lean.

Unfortunately, this does some weird things to the chemistry of the exhaust. When you run lean, you get a lot of NOx (the x is a placeholder for a 1 or a 2). This stuff causes smog and acid rain and some other bad stuff. Therefore, the US gov makes car manufacturers use catalytic converters to convert the NOx into nitrogen gas and oxygen. There are two types of catalytic converters btw. A reduction catalytic converter is for breaking down NOx and an oxidation catalytic converter is for burning fuel that didn’t explode in the cylinder. All cars have both. More info on catalytic converters:


http://www.howstuffworks.com/catalytic-converter.htm

http://www.swri.org/10light/catalyst.htm


So basically burning lean is completely ok to do as long as you clean up the NOx afterwards. Now here’s where the often quoted “sulfur problem” with US gasoline comes in.

The US has very lax restrictions on sulfur contaminants in gasoline. This wouldn’t be a bad thing except for the smell. What is bad is what happens to sulfur when you’re running your engine lean. The sulfur will oxidize and form SO2. Then, when the SO2 goes through the reduction catalytic converter it turns into SO3. Once it does this, it creates a film on the catalytic converter in the form of sulfates. The film blocks the catalyst from working the way it is supposed to and pollution blows right by into the atmosphere. This sulfate film is the reason we don’t have direct injection in the US yet.

Contrary to what I’ve been told before, the sulfate film does not result in permanent damage and can be “washed” off by running the engine rich for a little while (unburned fuel goes through the catalysts). The downside of this technique is you cancel out the efficiency gains of running lean. Also, washing the sulfates with gasoline creates hydrogen sulfide that will smell like a nasty, rotten egg fart.


So what can be done? Well, simply remove the sulfur from the fuel! The USA is slowly phasing out sulfur content in gasoline. So probably by 2008 we can have lean burning direct injection engines.

Does the sulfur problem guarantee that we won’t have direct injection? I still can’t figure it out for sure but here’s what I think. Basically, my idea is why not have direct injection but just not ever run the engine lean? You get the benefits of knock reduction and improved combustion. The only thing you sacrifice is gas mileage when you are cruising (when the fuel injection could go lean). See, direct injection engines only run lean when you’re going a steady speed. As soon as you accelerate you go to a perfect balance of air and fuel (stoichiometric) or if you accelerate even harder you go rich. So if you were driving a sports car like it should be driven, you’d never go lean anyways!

And just to re-cap, here’s the punch line again:


The 350Z could conceivably have direct injection in the US even with our high sulfur content fuel. It just wouldn’t have as good a fuel efficiency as a Japanese or European spec (lean burning) direct injection car. (This is total speculation and I doubt the Z will actually have direct injection.)


--
Jeff