A work of pure genius! - Brilliant "Revetec" Engine

[Matra et Alpine]

With at least a couple of dozen manufactured and sold variable valve systems and some of those outside of patents then it's not that hard
Besides Revetec are there to sell the technology, so perhaps Rover (China) will buy and mate it to VVC


BTW the web site is AU, but ithe pic is from a media publication site. So what is the graph, what does it refer to and where's the original site url ?

[revetec]

For a start, the image you posted was not of Australian origin as we are Metric over here and don't use lb/bhp-h.

Can you post a link to that whole article please?

As a note: The graph you posted means nothing without full explanation as far as the air/fuel ratio during the test. It is very rare to find consistent fuel mixtures across a load range to WOT. Most engines run in closed loop at around 14.7:1 up to around 50-75% manifold loadings, although most engines run around 13.5:1 towards the WOT setting and they are not in closed loop rather than "Open Loop". It is easy to run 14.7:1 at WOT on a dynamometer and get a good BSFC figure but if you have programed fuel injection maps on the dyno, as you get to WOT you program the map, to produce the top power figure. At WOT this is not as lean as 14.7:1.

If we were to use a consistent air/fuel ratio throughout the rev and load ranges, you are correct and the graph is accurate. The problem is that I was quoting a real engine in a vehicle situation and you posted a graph that I assume is running a consistent air/fuel ratio on a dyno. It is ok to argue this point and I suppose the misunderstanding is my fault for not explaining the issue in full.

Looking at your graph from 50% load and an air/fuel ratio of 14.7:1 it uses 0.425lb/bhp-h. At 100% load and using a common WOT mixture as rich as 13.5:1 it would use about the same amount of fuel. This is a common situation.

One thing I have found from setting fuel mixtures on a dyno is that once you put the engine in a vehicle you have to adjust the fuel mixtures to that vehicle a 14.7:1 or lean mixture at WOT produces a surge type feel, which is eliminated by richening the mixture up to 13.5:1.

You may or may not agree with me, but this is why all electronic fuel management systems go into "Open Loop" at high loading situations. If 14.7:1 was optimal at WOT, there would be no need for "Open Loop"

Anyways, I apologize for my WOT BSFC comments as I was commenting on the typical engine Map from an on road vehicle set up which we had and was discussed when I was going through independent testing. Typically, from 75% load to WOT the pumping loss changes are minimal while a typical on road engine's fuel mixture is en-richened.

As a further note: I just went to the Pattakon website and looked at the data logger. At WOT they were using an air/fuel ratio in the higher rev ranges about 12.5:1. Not knocking them at all, this is normal as I have stated above. I would also assume that they would be closer to 14.7:1 with lower load. This data log was definitely in a vehicle while the graph that was posted would have been on a dyno test at 14.7:1 or close to it.

[revetec]

Now attached is a typical BSFC map for a 2 valve engine in a vehicle. Note the best BSFC position.



Taken from Alternative and Future Technologies
Please read this article because it is quite in-depth and interesting to those who understand it.

Note that the lowest BSFC is around 75% loading and 2,000rpm producing about 30% of peak power, which is exactly what we got in testing and quoted.

[jrobson]

I'll look around later see if I can find the site.

Rovers VVC isn't infinately variable is it? (By that I mean lift from 0-XXmm in infinate steps)

There are distinct advantages that a infinately variable top end add to the system:
1. At low lift(part throttle) there are no pumping losses, this means that your BSFC figures are more steady accross the load range and in real world driving you will certainly use less fuel since a lot of driving is done at low loads.
2. At low lift the valve springs are not compressed much, so much less energy lost there, you may argue that the valves return much of the energy, however there is some lost, lets not forget much lower friction.
3. You can idle at 300rpm, a lot of fuel is saved in traffic vs a engine idling at 850rpm-1000rpm and remember those poor BSFC figures when the engine is under very low load. In any developed country, even here in our undeveloped country A HUGE AMOUNT of driving is done in traffic everyday by the average person. (Let's take an example, engine with 250g/kwh @ 2000rpm 75% load and with an infinately variable head vs a 200g/kwh @ 2000rpm 75% load engine with conventional head, if you sit in traffic for 45minutes at 2% load a day which engine would use the most fuel?)
4. Engine response must be quite nice, btw how is response with your sluggish looking bottom end? No offense of course, just saying it "looks" sluggish

My opinion is that if you want to put BSFC figures out, compare it to the industry standard at 100% load and let it be what it is, but of course that is just my personal opinion. If your graph is indeed correct then it looks like your engine is right around the same level as a very good conventional engine, but I could be wrong, perhaps everyone is publishing 75% results and not 100???

Edit: Okay I just looked at your site again and "14.5:1 of 238g/kWh (34.4%)" that looks "pretty much the same" as a decent conventional engine to me at the same ratio. Sorry I was just scanning this forum, though you got 207g/kwh at 14.7:1.

[jrobson]

You running 2 valve heads?

[hightower99]

Yes they are best at 100%, everyone knows or should know that, your post shocks me, especially where you have the throttle at both 40% and 10% and still have 75% load!!

Theoretically yes they should be, but in the real world most engines run richer air:fuel ratios to protect the engine and make sure that no knocking occurs, which leads to worse SFC figures. In the real world the best SFC figures are achieved at the highest load that maintains closed loop control at 14.7:1 (or if Orbital is doing the testing 14.5:1).

SFC has nothing to do with real world driving, it means the engine create X amount of power for Y amount of fuel used,

Not quite. SFC means it takes X amount of fuel to produce Y amount of power per unit time. It is a direct measurement of the efficiency of the engine and therefore has quite alot to do with real world driving.

Honda did slightly better with their latest Vtec I believe called A-Vtec where instead of just adjusting lift it also adjusts timing, forget about ever getting a license though.

Honda VTEC systems have been able to change timing since 2001 (2002 in the US) with i-VTEC. One of the best valvetrain systems out there now is the BMW Valvetronic and VANOS technologies. Used together they provide infinitely variable lift control (the engine is throttled by the lift of the intake valves it no longer has a throttle valve) as well as infinitly variable timing.

read about it here:BMW Valvetronic

[hightower99]

One thing I have found from setting fuel mixtures on a dyno is that once you put the engine in a vehicle you have to adjust the fuel mixtures to that vehicle a 14.7:1 or lean mixture at WOT produces a surge type feel, which is eliminated by richening the mixture up to 13.5:1.

Can you explain this alittle more. What do you mean by a "surge type feel"? Normally maps are designed to use open-loop rich mixtures at WOT to protect the engine from knock.

You may or may not agree with me, but this is why all electronic fuel management systems go into "Open Loop" at high loading situations. If 14.7:1 was optimal at WOT, there would be no need for "Open Loop"

But running at stoichiometric (14.7:1) is optimal (even at WOT) the only reason it needs to be rich is because you don't want the engine to knock at high load, high RPM.

[Matra et Alpine]

Honda VTEC systems have been able to change timing since 2001 (2002 in the US) with i-VTEC.

Need to keep up to speed with innovations if you want to be designing your own, ht Honda's latest is A-VTEC and patent was published over a year ago.

While BMW certainly trumped the rest of the market on getting such a system into production, Honda’s additional years of research seem to have paid off with several advantages. Take a look at the drawings here - BMW World - Technology You will notice several things about BMW’s application. First, Valvetronic increases the height of the valvetrain and cylinder head quite substantially. Second, BMW’s intermediary actuator (I can’t quite call it a follower) is quite large, adding extra moving mass in the valvetrain (perhaps explaining the rpm limitations of the first generation Valvetronic engines). Finally, BMW’s implementation does not alter valve timing by moving the cam centerline. This means that in order to optimize low lift valve timing, BMW’s VANOS VTC system _must_ be applied as well to advance valve opening. By comparison, VTC control seems far less critical on A-VTEC. So, in summary, reduced size, mass and self regulating VTC all would appear to be advantages of A-VTEC over Valvetronic

[revetec]

Engine response must be quite nice, btw how is response with your sluggish looking bottom end? No offense of course, just saying it "looks" sluggish

You must understand that the "trilobe system" is running at only 1/3 engine speed. This means that the trilobes on acceleration require only 1/3 of the inertia. If you go to our website and look at the videos of the CCE2003 engine, we show the revving response. It revs quite fast and is not sluggish on any of our engines.

My opinion is that if you want to put BSFC figures out, compare it to the industry standard at 100% load and let it be what it is, but of course that is just my personal opinion. If your graph is indeed correct then it looks like your engine is right around the same level as a very good conventional engine, but I could be wrong, perhaps everyone is publishing 75% results and not 100???

100% load is not an industry standard. The common test is to the NED European standard which relates to real driving cycles. And most companies publish their best figure.

Edit: Okay I just looked at your site again and "14.5:1 of 238g/kWh (34.4%)" that looks "pretty much the same" as a decent conventional engine to me at the same ratio. Sorry I was just scanning this forum, though you got 207g/kwh at 14.7:1.

In the comparison note that I designed the heads in 2 weeks with no CFD. The heads are two valve and is a hydraulic lifter push rod design. Our next round of testing will incorporate a higher level of top end technology.

Our engine uses different piston acceleration and piston dwell than a conventional engine, and our engines have always run better on a leaner mixture. Most of the tests were done at 14.5:1 due to the standard required for optimal Catalytic Converter operation. 15.2:1 is like a top limit for a Cat. There are Cats out there that can operate at a leaner mixture so this is not a problem.

We would like to test leaner but in our first test it was not necessary from our results of 207g/kW-h. Normally a conventional engine power drops at 15.2:1 so it is not used under any serious loading, although, many engines these days run up to 17:1 A/F under prolonged cruise.

Finally note the graph you posted with the two valve and four valve engines. Even the four valve engine has the best BSFC at about 75% load.

Hightower99: I've heard many engines knock, and most commonly it occurs at lower RPMs such as accelerating from a standing start or in the transition from cruise speed to a heavy load. Both I would say it is most common in the 2,000-3,000rpm range. I'm not saying it doesn't occur at higher RPM, just from my experience from being an automotive mechanical engineer for 25years and driving thousands of cars, this is where I have mainly heard it.

[hightower99]

Need to keep up to speed with innovations if you want to be designing your own, ht Honda's latest is A-VTEC and patent was published over a year ago.

Well I was replying to the comment that it was only recently that VTEC was able to control timing. VTC is part of the i-VTEC system which has been around since 2001.

I do know about the speculation surrounding the A-VTEC system but as of yet, it hasn't been made yet. AFAIK the patent that they think is A-VTEC is from 2005. I figure it is somewhat moot trying to compare a patent application to current working production units, as the actual production system that honda brings out could be very different. I have to say that I dissagree with the notion that valvetronic increases cylinder head height significantly. The componants do look to be taller but they are still stuffed into roughly the same hieght. I also think it is abit of a cheap shot to mention that the valvetronic needs VANOS (like it's a bad thing) even though the valvetronic package includes VANOS as part of the complete package. Not to mention that Honda will undoubtably include VTC in A-VTEC.

I've heard many engines knock, and most commonly it occurs at lower RPMs such as accelerating from a standing start or in the transition from cruise speed to a heavy load. Both I would say it is most common in the 2,000-3,000rpm range. I'm not saying it doesn't occur at higher RPM, just from my experience from being an automotive mechanical engineer for 25years and driving thousands of cars, this is where I have mainly heard it.

Yes that is right. But i would say that it is easier to notice knocking at low RPM and that you absolutely wouldn't want it to occur at high RPM (where you might have 5-10 heavy knocks happen before you can react and let up). My point was that the reason that engines run open-loop rich at WOT is to protect against knock (at all speeds).

[revetec]

Yes that is right. But i would say that it is easier to notice knocking at low RPM and that you absolutely wouldn't want it to occur at high RPM (where you might have 5-10 heavy knocks happen before you can react and let up). My point was that the reason that engines run open-loop rich at WOT is to protect against knock (at all speeds).

To some degree you are correct. Basically a fuel map is set up to provide a mixture that is lean enough to provide the best performance while providing a level of emissions to an acceptable point. Compression ratio, fuel rating, combustion chamber design, fuel system, fuel mixture, ignition map, engine and combustion chamber temperature etc. all play a part in this scenario. Some engines are more prone to detonate due to their design, and also carbon build up is also a factor. A lower compression engine will not be as prone to detonation as a higher compression engine as well.

Maybe sweeping statements from either you or myself on this point will not be 100% correct, due to the amount of variables in this argument.

There is no doubt that a richer mixture will aid in reducing detonation, but also a higher octane fuel will also do the same thing. Get my point?

Basically you tune an engine to the highest performance with a reasonable level of emissions. Included in this process is not allowing the engine to detonate. A slightly leaner mixture than 14.7:1 usually gives the best power result, but a consideration has to be made to Nox as a leaner mixture usually produces higher Nox. Funny thing is that our engine produced less Nox at a leaner mixture, but this is probably a combustion chamber design issue.

Then the closed loop parameters are set to provide an air/fuel ratio that allows the Catalytic Converter to operate properly.

I suppose we were both looking at this the wrong way around. Open loop is usually the optimal power Vs emissions program, while closed loop is a fine tuning for the Cat and the lowest emissions, (instead of the argument that closed loop is the set mixture and a richer mixture in "Open Loop" is used to reduce detonation?) Correct?

[hightower99]

I suppose we were both looking at this the wrong way around. Open loop is usually the optimal power Vs emissions program, while closed loop is a fine tuning for the Cat and the lowest emissions, (instead of the argument that closed loop is the set mixture and a richer mixture in "Open Loop" is used to reduce detonation?) Correct?

I have to say I totally agree.

I think I am going to look at the issue of fueling like this in the future, makes it easier to explain to those that are not overly car-literate.

[Revetec Raptor]

Revetec, it's has been a long time between beers !

Even though I personally (& probably many others) have had blind faith for the past 11 years, the independent BSFC figures were great to finally receive.
It has stopped all communications from the technical geeks & knockers on this forum - speculation has given way to information.

The BSFC figures have had little effect, other than a small price spike for a day or so.
So, I find myself asking what is needed ?
I think the answer lays in not making excuses, but simply producing some figures of long-term operational reliability (road testing), correct me if I am wrong, this has not been done for 11 years ?

Congratulations Brad, you have done some wonderfully upgrades to your web site over the last 12 months.
However, during the time you have spend building the website facade of Revetec, you appear to have not even bothered seriously calculating on your solid edge software.
A small Aviation (PPG 100~500cc) V60 degree or inline engine, as one of the most desirable 4stroke aviation engines in the PPG industry appears to be very reliable. Most of the 2 stroke engines currently in this field, only appear to have a short rebuild life span.
The 4 stroke engine Bailey Aviation use appear to be leading the way for a while. They don't seem to have any significant technical figures other than the reliability factor and better fuel economy over a 2 stroke.

Brad, when you tell me Revetec is about to do a mass marketing campaign, I hope you don't mean a web site upgrade !
Why can't Revetec simply fit the current X4 into a vehicle & actually produce some long term operational reliability of the engine. I consider this to be the only news that will ignite some serious interest in the Revetec Technology.

All the faithful shareholders as well as the NSX are long overdue for some real update on what has been happening within Revetec !

[revetec]

Dear Raptor,

I think these type of questions are most suitable to be sent to me in an email. This is because this is a technical forum on the technology, not a bulletin board or Shareholder information resource for Revetec.

If I treated it as a bulletin Board or a Shareholder information resource outlet, I think the Administrators to Ultimatecarpage.com would not like it. I would like to adhere to their guidelines and remain an active poster in these pages.

Another reason is that I am not going to discuss on forums what our company strategy is, and why we do what we do, and when.

Any company questions other than technical ones maybe sent to me via email from our website.

I have mentioned this to you before Dennis in a phone conversation, and I'm not going to break the forum rules for your lack of following the correct procedure, when asking such questions. An email is as easy as posting on a forum.

If you have a technical question directly relating to our technology, I will do my up-most to respond.

[Revetec Raptor]

Dear Raptor,

I think these type of questions are most suitable to be sent to me in an email. This is because this is a technical forum on the technology, not a bulletin board or Shareholder information resource for Revetec.

If I treated it as a bulletin Board or a Shareholder information resource outlet, I think the Administrators to Ultimatecarpage.com would not like it. I would like to adhere to their guidelines and remain an active poster in these pages.

This is simply semantics when it suits Revetec ! (a bit like a wheel stand, sounds good - means nothing)
Drop the conspiracy theory by blaming others on the inability of Revetec to market itself professionally.

Another reason is that I am not going to discuss on forums what our company strategy is, and why we do what we do, and when.

Many many companies announce what their business strategies are to the public. Stop hiding behind what appears to be fast becoming 'welfare recipient technology'.
Pouting to this forum that you are only spending a few hours setting up the heads & 15 minutes to set up the new piston configurations, just prior to spending $50`000 for Orbital to test the engine, makes Revetec appear incompetent & brain dead ...to say the least.
If/when the money dries up from the government grant or John L, I wonder what will become of Revetec !

Any company questions other than technical ones maybe sent to me via email from our website.

On the website we see old photos of a Revetec engine being fitted into a vehicle. I/ we have introduced hundreds of people to the Revetec technology and have found that most people are not stupid to understanding technology. The two most common questions are, "is it like a Rotary engine" or "has it been tested in a vehicle" !
So, why have we not heard of any engine reliability feedback ? An engine in a trike doing wheel stands is spin and bravado. Here is a revolutionary idea how about you show it simply being run in a vehicle ?
Also, why have all the previous engines not been tested for reliability ?

I have mentioned this to you before Dennis in a phone conversation, and I'm not going to break the forum rules for your lack of following the correct procedure, when asking such questions. An email is as easy as posting on a forum.

What you say to a shareholder should be public, unless you are talking about verbal marketing (pie in the sky conversations) that have no foundation on current reality !
We have always been sceptical to the fact we don't get any detailed minutes nor video (we see a video in the photos) from any previous shareholders meetings. It is not sufficient to satisfy the demands and obligations required by revetec to their shareholders. Inadequate one line spin, that leave us thinking, why is it more convenient to hold shareholders meetings on the Goldcoast ?

If you have a technical question directly relating to our technology, I will do my up-most to respond.

YEAH !