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

[pneumatic]

Brad,

This is the claim on your website that pi**ed off a lot of engineers, because they hate seeing people claiming to cheat science.

The power output is similar to a conventional engine, but given that the significant improvement in torque output is almost three times that of a conventional engine

For the power output to be the same, but one engine to have 3 times the torque, that engine must also then produce that torque at 1/3 of the rpm.

This is not open for arguement, it is the laws of physics / engineering / science.

The point is an engine that produces 3 times the torque at 1/3 the rpm is NOT better than the engine it is compared against. If you produce 50kW you produce 50kW. All it means is the engine that produces the 3xtorque at 1/3rpm must be geared 3 times higher to be capable of achieving the same vehicle speeds. If this is done the acceleration of both will be the same.

That also cannot be argued. So us engineers have said the marketing is misleading, because it doesn't tell the general population that 3 times the torque at 1/3 the rpm is NOT any better. It is just different.

From what you have said above, the revetec now gears up the output shaft 3:1. Therefore this 3xtorque has now been reduced to 1xtorque, and the 1/3rpm has been increased to 1xrpm. So with the 3:1 gearing the rpms, torques and powers are now comparable to a conventional engine. This is what I and others have been saying the whole way along.

You have to realise that when the general public (and the first 6 pages of this thread) read your marketing documents, they think your engine is 300% more efficient / better than a conventional engine - which is not correct.

[revetec]

Dear Pneumatic,

Our engine does some funny things, some of which we can't explain. One is that at a constant lambda set to the fuel mixture of 14.7:1 the fuel consumpton decreases with revs and load.

I don't know whether you are familiar with Wayne Jones (previously from Bert Jones racing cams, Joint owner of Haltech and now engine tuner for a lot of race teams including the Stones Brothers) but he has been our leading programmer for years back to our Motec association. Everytime we get someone involved such as Haltech he states to new consultants to forget everything they know about engine maps in fuel and spark.

Our fuel map drops off as load and speed are increased. Our engine also likes alot of ignition timing. Our piston is over twice as high in the cylinder at the same degree of rotation when the spark plug fires. We also do not need as much enrichment on cold starts (Usually 1/4 of a conventional engine). Due to this fact the fuel molecules are closer together when ignition takes place and being so oversquare and having such a large piston dwell we have found better heat soak in the next firing cycle. All this and other factors that are different have caused us to experience many characteristics that are beneficial but were also unexpected.

Due to our budget we have been concentrating on refining mechanical layouts and even though we have experienced so very unusual and exciting benefits we have not had the budget to revisit and prove many of the findings in actual tests.

Can I also state that in our tests power and torque have not been like your and my understandings of engineering suggests they should be. In one test maximum torque was at 1,800rpm and held steady to 4,200rpm even though the power curve was similar to a conventional engine. This is why it is very exciting times.

Yes the fuel used and fuel flow rate did not change much although the revs at full load doubled. Very hard for me to believe as I didn't expect that it would be as good as that due to my calculations to use 30% less. This was proved in Mahindra's engine test centre which has 7 Dyno rooms. I can't wait for the next round of trials with our 1350cc engine and our new engine currently in design which should be finished around Xmas if the grant comes though in two weeks.

[revetec]

BTW: We are planning to trial cams with 1.6:1/1.7:1 and 1.9:1 conrod ratios in our next engine which will have the same bore/stroke and setups. Hope to publish this data here when I get it so we can all see the difference in performance and characterists.

[revetec]

Dear Pneumatic,

As for the 300% more torque it depends on the setup of our engine. Many analysis' have been done on our design and the one that is shown is a low rev setup (from 2003) which we do not use now due to our automotive setup for our clients programs.

We can alter the torque lever to a great degree. Although testing of these setups have been performed, such radical setups won't make it to production. I will get an update to our current setup soon on our website. We are currently increasing torque by cam design picking up around 30% torque across the range. The previous setup does not suit any current project due to the low speed torque handling of transmissions limitations so we are not pursuing this characteristic and setup of such an engine currently. We did have an engine which is currently at Mahindra for training purposes that is 450cc and produces a peak torque of 78Nm at 1,800rpm. Again this engine is purly for pushing the envelope in design and has been disassembled in my presence 2 weeks ago where I also trained their staff on the technology limits.

[pneumatic]

Can I also state that in our tests power and torque have not been like your and my understandings of engineering suggests they should be. In one test maximum torque was at 1,800rpm and held steady to 4,200rpm even though the power curve was similar to a conventional engine.

This doesn't make sense, because the dyno only measures torque and rpm. So you cannot get a power curve that disagrees with the torque curve. Because the dyno calculates the power from the torque.

So if your power curve doesn't match your torque curve, then your dyno is not working (performing the calculations) properly.

Well designed conventional engines get relatively flat torque curves too. The torque curve of the V6 in my car has only about a 10% variation between 2,500rpm and 6,000rpm. All it has is a 4-stage variable length intake. All standard Mazda stuff. It therefore produces a fairly linear power curve.

Maybe I need to sign a confidentiality agreement and have a look at your numbers for you

[revetec]

It does make sense! As RPM's increase the torque stays flat so the calculation of power increases with revs.

See the torque lever is high initially due to higher initial mechanical advantage to the output shaft. So we have higher torque at lower RPM's and hold it. As RPM's increase, power increases. Our biggest benefit is at part throttle at cruise when the peak pressure is very early in the stroke due to a lean mixture being ignitied at a high advance. Providing an earlier good mechanical transfer is of huge benefit.

I might say now that our last engine had a stroke of only 50mm (A conventional engine would have a torque lever of 25mm) but produced a torque lever of around 80mm over almost 80% of the piston stroke whereas a conventional engine produces a good torque lever over about 30% of its stroke.

[santostripoli]

Gents

The best thing for all parties is for the two of you to get together. Pneumatic, are you in Brisbane, yes or no? If yes, then meet up with Brad. Please contact him at his office and meet up and discuss these issues.

Now, as soon as you have both reviewed the stats and the technology, you can get back on to this forum tell us simple folk what it all means.

I want to know whether or not it is worth following this or not.

[revetec]

We are achieving this flat torque curve without variable length intakes or variable valve timing. My dyno is very acurate and has been independantly checked, calibrated and certified. We are simply maximising the pressure in the cylinder transfered to the output shaft whereas a crank can only do so much. We also defect a further 60% of downforce on a main bearing journal into rotational force (Let that one mess with your minds) wasting only 11% in downforce instead of 26%.

[revetec]

Yeah! Lets get together and chew some fat. I have proved to many universities and around a dozen engine manufacturers that losses in an engine don't work out. Probably the biggest is frictional losses. I have argued that most friction causes heat and is measured in the heat loss measurements. Mechanical inefficiencies are the biggest losses. I'll explain....valve springs create resistance to move and consume power, so does the crank as you can imagine that at 20 degrees ATDC that the torque lever is small but the cylinder pressure is high which is a big loss in mechanical efficiency. A piston rubbing on a cylinder bore Whereas the friction causes heat is measured elsewhere such as the cooling system heat loss. My original pitch addressed calculating all the losses and I found a 26% void in the calculation that didn't address the engines mechanics. I have proved this to every engine and car company I have met. Pneumatic is not the only person who has challegned me on points like the ones he has posed. I had the same arguement with the GM of a Japanese car manufacturers' R&D department when they asked me over to Japan to talk. I quickly explained the function and losses of an engine and he had to agree with me, which he did begrudgingly.

[pneumatic]

The laws of science still hold. If something seems unexplainable it just means it hasn't been explained yet, not that it can't be explained

If you have Excel 2000 or better on your computer than go here and download this very detailed spreadsheet program I have developed;
http://www.offroadvw.net/exceldyno/

If you play with that for a bit, and mess around with engines with 300% torque at 1/3rpm and 3 times taller gearboxes, you also see everything I said is true. It will help some people understand how changing certain things effects the vehicle.

You also see on the engine sheet that you don't need to enter both power and torque, because one is simply calculated from the other.

A visit is probably premature at the moment. I just need to look at test data.

[revetec]

I have an excel spreadsheet I have developed that I already use for calculations.

It calculates trilobe cam design, VE predictions and calcs, power estimations, engine dynamics including side thrust and piston position/accelerations and velocities, injector selection, ram or organ tube optimum lengths, valve and port size selection and lift, valve cam selection, standard gearbox data and selections with predicted speeds, vehicle performance as well as 1/4 mile,, plus heaps more.

Everything you need to design a Revetec or standard engine. It's a work in progress so it's not quite fully linked yet but 90% there. Thanks anyway!

[pneumatic]

Everything you need to design a Revetec or standard engine.

Would be interesting to see that spreadsheet, if you ever decide to release it to the masses

I guess we will have to wait until you release more test data. Arguing the theory side of things is pointless without some test data backing things up.

[manolis]

A few corrections

Brad, in your acceleration versus conrod to stroke ratio there are two errors:
As Alastor wrote, the acceleration curve for 100 mm conrod is wrong.
Also the factor 1000 in the Y-axis title is mistaken too. The correct is 1,000,000.
Here is the corrected plot.



Brad, the conrod to stroke ratio has no effect on the mean piston speed. Only the maximum piston speed is increased for shorter conrod.

And Brad, as shown in the plot above, conrod to stroke ratio smaller than 1.5 increases even more the velocity around TDC while BDC dwell increases. But the thrust loads and the need for strong piston (i.e. heavy piston) imposes limits for the minimum conrod length.

Brad's / Revetec's work is important and respectable. They try to get in practice a different kinematic mechanism for the internal combustion engines.


PRE engine

Pattakon’s VVA has infinite modes of operation (as compared with the two only modes the Honda’s VTEC system provides), selected directly by driver’s right foot. So the conrod to stroke ratio, which may not be the perfect one for a specific valve lift profile, can be rectified by pattakon’s VVA system throughout the entire rev range. So, the pattakon PRE (pulling rod engine) combined to the pattakon VVA system seems a good solution. Another solution is the valve-less version of PRE engine.
Supercharging is always an option for the PRE, but the NA engine is simpler.

http://www.pattakon.com/pre/PRE13.exe
http://www.pattakon.com/pre/PRE14.exe
http://www.pattakon.com/pre/blueprint.pdf

If the total efficiency (due to improved combustion) and the pick power and the torque distribution are improved with the PRE engine, then who cares about the optimisation of particular factors like conrod to stroke ratio.


Harmonic engine

Pattakon has experience in making harmonic piston engines. A few photos are shown at http://www.pattakon.com/ppe/ppe.htm) . Here it is a single cylinder prototype, made more than 10 years ago.



It is completely vibration free (it can stand free on the floor, revving from 1000 to 9000 rpm, without any tendency to move). It was tested providing 3 Kp*m of torque around 3500 rpm from 354cc (bore 75mm, stroke 80mm). Info concerning this prototype is at www.pattakon.com/educ/harmonic.exe (details at selection 15). It seems it manages breathing too well for an 'infinite' rod - or pure sinusoidal - piston motion.


Pattakon's GRECO engine

I respect Brad's claim that he has to keep revetec's secrets.
But the rest ones don't. So they can comment the following.

Pattakon's GRECO crankless engine basic mechanism versus Revetec's (for the same piston stroke):


Pattakon's GRECO single cylinder.It is actualy made by two pieces, a shaft (or call it cam-shaft) and a piston having some Yoke roller bearings on it. That simple. That short. No need for a single gear.


The application of the previous in a four in line GRECO engine having a unique shaft


Pattakon's 8 cylinder in H arrengement GRECO engine having two counter-rotating camshafts


At http://www.pattakon.com/greco/index.html you can download some 20 animations regarding various arrangents and details of GRECO.


On the other hand, the PRE engine uses current - tested technology.

Thanks
Manolis Pattakos

[manolis]

Compared to the unconventional crankless engines like Revetec's trilobe, Pattakon's single lobe GRECO etc designs, Pattakon-PRE engine may seem as a very conventional design.

But think of a Junkers-PRE engine (with Otto or Diesel cycle). Like this one:



What do you think about its power concentration, its thermal efficiency, its reliability , its smoothness and its peak power rpm?

If it is as good as theory says, the next step is to think of an application like this:



Thanks
Manolis Pattakos

[pneumatic]

But think of a Junkers-PRE engine (with Otto or Diesel cycle). Like this one:

It's like a 4 cylinder 2-stroke with reed valves, and where 2 cylinders are supercharging the other 2. The not so pretty part is connecting the two cranks together to keep them in synch.