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

[revetec]

Hightower99

I think you are missing the fundamentals of power. Power is a calculation of torque considering RPM.
If we are to produce 200hp@5,500rpm then the torque is 191ftlb
If we are to produce 100hp@2,500rpm then the torque is 210ftlb

Acceleration is a direct link with the torque you have. So as a comparison you will get slightly better acceleration with the 100hp engine at 2,500rpm than the 200hp engine at 5,500rpm. One thing to note is that the engine producing 100hp@2,500rpm is using about 2/3 the fuel (2/3 the swept volume per minute) with a 2.4litre than the 200hp engine at 5,500rpm being 1.8litre.

At 1,200rpm we have 132ftlb (180Nm) of torque which is 30hp (22kW) and if accelerated in a vehicle to 3,000rpm which has 148ftlb (202Nm) which is producing 85hp (63kW) the average torque is about 140ftlb (190Nm) and average power of 57.5hp (42kW) throughout the rev range at full throttle.

Now driving the engine on the road. at the lower RPM ranges the engine with the higher torque off the mark will accelerated harder than the engine with the torque in the higher ranges. The benefit comes from a few things.
First: The feel of acceleration instantaneously off idle feels awesome and is very responsive which gives a feeling you are using more power than you actually have.
Second: This allows short shifting and a less tendency of the engine laboring up inclines in the lower RPM ranges which requires less down-shifting when driven (the taller the gear, the less revs and results in less fuel consumption.
Third: The lower RPM reduces fuel consumption due to the lower power required to accelerate or maintain speed.

If you look at a diesel engine in a truck. If you have a 250hp (186kW) engine with a peak torque of 596ftlb@2,200rpm (800Nm) the truck is quite able to pull a 10 tonne load. A petrol engine that produces 250hp or 186kW@6,000rpm has 218ftlb@6,000rpm (300Nm). Even though the power is the same, the pulling power is far less and that engine will not pull a 10 tonne load. If the capacity of the petrol engine is 2.0litre then the diesel engine at 5.4litre would have the same swept volume at their respective RPM values.

I don't want to argue the point too much, I just wanted to put it out there to you and others to think about. Our engine has unique characteristics that provide good acceleration at lower RPMs and thus uses less fuel in doing so.

BTW: Shane is waiting for you to call him on Skype or receiving an email.

[hightower99]

I have to say I am very disappointed in you Brad.

If you trully believe all that you wrote in your previous post then I really have lost some of my respect for you as a fellow inventor/engineer.

This is not the place to get into a big discussion about power and torque and there relation (as that has been done ad nauseum in other threads). However I would like to make a few counter-points (if you will) to put out there and I really hope that you will read what I have to say and actually think about it for awhile with an open mind (which requires that you completely forget the notion that you have in your head that you are right for just alittle while).

Power is a calculation of torque considering RPM.

While this is technically correct the implied context is not. Power is the rate at which work can be done. This means that if you have more power you can do one of two things: you can either do the same amount of work in less time or you can do more work in the same amount of time.

Acceleration is a direct link with the torque you have.

As that statement stands it is incorrect. There is no direct relation between engine torque and vehicle acceleration (i.e. 200lbs-ft. of torque does not incur the same rate of acceleration in all vehicles of the same mass). However there is a direct relation between torque at the wheels and acceleration and this is because torque at the wheels is a function of power. Acceleration has a direct relation to power, especially power at the wheels (i.e 200HP at the wheels will incur the same rate of acceleration in all vehicles of the same mass).

So as a comparison you will get slightly better acceleration with the 100hp engine at 2,500rpm than the 200hp engine at 5,500rpm.

Unfortunately this is also lacking in vital information to be valid in its own right (meaning it is not valid as it stands). If the speed is equal in both cases then the 200HP engined vehicle is producing greater torque at the wheels. Lets say the wheel speed is 1000RPM, then the 100HP engine can only produce 2.5 times the engine torque at the wheels (525lbs-ft.) but the 200HP engine is able to produce 5.5 times engine torque at the wheels (1050.5lbs-ft.). If the gearing is the same for both then the 200HP engine is traveling at much greater velocity then the 100HP engine and the comparison of rate of acceleration is no longer apples to apples.

If you look at a diesel engine in a truck. If you have a 250hp (186kW) engine with a peak torque of 596ftlb@2,200rpm (800Nm) the truck is quite able to pull a 10 tonne load. A petrol engine that produces 250hp or 186kW@6,000rpm has 218ftlb@6,000rpm (300Nm). Even though the power is the same, the pulling power is far less and that engine will not pull a 10 tonne load.

Unfortunately you are again totally incorrect. regardless of the RPM at which peak power occurs if you have two 250HP engines then they will perform exactly equally. This is basic physics. "There is no such thing as a free lunch" is the saying. A petrol engine that makes 250HP at 6000RPM is equally capable of hauling 10 tonnes as a diesel engine that makes 250HP at 2200RPM, all it needs is gearing that allows it to run at 6000RPM at the same vehicle speed as the diesel would be traveling at 2200RPM. Again if the wheel speed was 1000RPM then both engines would be able to produce 1313lbs-ft. at the wheels. (bare in mind the 250HP petrol engine is making closer to 218.83333lbs-ft. of torque at 6000RPM to make 250HP and the diesel is making 596.81818lbs-ft. at 2200RPM to make 250HP).

Shane is waiting for you to call him on Skype or receiving an email.

I have been quite busy lately (even though this is supposed to be a holiday week for me) I will get around to it quite soon though (within the next day or so).

[revetec]

There is no direct relation between engine torque and vehicle acceleration

Hmmmm...And you believe this to be true?

Twisting force is just that. How many times per minute is power. Half the force means that you need to do twice the RPM to achieve the same result.

Unfortunately there is friction between the tyres and the road and you cannot do double the RPMs if the vehicle is doing the same speed, unless you break traction or have an extra 2:1 gear ratio.

This is fine if you want to do twice the RPM through the gears which you are correct, but if the two engines are of the same capacity then your swept volume per minute has doubled.

I will again ask everyone on the way home from work to drive your vehicle in a selected gear (say 2nd) and bring the revs up to your engine's peak power and then give it full throttle and feel the acceleration. Then redo the test at peak torque or even half the revs and feel the acceleration. IT WILL BE GREATER. Yes the vehicle will be going a greater speed at the peak power which means more work is being done, but we are talking acceleration here and the power you will use at the better acceleration will be much lower than your peak power.

Again, Hightower99...Shane is waiting for your contact. Please talk to Shane before your next post.

[Alastor]

I will again ask everyone on the way home from work to drive your vehicle in a selected gear (say 2nd) and bring the revs up to your engine's peak power and then give it full throttle and feel the acceleration. Then redo the test at peak torque or even half the revs and feel the acceleration. IT WILL BE GREATER. Yes the vehicle will be going a greater speed at the peak power which means more work is being done, but we are talking acceleration here and the power you will use at the better acceleration will be much lower than your peak power.

This reasoning is flawed.

Let, Power = Torque x Speed

Assuming for a single gear that acceleration is directly proportional to torque, we can just look at torque.

So Acceleration = Torque, and Torque = Power / Speed

You are comparing different torque outputs, by varying both power and speed. How can you establish the influence of power on torque/acceleration when you don’t keep speed constant?

This question isn't unique to 'power vs torque'. It is a general question of engineering/scientific practice.

[revetec]

Alistor...Did you perform the test I described? Forget your reasoning, go try it in practice.

Can we agree that a constant acceleration is achievable with an engine that features a flat torque curve throughout a normal operational range?

Then can we agree that the acceleration in the lower half of the rev range uses less fuel than the top half of the rev range due to lower RPMs and swept volume per minute?

Can we also agree that we are producing less power in the lower RPM range.

Can we now agree that with a flat torque curve it is more economical to drive in the lower range if torque is constant?

Can we also agree that using an engine with higher torque down low provides enough pulling power to select a taller gear earlier and/or a taller final drive ratio, which then reduces engine RPMs and thus reduces fuel consumption.

And finally can we agree that higher torque in the lower RPM range provides good acceleration and performance, and we are able to use a taller gear ratio which reduces RPMs and fuel consumption.

[GTM]

Torque directly relates to acceleration.

I drove the trike with the X4 engine that produced a maximum 92hp but 180nm of torque across most of its usable engine rpm range, peaking to 200nm. Trike/X4 combination out accelerated a trike with an engine setup for out-right performance, an engine that made 220nm of torque @ 5500rpm and 185hp at near 6000rpm (I note Brad has got these figures quoted around the wrong way in a previous post).

At 2000 rpm the performance engine is producing approximately 80hp (I can't remember the torque figure), but the X4 with its 180nm essentially on tap at almost any engine speed out accelerated this trike combination.

For me the answer is torque, because nothing else in either trike is different, other than the engine. The transmission gear ratio, tyres, differential ratio etc. were identical.

For our group, the biggest benefit of the Revetec engine is that the X4 delivers substantial torque across the entire engine speed range, most importantly down low. There is no need to raise engine speed to where substantial torque is produced to get great acceleration, substantial torque is available at any engine speed.

After completing the test day, I have become a firm believer that torque is more important than horsepower. I made my decision based on my hands on experience.

For me, this link sums up my thoughts:
Yet another guide to Torque versus Horsepower versus Acceleration

Shane

[henk4]

For me, this link sums up my thoughts:
Yet another guide to Torque versus Horsepower versus Acceleration

Shane

It is like listening to Bob Ross explaining the workings of an engine....very convincing, thanks for that link.

[GTM]

Tommorrow I will post a report detailing what happened during our test day with the Revetec X4 engine in our trike.

Shane

[henk4]

Tommorrow I will post a report detailing what happened during our test day with the Revetec X4 engine in our trike.

Shane

Nice, and btw, welcome to UCP

[GTM]

Hi Henk, Thanks for the welcome. I posted here about 1 year ago. Since then I have watched this thread grow and I have read each person's perspective, opinions or arguements about theory and the Revetec engine technology.

I strongly support the Revetec technology and its advantages. I believe that the discussions held here are only the tip of the ice-berg. Once wider promotion of the technology is undertaken and the Revetec engine goes into production, I believe the Revetec X4 will spark a lot more discussions!

[hightower99]

Alastor: Thank you for pointing out the flaw in revetec's logic, comparing the rate of acceleration at two different speeds is not an apples to apples comparison.

Can we agree that a constant acceleration is achievable with an engine that features a flat torque curve throughout a normal operational range?

No we can't because that isn't true. Kinetic energy is 1/2 mass times velocity squared, running resistences (like aero drag. drivetrain friction ect.) also increase by velocity squared. If you had an engine with a completely flat torque curve it would still accelerate faster from 0-60km/h then it would from 100-150km/h. This is why comparing acceleration at two different speeds is not an apples to apples comparison.

Then can we agree that the acceleration in the lower half of the rev range uses less fuel than the top half of the rev range due to lower RPMs and swept volume per minute?

Yes but at lower RPM you will be making less power and you will not be able to do the same amount of work per unit time.


Welcome GTM aka Shane.

Thank you for answering one of my questions. If both the revetec and performance engined trike had the same transmission ratios and differential ratio, then didn't the revetec powered trike have a much lower top speed?

Did the revetec engine only rev up to 3000RPM?
If so did you have to change up quickly so as not to redline?

Thank you for the link but I find that it is lacking in several aspects. It keeps showing through the examples that higher power allows greater acceleration yet fails to mention that directly and tries to cloud the issue by only talking about torque. It also creates some odd contexts. It says that an engine that only makes 100lbs-ft. of torque will not be able to lift a 200lb weight (it underlines this point) then goes on to say that if a simple gear is added it will be able to lift the weight and it will be able to do it faster. This masks the underlying point that it is not engine torque that matters. It is torque to the wheels which is a function of power. He also notes that certain engines can create torque at 0RPM but fails to mention that they cannot move anything at 0RPM (he implies that they can but at 0RPM no power is generated and any torque generated can only be used to arrest motion).

Question: If engine torque is directly related to acceleration then somebody should be able to tell me how fast 200lbs-ft. of torque can accelerate a 1000lb vehicle?

Noone has been able to yet (without calculating power first).

However I can tell you how fast 200HP can accelerate a 1000lb vehicle because there is a direct relation between power and acceleration.

[Alastor]

Alistor...Did you perform the test I described? Forget your reasoning, go try it in practice.

I don’t need to try it, I understand your point.

I do not take issue with the results, it is with the deduction and conclusion of that line of reasoning.


My question is very simple. If you have three related variables (a,b, and, c) and you want to know what the influence of b is on a, how would you find this?


I would say that one would have to vary b and measure the change in a. However, to ensure this result is useful between two different systems of a,b, and c, then I would keep the third variable c constant while varying b.


The rest of your points, while valid, are beyond the scope of the problem above.

[GTM]

The top speed on the test day was around 100km/h (Engine speed approx. 2,700rpm - 4th gear). The top speed was limited because the road test was done on public roads, where the maximum speed is limited to 100km/h.

During the test day, we operated the X4 upto 4,000rpm.

Once the engine is returned from independant certified testing, it will be refitted to the trike and we will do the next round of testing. We intend to do a range of tests including 1/4 mile, 0-60km/h, 0-100km/h etc. timed acceleration tests, city environment fuel consumption tests etc.

[The Raptor]

Brad,
On page 70 of the Revetec prospectus on the NSX, It reads that an earlier/older inline-4 (I4) Revetec engine produced 925.2Nm of torque, this is verrry interesting to me as the current X4 only produces 200Nm odd.

1. Can you give some insight of the actual configuration of this engine that produced such figures ?
2. Has the X4 now been removed from the trike for shipment to Orbital ?
3. Will the independent testing as informed in a previous post be completed by the end of this month ?

I do see a light at the end of the Tunnel ....what will it be !
Maybe it will be a train .....POWERED by Revetec !!!

[hightower99]

During the test day, we operated the X4 upto 4,000rpm.

How did the revetec engine sound and feel being revved that high?

Once the engine is returned from independant certified testing, it will be refitted to the trike and we will do the next round of testing. We intend to do a range of tests including 1/4 mile, 0-60km/h, 0-100km/h etc. timed acceleration tests, city environment fuel consumption tests etc.

Well I will certainly looking forward to the results of those tests. Hopefully they will be published with the results of the same tests with the 185HP conventional engined trike?

Still I would be surprised if the actual tests showed that the revetec performs any better, except for the fuel consumption tests of course.