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

[revetec]

"GTM
POST 823 The top speed on the test day was around 100km/h (Engine speed approx. 2,700rpm - 4th gear).
GTM
POST 835 The current slated top speed fo the Revetec X4 in the trike is 180km/h, based on Revetec's internal dyno results."

So, GTM do you think the trike could of achieved 80% more speed with the last 1300 rpm ? or do you have a 6,7 speed gear box?
Also I must say I am very surprised you have posted this and not Revetec.

Dear 3yearshareholder,
Can you remember that the current setup is for aircraft.
A full rev range will be available for GTM trikes with minor modifications such as camshafts ground to an automotive type rev range and the Engine Control Module programmed to suit. The current camshafts have been ground to provide maximum torque at 3,000rpm and maximum power at 3,500rpm. This is not a limitation, it is a designed operating range for the aircraft market. Over 3,500rpm a propeller (that is commonly used) becomes inefficient due to cavitation. The requested rev range from GTM trikes is 5,500-6,000rpm which we have previously achieved, and will provide. Also as a note we have performed our latest update, shedding 40% of the piston's weight while maintaining the same strength as well as raising the compression ratio. The results of this update will show in the independent certified testing of the X4v2 engine.

[revetec]

Keeping the same wheel diameter the engine RPM with the new transmission in 5th gear@250kph will be revving about 5,250rpm for everyones info, not that I want to go 250kph (my heart isn't that big) and our road rules prohibit it. Keep driving safely!

Shane: What is the highest speed you have driven on one of your trikes?

[GTM]

On one of our trikes with a performance 1776cc engine fitted, I rode to a top speed of 170km/h, maintained that speed for about 1 minute or little less, then slowed down. Gordon was riding the second trike at the same time and we both did the same speed.

With the new transaxle, the top speed is slated at 180km/h, achieved at an engine speed around 3,800rpm. Our new instrumentation has a speed limiter built-in which will activate at 180km/h (our current plan speed). The fifth gear ratio was choose for fuel economy reasons and not for achieving a specific top speed.

[hightower99]

Revetec:I don't quite understand your point about power per swept volume? I would like to point out that the 110HP I was referring to is at the wheel, Suzuki 600cc engines have made 110HP at the crank since 1999, also note that the 2006 GSX-R600 makes 125HP at the crank and peak power occurs at 13500RPM (16000RPM is redline) meaning that even when the MC engine is sweeping significantly less volume per minute (4050L/min vs. 4200L/min) it makes 31.6% more power and a whopping 36.7% more power per L/min of swept volume.

You then go on to explain that the revetec is somehow at a disadvantage because it only has 2VPC and "mild cam grind".

What you completely fail to mention that the X4 is 2.4L displacement and the MC engine is only 600cc. Your engine doesn't need 4VPC and high performance cam grind to achieve good VE at the low RPM you are achieving and I doubt you will be able to get much better performance out of a 4VPC head.

Mind you if the "automotive" style X4 is capable of revving to 6000RPM then you will be able to get more from 4VPC heads as well as variable technologies.

[hightower99]

Keeping the same wheel diameter the engine RPM with the new transmission in 5th gear@250kph will be revving about 5,250rpm for everyones info, not that I want to go 250kph (my heart isn't that big) and our road rules prohibit it. Keep driving safely!

Not that 95HP is even close to enough to propel the trike to anywhere close to 250km/h...

I think the projected 180km/h topspeed is abit optimistic aswell.

140km/h sounds about right.

[drakkie]

Not that 95HP is even close to enough to propel the trike to anywhere close to 250km/h...

I think the projected 180km/h topspeed is abit optimistic aswell.

140km/h sounds about right.

I'd love to see the Matlab files of this one. Is there any way you can send the m-files with calculations to me ?

[GTM]

Not that 95HP is even close to enough to propel the trike to anywhere close to 250km/h...

I think the projected 180km/h topspeed is abit optimistic aswell.

140km/h sounds about right.

Our original series of production trikes were fitted with 50hp VW 1600 engines. The VW Type 1 - 1600 engines were manufactured by VW Mexico (as a new engine for their beetle production). This series of trikes reached a top speed of 140km/h. This top speed figure is stated on our first DOT ADR Approval. Our independant engineer at the time rode the laden homologation trike to this top speed. We reached this top speed many times through our own riding experience.
The Mexican VW 1600 engine produced 50hp @ 4000rpm (VW factory spec's) at the flywheel.

HT, your 'subjective comments' show you are bias against the Revetec engine regardless what information is put up.

[hightower99]

If that is the case (140km/h achieved with 50HP engines) then 180km/h sounds about right with the revetec.

It seems that the running resistences of your trikes are less than I thought.

[GTM]

If that is the case (140km/h achieved with 50HP engines) then 180km/h sounds about right with the revetec.

It seems that the running resistences of your trikes are less than I thought.

Ahhh, that must explain it. Thank goodness the trikes have a lower running resistence then you thought, the Revetec engine with its 95hp is saved. You probably thought, really how can any vehicle powered by an engine with just 50hp reach these speeds. I guess you thought that would justify your original statements?

There are many vehicles powered by engines producing 50hp that achieved top speeds within this range:

1950's-1970's VW Beetle models powered by the 50hp engines had a factory rated top speed of 135km/h. The acceleration wasn't the greatest but they can, would and did achieve this top speed.

Karmann Ghia models powered by the 50hp engine had a factory rated top speed of between 135 - 148 km/h depending on the model and country designation.

Porsche 356 1600 (1956) - powered by a massaged 1600 producing 59hp had a top speed of 163 km/h.


HT, your 'subjective comments' show you are bias against the Revetec engine regardless what information is put up.

[revetec]

Not that 95HP is even close to enough to propel the trike to anywhere close to 250km/h...

I think the projected 180km/h topspeed is abit optimistic aswell.

140km/h sounds about right.

I don't know whether you actually read this forum properly or have been to our website and/or actually understand what power actually is and how it's arrived at. I suppose I'll give you a concession since you are a student.

We have a government grant to design, build and test an aircraft engine. This is the setup we currently have. Two of our previous prototypes has had 4 valves per cylinder. In aircraft it is not desirable to use any cam chains or belts due to reliability. The market also requires a more simplistic engine due to the maintenance procedures. They also require an operating rev range of around 3,000rpm due to the propeller speed.

If you have an engine that is set up for aircraft you need to provide the above. The 3,000rpm in some models is done with a reduction box to the prop in some engines such as Rotax. This adds to the cost and is generally done on very small capacity engines.

At 3,000rpm you are limited to the power that you can produce. Let's look at the R600 engine and if we were to use it in aircraft doing 3,000rpm the power is 16hp and 22ftlb. Even geared at the commonly used 2:1 gearing the figure is 40hp and 35ftlb. I know this means not much as the R600 is not an aircraft engine and the X4v2 is currently not an automotive or motorcycle engine.

My point is that at 3,000rpm 95hp is an aircraft setup engine. When we modify the camshafts etc to provide a good performing engine to 6,000rpm then the power will increase as power is a calculation of torque and RPM. The higher the RPM the engine is designed for, the more power you can produce.

By my calculation spreadsheet running a standard type automotive camshaft we should be producing 193hp@6,000rpm using existing top end at a volumetric efficiency of 90%. We could improve on this with a performance camshaft. But at the moment we have an aircraft setup as per our development project and Federal Government Grant.

So why did we test in the GTM trike? Firstly it's good to see the high torque in the lower rev ranges on the dyno, but it gives no feel how the engine acceleration actually feels. We needed to put the engine on the road to gauge the characteristic we have achieved. After driving it for the first time I was very impressed with the acceleration and I wanted GTM trikes to fly over and test it as a comparison to what they are currently using. Like myself, they were also impressed with the off line performance, and it gave them an insight into what our engine's characteristic would be when supplied. The increase in acceleration has led them to their own development program to integrate the X4 series engines into their product. The increase in low down torque has led them to investigate other transmissions to maximise the characteristics into their product.

I'll honestly say that the engine accelerates off the mark like no other engine I have ever driven. The light throttle response has to be experienced to believed. The torque is incredible an does not require an aggressive style of driving to produce a hard acceleration. This at first is a driving characteristic you have to adapt to, consciously not opening the throttle wide open on take off and gear changes.

[hightower99]

You probably thought, really how can any vehicle powered by an engine with just 50hp reach these speeds.

Nope I never thought that at all. I know of several vehicles that have around 50HP that go around 140-150km/h however I would (after only a quick glance) guess that your trike is less aerodynamically efficient (big open wheels, relatively large frontal area ect.) and that it had larger rolling resistence (because of the huge rear wheels with most of the weight on them). Therefore I thought that it would be reasonable to assume that your trikes require somewhat more power to achieve the same top speed. However as you say that your trikes are capable of 140km/h with only 50HP then the running resistence isn't as bad as I originally thought.

[revetec]

I don't know what the rolling resistance is but it is easy to push around the shop.

[hightower99]

I don't know whether you actually read this forum properly or have been to our website and/or actually understand what power actually is and how it's arrived at.

I do read your posts in full and think before I reply to them. I would ask that you do the same. Yes I have visited your website (several times as I do like to study the pictures put up). Do not question my understanding of power. Power isn't arrived at (it isn't just a calculated value), it is produced.

We have a government grant to design, build and test an aircraft engine. This is the setup we currently have. Two of our previous prototypes has had 4 valves per cylinder. In aircraft it is not desirable to use any cam chains or belts due to reliability. The market also requires a more simplistic engine due to the maintenance procedures. They also require an operating rev range of around 3,000rpm due to the propeller speed.

I understood that way back when you first stated that you had won the government grant to produce an aircraft engine. To be honest I have absolutely no idea why you keep bringing it up? It's not like I have forgotten...

If you have an engine that is set up for aircraft you need to provide the above. The 3,000rpm in some models is done with a reduction box to the prop in some engines such as Rotax. This adds to the cost and is generally done on very small capacity engines.

Yep knew that aswell. I do see that the fact that the revetec doesn't need a reduction gearbox can be an advantage.

At 3,000rpm you are limited to the power that you can produce.

Only by the amount of torque you can produce at that RPM

Let's look at the R600 engine and if we were to use it in aircraft doing 3,000rpm the power is 16hp and 22ftlb. Even geared at the commonly used 2:1 gearing the figure is 40hp and 35ftlb. I know this means not much as the R600 is not an aircraft engine and the X4v2 is currently not an automotive or motorcycle engine.

Umm why not use a 4.5:1 reduction gearbox? This would allow full power at 3000RPM prop speed. But again as you stated you still have to think about reliability and a high stung DOHC 4VPC engine running at 13500RPM for long periods of time doesn't instill a sense of reliability.

When we modify the camshafts etc to provide a good performing engine to 6,000rpm then the power will increase as power is a calculation of torque and RPM. The higher the RPM the engine is designed for, the more power you can produce.

1:Power is not just a calculation of torque and RPM, it is a physical rate of work that the engine is capable of.
2:Power will only increase if sufficient torque is produced at the higher RPM, which brings up another interesting point. If you are achieving good peak piston speeds with the cam (trilobe) design meant for aeromotive use then you are going to have to reduce the leverage (ie radius) of the cam to achieve the higher speed of 6000RPM (in fact the mean radius will have to be cut in half to achievce the same piston speed at 6000RPM) which means torque will be reduced.

By my calculation spreadsheet running a standard type automotive camshaft we should be producing 193hp@6,000rpm using existing top end at a volumetric efficiency of 90%. We could improve on this with a performance camshaft. But at the moment we have an aircraft setup as per our development project and Federal Government Grant.

That is interesting news. Is it possible that you might give me a copy of the spreadsheet program? (I know you probably can't as it has the physical dimensions of the trilobe aswell as other things you would probably like to keep private/revetec only info). It does sound interesting but did you use the value of 90% VE at peak power RPM? isn't that alittle high? Isn't that more of a peak torque figure? 193HP out of 2.4L at 6000RPM sounds pretty good and if it turns out to be in that region then I will be happy for you but that does require the engine to make 229Nm of torque at 6000RPM...

I'll honestly say that the engine accelerates off the mark like no other engine I have ever driven. The light throttle response has to be experienced to believed. The torque is incredible an does not require an aggressive style of driving to produce a hard acceleration. This at first is a driving characteristic you have to adapt to, consciously not opening the throttle wide open on take off and gear changes.

Again I ask: how did you size the throttle for the engine? At 25% throttle the engine should only be producing 1/5 to 1/4 of peak torque over the rev range.

[hightower99]

I don't know what the rolling resistance is but it is easy to push around the shop.

As opposed to say pushing a beetle around?

[Matra et Alpine]

ht, as I've friends with trikes then I can assure you that most of them are extremely light and very easy to maneouver. Without the need for a bodyshell and especially GLASS they are very light
and re frontal area, it is only that. It's not the width x height. That's ok for most cars, but bikes and trikes are a different shape and so their actual frontal area presented to the airflow is much lower than cars.