Rpm for CU2 Euro Lux Auto vs Euro Lux Manual at 100kph

[ahefara]

We have a Euro Lux Auto which at 100kph does 2000rpm (5th gear auto transmission). It is a CU2 built in May 2010.

A friend of mine has a Euro Lux Manual which at 100kph in 6th gear does 2500rpm. This is also a CU2 built in May 2010.

Does anyone have any comment about their CU2 manual and auto rpms at 100kph? I'm interested to hear what rpms readers have.

Surely the fuel consumption doing highway kilometres in the manual would have to be more, yet Honda claim a slightly better fuel consumption for the manual version of the Euro. Any comments?

[buddah51au]

I have a base model CU2 auto & at a true 100kph (by GPS) it is doing 2200 RPM. Best recorded hwy fuel consumption is 6.23L/100

[aaronng]

The gear ratios are different between the auto and the manual. That's why they have different RPMs at 100km/h.

The way fuel consumption numbers are tested are based on combined driving. There is a portion of the test in a suburban area, so the manual gets a slightly better score there.

[Euro08Jaz]

I imagine it also depends on whether it is 5 speed or 6 speed, I think most of the cl9 manuals were 6 speed? well mine is anyway.

[ahefara]

Thanks for your comment aaronng - but help me understand why the manual car uses less fuel when the engine is turning over faster at 2500rpm than compared to the auto at 2000rpm. To me, the manual engine is running faster at 2500rpm (thereby using more petrol) than the auto running at 2000rpm (thereby using less petrol). I am having trouble understanding this.

[buddah51au]

The Manual will be slightly better in urban areas due to lack of torque converter slippage on an auto while the manual has direct drive through the gearbox. On highway cruising the torque converter locks up on the auto giving direct drive.

All Euro's have a 6 speed manual or a 5 speed Auto.

[Euro707]

We have a Euro Lux Auto which at 100kph does 2000rpm (5th gear auto transmission). It is a CU2 built in May 2010.

A friend of mine has a Euro Lux Manual which at 100kph in 6th gear does 2500rpm. This is also a CU2 built in May 2010.

Does anyone have any comment about their CU2 manual and auto rpms at 100kph? I'm interested to hear what rpms readers have.

Surely the fuel consumption doing highway kilometres in the manual would have to be more, yet Honda claim a slightly better fuel consumption for the manual version of the Euro. Any comments?

My Euro is exactly the same as above and sits on 2000rpm @100kph.

I just returned from a 7 day/ 2,650 km trip : Sydney-Mildura-Broken Hill-Dubbo-Sydney. 3 people in car. Only used BP Ultima. Averaged 7.8 L /100. The roads from Hay -west to Mildura and Broken Hill to Cobar are s-t-r-a-i-g-h-t .....and with cruise control locked on a speed of (lets say =a number between 110 and 130kph:angel:) makes the journey one of.... "sheer driving pleasure" (couldn't think of a better description !)

Overtaking road trains etc when you're sitting on 120kph -is a breeze. Just use the paddles and the engine just roars to life and laps it up.

Really .......this vehicle just loves being booted at high rev range. Getting this much performance and economy from a 2.4 litre power plant is remarkable.

My previous car was a Subaru Liberty Spec B. Sure - a high performance car ....BUT I would of paid at least 50% more on my fuel bill for the same trip.:eek:

[buddah51au]

My fuel consumption has never been that high in 33,500km

[Type R Positive]

7.8l/100kms? On the highway? I get that around town! Seriously.

[SPQR]

The Manual will be slightly better in urban areas due to lack of torque converter slippage on an auto while the manual has direct drive through the gearbox. On highway cruising the torque converter locks up on the auto giving direct drive.....

^^ Spot on!

For those with an academic interest, I believe that the following specs are correct for a CU2 with AT and MT:

AT: 5th gear 1:0.57, Final drive 1:4.44
MT 6th gear 1:0.69, Final drive 1:4.76

Assuming that it is for a non-luxury model with the 225/50R17 tyres: These tyres have a theoretical circumference of 2 x pi ((225x0.5)+(17/2x25.4))/1,000 = 2.0634 metres
(Note: Division by 1,000 to convert millimetres to metres)

At 100km/h, this tyre undertakes 100 x 1,000/2.0634 = 48,463.7 revs per hour (r.p.h.).
(Note: Multiplication by 1,000 to convert kilometres to metres)

48,463.7 r.p.h. / 60 = 807.7 revs per minute (r.p.m).

Multiplying the various gear ratios for the AT and MT gives theoretical engine r.p.m. at 100km/h:

AT: 807.7 x 0.57 x 4.44 = 2,044 r.p.m. at 100km/h

MT: 807.7 x 0.69 x 4.76 = 2,653 r.p.m at 100km/h.

There is no allowance for tyre growth at speed or actual real world tyre inflation or wear or torque converter slip if not locked at 100km/h.

buddah51au is correct on why there is the difference in real world fuel economy.

[buddah51au]

But in reality you can't use the overall circumference of a tyre to gain true figures as once the tyre is loaded with the weight of the car the circumference changes slightly (unless you were to run 60psi).
A GPS is far more accurate than a speedo, I stand by my figure of 2200 RPM @ a true 100kph for the auto.

[Euro707]

7.8l/100kms? On the highway? I get that around town! Seriously.


My fuel consumption has never been that high in 33,500km

Thats great guys........I'm pleased.

I -too get better L's/ kms on shorter highway trips with just me in the car and sitting on 80-100kph.

But, my point was for a trip that long..... sitting on extended high speeds with 3 adults and a boot full of luggage.......

Not bad......

And yes comparing a Spec B.. 6 Boxer engine with the 2.4 L i-v-tec =unfair comparison

[aaronng]

Thanks for your comment aaronng - but help me understand why the manual car uses less fuel when the engine is turning over faster at 2500rpm than compared to the auto at 2000rpm. To me, the manual engine is running faster at 2500rpm (thereby using more petrol) than the auto running at 2000rpm (thereby using less petrol). I am having trouble understanding this.
In the test under highway conditions where the manual runs at 2500rpm and the auto at 2000rpm, the auto gets better fuel consumption. However, the car is also tested in city conditions and here the manual has a much better result with fuel consumption compared to the auto because manuals are just more frugal with fuel when acceleration is required frequently (no torque convertor). When the results for both highway and city are totaled to give the combined result, the manual ends up with a lower fuel consumption.

[ahefara]

Thank you all for your contributions so far - they have been very constructive.

On both the vehicles I have described (CU2 Manual and Auto), they have the Michelin 235/45/18.

Theoretically, based on the formulae that SPQR has supplied and used, 2 x pi(235x0.5)+(18/2x25.4))/1,000 = 2.1754 metres

At 100km/h, this tyre undertakes 100 x 1,000/2.1754 = 45,968.6 revs per hour (r.p.h.).

45,968.6 r.p.h. / 60 = 766.14 revs per minute (r.p.m).

Multiplying the various gear ratios for the AT and MT gives theoretical engine r.p.m. at 100km/h:

AT: 766.14 x 0.57 x 4.44 = 1,939 r.p.m. at 100km/h

MT: 766.14 x 0.69 x 4.76 = 2,516 r.p.m at 100km/h.

However, as buddah51au has said, the circumference of the tyre changes with the car body's weight and the theoretical figures we calculated above would be slightly incorrect - his GPS figures are more likely to be reflective of what is reality.

So, now I can conclude that Honda's Euro with automatic transmission at 100kph does have less rpm compared to the Euro manual transmission.

This now raises a new question - with the Euro with manual transmission revving much higher than the Euro automatic transmission, surely the cabin noise within the manual Euro is higher than the automatic Euro?

It would be interesting to know the cabin noise results in Euro manual and Euro automatic vehicles - ie decibel readings within these vehicles at 100kph.

So, the question now for me, is the manual Euro a noisier car within the driving cabin than compared to the Auto Euro?

Or has Honda factored this in and inserted more insulation? Any comments?

[ROBERT]

CL9

I have a CL9 auto and live in the country. My SHORTEST drive from home is 10km on open roads, no trafic lights and only one junction. Apart from 4 of 6 weekly trips to Sydney on the F3 my most frequent drives are to Forster at around 17 km. also clear roads no lights. So I expect my OVERALL consumption would be better that that of a manual as probably 85% of ALL my driving is around 90kph.

At what speed does the thranmission lock kick in?

[aaronng]

So, now I can conclude that Honda's Euro with automatic transmission at 100kph does have less rpm compared to the Euro manual transmission.
We knew about this back in 2004 for the CL9. Info is in all the old threads. CU2 has the same thing with the auto having longer ratios than the manual, so the auto will have a lower RPM than the manual as well.



This now raises a new question - with the Euro with manual transmission revving much higher than the Euro automatic transmission, surely the cabin noise within the manual Euro is higher than the automatic Euro?

It would be interesting to know the cabin noise results in Euro manual and Euro automatic vehicles - ie decibel readings within these vehicles at 100kph.

So, the question now for me, is the manual Euro a noisier car within the driving cabin than compared to the Auto Euro?

Or has Honda factored this in and inserted more insulation? Any comments?
The difference between 1900rpm and 2500rpm is NOTHING compared to the road noise coming from the tyres! You won't notice any difference between a manual and auto. Plus when cruising at 100km/h and then having to accelerate gently away, the manual can do it in 6th gear at 2500rpm, while the auto will have to downshift to 4th, putting the RPM at the same or higher than the manual before being able to accelerate. So there difference that you think is there just isn't.

[buddah51au]

Engine noise is not a concern, I suspect there would be very little if any difference between 2000 & 2500 RPM. The main Noise problem you will have is tyre noise, especially if you spend a lot of time driving on course chip bitumen such as we have in rural QLD. On Hot mix roads there is very little tyre noise.

Gentle acceleration from 100kph in an auto doesn't normally cause it to shift back to 4th, it depends how quickly you need to accelerate. When overtaking i normally use the paddles to shift down 1 or 2 gears depending on how quickly I need to get passed whatever is in front of me.

[Type R Positive]

I think you guys are missing a huge factor. It is not the engine rpm's that are of particular concern, rather it's the engine load.
I use less fuel at 110km/h than at 100km/h, but use a fair bit more at 130km/h. Still, at these speeds, I use less fuel than driving around town. Less engine load = less fuel used. I focus my driving on being smooth, regardless of being sedate or giving it a hard time!

[ministig]

Based on the formulaes, does that mean AT has higher top speed? Who has tried? Lol.

I got a obdII reading thing, will post engine load figures at 100kph when I have a chance.

[aaronng]

Based on the formulaes, does that mean AT has higher top speed? Who has tried? Lol.

I got a obdII reading thing, will post engine load figures at 100kph when I have a chance.

The auto has a theoretically higher top speed but you won't reach that as both the auto and manual will be drag limited before you reach redline in top gear.

[buddah51au]

I know what the (indicated) top speed is of my base CU2 Auto, but I am not about to post it for obvious reasons. Obviously i don't know how far out the speedo is at that indicated speed.

[SPQR]

Thank you all for your contributions so far - they have been very constructive.

On both the vehicles I have described (CU2 Manual and Auto), they have the Michelin 235/45/18.

Theoretically, based on the formulae that SPQR has supplied and used, 2 x pi(235x0.5)+(18/2x25.4))/1,000 = 2.1754 metres

The tyre on the Luxury is 234/45R18 as you said so the formula is:

2 x pi(235x0.45)+(18/2x25.4))/1,000 = 2.1008 metres.

The physical/actual circumference of the tyre does not change with load but the radius does reduce with load and as the radius reduces the tyre's effective circumference reduces. This affects the true speed in that to travel at the true 100km/h the engine revs are higher. That's why buddah51au says the revs are 2,200 rpm at 100km/h.

As I said "There is no allowance for tyre growth at speed or actual real world tyre inflation or wear or torque converter slip if not locked at 100km/h." The theoretical speed calculated in not the real world speed. And so buddah51au is correct.

The theoretical speeds calculated from gearing is what is quoted in motoring magazines as a means of comparison that elliminates the many variables (wind speed, tyre inflation, tyre wear, torque converter slip, etc) between different cars.

As I live in the NT and at the time it was legal, my CL9 would top out at an indicated 229km/h. My MY97 WRX would top out at and indicated 239km/h.

[buddah51au]

SPQR, I know you have a CL9, but not sure if it is manual or Auto. As the CL9 is a lighter car than the CU2, I thought the CL9 would be quicker. You don't say if 229 was indicated or GPS recorded. I have only ever tried mine out once & I didn't have a GPS at that time, but think of a black Friday number above the figure you stated, a whisker under 5400RPM. In a wheels road test, they stated the top end was 226, so that sounds more realistic allowing for speedo error.

[tron07]

Does the autobox allow the car to be rev to redline, holding the gears?
Bassed on my experience with other cars overseas, manual tend to be able to achive a higher top speed due to the reason being able to hold the gears towards redline. Else you probably need tons of straight road doing speed excess of 200km to achive max top speed, and risk loosing your car and license trying...

[buddah51au]

In sport Mode using the paddles you can take it to the limiter, a shade over 7000RPM. I rarely take it that high, but have learnt to change up @6500 due to human reaction time & the slight delay in response from the paddles. By taking that approach I usually pick up the next gear around 6900.

[aaronng]

SPQR, I know you have a CL9, but not sure if it is manual or Auto. As the CL9 is a lighter car than the CU2, I thought the CL9 would be quicker. You don't say if 229 was indicated or GPS recorded. I have only ever tried mine out once & I didn't have a GPS at that time, but think of a black Friday number above the figure you stated, a whisker under 5400RPM. In a wheels road test, they stated the top end was 226, so that sounds more realistic allowing for speedo error.

Weight doesn't matter as much when you are talking about talk speed because wind resistance will be a much bigger factor. Weight affects acceleration rate when not limited by wind resistance.

[SPQR]

SPQR, I know you have a CL9, but not sure if it is manual or Auto. As the CL9 is a lighter car than the CU2, I thought the CL9 would be quicker. You don't say if 229 was indicated or GPS recorded. I have only ever tried mine out once & I didn't have a GPS at that time, but think of a black Friday number above the figure you stated, a whisker under 5400RPM. In a wheels road test, they stated the top end was 226, so that sounds more realistic allowing for speedo error.

My CL9 is an Auto and the speed was an indicated 229km/h. The CU2 is faster because it cleaves the air better.


Does the autobox allow the car to be rev to redline, holding the gears?
Bassed on my experience with other cars overseas, manual tend to be able to achive a higher top speed due to the reason being able to hold the gears towards redline. Else you probably need tons of straight road doing speed excess of 200km to achive max top speed, and risk loosing your car and license trying...

Yes the autobox does allow the revs to redline but you need to use manual mode to go to the rev limiter. I've hit the limiter in my car on rare occasions.

I don't speed much these days as the flavour of government in the NT since 2001 has turned the place into something approaching all the other same flavour states: Rapacious, money-hungry speed measurers, hell-bent on destroying the last free place in OZ. We do have mega-tons of straight (but now heavily policed) roads in the NT.

When it was legal, one of my favourite trips (for work) used to be Darwin to Katherine (320km one way) in 2hours 10minutes, including two 10 minute stops along the way. The first 40km were spent getting out of the greater Darwin area with speed limits of less than 100km/h. Still, the average was 174km/h but the maximum was 210km/h at any point. And yes I did overtake police cars.

The last time I went really fast was just before the speed limits came in: 249km/h in an AMG. I wouldn't do it now.

[Type R Positive]

Yeah, Darwin - Katherine and Darwin - Jabiru were my favorites. Now, just have to stick to the 130km/h.

Funny how the road toll is way higher now though?

[tron07]

Funny how the road toll is way higher now though?
Cause we spend too much time looking at the speedo instead of the road and also falling asleep due to the slow speed

[Type R Positive]

Cause we spend too much time looking at the speedo instead of the road and also falling asleep due to the slow speedlol!
My theory is that now with the 130km/h speed limit, people feel obligated to do that speed. Before, people would just do what they were comfortable, which for most, was still 100.

Most of our deaths are single vehicle accidents on dirt roads, aboriginals run over while sleeping on the road, pedestrians being hit on the road. These are all counted in the road toll. All missleading crap they use to promote revinue raising speed cameras, which of course, don't have any effect what so ever on these deaths.