Honda Legend V6 SOHC, WHY?

[Twofouronenite]

Er I am worse, I thought legend's SOCH uses only two valves per cylinder before this. I think i have become a frog in the well long back, we need more technical discussion in MCF like the old days

 

2 valves, 2 stroker engine? Judging by the views 1141 in 2 days as of time of writing this reply, shows that there are many out there wanting to know techinical details.

 

Perhaps if the views increase, maybe can we get management to start a Technical column?

 

 

 

[Wt_know]

2.0 (SOHC), 2.4 (DOHC), 3.5 (SOHC)

 

2.4 = not worth it since SOHC is better than DOHC ?

 

Accord 2.0 specs:

Engine type SOHC i-VTEC 16 Valves, In-line 4-CYL

Fuel Supply System Honda PGM FI (Programmed fuel injection)

Bore & Stroke mm 81.0 x 96.9

Displacement cc 1997

Compression Ratio 10.6:1

Maximum Power kW(PS)/rpm 115(156)/ 6300

Maximum Torque N-m[kg.m]/rpm 189(19.3)/ 4300

 

Accord 2.4 specs:

Engine type DOHC i-VTEC 16 Valves, In-line 4-CYL

Fuel Supply System Honda PGM FI (Programmed fuel injection)

Bore & Stroke mm 87.0 x 99.0

Displacement cc 2354

Compression Ratio 10.5:1

Maximum Power kW(PS)/rpm 133(180)/6500

Maximum Torque N-m[kg.m]/rpm 222(22.6)/4300

 

Accord 3.5 specs:

Engine type SOHC i-VTEC 24 Valves, V6

Fuel Supply System Honda PGM FI (Programmed fuel injection)

Bore & Stroke mm 89.0 x 93.0

Displacement cc 3471

Compression Ratio 10.5:1

Maximum Power kW(PS)/rpm 202(275)/6200

Maximum Torque N-m[kg.m]/rpm 339(34.6)/5000

Edited January 10, 2009 by Wt_know

[Twofouronenite]

2.0 (SOHC), 2.4 (DOHC), 3.5 (SOHC)

 

 

Accord 2.0 specs:

Engine type SOHC i-VTEC 16 Valves, In-line 4-CYL

Fuel Supply System Honda PGM FI (Programmed fuel injection)

Bore & Stroke mm 81.0 x 96.9

Displacement cc 1997

Compression Ratio 10.6:1

Maximum Power kW(PS)/rpm 115(156)/ 6300

Maximum Torque N-m[kg.m]/rpm 189(19.3)/ 4300

 

Civic Engine data taken from AD website

Engine type 4-stroke DOHC 16-valve i-VTEC

Fuel Supply System Honda PGM FI (Programmed fuel injection)

Bore & Stroke mm 86 x 86

Displacement cc 1998

Compression Ratio 9.6

Maximum Power kW(PS)/rpm 114(155)/6000

Maximum Torque N-m[kg.m]/rpm 188(19.2)/4500

 

Seem like this 2 Engine would be a very good base for reference. Believe they are the same or just a variant of it.

SOHC engine Tq peak at lower rpm compare to DOHC whereas it is the opposite for Power. Is this the proof that the statement SOHC have better torque?

[Wt_know]

higher bhp (max power) vs higher torque in lower rpm

so which one is better ?

Edited January 10, 2009 by Wt_know

[Paddie]

It's important to consider not just the peak torque figure, but how much torque is produced throughout the rev range.

 

For example, engine A might have peak torque of 200Nm at 4800rpm, engine B has 200Nm at 3000rpm.

 

A lot of people will say, 'wow, engine B is much better for city driving because it has so much more torque at low RPMs.'

 

But the torque curve for engine B may be like this: 1000rpm: 100Nm, 2000rpm: 120Nm, 3000rpm: 200Nm, 4000rpm: 120Nm, 5000rpm: 110Nm...

 

In other words, there is a very steep peak at 3000rpm and little else on either side. This engine will definitely not feel good to drive.

 

Engine A's torque curve may be: 1000rpm: 180Nm, 2000rpm: 190Nm, 3000rpm: 199Nm, 4000rpm: 199Nm, 4800rpm: 200Nm, 5000rpm: 190Nm...

 

This engine produces a lot of torque throughout the range. It's academic that the peak is at 4800rpm, since at almost all other points in the rev range it's producing more torque than engine B.

 

So guys, try to look beyond the published figures!

Edited January 10, 2009 by Paddie

[En0203]

2 valves, 2 stroker engine? Judging by the views 1141 in 2 days as of time of writing this reply, shows that there are many out there wanting to know techinical details.

 

Perhaps if the views increase, maybe can we get management to start a Technical column?

 

I think any post related to honda also will have high view count in singapore

[En0203]

Civic Engine data taken from AD website

Engine type 4-stroke DOHC 16-valve i-VTEC

Fuel Supply System Honda PGM FI (Programmed fuel injection)

Bore & Stroke mm 86 x 86

Displacement cc 1998

Compression Ratio 9.6

Maximum Power kW(PS)/rpm 114(155)/6000

Maximum Torque N-m[kg.m]/rpm 188(19.2)/4500

 

Seem like this 2 Engine would be a very good base for reference. Believe they are the same or just a variant of it.

SOHC engine Tq peak at lower rpm compare to DOHC whereas it is the opposite for Power. Is this the proof that the statement SOHC have better torque?

 

Not true, if u compare both, the one with longer stroke will give u higher torque for the same capacity, not so much about SOCH vs DOCH :)

Edited January 10, 2009 by En0203

[En0203]

It's important to consider not just the peak torque figure, but how much torque is produced throughout the rev range.

 

For example, engine A might have peak torque of 200Nm at 4800rpm, engine B has 200Nm at 3000rpm.

 

A lot of people will say, 'wow, engine B is much better for city driving because it has so much more torque at low RPMs.'

 

But the torque curve for engine B may be like this: 1000rpm: 100Nm, 2000rpm: 120Nm, 3000rpm: 200Nm, 4000rpm: 120Nm, 5000rpm: 110Nm...

 

In other words, there is a very steep peak at 3000rpm and little else on either side. This engine will definitely not feel good to drive.

 

Engine A's torque curve may be: 1000rpm: 180Nm, 2000rpm: 190Nm, 3000rpm: 199Nm, 4000rpm: 199Nm, 4800rpm: 200Nm, 5000rpm: 190Nm...

 

This engine produces a lot of torque throughout the range. It's academic that the peak is at 4800rpm, since at almost all other points in the rev range it's producing more torque than engine B.

 

So guys, try to look beyond the published figures!

 

true, this was what i was trying to tell kelpie :)

[Bulls_is_back]

And to answer the original question (Honda Legend V6 SOHC, WHY?) ...

 

Honda keeps DOHC, Mid engine layout RWD and all round double wishbone (or multilink) suspension for its best cars like the NSX and S2k.

In the other cars for the rest of us, the implementation of all these (concurrently) is deemed unnecessary and cost more to build.

 

Who wouldn't want to built a product at lower cost and sell them at prices that reflects the bulletproof reputation of their more potent siblings.

(ok I am biased)

 

The torque curve of this DOHC look plenty smooth to me. I reckon it has 90% of the peak torque throughout the rev range (sub 2k - redline rpm).

Edited January 10, 2009 by Bulls_is_back

[Twofouronenite]

It's important to consider not just the peak torque figure, but how much torque is produced throughout the rev range.

 

For example, engine A might have peak torque of 200Nm at 4800rpm, engine B has 200Nm at 3000rpm.

 

A lot of people will say, 'wow, engine B is much better for city driving because it has so much more torque at low RPMs.'

 

But the torque curve for engine B may be like this: 1000rpm: 100Nm, 2000rpm: 120Nm, 3000rpm: 200Nm, 4000rpm: 120Nm, 5000rpm: 110Nm...

 

In other words, there is a very steep peak at 3000rpm and little else on either side. This engine will definitely not feel good to drive.

 

Engine A's torque curve may be: 1000rpm: 180Nm, 2000rpm: 190Nm, 3000rpm: 199Nm, 4000rpm: 199Nm, 4800rpm: 200Nm, 5000rpm: 190Nm...

 

This engine produces a lot of torque throughout the range. It's academic that the peak is at 4800rpm, since at almost all other points in the rev range it's producing more torque than engine B.

 

So guys, try to look beyond the published figures!

 

 

true, this was what i was trying to tell kelpie :)

 

Got both point. Porblem with most manufacturer, they project the peak and we don't see the true operating range of the engine RPM and commonlly assume like I did that the peak remains after it is achieved!

 

[Twofouronenite]

And to answer the original question (Honda Legend V6 SOHC, WHY?) ...

 

Honda keeps DOHC, Mid engine layout RWD and all round double wishbone (or multilink) suspension for its best cars like the NSX and S2k.

In the other cars for the rest of us, the implementation of all these (concurrently) is deemed unnecessary and cost more to build.

 

Who wouldn't want to built a product at lower cost and sell them at prices that reflects the bulletproof reputation of their more potent siblings.

(ok I am biased)

 

The torque curve of this DOHC look plenty smooth to me. I reckon it has 90% of the peak torque throughout the rev range (sub 2k - redline rpm).

 

Cost of manufacturing the engine? and Design for manufacturability?

[Bulls_is_back]

Cost of manufacturing the engine? and Design for manufacturability?

 

Well DOHC (vs SOHC) means more parts and weight based on what the others had mentioned earlier.

The interesting thing is that in the new accord, the 2L SOHC car is only 45kg lighter than the 2.4L DOHC version. Equipment level being similar between the 2L vs 2.4L, the weight diff is probably down to the engine ... which is not a lot (+3%) on a 1.5ton car.

 

A more complex double wishbone or multilinked suspension is again more parts and weight. Furthermore they eats into the interior space of the car.

 

RWD or AWD ... transmission losses + the centre tranny tunnel that some people hates (flat rear floor is important to some)

 

 

[Kelpie]

Hi, thanks for digging out the performance figures

 

Firstly, I supposed the 1.56 ton and 1.9 ton is curb weight and not engine weight. Do you know the actual weight of the engine block? Given the same engine construction material and same capacity I believe DOCH is always heavier than SOCH because of the additional cam, and in this case, a V6 will be two cams more.

 

Secondly, Legend's SOCH has got VTEC implementation so it ought to have higher bhp output compared to the Teana's DOCH without lift / multistage cam phase. When I said performance advantage, it only makes sense to compare the engine with same configuration, DOCH VTEC and SOCH VTEC. Notice how Type R engine are all DOCH, because DOCH allows additional control of valve opening/closing timing with the additional cam so it's always better to have DOCH for the same engine configuration. As for the accord SOCH vs legend SOCH performance difference, my guess is that the VTEC implementation is different. the one in legend probably gets the more expensive 2-stage VTEC while the one in accord probably gets the variable cylinder management only but I really don't know as I am not engine expert, let alone specific engine model as honda got so many VTEC variant

 

Thirdly, no offence, but It seems like you have the habit of judging a car based on the peak bhp / torque figures alone. You may want to also consider the weight of the car aka the power to weight ratio and the torque curve of the car. You won't know whether a car is good to drive or not until u see the torque curve of the car. Some cars may have lower bhp / torque figures compare to another but it may have a better low end torque distribution and that makes it a better car to drive in start/stop traffic given the same weight and gear ratios. But of coz if you are a hardcore tracker and like to rev the hell out of your car then high bhp car at top end may suit you more, but that doesn't mean that a lower bhp car with fatter low end is bad, it just suits different driving styles that's all

 

Last but not least, thanks for the good luck wish though i am not looking for job. that was a head-hunt

 

Keep the discussion going, I really like technical discussion in MCF because I am not very good at technical stuff and I can really learn a lot from these discussions And please feel free to correct me when you spot any mistakes in my statement due to my limited technical knowledge [sweatdrop]

 

 

Thanks for the technical detail. Anyway, I'm just a driver and I rely on the manufacturer's technical specification and test drive to dervie my judgement about a car. Sometimes, you gotta to really take the drive seat to experience it. I was told the A4 3.2L NA, sub 7secs of 0-100Km/h is deem unbelievable by some of the reviewers of this car.

 

You're right about the power to weight ratio. Based on the car specifications that we get from the magazines, generally most car that is heavier of the same class, tend to have slower 0~100km/h result. Lets OT abit and study an example on two DOHC 2L on power to weight:

 

Example A (Turbo-Charged):

Horespower =147hp/3800

Torque =2800/2000

0-100Km/h =11

Weight = 1.6 ton

Transmission=4 speed auto/5 speed manual

Max speed =200Km/h

 

Example B (NA)

Horsepower=155hp/5500

Torque=190/4300

0-100Km= 9

Weight=1.35ton

Transmission=5 Speed Auto/Manual

Max speed=210Km/h

 

So which is faster in pick-up and 0-100Km/h? Note that example A is a heavier TC car but can example B outruns it?

 

 

Got head hunted not bad leh , especially at this time. Ont the other hand, Good staff is hard to find and retain duirng good time.

 

Regards,

Edited January 11, 2009 by Kelpie

[Kelpie]

Dun be modest lah?! There's a saying, No need to own a cow to be able to noe how to drink milk mah!

 

Ur opinion on Y use SOHC for V configuration.

 

Just my thought. The current Accord, doesn't have the frontal look that appeal to me and the Accord Euro is a smaller car. It really depends on what one likes about the 2.

I'm not an engineer. From a layman point of view and the way I read it, Honda emphasizes alot on fuel economy of using SOHC V6 implementation without compromising performance in their articues. The intelligence of shutting down some values on low speed and opening up the rest when at high speed is an effort to redue fuel consumption on their bigger engine.

 

VTEC was still used in their low-end offering such as the City at one stage when their Civic and Accord have all moved onto i-VTEC. So with new Jazz and City moving to i-VTEC now, I'm quite sure it is just a matter of time that we will see i-VTEC in their SOHC V6 implementation.

 

Regards,

[Twofouronenite]

Just my thought. The current Accord, doesn't have the frontal look that appeal to me and the Accord Euro is a smaller car. It really depends on what one likes about the 2.

I'm not an engineer. From a layman point of view and the way I read it, Honda emphasizes alot on fuel economy of using SOHC V6 implementation without compromising performance in their articues. The intelligence of shutting down some values on low speed and opening up the rest when at high speed is an effort to redue fuel consumption on their bigger engine.

 

VTEC was still used in their low-end offering such as the City at one stage when their Civic and Accord have all moved onto i-VTEC. So with new Jazz and City moving to i-VTEC now, I'm quite sure it is just a matter of time that we will see i-VTEC in their SOHC V6 implementation.

 

Regards,

I'm gamed for any good openminded discussion here Bro ! Layman or Engineer views, no problem too! Extract from magazines, book etc.

 

You are quite right, the Accord 3.5L is already SOHC V6 using iVTEC.

 

[Trex101]

202kw is not exactly weak in any terms, I would say that this 3.5L gem is one of the strongest in most mid level sedan.

[Twofouronenite]

202kw is not exactly weak in any terms, I would say that this 3.5L gem is one of the strongest in most mid level sedan.

Err... In other words?

 

[Mt88]

Anyone know why the Honda Legend Engine's a V6 but SOHC? Would it not be better off in DOHC?

 

No.

 

No reason to go for DOHC if the "patented" SOHC ivtec can already control 4 valves per cylinder plus variable timing and lift control to achieve what dohc vvt-iL does. The logic is like this: If one can drive a car smoothly with one leg to operate gas and brake, there is little reason to use both leg seperately for brake and gas.

 

Less friction and less weight is not a bad thing. It is the same misconception people have that twin exhaust tip is more powerful than single exhaust tip.

 

More of J engine: http://en.wikipedia.org/wiki/Honda_j_engine

 

Legend is still using the older J35 without VCM but higer power and torque (309ps, 370nm) with higher compression and need premium petrol 98 or 100. Legend fc is higher because it is 4WD!

 

Legend J35 non VCM (premium petrol)

 

Accord J35 VCM (regular petrol)

 

The newer J35 with VCM in accord/inspire is economy tuned. Lower compression, lower power (280ps, 342nm) but able to take regular 95 petrol. The key is ability to take lower RON petrol which lower down the operating cost for owner. The legend is made for premium sector who can better afford premium petrol.

 

VCM is unique to Honda still. It really works to lower fc and lower pollutant but yet giving high power. More of vcm: http://www.honda.co.jp/tech/auto/vcm/

 

J30 and J35 has no shortage of torque. I am using one and can testify that there is no vacuum like smaller engine. The torque is more than enough even from 1000rpm. There are times when the front wheel spins uncontrollably from start due to high torque.