4 Cylinder vs 6 & 8 Cylinders





Page 1 of 3 1 2 3 LastLast
Results 1 to 20 of 45
  1. #1
    Join Date
    Jul 2012
    Location
    Pretoria
    Age
    62
    Posts
    64
    Thanked: 4

    Default 4 Cylinder vs 6 & 8 Cylinders

    Why is it that in many instances the Diesel version of a vehicle is a straight 4 cylinder and the petrol version is a V6. The Pajero's are an example. The 3.2 Diesel is a 4 cylinder and the 3.8 Petrol is a V6. The Toyota's are another example. The Fortuner 2.8 Diesel is a 4 cylinder while the 4.0 Petrol is a V6. The LC Prado 3.0 Diesel is a 4 cylinder and the 4.0 Petrol is a V6. Then some of the Diesel engines, like in the VW Amarok 2.0 Diesel is a 4 cylinder but the 3.0 Diesel is a V6.

    The manufacturers are also very prominent with the V6 & V8 badges on the rear of the vehicle. In which way is a 3.2 liter 4 cylinder Diesel engine worse (less torque, Kw, towing capacity, durability etc.) than a 3.2 liter V6 Diesel engine? Or is it a status issue? Why is it that petrol engines generally have more cylinders as alternatives to diesel engines in the same body?

  2. #2
    Join Date
    Nov 2009
    Location
    Richardsbay, KZN
    Age
    45
    Posts
    5,363
    Thanked: 13227

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    A quick assumption would be to get the petrol version to give more or less the same torque it needs bigger capacity and more cylinders.
    "Stare, pry, listen, eavesdrop. Die knowing something, you are not here long"
    Walker Evans, Photographer

  3. The Following User Says Thank You to Riaan van Wyk For This Useful Post:


  4. #3
    Join Date
    Feb 2020
    Location
    Johannesburg
    Posts
    34
    Thanked: 45

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    Large capacity diesels need less cylinders as diesels can have a longer stroke and still be in safe piston speeds due to lower engine revs.

    3.2DID has a 98.5mm bore and 105mm stroke (mean piston speed @ 4000rpm = 2x(0.105)x(4000/60) = 14m/s)
    3.8 v6 has a 95mm bore and a 90mm stroke (mean piston speed @ 6000rpm = 2x(0.09m)x(6000/60) = 18m/s)

    A theoretical 3.8 4-cyl (98.5mm bore and 125mm stroke) @ 6000 rpm would have a piston speed of 25m/s
    That is the same piston speed as a Honda S2000 engine @9000 rpm and the larger and heavier pistons would generate incredible forces before making piston sized holes in the bonnet.

    So if you want high RPM and a large capacity you need more cylinders as you can not just add stroke.
    Fewer cylinders are much cheaper to manufacture, so if you don't need them...
    Last edited by Cyclone101; 2020/04/13 at 02:04 PM.

  5. The Following 11 Users Say Thank You to Cyclone101 For This Useful Post:


  6. #4
    Join Date
    Oct 2013
    Location
    Postmasburg
    Age
    43
    Posts
    491
    Thanked: 255

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    One of the biggest misconceptions out there is that diesels have more torque than petrols.
    It was even mentioned in post 2.
    TURBO diesels give more torque than petrol engines. N/A petrol engines tend to have much higher kw and very comparable torque to N/A diesels.
    To the original poster:
    The petrols are generally bigger because theres no turbo/intercooled charging on them.
    Its been changing the last couple of years and theres a plethora of new turbocharged/supercharged petrol engines seeing the light.

  7. The Following User Says Thank You to Mapog For This Useful Post:


  8. #5
    Join Date
    Sep 2006
    Location
    Robertson/ Larissa, Greece
    Age
    56
    Posts
    5,438
    Thanked: 3318

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    Quote Originally Posted by Mapog View Post
    Its been changing the last couple of years and theres a plethora of new turbocharged/supercharged petrol engines seeing the light.
    With the result that petrol engines have gone a lot smaller for the same output now as well.
    We can't change the wind but we can set our sails

  9. The Following User Says Thank You to Francois Theron For This Useful Post:


  10. #6
    Join Date
    Oct 2019
    Location
    Birchleigh
    Age
    61
    Posts
    125
    Thanked: 50

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    In simple terms we learned that Diesel is about 40% more volumetric efficient than Petrol.
    Skihili

    2019 Ford Ranger 2.2 DC 4x4 Auto
    Old school. QL is not an instructor.

  11. The Following User Says Thank You to Skihili For This Useful Post:


  12. #7
    Join Date
    Mar 2008
    Location
    De Wildt
    Age
    57
    Posts
    37,457
    Thanked: 13618

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    Turbo diesel engines are brilliant as long as you don't put garbage on them like DPFs and EGRs.

    I'd rather have a nice big old school intercooled turbo diesel than a similar sized petrol engine any day.

    In fact, the Australian Defense Force took their Land Rover Defenders, threw away the 3.5 V8 petrol engines and dropped in a 3.9L Isuzu truck turbo diesel.

    Google "Land Rover Perentie".

    Some Ozzies have squeezed 140kW and 550Nm out of that engine with no compromise on reliability while returning under 10L/100 during normal driving.

    You can't do that with an old school petrol engine.
    2012 Jeep Sahara Unlimited 3.6 V6
    Percivamus

  13. The Following 2 Users Say Thank You to jelo For This Useful Post:


  14. #8
    Join Date
    May 2012
    Location
    Cape Town
    Posts
    2,887
    Thanked: 223

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    Power is derived from the work done over a given time (hour) P = W/Δt
    To achieve more power there are a few ways.
    • Increase the work (torque) - longer power stroke, bigger bore, increase the air pressure.
    • Increase the rate of fire by either spinning the engine faster or increase the amount of cylinders which fires per second.



    The main problem with increasing the rpm's are that these engines are designed to produce more torque by using a longer power stroke which is great for towing at lower engine speeds, but they can't sustain the high forces of the increased piston speeds.


    If you are comparing a N/A with a boosted engine then a Turbocharged/Supercharged engine will always have more torque than it's N/A equivalent due to the amount of extra oxygen forced into the cylinders to burn.

    I'm a huge fan of inline 6 cylinder engines as they are naturally balanced and deliver great linear torque throughout the rev range in either petrol and diesels.
    Their biggest problem is the amount of space they require hence manufacturers use the V6 configuration with counter balancing shafts.
    Last edited by Sandboarder; 2020/04/14 at 05:25 PM.
    (SUPERCHARGED ZOMBIE ZOOK)
    (DEFENDER 130 300HP V8 "MR PUGLY")
    (LC 80 VX 1HDFT TOURER)

    --->YouTube channel<---
    Hendri Mouton (Zombie)

  15. #9
    Join Date
    Nov 2007
    Location
    Kathu
    Age
    59
    Posts
    9,311
    Thanked: 2839

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    Quote Originally Posted by jelo View Post
    Turbo diesel engines are brilliant as long as you don't put garbage on them like DPFs and EGRs.

    I'd rather have a nice big old school intercooled turbo diesel than a similar sized petrol engine any day.

    In fact, the Australian Defense Force took their Land Rover Defenders, threw away the 3.5 V8 petrol engines and dropped in a 3.9L Isuzu truck turbo diesel.

    Google "Land Rover Perentie".

    Some Ozzies have squeezed 140kW and 550Nm out of that engine with no compromise on reliability while returning under 10L/100 during normal driving.

    You can't do that with an old school petrol engine.
    I cannot fully agree with you if you compare same era petrol and diesel engines. Turbo diesel engines only catch up in the last 20 years. Then if you compare the modern diesel turbo with engines like the Ecoboost petrol engines, diesels does not have that many advantages.

    With old school petrol vs diesel diesel only won the consumption stakes

    The normal aspirated 4BD1 Isuzu engine you refer to only made 64kw and 270nm when introduced in 1976.
    Turbo charged versions introduced in 4BDT in 1988 made 100kw and 330nm.
    Compare that with a normal aspirated 3.9l I6 Ford SOHC petrol engine from 1988 which made 139kw and 338nm.
    Later Barra developments of the same engine turbo charged developed 270kw and 533nm. What is more reliable than a Barra

    If you take the power output of the newest 3.0l V6 Ecoboost 368kw and 630nm the 2020 model I cannot think of a turbo diesel production engine with a capacity of 3.0l that can compare. I also do not think that the modern turbo diesel is that far ahead anymore with its fuel efficiency compared to the modern petrol turbo`s like the Ecoboost range.
    It is not what you buy its what you build.

  16. The Following 2 Users Say Thank You to grips For This Useful Post:


  17. #10
    Join Date
    Mar 2008
    Location
    De Wildt
    Age
    57
    Posts
    37,457
    Thanked: 13618

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    Quote Originally Posted by grips View Post
    Turbo charged versions introduced in 4BDT in 1988 made 100kw and 330nm.
    Compare that with a normal aspirated 3.9l I6 Ford SOHC petrol engine from 1988 which made 139kw and 338nm.
    And please compare the fuel consumption of both...........
    2012 Jeep Sahara Unlimited 3.6 V6
    Percivamus

  18. #11
    Join Date
    May 2016
    Location
    East London
    Age
    68
    Posts
    2,394
    Thanked: 3042

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    Uhmmm!

    How did this change to an argument about petrol vs diesel?

    I thought it was about 4, 6 & 8 cyl engines.
    "Nothing in the world is more dangerous than sincere ignorance and conscientious stupidity" - Martin Luther king Jr

    2006 VW Touareg V10 TDi
    (currently done more than 407 000 km)

  19. #12
    Join Date
    Oct 2007
    Location
    Uitenhage
    Age
    41
    Posts
    2,007
    Thanked: 537

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    Quote Originally Posted by 4eTouareg View Post
    Uhmmm!

    How did this change to an argument about petrol vs diesel?

    I thought it was about 4, 6 & 8 cyl engines.
    The OP was about diesel vs petrol as well as number of cylinders.

    All things being equal. Less cylinders = more torque (bigger cylinders, more air being burnt), more cylinders = more power (smaller pistons, lower inertia, means higher RPM is possible).

    As far as I know diesel motors don't necessarily produce more absolute torque but they produce torque lower down the rev range. That probably has something to do with it.

    I have found large N.A. 4 cylinder petrol engines to be down on torque and very heavy on fuel. Real hill indicators and didn't like a heavy load or towing. (I'm thinking about the 2.4L Nissan motor and the 2.6L Mazda motor). The 3.0L V6 counterparts offered better performance at a similar fuel consumption.
    Last edited by Fontuin; 2020/04/15 at 10:10 AM.
    2004 Land Rover Discovery 2 Td5 ES

  20. #13
    Join Date
    Mar 2008
    Location
    De Wildt
    Age
    57
    Posts
    37,457
    Thanked: 13618

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    Quote Originally Posted by 4eTouareg View Post
    Uhmmm!

    How did this change to an argument about petrol vs diesel?

    I thought it was about 4, 6 & 8 cyl engines.
    ask Grips, he started down that road
    2012 Jeep Sahara Unlimited 3.6 V6
    Percivamus

  21. #14
    Join Date
    Nov 2007
    Location
    Kathu
    Age
    59
    Posts
    9,311
    Thanked: 2839

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    Quote Originally Posted by jelo View Post
    Turbo diesel engines are brilliant as long as you don't put garbage on them like DPFs and EGRs.

    I'd rather have a nice big old school intercooled turbo diesel than a similar sized petrol engine any day.

    In fact, the Australian Defense Force took their Land Rover Defenders, threw away the 3.5 V8 petrol engines and dropped in a 3.9L Isuzu truck turbo diesel.

    Google "Land Rover Perentie".

    Some Ozzies have squeezed 140kW and 550Nm out of that engine with no compromise on reliability while returning under 10L/100 during normal driving.

    You can't do that with an old school petrol engine.
    Jelo started it.

    But lets get back to cylinders I have yet to drive an engine that can duplicate the torque of a large capacity v8. Let it be diesel or petrol.
    It is not what you buy its what you build.

  22. The Following 2 Users Say Thank You to grips For This Useful Post:


  23. #15
    Join Date
    Mar 2008
    Location
    De Wildt
    Age
    57
    Posts
    37,457
    Thanked: 13618

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    Quote Originally Posted by grips View Post
    Jelo started it.

    But lets get back to cylinders I have yet to drive an engine that can duplicate the torque of a large capacity v8. Let it be diesel or petrol.
    naturally aspirated or not?
    2012 Jeep Sahara Unlimited 3.6 V6
    Percivamus

  24. #16
    Join Date
    Mar 2008
    Location
    De Wildt
    Age
    57
    Posts
    37,457
    Thanked: 13618

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    GM 6.2L diesel V8: 97 kW at 3,600 rpm / 325 N⋅m at 2,000 rpm

    Isuzu 5.9L inline 6: 118 kW at 3200 rpm / 380 N⋅m at 2000 rpm

    Both naturally aspirated. You said what?
    2012 Jeep Sahara Unlimited 3.6 V6
    Percivamus

  25. #17
    Join Date
    Nov 2007
    Location
    Kathu
    Age
    59
    Posts
    9,311
    Thanked: 2839

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    Quote Originally Posted by jelo View Post
    GM 6.2L diesel V8: 97 kW at 3,600 rpm / 325 N⋅m at 2,000 rpm

    Isuzu 5.9L inline 6: 118 kW at 3200 rpm / 380 N⋅m at 2000 rpm

    Both naturally aspirated. You said what?
    97kW were the first version the later 6.2`s did 138kw and 477nm. You know there were a Isuzu 7.1l six cylinder that only made 121kw and 450nm. The GM 6.2 were junk any way.

    The more cylinders the better the torque will be for engines of the same capacity and design. Straight engines have the advantage of heavier rotating assembly which help them with low down grunt.

    But this type of subject were flogged to death on the forum.

    Think the v10 Touareg still is king in the 5.0l turbo diesel class with 850nm.
    It is not what you buy its what you build.

  26. #18
    Join Date
    Mar 2008
    Location
    De Wildt
    Age
    57
    Posts
    37,457
    Thanked: 13618

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    Quote Originally Posted by grips View Post
    97kW were the first version the later 6.2`s did 138kw and 477nm. You know there were a Isuzu 7.1l six cylinder that only made 121kw and 450nm.
    Incorrect. The 6.5 was higher because it was turbo charged. The final specs on the 6.2 are as follows:

    Horsepower / Torque (final): 160 hp (119 kW) at 3,600 rpm / 285 lb⋅ft (386 N⋅m) at 2,000 rpm

    Quote Originally Posted by grips View Post
    The GM 6.2 were junk any way.
    No, you can't sidestep now.
    2012 Jeep Sahara Unlimited 3.6 V6
    Percivamus

  27. #19
    Join Date
    Jun 2012
    Location
    Benoni
    Age
    45
    Posts
    1,035
    Thanked: 1046

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    Quote Originally Posted by grips View Post
    The more cylinders the better the torque will be for engines of the same capacity and design.
    No, the reverse is typically true, individual bigger cylinder size (i.e. less cylinders) = more torque

    Typically More cylinders = lighter individual cylinders = higher RPM = more power (not torque)
    Nothing screams "Bad workmanship" like wrinkles in the duct tape

    2012 Q7 4.2 TDI
    Birkin SR20VET race car


  28. The Following User Says Thank You to mullerza For This Useful Post:


  29. #20
    Join Date
    Nov 2007
    Location
    Kathu
    Age
    59
    Posts
    9,311
    Thanked: 2839

    Default Re: 4 Cylinder vs 6 & 8 Cylinders

    Quote Originally Posted by jelo View Post
    Incorrect. The 6.5 was higher because it was turbo charged. The final specs on the 6.2 are as follows:

    Horsepower / Torque (final): 160 hp (119 kW) at 3,600 rpm / 285 lb⋅ft (386 N⋅m) at 2,000 rpm


    No, you can't sidestep now.
    The Mil spec 6.2 normal aspirated in the HMMWV made 123kw and 447nm. I have studied this engine in depth. Were a candidate for the F250 I had.
    The 138kw in my previous post were wrong sorry


    https://www.areiosdefense.com/produc...diesel-engine/
    It is not what you buy its what you build.

Page 1 of 3 1 2 3 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •