SOHC vs DOHC valvetrains – a comparison

Plenty of people have been talking about how the Savvy only has an SOHC engine so it is inferior, and old technology, so I decided to post this entry so that people will be better informed on what SOHC or DOHC really is.

SOHC and DOHC are basically two different ways to configure the valvetrain. In the whole valve train setup there are camshafts, lifters, rockers, valves and springs. It is best that the valvetrain is light. Valves open at intervals of 25 times a second at 3000rpm.

If the valvetrain is heavy, when the camshaft lifts it the valvetrain will just keep going up until the valve spring catches it. This is called valve float. You can overcome this with stronger (which means heavier) springs, but this extra weight increases the power requirements to open the valve.

The cams are driven by the crankshaft, using either a belt or chain called a timing belt or timing chain. If the timing belt/chain snaps and the camshaft stops spinning, the piston coming back up the combustion chamber might hit the open valves. This is very costly. That’s why you should always change your timing belt/chain at the interval specified by your car manufacturer.

SOHC refers to Single Overhead Camshaft. In the days before DOHC, it was known as OHC, with no need to differentiate between a single or double camshaft. In SOHC, the camshaft is situated in the cylinder head, above the valves. The valves are opened and closed either directly with a shim between the cam lobe and the valve stem, or via a rocker arm.

SOHC engine valve configurations typically have 2 or 3 valves per cylinder. It is also possible to have 4 valves per cylinder using SOHC but this translates into a complicated combination of rocker arms and cam lobe shapes. An example would be the 4G92P in my car which is a SOHC but has 4 valves per cylinder.

DOHC refers to Double Overhead Camshaft. This arrangement uses two camshafts in each cylinder head. Two cams per cylinder head means that a DOHC V engine has 4 camshafts because it has 2 banks of cylinder heads. This allows the manufacturer to easily implement a 4 valve per cylinder setup. Most of the time it also allows the engine to rev higher. It also allows better placement of the valves in an optimized setup that gives you maximum performance.

But the disadvantage of such a setup is more weight, more cost and more complexity. It takes more stuff to drive two camshafts. The main reason to use DOHC is to drive more valves per cylinder. If a SOHC setup can allow 4 valves per cylinder, having a DOHC engine will not bring that much benefits over SOHC and the additional weight becomes a burden instead. DOHC engines also allows the spark plug to be placed right in the middle of the combustion chamber. This promotes efficient combustion. With SOHC, the camshaft is usually in the middle of the head because it has to drive both the intake and exhaust valves, robbing the sparkplug of it’s optimal location.

In the end, a SOHC 16 valve engine would have better torque on the low end where the DOHC valvetrain’s weight results in lower torque. But at high engine speeds, the 16 valve DOHC engine’s peak torque and horsepower would be greater. That’s the trade-off. With the amount of valves being equal, SOHC has better low-end torque because the valvetrain package is lighter while DOHC has better top-end power.

Other benefits of DOHC would be making it easier to implement variable valve timing technologies (which I will cover in another blog post) and also you can tweak it better with adjustable cam pulleys. If you were to put high-profile cams in your DOHC engine, the cam lobe profile can also be more optimized than a SOHC engine because you can play around with the lobe shape easier with separate camshafts for the intake and exhaust valves.

Why more valves per cylinder? Why not just make 1 huge intake valve and 1 huge exhaust valve? Bigger valves weigh more than the smaller one, so controlling the extra weight as it gets flung open and close becomes difficult. The spring has to be stiffer. A stiffer spring means more energy has to be spent overcoming the valve pressure. This partially oversets the gains which a bigger valve has to offer. Another problem with a single big valve is at lower RPMs the intake velocity will be lower.

I’m sure you guys know this… the same amount of air going through a big pipe will have lower pressure than the same air going through a smaller opening. Think of how you can control the water pressure of your garden hose by adjusting the opening size with your finger. Because of the velocity drop, low RPM torque and driveability will suffer. Although two smaller valves weigh the same as 1 big valve, and with the extra rocker arms and springs they can actually end up weighing more, this is offset by less mass to be overcome when opening and closing the valves.

So, are more valves per cylinder really that beneficial? Here’s comparing a Nissan VG30E to a VG30DE. Both are 3 litre electronic fuel injection engines, but one is a SOHC with 2 valves per cylinder and the other is DOHC with 4 valves per cylinder.

We can see that torque at low RPMs are about the same for both engines, but at higher speeds the 2-valve per cylinder engine has reached it’s peak and has to switch to the next gear while the twincam 4 valve per cylinder engine continues making more power at the top-end of the powerband. The powerband is also longer. (Note: I’ve added this graph here to show you the difference between 2-valve and 4-valves, not SOHC vs DOHC. Couldn’t find any graphs for SOHC vs DOHC. Sorry!)

So to sum it all up, SOHC has better low-end power, DOHC has better high-end power and overall maximum power. 4 valves per cylinder is much better than 2 valves per cylinder and it doesn’t matter whether 4-valves is achieved via SOHC or DOHC.

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Paul Tan

After dabbling for years in the IT industry, Paul Tan initially began this site as a general blog covering various topics of personal interest. With an increasing number of readers paying rapt attention to the motoring stories, one thing led to another and the rest, as they say, is history.

 

Comments

  • karheng on Jun 23, 2005 at 2:49 am

    Informative! I always knew what SOHC and DOHC were good at, but never known why really…this post explains it all!

    Like or Dislike: Thumb up 11 Thumb down 0
  • Clauz on Jun 23, 2005 at 5:32 am

    IMPRESSIVE… Are you mechanical pro…

    Like or Dislike: Thumb up 2 Thumb down 1
  • NSDS3HvLDjJd on Jun 23, 2005 at 5:46 am

    I'm seeing stars…

    Like or Dislike: Thumb up 3 Thumb down 0
  • Raj Singh on Jun 23, 2005 at 6:41 am

    I still reckon a DOHC engine would do some justice to the already small 1.2L savvy. The reason is because you are going to have to push the car harder in each gear (this is where the high end torque would benefit) to get it to the required speed faster. allowing twin cams wold also allow easier profiling of the intake and exhaust valves for a slightly optimum perfomance. This would increase the price of the car though, if it was done.

    Like or Dislike: Thumb up 1 Thumb down 0
  • waaah… barulah clear skit!!! hehehe good work Paul!!! i did my automotive subject in those univ day, but in arabic country in the middle east the abriviation always wind my head in pening kepala… hey, i thik you should post these article of yours to the univ or college that major in auto as a side reference, it will felp a lot to student to understand more easy!!! good work Paul!!!

    Like or Dislike: Thumb up 4 Thumb down 0
  • thik = think

    felp = help

    hehe… sorryyy, speed typing, but not speed driving..

    Like or Dislike: Thumb up 1 Thumb down 3
  • Good job Paul.

    Never did understand this till now, with more and more car going to DOHC, I always think DOHC is better then SOHC… but it become clear now.

    Like or Dislike: Thumb up 2 Thumb down 0
  • karheng on Jun 23, 2005 at 7:38 pm

    hmmm…just hit me…ur car running on a mivec? I know it's 4G92 but i duno where ur P came from..ehhehe

    Like or Dislike: Thumb up 0 Thumb down 0
  • karheng: 4G92P… the P stands for Proton! LOL! It's a normal single cam 1.6 lar… not Mivec. 4G92 engine code as far as I know could mean 3 engines… 4G92 SOHC, 4G92 DOHC and 4G92 DOHC Mivec

    Like or Dislike: Thumb up 2 Thumb down 0
  • Ezmil on Jun 23, 2005 at 11:00 pm

    Very good explaination. It is interesting to know that Honda City and Jazz are using SOHC config to their engine, and nobody complains about it :-)

    Like or Dislike: Thumb up 3 Thumb down 0
  • maniam on Jun 23, 2005 at 11:06 pm

    macam tu sesuai ler savvy pakai SOHC emmmm …tak ler ketinggalan cam tu

    Like or Dislike: Thumb up 1 Thumb down 0
  • Ezmil: the honda city and jazz are using SOHC, and only has 2 valves per cylinder for the i-DSI versions. they couldn't fit more valves per cylinder because of the dual sparkplug design. takes up alot of space.

    the VTEC SOHC 1.5 in the honda jazz vtec uses a 12V/16V design where there are 4 valves per cylinder but only 3 valves work at low RPM and all 4 valves work at high RPM.

    Like or Dislike: Thumb up 10 Thumb down 0
  • bangau on Jun 25, 2005 at 5:48 am

    Good job!!!!! We always have some idiots who would thrash Proton for using SOHC engine, but Honda is also using it but goes scot free without any bashing.

    Anyway, if you are referring to the Savvy and MyVi, it wont be a fair comparisons because the SAvvy, eventhough has a lower hp rating, will still run circles around the MYVI since the MYVI is a class larger and heavier. I've tried both cars back to back.

    Like or Dislike: Thumb up 0 Thumb down 0
  • sakaic on Aug 28, 2005 at 12:06 pm

    I feel there is something small to clarify and I'm sorry if I unintentionally offend anyone.

    The main reason why there is a difference in torque between the 2 engines is not because of the no. of camshafts but the number of valves.

    When you have 2 valves, the intake pressure at low revs is actually higher cos the intake port is smaller and that gives more pressure. Thats why at one time toyota 16v heads came with T-VIS. it shut one of the 2 intake ports per cylinder to increase intake speed at low revs. Higher pressure increases intake speed resulting in more air.

    Nowadays, they put a medium sized port size to reduce this problem.

    Like or Dislike: Thumb up 3 Thumb down 0
  • sakaic: yup, that was what i was trying to say in my blog post. honda's 1.5 vtec used in the jazz and city vtec actualy works like the T-VIS you mentioned.

    Like or Dislike: Thumb up 2 Thumb down 0
  • Mohd Fairuz on Sep 12, 2005 at 1:41 am

    I'm thinking of getting a Honda Accord 2.2 with auto transmission.. but I don't know what to choose.. sohc vtec or dohc vtec.. the salesman told me that if I'm going for auto, then dohc will make no big difference over the sohc.. so sohc is a wise choise.. is that true?

    Like or Dislike: Thumb up 0 Thumb down 0
  • Jimmy on Oct 07, 2005 at 12:35 pm

    Let's say a race a DOCH VTEC with my SOHC 16 valves, you think i will bet the DOCH VTEC? What is the difference what are my advantages.

    Like or Dislike: Thumb up 2 Thumb down 2
  • Vince on Nov 06, 2005 at 1:43 pm

    Hi Paul,
    I found this Blog on SOHC vs. DOHC to be very informative. I just have a question or two concening today’s technology and your information in relation to the new 2006 Honda Civic (Si). Obviously changes in technology are always changing things, and create new alternatives.
    Now, if you compare two vehicles with the same amounts of valves, the new 2006 Honda Civic’s (Si) SOHCs with it’s systematic timing and control in valve configurations (i-vtec), to let’s say the Scion tC’s DOHC (possibly w/o a supercharger), same engine used on the Toyota Camry, Would these new configurations change the overviews (rules)?
    According to your explanation and my limtied knowledge, the Civic (Si) would probably beat the tC in a 1/4 mile but not in the long-run. I cannot say I understand the Si’s engine configurations completely, but Would these rules still apply in low-end torque, high engine speeds, peak torque, and horsepower?

    Like or Dislike: Thumb up 3 Thumb down 0
  • Vince on Nov 06, 2005 at 2:20 pm

    Just a note, I realized I placed the Si model in my questions to what may seem, as a SOHC. I know it is a DOHC, but I just wanted to know the comparisons results or theory between these 2 DOHC engines just as well as the SOHC vs. DOHC results.

    Like or Dislike: Thumb up 0 Thumb down 0
  • Prometheus on Nov 13, 2005 at 3:18 am

    These were better times in your blog Paul.. Less flaming, more information. Time to change all that.. You have to make the change

    Like or Dislike: Thumb up 0 Thumb down 0
  • Honda Man on Dec 31, 2005 at 12:04 am

    Wait a minute Paul, are you saying that the City 1.5 VTEC actually just shuts one intake valve at low rpm, and have all intake valve operating at higher rpm? What about valve timing and lift? Does that stays the same or does that varies too?

    Like or Dislike: Thumb up 0 Thumb down 0
  • maxmatterz (Member) on Jul 17, 2008 at 7:40 pm

    Between DOHC and SOHC which one is more fuel saver?

    Like or Dislike: Thumb up 1 Thumb down 3
  • Susan Loving on Mar 18, 2009 at 11:07 am

    Paul,

    I may be stupid on all of this but can you just tell me which one would be best for normal driving on a 1991 Dodge Stealth RT 3.0 5 speed.

    Susan

    Like or Dislike: Thumb up 0 Thumb down 0
  • pranesh on Mar 22, 2009 at 7:29 am

    its great dude.. can u give more detail over the complication of having 4 valves in sohc and explain me the example 4G92P which you have used…

    if possible post to my mail…please…..great work

    Like or Dislike: Thumb up 0 Thumb down 0
  • Charlie Bader on Apr 07, 2009 at 8:50 pm

    You left out the biggest reason for 4 valves/cyl- valve area. The total area of the valves is much greater because the non-valve area is smaller with 4 valves. It's like the jar of marbles problem- you can fit more in if the particles are smaller.

    Like or Dislike: Thumb up 0 Thumb down 0
  • Yantho on Apr 12, 2009 at 12:27 am

    hey paul, i've had a mazda 323f 1.6L 16v dohc for ebout 250000kms, now i've bought the exact same car but in a 1.8L grsi 16v dohc version at around 175000kms,

    now i'm looking to transplant some parts from my old one, but i can't quite get my finger around that grsi thingy sticking on to the back end like ted kennedy on a hogie, what does it mean, and is it possible to somehow supercharge the engine (turbo)? as you have no doubt guessed i know jack about car engine's but i know what i like so can anyone help, some tips on how to do this, and what grsi stands for?

    cheers,

    Y

    Like or Dislike: Thumb up 0 Thumb down 1
  • ken nguyen on May 22, 2009 at 2:25 pm

    I just visited a Dodge dealer. I saw the Grand Caravan I like very much, but one of the main differences between its engine and the toyota minivan is the SOHC (toyota van has DOHC). I wonder if this makes the Toyota more reliable van, but after reading your article, I understand this is not the reason why Toyota is more reliable. Thank you!

    Ken N.

    Like or Dislike: Thumb up 0 Thumb down 0
  • frank on Jul 20, 2009 at 7:21 am

    SOHC has better low-end power, DOHC has better high-end power and overall maximum power.

    what do you mean by low end power and high end power ? from your conclusion DOHC is better ??

    Like or Dislike: Thumb up 2 Thumb down 0
  • Cicma on Aug 08, 2009 at 3:27 pm

    Low end and High end is referred to the RPM's, that means to low RPMS (a soft drive) or high RPM (accelerating to the top), so when you are a high speeds your engine will need be in high end (High RPM's) to maintain the power (velocity) that's when a DOHC is better. Of course that was just an example, also depends of the engine configuration; so if you like rev your car a top that means drive fast with fast shift changes its better a DOHC, but if you drive smooth in the city you will no need a DOHC and with SOHC would be enough, the difference could be more noticed, as said, in how many valves per cylinder the engine has

    Like or Dislike: Thumb up 3 Thumb down 0
  • Frank on Aug 10, 2009 at 8:31 am

    Thanks for the info. But for a layman …all I want to know is ….the new Honda Accord VTiL has a SOHC configuration while the older generation has a DOHC configuration . Just tell me which is better !!! Thanks .

    Like or Dislike: Thumb up 0 Thumb down 0
  • Frank on Aug 10, 2009 at 8:32 am

    Thanks for the info. But for a layman …all I want to know is ….the new 2009 Honda Accord 2.0 VTiL has a SOHC configuration while the older generation 2005 Honda Accord 2.0 iVtec has a DOHC configuration . Just tell me which is better !!! Thanks .

    Like or Dislike: Thumb up 0 Thumb down 0
  • Hey!!!! This is a really good piece of info. Really informative. Keep up the goodwork…..

    Like or Dislike: Thumb up 0 Thumb down 0
  • vikas on Sep 12, 2009 at 5:46 am

    kindly advice fire 1.4 starjet in linea is better than ford duratech technically or if compare fire with duratech and i vtech which is best

    Like or Dislike: Thumb up 0 Thumb down 0
  • Saibal Das on Oct 01, 2009 at 11:26 pm

    Being a marine engineer i always work with pushrod-rocker type engine( medium speed diesel engine) or hydraulically operated exhaust valve( slow speed diesel engine) and i donot have any exposure to petrol/gasoline engine. my question is there any cam follower in the dohc system and how the valve clearance is adjusted? how valve timing is adjusted?

    Like or Dislike: Thumb up 0 Thumb down 0
  • paco paquito on Dec 18, 2009 at 9:53 pm

    newer engine like R18 or R20 in honda went full circle went they all came back to SOHC instead of DOHC. a number of followers questioned this honda moved. honda explained that going back to SOHC but an improved configuration based from the legendary D15B vtec SOHC has all to do with weight. the K20 is so nose heavy that in a quarter mile a lighter R20 (lighter than a D16 i heard) could readily smoked it. by introducing a simple set up with SOHC configuration in recent variants like the new crv and 2009 lines honda choose weight as the end of it all.

    Like or Dislike: Thumb up 2 Thumb down 0
  • Guilherme on Jan 08, 2010 at 4:32 pm

    Great article, but you got some things wrong.

    Having a single big valve doesn't effect low-rpm torque negatively, because the valve has plenty of time to open and close. The "hose" argument doesn't apply here, simply because when you use two valves, each valve gets only half the air mass as a larger one would get, therefore, pressure is equal (assuming the smaller valves have half the diameter of the big one).

    Another thing is that your conclusion that DOHC has more peak power than SOHC depends on other factors. The good old Honda D16 was offered in many configurations, and at one point in the late 80's, in Europe, it was possible to have either SOHC 16V or DOHC 16V, with all other things being equal.

    Power ratings for the engines were:

    SOHC 16V: Power – 115hp@5900 rpm, Torque – 13.9kgfm@4800 rpm

    DOHC 16V (Civic): Power – 125hp@6800 rpm, Torque – 14.9kgfm@5900 rpm

    DOHC 16V (Integra): Power – 118hp@5600 rpm, Torque – 14.3kgfm@4800 rpm

    From these numbers, one can see that the DOHC version used in the Integra has an earlier power peak than the SOHC, while the DOHC Civic indeed has more power and at higher rpm than the SOHC Civic. Later SOHC VTEC iterations of the engine would deliver more power and have a longer powerband than any of the listed engines.

    So I think a better conclusion would be that all things being equal, DOHC engines have more potential to have more power than a SOHC engine due to the finer control of valve timing. However, DOHC engines are more complex, less reliable, weigh more and are more expensive than a SOHC design, which explains that Honda was right in their decision to switch back to SOHC, as they can achieve similar performance results.

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  • Lee Debono on Feb 09, 2010 at 11:41 pm

    Nice Post there Paul.

    1 small thing that id like to point out.

    In Nissan's the D after the litre-age (either 20 – 2.0 litre, 24 – 2.4 litre or 30 – 3.0 litre) means that its a DOHC.

    The VG30E is a SOHC engine.

    The VG30DE is a DOHC engine.

    So you technically you did show the difference between the DOHC and SOHC systems.

    Like or Dislike: Thumb up 2 Thumb down 0
  • speedfreak on Mar 10, 2010 at 8:19 pm

    which is better in terms of speed?OHV or OHC?lets say that the speed that we need to meet is like 160km/h

    which is better to get to the said speed?

    Like or Dislike: Thumb up 0 Thumb down 0
  • Robin on Apr 07, 2010 at 1:11 pm

    Good. Very informative.

    Like or Dislike: Thumb up 0 Thumb down 0
  • KCivic on Apr 11, 2010 at 10:19 pm

    Its amazing that ppl are using this Blog for reference and information related to cars and driving cos after original posting of this dohc vs sohc article since mid 2005, ppl are still sharing opinions here. I always tot driving dohc is better than sohc or more powerful.

    Like or Dislike: Thumb up 0 Thumb down 0
  • Beryuyuyuyu on Apr 16, 2010 at 7:29 am

    Daily driving, they’re both more or less Equal I’d say. Unless you were racing with a stock motor, the DOHC takes it. But if you were racing, both of the motors etc would be modded which kinda balances everything out. Because who would wanna risk those high rpms with a stock motor?

    Like or Dislike: Thumb up 2 Thumb down 0
  • Kevin W on May 21, 2010 at 2:24 am

    Hi Paul, do u know is Ford Ranger 2.5cc TDI/WLT SOHC a 12 valve or 16 valve design?

    Please advise,

    regards,
    Kevin.

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  • thanks man. great work….!

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  • When you say “A stiffer spring means more energy has to be spent overcoming the valve pressure”, are you forgetting that the same amount of energy is returned. That said, stiffer springs do create more friction…
    Also, the rockers in an SOHC add to the reciprocating mass. And you cant have a 4v SOHC without rockers. There’s no arguing the low end punch of an 2v SOHC though (look at the 205gti).

    Like or Dislike: Thumb up 0 Thumb down 0
  • helman on Aug 11, 2010 at 10:14 pm

    can you give more???

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  • miker on Sep 18, 2010 at 11:17 am

    as for me, power and torque depends on the cam lobe profile, the lift and valve opening/closing degree. as an example, daihatsu acsend 1.6 SOHC 16v engine, and high performance daihatsu charade detomaso 1.6 SOHC 16v using a same engine but different in cam profile. it produces a different output. single cam engine normally uses a rocker arm as a link between cam lobes to valves. so, there will be much more friction, (cam lobe to rocker arm, rocker arm itself and rocker arm to valve). because of this, single cam engine cannot be design to rev higher, high rpm produces higher BHP per cubic capacity. ” to produce high power, sacrifice the torque” vtec, dvvt, vvti, tvis, cps, etc, engine is design to automatically ”tweak the sentence” by means of opening more valve, lifting the valve wider, or longer on certain RPM so that we can get both torque and power when we needed the most.

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  • Kentthegreet on Sep 20, 2010 at 1:48 pm

    Hi Paul,

    Thanks for this very informative blog. I have a question in summary. If I am only in normal driving like going to office and home and off town vacation at normal speed, should I get the SOHC? What about the SOHC’s fuel consumption compared to DOHC?

    Thanks.

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  • Abhishek on Oct 06, 2010 at 9:32 pm

    Thank you author for this informative post. I just had a query…

    In the beginning paragraph you have mentioned that,

    “If a SOHC setup can allow 4 valves per cylinder, having a DOHC engine will not bring that much benefits over SOHC and the additional weight becomes a burden instead”, but in the concluding paragraph it is written that,

    “4 valves per cylinder is much better than 2 valves per cylinder and it doesn’t matter whether 4-valves is achieved via SOHC or DOHC”.

    I am a bit confused about which one is better according to the city driving conditions where frequent grear shifting is needed and secondly, which one would be better in terms of ‘fuel-efficiency’.

    I request you to please clarify on this, thank you.

    Abhishek

    Like or Dislike: Thumb up 1 Thumb down 0
  • ProDigit on Nov 27, 2010 at 12:19 pm

    in other words a SOHC engine technically would use less gasoline (better mpg) for the fuel conscious driver?
    Because you can run the engine at lower RPM’s, have better torq there, the engine sucks less gasoline at lower RPM’s, and the engine’s bearings last longer (lower RPM means less heat; high revs are especially worse on a cold engine).

    Like or Dislike: Thumb up 1 Thumb down 0
  • mitch eppler on Jun 18, 2011 at 11:00 am

    you jump back and fourth between sohc and dohc info,too many words.Give me some specs.I will let you pick the cars

    Like or Dislike: Thumb up 0 Thumb down 0
  • brilliant!

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  • tawajas on Feb 02, 2012 at 7:44 am

    heyy Paul
    can u plz tell me which one’s more fuel efficient…
    dohc or sohc…

    i want sme real advice as i want to buy a bike in Indian market n my choices are KTM Duke 200 (dohc) & Bajaj pulsar 200 ns (sohc)…

    my priorities are performance, durability, low maintance, fuel efficiency…

    m more leaned towards Duke 200 bt m suspicious of its fuel efficiency as pulsar 200 ns is offering a huge 58 kmpl…

    plz do reply…

    i’d b greatful

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  • hi Paul and forumers,
    i am using waja auto 4g18 sohc.recently i found a shop at sg buloh who transform sohc head to dohc head package.he did few cars n only 4g18 sohc engine.
    plan to change to dohc head.the price is rm2k.
    any comments?

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  • So that’s mean SOHC better for city driving and DOHC for highway?

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  • Fiq 4g18 on Jan 07, 2013 at 11:32 pm

    hey Paul, quick question here . you think i should really convert my 4g18 sohc to a dohc?

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  • Satish on Apr 15, 2013 at 5:01 pm

    As an common man, I know very little or no knowledge of automobile. I got good information about SOHC and DOHC, thanks to Paul!
    I am bit confused in buying Toyota Liva Or Etios [sedan] and new Honda Amaze. As far test drive found Etios/Liva and Amaze equally good. Only Honda Amaze runs smoothly at low speed [30/40 km] even in 4th gear.
    Now can you suggest which one is better and why?

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  • mfendi on Jun 13, 2013 at 4:51 pm

    I used to think that DOHC was better, as in ‘more modern engine’. It was a bad assumption as I didn’t really understand the logic behind it. It was only up until recently I knew the difference, when I started looking to buy a new car. Now, this article here confirms my understanding, that the term should be looked at from multiple point of view instead. I blame this confusion on the marketing strategy that was carried out by the makers at that time. There is a lot more confusion still exist out there currently, surprisingly. I’m not good at automotive still but I will surely not be influenced nor cheated easily now. Thanks again for this article.

    Like or Dislike: Thumb up 2 Thumb down 0
  • marvin on Jan 26, 2015 at 1:03 pm

    good job sir!
    i have question, im just newbie interms of cars i bougth Mitsubishi Galant 2.0 Mpi 92 AT model(no idea about the history of this car) with 4G63a engine my question is how can you determine if this a SOHC or DOHC? is there any signs or markings to know what it is?

    thanks sir hope you can reply to question

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  • mohammed on Mar 13, 2015 at 11:28 pm

    Hello Sir,
    Thanx a lot for this post. It helped me a lot bcz i m mngmnt student n i dnt knw anythng abt engines. I hv one qstion ca, u xplain wht u wrote in 5th para abt dohc… spcly 3rd sntnce. DOHC refers to Double Overhead Camshaft. This arrangement uses two camshafts in each cylinder head. “Two cams per cylinder head means that a DOHC V engine has 4 camshafts because it has 2 banks of cylinder heads”. This allows the manufacturer to easily implement a 4 valve per cylinder setup.

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  • Oh mak lu cina on Jan 18, 2016 at 10:05 pm

    2 valves gives better flow because of having more surface area. Not so much because of the weight. According to your explanation, ONE lightweight titanium Valve configuration will flow more than TWO regular valve engine configuration.

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  • Hi Paul, I’m loving your work in here , it is very informative as I am a novice in car engines. I just acquired a Dodge Durango 4DR Sport utility(4.7L SOHC 16V), it has always been my dream car seeing the ruggedity and performance from other users ,My question is/are there any car brands/models engine that fits into this dodge Durango if I decide to change the engine or in the case the engine is no more in production. 2. what other car brand/models uses almost same engine parts or body spare parts as a Dodge Durango 2002.Thank you.

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  • I’m reading this is 2017.

    Woohoo! You Go Paul!

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