sohc vs dohc

[sittinsideways]

i searched and found nothing comparing the two engines. what are the advantages of one over the other? disadvantages? any info would b greatly appriciated. flaming....not so much

[90RS13]

Well, if you searched about dohc and sohc KA's and found nothing comparing them, I feel you have serious issues with searching.

For most poeple the DOHC is better. I say most people cause most people are going to do basic bolt-on's and if they get alot of cash they will get a something imported. So the dohc's base power being higher is a plus. The valvetrain is also a plus. If you plan on dumping alot of cash into it, you may want to go sohc. the sohc has a better aftermarket, like, dry sump oil pans, carb manifold (which you can use with TWM ITB's). And the best (my opinion) feature of the sohc is that there is alot more room to port on the sohc. You can take more material away, so it would seem ultimately make more power on the sohc.

More info can be found in our beautiful forums.....

[theicecreamdan]

dry sump pans will work for either motor.
There is more NA support for the SOHC
Turbo seems to be favored by the DOHC aftermarket.

[BigVinnie]

The SOHC head can get more porting than the DOHC.
Hydraulic lifters suck for high rev, bucket hydraulics on the DOHC are better for rev.
DOHC comes standard with a knock sensor easier tuning with fuels, although a dohc ecu can be modified to sohc with a knock sensor.
DOHC has more advantages with cam timing configurations.
DOHC has a stronger bottom end using a girdle.
Overall both are great engines.

[wootwoot]

I like SOHC simply because it is enough for my needs and power goals if I were to build it. Simplicity works well

[Rickrak77]

I like the SOHC cuz that's what I've got, and truth be told, I don't really know anything bout the DOHC.

Unfortunately for me, no one makes any kits for my particular engine installation.

Fortunately I'm a pretty good fabricator, so I get to make my own stuff.:smash:

[infinitexsound]

this topic is retarded....cant wait to see someone start arguin with whats better then what....

[ledzeppelin240]

Bottom End on DOHC and SOHC is just about identical. My SOHC has a knock sensor that is part of the ignition system…Solid lifter conversion will solve any high RPM issues with the SOHC.

I am building a 350hp SOHC engine because I already have 3 of them sitting in my garage and they are so easily available. The aftermarket is huge; you just have to look a little harder. The only downfall is that the SOHC does not have oil squinters, but the DOHC ones will work with some machining.

Most people believe that just because it has 1 less valve it is useless, but a Chevy 350 only has 2 valves per cylinder…I have had no problem beating DOHC 240’s with my stock SOHC, but that could be driver error?

It’s a 10hp difference so read up more on each of the engines and decide what you want to spend your money on. By the way the SOHC has been proven for years as a solid race engine...

[infinitexsound]

yeah but that'll change.. u can totally believe that...about the racing part...

[macidcrook]

who cares whats better you can turbo them both. hahahaha

[RB26Sileighty]

dohc greatness out weighs sohc by a million...

[SochBAT]

Guess what? I win!

Yea, SOHCs have a large span of racing history. pretty powerful if you've got the cash, and knowledge.

Then again, doesn't everything have potential if you've got cash and wisdom?

Depends on your budget. And seriousness.

[macidcrook]

money will make anything better. it always does. hahaha

[stannyboy]

sorry found my answer..

[sittinsideways]

all this info is great and very helpful. what i'm lookin for is for a stock engine, what are the advantages and disadvantages between them. i would b replacing a blown motor. and somewheres down the rd replacing with a sr.

so on a daily driving side of things what is better? or is there any diff? i.e gass milage, cheeper and/or easier to maintain, more reliable and what not

[unwed_transient]

so on a daily driving side of things what is better? or is there any diff? i.e gass milage, cheeper and/or easier to maintain, more reliable and what notdaily driving? no difference at long as it runs

[macidcrook]

so on a daily driving side of things what is better? or is there any diff? i.e gass milage, cheeper and/or easier to maintain, more reliable and what not


there about the same when it come to that. the only diff is the power. all the maitenence parts all pretty much the same and the same price.

[infinitexsound]

like i said this topic is retarded..............

[BigVinnie]

there about the same when it come to that.

Actually NO. SOHC is defenitely the weaker of the two as far as performance is concerned. Exhaust flow is increased on the DOHC by utilizing curtain space with an additional valve per cylinder. SOHC's are more suseptible to rod knock, because they don't come with oil squirters to well lubricate the the entire bottom assembly. SOHC's also run a lower compression so that it could utilize 87octane more effeciently, if the DOHC uses that shitty fuel, gas mileage would decrease from the knock sensor responce. DOHC bottom ends are stronger, even stronger than the sr bottom end by using one single casted girdle, sohcs do not come with a girdle at all. Obviously the SOHC wasn't designed as a high rever, but rather a low torquer, the dohc engine and it's block was made for high rev, if the proper modifications are made to the bottom end such as windage trays, and scrapers, or a knife edged crank to help better harmonic distubances. Although scrapers are also available for the SOHC as well.

the only diff is the power.

Thats not all that true either, Engine management is what will increase performance and power. If the sohcs utilized 16bit ECU's instead of the 8bitters there defenitely would be more power if not just as much as the DOHC's in stock trim. Utilizing a knock sensor is really the true advantage of the DOHC's and it's power produced in stock trim, 16bit ecu's also have a tendancy too tune more aggressively than the 8 bitters. Stock for stock they can run head up, the DOHC engine is obviously primed and ready for performance, the sohc would need some work....

like i said this topic is retarded..............

Agreed next subject please... Before some jack ass gets mad at my asshole remarks and docks me some more negative rep points.......

[infinitexsound]

big vinnie.. honestly the de.... has way more f'kn potential then the 12 valve... both are good motors just that the 16 valve is just a better built motor from the factory.... ive seen both motors fully built firsthand....maybe when im not to busy busting my ass in the paddock.. ill take some pics of the motors... but honestly pics dont define shit unless u see it first hands at a race track....... ill let u guys know when were going to be at infineon... maybe u guys can come buy and say hello...

[BigVinnie]

I was stating that the 16valve was better as well.... Everything on the DOHC did come better from the factory....
Yeah I'm down to meet up at infineon when they open this year..... Down to hit some auto x in the scca???? I just need to get some steel braided lines for my 91 this year.....

[SilviaNinja240]

honestly, I don't see THAT much difference between the two. If you took a blindfold test (though I don't recomend driving while blindfolded), you probably wouldn't be able to destinquish one engine from the other, unless you are the rain man or something.
anywho, dohc vs. sohc, 150 vs. 155hp or whatever, tuning possiblities... these are all just numbers on the internet. A more realistic difference would be in the engine compression, kilometers driven, etc.. And that all varies from motor to motor.
So I wouldn't lose sleep over it, just pick the motor that is in better condition :)

[infinitexsound]

honestly, I don't see THAT much difference between the two. If you took a blindfold test (though I don't recomend driving while blindfolded), you probably wouldn't be able to destinquish one engine from the other, unless you are the rain man or something.
anywho, dohc vs. sohc, 150 vs. 155hp or whatever, tuning possiblities... these are all just numbers on the internet. A more realistic difference would be in the engine compression, kilometers driven, etc.. And that all varies from motor to motor.
So I wouldn't lose sleep over it, just pick the motor that is in better condition :)

u have no idea

[macidcrook]

Actually NO. SOHC is defenitely the weaker of the two as far as performance is concerned. Exhaust flow is increased on the DOHC by utilizing curtain space with an additional valve per cylinder. SOHC's are more suseptible to rod knock, because they don't come with oil squirters to well lubricate the the entire bottom assembly. SOHC's also run a lower compression so that it could utilize 87octane more effeciently, if the DOHC uses that shitty fuel, gas mileage would decrease from the knock sensor responce. DOHC bottom ends are stronger, even stronger than the sr bottom end by using one single casted girdle, sohcs do not come with a girdle at all. Obviously the SOHC wasn't designed as a high rever, but rather a low torquer, the dohc engine and it's block was made for high rev, if the proper modifications are made to the bottom end such as windage trays, and scrapers, or a knife edged crank to help better harmonic distubances. Although scrapers are also available for the SOHC as well.



Thats not all that true either, Engine management is what will increase performance and power. If the sohcs utilized 16bit ECU's instead of the 8bitters there defenitely would be more power if not just as much as the DOHC's in stock trim. Utilizing a knock sensor is really the true advantage of the DOHC's and it's power produced in stock trim, 16bit ecu's also have a tendancy too tune more aggressively than the 8 bitters. Stock for stock they can run head up, the DOHC engine is obviously primed and ready for performance, the sohc would need some work....




whoa whoa whoa. i was not refering to the performance or the ablility of the motors. when it comes to that the de is much better. he was refering to point a to point b driving. no one cares if the car has a knock sensor or if the oil getter where is supposed to go when you just want to go get some food. you just want it to start and drive. im sorry you missunderstood what i was saying.

[downshift_sideways]

lmfao...i'm just waiting to hear a gunshot. i had a sohc engine, the engine got rod knock, switching to dohc engine..installing it now..will let you know if i feel a diffrence and as infinite said..this thread is wack. but you give them hell vinnie!

[EchoOfSilence]

the only good thing that can come about this is if infinitexsound comes through with those pictures and more info...

[BigVinnie]

Long intake runners of the DE lick balls though....
It would be great if a company could make a smog legal one for the DE with really short runners.....

[ledzeppelin240]

Long runners increase torque...I like that. Are you talking about the main bearing caps, cause on my SOHC it is one cast girdle.

[RBS14]

long runners also create a 30-40 hp falloff past peak hp which I don't like.

[BigVinnie]

Long runners increase torque...I like that. Are you talking about the main bearing caps, cause on my SOHC it is one cast girdle.


Should of clarified........ SOHC TRUCK BLOCKS. Which I realized alot of KA sohc guy's use for there builds....... They use non girdles in order to use a dry sump pan for the GT3 class.. or just one that would want to use a dry sump system, girdles get in the way of dry sump pan clearance.

Long runners suck, it makes the KA anemic and suffocate in high rev.....
KA already makes all the torque it needs with it's stroker crank, why add more crap that prevents high rev???

[infinitexsound]

the funny thing about a race motor... is that it looks like a typical motor... until u open it up.......ill post pics when i get a chance... but dont keep ur hopes up... GO TO A RACE! the de uses a alluminum intake manifold.. and runs a honda billet TB..