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Cam in block, pushrod OHV VS DOHC
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Thread replies: 19
Thread images: 1
Am I missing anything here guys?
>>
>>14216708
>sohc has none of the easy multivalve technology of dohc
There are multivalve sohc engines with vvt
>>
>>14216708
Think you pretty much nailed it, OP.
>>
>>14216737
But they're usually a complicated mess. Also, having a single cam they usually don't have fully independent VVT (so both intake and exhaust).

There are also multivalve pushrod engines, but fact of the matter is that if you want multivalve, DOHC is the easiest way to get it.
>>
>>14216708
Selfbump
>>
>>14216708
I thought the corvette got decent gas mileage compared to a lot of cars with dohc
>>
>>14217181
considering the power, the gm v8 and chrysler v8 get pretty good mpg. Definitely on par with ohc.

in the end what is the most efficient way to move air through engine. If you have small displacement you will need high revolutions.. and ohc will be better. If you can have high displacement, revolutions don't matter as much and a pushrod will work.

personally I think SOHC is probably the most durable and easiest to work on.
>>
>>14216708
SOHC is better than OHV in every possible way.

You're an idiot.
>>
>>14217181
It does, because
A. really, really, really tall final gearing for highway MPG
B. variable displacement

>>14217200
>similar valve control
>similar airflow
>just as easy to do multivalve
Yet SOHC weighs a lot more on V engines. Either go full DOHC, or stay OHV.
>>
>>14216708
>Doesn't know what he's talking about
>Still wastes his time making some shitty graphic
autism
>>
>>14217200
>>14217204
>not giving any arguments
Really helping the discussion here guys.
>>
>>14217203
You're a moron..

>less weight
>better port design

SOHC is better than OHV. It's not a debate. It's just better.
>>
>>14217216
>less weight
Two cams weigh more than one? That's some wierd maths there buddy.
>port design
Show me a SOHC head that outflows a third gen Hemi head.
>>
>>14217220
>He thinks I'm talking about overall weight of the engine
Proves how little you know about the subject.

>find me an engine that outflows this engine
hm, yes let me open up my book of bench flowed amerishit v8 heads with 5+ liters
fuck off idiot.
>>
>>14217203
the g8 gxp/gt got the same mpg as the m5/550i. Actually it got slightly better i think.

But as you say, mpg really isn't a good indicator of an engines efficiency as it is a measure of the entire car. You need to look at brake specific horsepower, and in that case.. the modern OHV is about the same as the OHC.
>>
>>14217237
Then say they have less valvetrain weight, instead of engine weight.
Anyways, it doesn't really matter. Valvetrain weight is only your enemy if you're spinning it up to high RPM (as mentioned in the OP), and you run into valve float. As long as you stay below that point, (7 to 9K, fine for a street engine) you don't need OHC at all.

I'm not talking about a specially ported head, I'm talking about a bone stock, facotry head. Head flow isn't just used for V-ates anyways, it's used to measure port efficiency in ANY engine. If you want to bring up the
>better port design
argument, be prepared to back it up.
>>
>>14217237
Now, let's compare some head flow, since you're clearly not into talking numbers. All at .500'' of lift, intake airflow.

Ford SOHC:
http://www.hotrod.com/how-to/engine/hrdp-1006-trick-flow-cylinder-head-upgrade-for-2-valve-46-l-ford-modular-engines/
Stock: 169
Stock, ported: 194
Trick flow heads: 250
Trick flow heads, ported: 268

Third gen Hemi:
http://www.hotrod.com/how-to/engine/mopp-1208-cnc-porting-late-model-hemi-heads/
Stock: 269 cfm.
ported: 303cfm

Oops. Stock third gen Hemi beats the stock SOHC head by a mile, and then proves to be on par with a ported aftermarket head specifically designed for performance.

And now for the kicker:
http://www.hotrod.com/how-to/engine/1601-top-ten-tricks-to-optimize-the-chrysler-6-4l-hemi-cylinder-head/
>350 cfm @.500'' intake
>>
>>14217323
hey i'm not going to read through that, and not that guy, but are the valves the same size? the 5.7 has a larger bore than the 4.6, so I would think the valves would be larger.
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>>14217341
Ford SOHC in that test used 46m valves, Hemi used 50.8mm. That's only a 9% increase in valve curtain. Given the 269cfm the Hemi has stock, that would mean it'd produce about 245cfm with a 46mm valve. That's still on par with the 250 cfm, completely re-engineered Trick Flow units.
Thread replies: 19
Thread images: 1
Thread DB ID: 405407



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