[DeTomaso] NPC: DOHC or Pushrod holy war.....Was: New CorvetteEngine

Dave Londry davel at emspace.com
Sat Jun 4 17:50:49 EDT 2011


Some good points here.....
- VVT yes. Simple advance is OK with SOHC, but anything more complex 
than that is just stupid difficult.

- 2 cam pushrod makes sense if you have a rule-book to bend; otherwise????

- I really don't get why Ford went to 3.937" bore centers for the 
modular engines.
   It's too small, and going to 4.25' would have cost them a whole inch 
of block length.
    Must have been a marketing decision.
    GM made the same decision with the North Star (4.00") so it was  was 
contagious.

    The AMG 6.3 engine has 4.29" centers  which is a little less than a 
Cleveland
     but it's pretty good and it's the only one of the new, new engines 
in that range.

dave



On 6/4/2011 7:12 AM, Will Kooiman wrote:
> I think it really boils down to this...
>
> DOHC has many advantages - rev higher, more hp per cubic inch, etc. - but it
> comes at the cost of more complexity.
>
> The biggest problem with DOHC engines is they tend to be smaller
> displacement.
>
> The other problem is the complexity doesn't seem to be worth it.  DOHC has
> lots of small improvements over pushrod.  The only one I consider a big
> improvement is the ability to rev 8,000 without mongo springs.
>
> -----Original Message-----
> From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] On
> Behalf Of Sean Korb
> Sent: Saturday, June 04, 2011 8:39 AM
> To: List Pantera
> Subject: Re: [DeTomaso] NPC: DOHC or Pushrod holy war.....Was: New
> CorvetteEngine
>
> I would very much like a pushrod engine with two camshafts.  The lower
> for exhaust and the upper camshaft for intakes.  Then you could have
> independent and variable movement of intake and exhaust in the same
> small lightweight package.
>
> Not a new idea.  Ford was going to try this on their big block can-am
> cars, but they quickly changed the rules.
>
> sean
>
> On Sat, Jun 4, 2011 at 8:58 AM, corey price<coreyjprice at gmail.com>  wrote:
>> Okay, I just have one comment:
>>
>> DOHC makes it much easier and cheaper to implement independent
> intake/exhaust variable valve timing.
>> Just my two cents.
>>
>>
>>
>>
>> On Jun 3, 2011, at 1:43 PM, Dave Londry wrote:
>>
>>> Now if you said:
>>> "There is no reason to build a DOHC engine instead of a SOHC engine"
>>>   - I could get that. Twin cams are just more shit to keep spinning and
>>> the width is ugly,
>>>      So long as you manage to place big valves, across a hemi chamber, a
>>> single cam is fine.
>>>
>>> But a pushrod with in-line valves - that's just still more heavy shit to
>>> keep moving and to no benefit.
>>>
>>> Now the direct injection system in the new LS is very fine - keep that
> part.
>>> dave
>>>
>>> (duckin' and weavin')
>>>
>>>
>>>
>>> On 6/3/2011 12:28 PM, michael frazier wrote:
>>>> Weak...very weak.  If you want to start a holy war, well then:
>>>>
>>>> I hope the new Vette doesn't go to a OHC engine more like the high-end
> Euro competition.  That would be a step
>>>> backwards in performance if it ran like a F-car or Lambo.  Ford now
> builds engines bigger on the outside that an old Hemi,
>>>> smaller on the inside than a 289, and just overly complicated.  I think
> you're now required to put your testicles in your
>>>> purse when you buy a new (plastic magnet) Mustang.
>>>>
>>>> On an only slightly more serious note...I don't think they would gain
> anything over the LS engines.  Those are beautiful
>>>> engines capable of much much more than they than come off the assembly
> line with.  Pushrods, overhead cams,
>>>> in the real world one's not "better", they're just different.
>>>>
>>>> Michael Frazier
>>>> Gruppo Rompiculi Corsa
>>>> Pushrods are better.
>>>>
>>>>
>>>>
>>>>> Date: Fri, 3 Jun 2011 15:07:01 -0400
>>>>> From: rob at dumoulins.net
>>>>> To: detomaso at realbig.com
>>>>> Subject: [DeTomaso] NPC: DOHC or Pushrod holy war.....Was: New Corvette
> Engine
>>>>> Personally, I believe a Dual Overhead Cam design is superior and
> wondered
>>>>> why it took so long for US manufacturers to adopt it in their high-end
>>>>> motors.
>>>>>
>>>>> Flame On
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