Intake manifold construction, intercoolers

[Bernd Felsche]

Bruce tapped away at the keyboard with:
> From: "Kevin _" <kiggly at hotmail.com>

>> And when you're making a high rpm engine you keep the valves
>> unseated for over 300 cranshaft degrees.  Usually about 250 to
>> 260 degrees for 0.050" valve lift or more.  The more/less air
>> being packed at a certain time during the intake stroke is no
>> different at all for a turbo or non-turbo engine.  The only
>> thing you design slightly differently for a turbo is the speed
>> of sound is higher because the intake air temp is higher in a
>> turbo application.  Thus, you need slightly longer runners for
>> the same Helmholtz rpm, but its nearly inconsequential.

> Higher rpm, OK, how high are you talking about.  The thread
> started with street cars, are you still working the street or
> moving into the race field I'd hardly call 250d at .050 as a
> street engine.

Depends on number of cylinders and method of induction.
My 4-cylinder car's NA with 270 degrees and more than 10mm lift.
It's only a bit lumpy at idle.

>>>If atmospheric pressure doubled, I don't think it will make an
>>>appreciable difference in the way an intake manifold worked.  The
>>>whole question still seems inconsequential to me, since by tuning
>>>an intake you are trying to increase intake air pressure by a
>>>small number of pascals.

>> Have you ever datalogged and seen pressure pulses at the back of
>> a valve?  When its all tuned right with the proper sized runners
>> it can be over 20% beyond atmospheric pressure during valve
>> closing.  We're certainly not talking single Pascals here.

> At the back of the valve, OK, and how fast does that decay as you
> move back from there?

Doesn't matter. It's the pressure at the back of the valve that acts
to fill the cylinder.

>> BTW - Bruce said he was looking for 'new' stuff in engines.
>> Check out F1 stuff before you call everything old and pushrods
>> good.  Approximately 300hp/liter naturally aspirated on gasoline
>> (yes, I do use that term loosely) and revving to near 20k rpm
>> isn't trivial.

> To whom?
> I haven't seen any of that wizz bang technology filtering to
> anything on the street yet.  They still have reached any level of
> performance that can't be done with engines that would have
> transferable technology to the street.  The rules in F1 are just a
> game anymore to see who can spend the most for something that can
> win.

Same in all motorsports.

If you want to see how much of that technology is filtering down
into production cars, I suggest you browse through SAE's Automotive
Engineering magazine occasionally.

Cars built on space-frame: yes - FIAT and Audi
Multi-valve engines with variable manifolds: yes - most manufacturers
Dierect gasoline injection: yes - Toyota, VW-Audi, Mitsubishi
Turbo-multivalve engines: yes - Volvo, VW-Audi, Subaru, etc.
Independent cylinder throttling: yes - BMW (3 series and 7-series)
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