On Tue, 23 Jun 2015 00:45:12 -0400, Ed Huntress
wrote:

On Tue, 23 Jun 2015 09:16:40 +0700, John B.
wrote:

On Mon, 22 Jun 2015 21:01:32 -0400, Ed Huntress
wrote:

On Tue, 23 Jun 2015 07:58:35 +0700, John B.
wrote:

On Mon, 22 Jun 2015 13:39:32 -0400, Ed Huntress
wrote:

On Mon, 22 Jun 2015 10:26:25 -0700 (PDT), rangerssuck
wrote:

On Sunday, June 21, 2015 at 5:40:25 PM UTC-4, Ed Huntress wrote:
For the gearheads:

If you think that engines are getting too complicated, you'll want to
take a look at Volvo's T6 engine. It has both a mechanical
supercharger and a turbocharger.

This has been in the press for around a year, but the engine is
available in two cars, is in production, and is getting some reviews.
Apparently it's very nice to drive. I wonder how nice it is to
repair...

The Eaton supercharger is there for low-end boost, to make the 2-liter
4-cyl. feel like a V8, with no turbo lag. At around 3500 rpm, a clutch
disingages the supercharger and the turbo, which is now fully spooled
up, takes over. It produces 302 hp and 295 ft.-lb of torque.

It's impressive engineering but I think they just tipped over the
edge. With direct injection, variable cam timing, and two types of
superchargers, it has to make mechanics gulp. I hope they've given as
much thought to maintenance and repair.

--
Ed Huntress

Pushrods or... oh, never mind ;-)

And the model should be that extremely advanced Bristol engine of the
1950s, used in a variety of cars, that had 6 cylinders, 12 valves, and
18 pushrods. g

I've worked on stationary diesel engines that had three cam lobes per
cylinder :-)

But we were talking about *advanced* engines. That's all about
pushrods, if you've been following the unending discussion. d8-)

So, how many pushrods did it have per valve? g

Only one push rod per valve.

In thinking about it there may have been 4 cam lobes per cylinder :-)
The extra ones were for the injection pump and (I think) there was a
fourth that operated the air start valve.... but it was a long time
ago :-)

I believe that they were considered "advanced" back in their day. 750
Kw @ 900 RPM.

You realize, I'm sure, that I meant "advanced" in an ironic way. d8-)

As I did when I said "back in their day" :-)

Certainly makes some of the more modern push rod engines
look anemic :-) Some versions even had "variable valve timing".... so
they could run in the other direction :-)

The historical variations on IC engines are pretty amazing. There's
very little going on that han't been tried before. The big difference
now is the electronics.

Apparently everything is electronic. My wife got a notice to bring her
Honda (car) into Honda Service to have the "Transmission Software
updated".

I owned one of those 18-pushrod Bristols, BTW, and eventually learned
(was taught, actually, by a Bristol expert) how to keep those valves
adjusted. They needed to be adjusted almost constantly. The lash on
the exhaust side, where there were two pushrods and two rocker arms
for each valve, would open up in a month of regular driving. That is,
unless you had a recent valve job, in which case it would first
*close* up. Sheesh.

I've always wondered about Roll Royce's reputation coming from a
country where valves had to be adjusted weekly, where SU carbs were
invented and the amazing Lucus electrical system originated.
I remember looking at a, probably, late 1930's Rolls in a vintage car
place in Miami and under the hood it seemed to be about as prosaic as
my 1937 chevy. I've always wondered if that might not have been their
secret :-)
--
cheers,

John B.