Date: Sun, 14 Feb 2010 12:04:41 -0800
Reply-To: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject: Re: Exhaust Design
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Hi All,
well , that is certainly exotic looking and is bound to help some.
What I would think though is .....
given the relatively extreme crudeness of the intake runners and plenum,
is that if you can't get much good air flow going in, getting it out
downstream of the cylinders isn't going to help very much.
I am talking about that small square hole in the air flow meter that all air
that enters the engine has to go through, and
the crudeness of plenum and intake runners, and only one intake valve per
cylinder , and 'ok' ports.
for comparison ..........and to look at a somewhat similar engine
........and aluminum block opposed four , ( just a decade-plus newer in
design ) like the waterboxer but 'a whole lot more' ..........just look at
the intake system on a Subaru engine , starting with the 1990 EJ22.
The throttle body is nice and big. The air mass meter obviously has to flow
better ........since the air does not pass through a small squareish hole ,
like it does in the waterboxers Air Flow Meter, and there is no flapper
valve in an air mass meter, like an air flow meter has.
Then look at the plenum area and intake runners.
The subaru plenum area is nicely cast into nice, large, 'swooping' cast
aluminum intake runners.........one nice casting.
They squeazed in a little more intake runner length by curving the intake
runners up some, then they turn and go straight down into the heads and have
2 intake valves per cylinder. You just look at that shape ...and you know
there is going to me more air getting into the cylinders than in a wbxr
engine, by far, is my guess. Inatake runner length is good for low end
power, more is better in that regard.
< some modern engines even have two different pathways through the intake
system....one for low end, one for top end )
You just look at the soobie intake ...and see how much more air is likely to
flow nicely with those intake runners compared to the
really...........'industrial grade' , like farm equipment almost
,......waterboxer intake set up.
I even have late-night wild plans to fit a subaru intake onto a waterboxer
engine ....though ........that might be impractical, and not even produce
that much of an improvement.
There must be bigger air flow meters around that would work.
There have been attempts to fit an air mass meter to a waterboxer engine
.....not totally successfully I don't think.
Besides flow reasons, and air mass meter has no moving parts in it , and is
thus likely to be far more reliable, than an air flow meter with mechanical
sweep arm on electectrical contacts. I have said this for years (
regarding fixing things , especially cars ) ...wherever electrons and
something mechanical interface - that's a weak spot. Arcing in switch
contacts would be an example, and the air flow meter sweep contacts are a
really good example.
In air mass meters ........in my experience, I've never seen a problem
with a subaru one. In my 88 740 turbo volvo sedan,
I have to clean the fine wires in the air flow meter every once in a great
while. You can even buy 'air mass meter cleaner' in a spray can, like
electrical contact cleaner, which probably works as well.
anyway ..sorry to get off there...
but , I would have to say the entire intake area of a waterboxer engine is
rather restrictive, just eyeballing it.
and ...don't forget ........
One of VW's traditional strategies ( not true in late model VW's ...but in
all air-cooled VW's , and waterboxers too ) .....is to keep it underpowered
to reduce stress on the somewhat underbuilt engine, to help it last longer,
at least with stock internal parts.
The exhaust here looks wild and exotic - might as well plumb a turbo into
it if going to all that trouble !
.
and ....I 'bet I could' fit Subaru sequential distributorless ( though I'd
use a distributor body for a place to mount a cam position sensor ) Fuel
injection to a waterboxer engine. Can't think of any real reason that
wouldn't be possible. Those are darn strong and consistent fuel injection
systems.
Scott
www.turbovans.com
Subject: Re: Exhaust Design
> Here's a good read with pics on a tuned system.
>
> http://www.thesamba.com/vw/forum/viewtopic.php?t=270833&highlight=exhaust
>
>
> On Sat, Feb 13, 2010 at 10:36 PM, Kim Springer
> <kimspringer@astound.net>wrote:
>
>> Hey listers,
>>
>>
>>
>> Has anyone ever measured up a stock exhaust system to see where it's
>> designed to make HP. I assume VW did this a long time ago.
>>
>>
>>
>> I guess another way to ask this question is: Did the folks making SS
>> exhaust
>> systems in a 4-2-1 or 4-1 design improve on what VW designed?
>>
>>
>>
>> I have a book that helps to design 4-Stroke intake and exhaust system
>> lengths, inner pipe diameters, etc.
>>
>>
>>
>> All this talk about hollow cats makes me wonder about the secondary pipe
>> length. Not that anyone is going to gain 10 HP out of this.just
>> wondering.
>>
>>
>>
>> Kim
>>
>> 88 Tristar #7 (it's either going to get painted or sold in the next year)
>>
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