Which Porsche engine fits?
Gerry & Robin Lempicki
Hi! I ahve a dune buggy that has a mid '60s transaxle and 1200
40 HP engine. I haven't seen any real deals in my area on 1600 VW's, but
I have seen some cheap Porsche engines...which one(s) fit easily and how
much modification is involved? -Gerry
Neb79
Well, as far as I know, the 914 is the only porsche motor that will work.
It is air cooled, and.......it is a type 4 motor. Some VW vans used T-4
motors untill '83 I believe ...which are basically the same as the porsche
motors. ANyway, you might want to be careful about it, because if the
motor that came with the tranny was a 40 horser, it might be a weaker
transmission. I am not exactly sure which parts would be necessary to
modify, but you'd need the original porsche cooling fan/shrouds, or an
upright fan kit...which runs around 300-600 dollars. The transmission
will need to be modified to accept the larger motor's bolt pattern. Also,
I am not sure what type of clutch, flywheel..etc. must be used.
bend...@yo.mamas.net
Jouko Kenttä
914's motor is "vw"-motor, but as you know 911 has also an aircooled boxer
too. It's little longer, but if you have dune buggy or something fitting is
not the problem, transaxel is :)
A better option might be 912's flat four. It fits fine in bug and has an
upright fan already. Only thing that needs adapting is clutch. So if you
want "real" porsche 912's four is the key :)
regards
Jouko Kentta
Jan Andersson
Jouko Kenttä wrote:
> 914's motor is "vw"-motor, but as you know 911 has also an aircooled boxer
> too. It's little longer, but if you have dune buggy or something fitting is
> not the problem, transaxel is :)
> A better option might be 912's flat four. It fits fine in bug and has an
> upright fan already. Only thing that needs adapting is clutch. So if you
> want "real" porsche 912's four is the key :)
>
> regards
> Jouko Kentta
Whee!
Nice to see I'm not the _only_ Finn
messing around here...
Anyway, it is possible to put a 911 six-cyl
or a 912 engine in a bug, but why do it?
All the spare parts are a lot more expensive,
and concidering all the work needed to make
the Porche engine sit in there...
Well, I must admit that a -85+ 911 engine
would be a nice thing to have back there...
Anyhow, a well built big VW engine should be
enough for the majority of people. When
built right, they are also reliable, drivable,
and economical to maintain.
Jan
(Just some thoughts)
mess ar
John Connolly
stick with the T-1 engine, or if you have a little
extra $$$ the T-4. the T-4 engine will bolt right up, you just
have to use a bus flywheel, and bus clutch. Both of these
should be from 72-75. Just use the 210mm or 215mm clutch and
flywheel assy and you will have no problems.. I can't remember,
but I think the 228mm assy you need to clearance the trans,...
can't remember. I have it written down though, somewhere...
The T-4 engine is a much better engine design, and is way more
reliable, has the oil filter stock, but the exhaust system
design sux. The T-4 engine is limited in rpm because the
connecting rods are too short, and the valve train is so so.
Both these problems can be addressed easily at rebuild time, so
don't worry about them. The valve train deal costs $50 to fix,
but the rods cost around $400. But heck, the stock 2L rods cost
$200 for the core, so if you have damaged stuff, don't mess
with em'...One of the best things you can do is put the bug
rods into the T-4. Longer, cheap, and strong. But, then you
have to use a piston set with 22mm wrist pins instead of the
stock 24mm...
chow
John
--
Joshua Van Tol
In article <Dy38o...@murdoch.acc.Virginia.EDU>,
jl...@watt.seas.Virginia.EDU (John Connolly) wrote:
Why would shorter rods be bad? Maybe you mean that heavier rods can be
bad, which the 2.0 liter rods are, but I would think that shorter rods,
along with a short stroke, would be better for high revving engines.
Besides, longer rods would have the pistons sticking out of the cylinders
at TDC.
>
> chow
>
>
> John
> --
--
Joshua Van Tol - jjva...@cc.memphis.edu
Randy Hubbard
FWIW,
From an engineering standpoint, longer rods reduce thrust loading on the
piston skirts, which reduces fiction and wear. But there are also MANY
other considerations with rod length as it effects piston acceleration,
dwell time at TDC, airflow inertia and reversion, etc. VW originally use
a "long" rod in the Type 1 engine. It effectively has a 1.99:1 ratio.
Indy engines use rod ratios in the 2.3:1 range. Many high torque engines
user lower rod ratios on the order of 1.55-1.85:1
The VW water-cooled engines use a very low rod ratio. To reduce
vibrations and improve top end power VW lengthened the rods in the newer
VW 2.0L water-cooled engines over the earlier 2.0L. Porsche has used
only two lengths of rods in the 911 series engines since 1965, but they
have continued to increase the crank stroke, effectively lowering the
rod ratio. This has been in keeping with a desire for more low end and
mid-range power. With shorter rod ratios you generally need better air
flow thru the engine to produce good top end power. Otherwise you need
to limit the peak rpm. Camshaft selection also changes with rod ratio.
There are many other issues, but this provides some background on rod
ratios that may be useful for people building performance engines. BTW,
the 914 con rod is a good rod, just too heavy for performance use. It
CAN be significantly lightened and balanced by a professional and work
fine up to about 7,500 rpm without problems. Beyond that a QUALITY
billet rod is desirable.
Regards,
On the 'Bahn,
Randy, a.k.a. BoltMeister
*** See VW/Porsche/BMW Interest At: HTTP://HOME.AOL.COM/RACEWARE1 ***
John Connolly
jjva...@cc.memphis.edu writes:
>
> Why would shorter rods be bad? Maybe you mean that heavier rods can be
> bad, which the 2.0 liter rods are, but I would think that shorter rods,
> along with a short stroke, would be better for high revving engines.
> Besides, longer rods would have the pistons sticking out of the cylinders
> at TDC.
>
> >
shorter rods move the piston at a different time
compared to longer rods... next time you have an engine apart,
put long rods (5.7" or so) on one rod journal, and stock rods
(5.35 or so) on the other.. I am referring to bug length..
anyways, put the engine to tdc for the short rod cylinder, and
rotate the engine clockwise until the piston moves down .1" or
so... then check the long rod cylinder for the same thing...
What you will find is that the long rod piston stays at TDC for
more crank degrees than the short rod cylinder...this allows
the crank pressure to build up more, and performs more work per
cycle at higher rpms... The long rod engines also have less
piston ring wear (the piston is loaded vertically, and the
short rod engine loads the piston more laterally) and rod
bearings last longer...
Short rods engines have more torque at low rpms, long rods at
higher rpms...
And in VW flat 4engines, I have found that the beetle
length rod is borderline on 78mm stroke or longer...The T-4 rod
is even shorter than the T-1.... I use T-1 rods in T-4s
because of expense, and weight.. you are right, heavy rods are
bad...
the ideal high rev engine has a short stroke, and real long
rods.... we won't even discuss valve train issues....
As far as the piston sticking out of the cylinder, this is why
we use cylinder spacers... keep in mind, that short rods create
a problem with piston skirt interference with crank
counterweights, which long rods address...
John
--
Ben
:
:FWIW,
Randy,
Why/how does rod length affect piston acceleration, TDC dwell time, etc,
over a shorter rod? It seems to me that the only thing that affects these
things is the stroke, which is not affected by the connecting rod. There
is a definite possiblity that I am missing here, so please enlighten me.
Thanks,
Ben Pender
:
:*** See VW/Porsche/BMW Interest At: HTTP://HOME.AOL.COM/RACEWARE1 ***
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