Re: bigger engines

[Toby Erkson <Toby_Erkson@ccm2.hf.intel.com>]

Why do you want a bigger engine?  If it's just a matter of better pulling 
power a less expensive alternative is having your gearbox re-geared, like 
putting in lower 1st & 2nd gears or changing the ring & pinion.

As for what to put in a larger engine, well, how big is your wallet? :)

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I would recommend you talk with *several* VW engine builders who specialize 
in performance engines and ask for their opinion.
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Once you move to a bigger-than-stock engine you will start to face more 
heat generation.  There are a couple of ways to dissipate this extra energy 
and it'll depend upon your engine builder.  Also remember that an engine is 
a synergistic device, thus changing one thing can affect other components 
and engine operation i.e. bigger ratio rocker arms are detrimental to 
engines that have short deck heights, bigger valves, improper cam 
durations, etc. since a valve could smash into a piston head!

Because a carbed T3 has such short intake manifolds there isn't much room 
for a good, proper atomization of the fuel mixture (like what one could get 
on an upright engine).  This is why FI is so much better on the pancake 
engines!  So, bigger carbs don't mean better performance.  34mm carbs would 
be plenty big enough for up to a 2000cc engine and are what I would like on 
my baby (I'm running with 36mm carbs).  I know that 36mm was way too big 
when my engine was mildly bumped up to 1641cc.  The air flow 
characteristics just aren't right with the wide venturies, short manifolds. 
 I'm taking a stab here but I believe that 32mm carbs would be just perfect 
for a 1776 and possibly 1.8L (well, maybe 34mm for the 1.8L).  Again, an 
experienced performance engine builder should know carb and corresponding 
jet sizes needed for the performance engine.  And you still may have to 
change jets to get the engine fine tuned.

My carbs are dual Dellortos.  My recent engine builder recommended using 
Webers.  He told me that the Webers are used on the carbed Ferraris because 
of similar atomization restrictions.  I'm happy with my setup and have 
heard arguments either way.  I bought my carbs many years ago and really 
don't want to got to the expense of switching carbs.  Besides, I plan on 
going to an after-market FI system in the future.

     Toby Erkson
     air_cooled_nut@pobox.com
     '72 VW Squareback 1.6L bored and stroked to 2.0L
     '75 Porsche 914 stock 1.8L for sale


______________________________ Reply Separator _________________________________
Subject: bigger engines
Author:  type-3-errors@umich.edu at SMTPGATE
Date:    3/12/97 7:47 PM


Hi everybody,
     I'm thinking building a bigger engine for one of my t3's but I'm still
not sure.  What I'd like to know is if the 1776 & 1835cc engines
improved the power of your VW enough to justify less gas mileage.  I
know what your going to say (your not worried about gas mileage if you
go bigger) But if the increase in power isn't that great why have worse
gas mileage.  I'd also like to know if there are any cooling problems
with the bigger engine sizes, what size valves you use or would
recommend.  I would also like to know how much carburation is needed to
get enough gas for optimum performance.(what size carbs)

Thanks all!

Sean Scattergood
66 sqbk
66 fb