more head swapping questions (a bit long-winded)

[drew <drew@dyermaker.cs.uoguelph.ca>]

OK, thanks to insight from Potterman (all hail, will he take Canadian
money at par???) and Mark Peele, I have made some progress on this bench
racing head swap.

#1 - the block motor I'm dealing with is the Canada-only MZ motor, which
as far as I can tell is a GX with no K-lambda or cat.  Per Bentley this
motor develops 90hp @ 5500 and 98lb-ft @ 3250, vs the 85hp @ 5000 rpm on
the GX.

#2 - there are no issues with oil passages when dealing with 1.8L blocks
(an assumption I mistakenly made based on 1.6L diesel blocks)  One should
use a 30mm minimum oil pump when using hydraulic valves.

#3 - the MZ (and GX)  motor is 9.0:1, and the consensus is that this is
dictated by the piston, not the head.

Based on this information, which would be the most powerful and reliable
combination (without spending $$ on extra bolt-ons or other performance
upgrades?) The destination for the motor will be an A2 Jetta, with its
larger TB, longer (and larger) intake runners, and larger diameter
exhaust. There's also no Cat, which was stock on both my 84 Scirocco and
84 GLI.  The transaxle will be a 4+e with a 3.94 final drive to provide a
blend of mild performance and economy.

OPTION 1: MZ 9.0:1 block (90hp stock) with RT big valve head = ~95hp
(guessing here)

or 

OPTION 2: JH 8.5:1 block with RT big valve head = 90 hp stock with a more
reliable bottom end.  How much power will I lose to the extra .5 point in
compression?
	(note that this number does not take into account gains from stock
A2 intake and exhaust over stock A1 intake and exhaust - should these not
add up to close to 5 hp by themselves? - the same gain would be seen with 
a stock JH motor in an A2 chassis)

OPTION 3: JH longblock with N (free) or G grind cam to take advantage of
the intake and exhaust improvements.  Is this engine likely to outperform
option 1? I'm assuming that the stock RT cam is a better low-mid performer
than the _stock_ JH cam... is this a valid assumption?

And the final question, for those who haven't already given up on the mail
message:

Does the stock A2 GTI (85,86) manifold use the dual-port 6-bolt setup that
is used on the Jetta GLI and Carat models of the same vintage?

Thanks in advance for the collective brain trust,

Drew (84 Wolfsburg Ed. that got to play in the snow today)


Drew MacPherson, Network Analyst, University of Guelph

drew@dyermaker.cs.uoguelph.ca           |  visit the Massey-Harris page:
http://dyermaker.cs.uoguelph.ca/~drew   |  http://m-h.cs.uoguelph.ca


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