VW - PERFORMANCE #2/5
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Author: Robert Collins
Some editing: Jan Vandenbrande
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These articles should be regarded as opinions and not fact.
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Severe damage, injury or loss of life may result from applying the ideas
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as long as the original authors or origine are identified if available.
===============================================================================
PART - 2 -
Article 3933 of rec.autos.tech:
Path: oberon!sdcrdcf!trwrb!felix!ccicpg!turnkey!conexch!rob
>From: rob@conexch.UUCP (Robert Collins)
Newsgroups: rec.autos,rec.autos.tech
Subject: VW High Performance (Microview Part 2)
Keywords: killem
Message-ID: <303@conexch.UUCP>
Date: 28 Apr 88 06:43:15 GMT
Distribution: na
Organization: The Consultants' Exchange, Orange County, CA. (714) 842-6348
Lines: 345
Xref: oberon rec.autos:11739 rec.autos.tech:3933
In this article, I'll examine the VW bottom end. Topics are:
Motor blocks (1.5 1.6, 1.7, 1.8)
Cranks (Steel billet, forged billet, cast)
Connecting Rods (1.6, Audi, 1.8, Carillo)
Rod bolts (1.6, Audi, 1.8, Drake, Stainless steel)
Bearings (Clevite 77)
Pistons Forged vs. cast
It has been said:
Horsepower costs money...how fast can you afford to go?
The block:
Throughout the years, VW has manufactured three basic blocks. There have
been at least a dozen variations, but only three basic blocks. Each
block housed the following motor sizes:
VW has had four basic motor sizes (all sizes are metric):
Block CC's Bore Stroke Years of production
1.5L 1471 76.5 80 74-76
1.6/1.7L 1588 79.5 80 77,79,80
1.6/1.7L 1457 79.5 73.4 78
1.6/1.7L 1716 79.5 86.4 78-80 Dodge Omni
1.6/1.7L 1716 79.5 86.4 80-83
1.8L 1781 81 86.4 83-?
The early 1.5 block (76.5mm bore) is a bad block to use for any purpose.
At Drake, we used to tell people to use them as anchors. They can't
be bored out even to 79.5mm because of the lack of proper water
passages at the bottom of the cylinders. Technically, they aren't
siamesed together at the bottom.
The 1.6 & 1.7 blocks are dimensionally identical. Most blocks stamped
1.7 actually came from the Dodge Omni. VW used a 'generic' block for
its own 1.7's. The block was labeled simply 'H' and is considered the
best all around block for building a high performance motor that uses
a 1.6 head. The H block can be bored out to a maximum 83mm, and take
a maximum 94.5mm stroke crankshaft. It should be noted however, that
even putting a 90.5mm crank in this block requires some machining to
allow the connecting rods to clear the side of the block - thus
rotate without hitting the block. For the 90.5 crank, you're looking at
a couple hours labor - minimum. Any crank larger, requires much more
machining - usually to the block, rods, and possibly the crank
(see cranks below).
On the 1.6/1.7 (henceforth referred to as 'the H block') block, oil is
returned back to the sump via two oil galleys at the rear of the block,
and a single one in the front.
The 1.8 block has the same basic outer dimensions as the H block, but
in reality, the block is a complete redesign. The most noticeable
difference is a larger main oil galley at the front of the block,
accompanied by a second, somewhat smaller, galley not found on the H
block. The 1.8 block is also a little larger internally. Only slight
machining is required to clearance for large stroke crankshafts.
Like the H block however, the 1.8 can only be bored to 83mm.
I guess now is the time to point out that boring to 83mm is not
recommended. By doing so, you must junk the block when it comes time
for the next rebuild. By boring to 82.5mm, you have two rebuilds before
the block must be junked - 82.75, and 83mm.
At Drake, we have found that it makes no difference where the block
was manufactured - quality control is very good. I was constantly
plagued with questions, and scepticism regarding the blocks made in
Mexico, or Brazil. I never saw blocks from anywhere but the former
two counties, and of course, Germany.
Crankshaft:
VW has manufactured four different crankshafts, using three different
stokes. The early 1.5L and all 1.6L motors used a 80mm forged crank;
the '78 1.5L used a 73.4mm cast crank; 1.7L & 1.8L motors both used 86.4mm
forged cranks, but with different connecting rod journal diameters (more
on that in 'connecting rods'). In addition to VW crankshafts, there
are various aftermarket cranks in various strokes, and of course
welded strokers can be made to any stroke and with any size rod
journal diameter.
Choosing a crank needn't be a painstaking process, just a matter of
economics. Here is the formula (as I perceive it) for choosing a
crank:
CRANK = (Piece of mind)^3 + (type of material)^2 - how much I can afford
for you, the formula might be:
CRANK = (How much you can afford)^2 + 2(desired stroke) - piece of mind
To me, piece of mind is the most important part of choosing a crank. I'm
willing to spend extra, no matter what it takes, to get the best crank
for my car. This doesn't mean I am willing to spend 2000 on a steel
billet crank, but I wouldn't hesitate to get something 90% as strong for
50% the money. So, I suppose I should explain about different types of
cranks.
For simplicity, there are four different types of cranks: Steel billet,
Forged billet; welded; cast.
A steel billet crank is by far the strongest. A steel billet crank
is made by taking a big chunk of solid steel, and machining it until
a crankshaft is the finished product. Steel billet cranks cost
between 1500-2000 for a four cylinder motor and can rev above 12000
rpm's. Drake makes a 93.5xx steel billet crank for about $1800, but
can only be used on a racing motor (no accommodations for VW pulleys).
Most pure racing motors use steel billet cranks, because not enough
cranks will be used to facilitate making a mold for a forged crank.
The forged billet crank is the probably 80-90% as strong as a steel
billet crank, but costs less than 1/2 the price. Forged cranks will
cost you between $125 (for a factory VW) to $1300 (for the Oettinger
'OKRASA'), and can rev beyond 10000 rpms. Forged cranks are also
popular because you can weld them when they become damaged, or weld them
to become strokers. Currently, Oettinger makes two (aftermarket)
forged billet cranks in 90.5mm and 94.5mm strokes. They are a bit
pricey - costing over $1200 ea., but are well worth it if piece of mind
is as important to you as it is me.
Welded strokers are for those people that are willing to settle for
a little less than the best. In general, I don't recommend welded
strokers unless you have control over who makes it for you. Keep in
mind, strokers can vary in cost from $100 - $600+ (for the same
end-product), and YOU GET WHAT YOU PAY FOR. If you're going to get
a welded stroker, don't settle for anything but the best. Do yourself
a favor, call Pauter Machine (619-422-5384) and have them make it
for you. It will cost you ~600 plus shipping, but I wouldn't trust
ANYONE else. (I don't mean to step on Techtonics, but keep in mind
that Techtonics doesn't make the cranks themselves, and that
if Darrell markets his cranks for 500, then he probably pays
about 300 for them. This puts his in the mor [middle-ofthe-road]
quality bracket). I had a crank done by Pauter, and even John
Drake was impressed with the quality (he's typically like 'Mikey').
The rpm limit on a welded stroker will depend on the quality of
the welding. I would suggest the following rpm limits on various
welded strokers (remember Pauter Machine is the benchmark, the cream
de la cream):
7500 Pauter
6700 Techtonics
6000 All others
One final word on welded cranks. If your motor reaches max hp at
7500 rpms, and that is the limit of safety for your crank, then
how much piece of mind do you have in owning it? None. Effectively,
you have no margin of safety for overreving, or misshifting. Whenever
you take your motor to its hp limits, you are also taking the crank
to the limits of its structural integrity. And it's for this reason
that I, and Drake Engineering recommend not using welded cranks for
any motor. Look at the question like this: would the factory use a
welded crankshaft (suppose one was damaged in the assembly line)? No.
Then why use one in a high performance motor, that will undergo
much more stress than a stock motor? Let alone, use a welded crank
in the name of high performance. It's an irony, and I could never
understand why people would even buy them.
Cast cranks have their virtues, but have as many drawbacks. First of
all, they are cheap, but if they get damaged, they can't be
repaired. You can't weld on a cast crank. Cast cranks cost ~500 and
can rev to at least 8000 rpms. For a while at Drake, we marketed a 90.5
cast crank that worked out very good. The crank was good, but
needed extensive machining just to make it work. Once the machining was
done, I would say it was a very good crank. The crank itself was about
$300, + $200 machining = $500 crank. Still cheap, and much safer, and
more reliable than a welded stroker.
The best of the VW cranks is the 1.8 crank because the 'snout' (hub
where the pulley's attach) has a wedge-shaped notch that is much
stronger than the woodruff key type snout on the earlier cranks. In a
motor that is VERY strong (200hp or more), the woodruff key can sometimes
break, or become deformed. I have seen this happen. Also putting too
much load on the woodruff key could cause damage. Generally, there isn't
much you can do to put more load on the woodruff key, except add accessories
that run from the crankshaft, or camshaft (superchargers, air conditioning).
Connecting rods:
VW made three different connecting rods. 1.6 (stud & cap); Audi
(Bolt into rod); 1.8 (stud & cap). The 1.6 & Audi rods fit both
the 1.6 & 1.7L crank and have the same length. The 1.8 rod is
a bit longer, and has a smaller journal & piston pin diameter.
The longer the rod, the less piston velocity, the more torque.
But, in the case of these particular rods, the Audi rods are
the recommended rods of use. They are stronger, and can twist above
9000rpm's reliably.
With the advent of the 1.8L block, VW introduced a rod with different
dimensions. The following is a chart of various dimensions (in mm):
Length Journal Piston_pin
C-C diameter diameter
---------------------------
1.6L 136 45.96 22
Audi 136 45.96 22
1.8L 144 47.758 20
Drake 16v 143.76 45.96 22
Racers use Carillo rods (about $200 ea.) that use an H-beam construction.
They are about 1/3 lighter than VW rods, and immeasurably stronger.
Carillo rods can twist to any RPM the motor is capable of making power.
Carillo rods can be made to any length, and journal or piston pin
diameter. At Drake, for our 16v racing motor, we use Carillo rods that
are ~8mm longer than the 1.6L rod.
Rod bolts:
Until recently, the only choices for rod bolts were: stock VW;
SPS; or stainless steel. Now, Drake markets rod bolts (that are
manufactured specifically for Drake) as replacements for VW bolts.
For a while, SPS was the hot setup for VW motors. One drawback with
the SPS rod bolts was that the rod needed machining to make them work.
And as a result, after a while, the rod would fatigue where it was
machined, and eventually crack. The new Drake rod bolts are stronger
than SPS, and are intended as a high performance replacement for the
stock VW bolts.
When you work at a place like Drake, you learn a lot about the 'right'
way to do things. I suppose part of this philosophy includes the
notion that anything else is wrong. One such notion is NEVER reuse
rod bolts. VW suggests that the 1.6L & Audi rod bolts are ok to use
twice, but no more. The 1.8L bolts are made as 'stretch' bolts. This
means that once they are torqued down, they are stretched. Consequently,
VW recommends NEVER reuse the 1.8L rod bolts. We confirmed this with
a guy that was building a motor, and bought all his components from
Drake. He thought he was building the motor the 'right' way. Within
a few hundred miles, the motor grenaded itself by breaking a rod bolt.
He blamed it on Drake, because he bought all the parts from Drake;
and built the motor to what he thought was Drake quality. One of
the first questions that came up was "what did you do for rod bolts?"
This came about after noticing that he didn't buy any rod bolts from
Drake. The answer was that he reused them. We were made as the
bearers of bad news. We had to tell him, and point out to him, that
in the VW service manual, it even states not to reuse the rod bolts.
As a general practice, Drake recommends NEVER reuse any rod bolt,
1.6, Audi, and especially 1.8L. Piece of mind is worth more than
$40 - $125 isn't it?
Engine bearings:
At Drake, we felt that TRW Clevite-77 were the best bearings out
there. Unfortunately, I can't elaborate too much on this subject,
so I'll leave it at that.
Pistons, forged vs. cast:
The following is a displacement chart for various bore/stroke combinations.
80.0 86.4 90.5 92.5 94.5 (strokes)
79.5 1588 1716 1797 1837 1876
80.0 1608 1737 1820 1860 1900
80.5 1629 1759 1842 1883 1924
81.0 1649 1781 1865 1907 1948
81.5 1669 1803 1888 1930 1972
82.0 1690 1825 1912 1954 1996
82.5 1711 1847 1935 1978 2021
82.75 1721 1859 1947 1990 2033
83.0 1731 1870 1959 2002 2045
(bore)
This next chart documents the availability of piston for each of these
bore/stroke combinations. This list is for the 1.6/1.7 connecting rods,
not GTI connecting rods (see connecting rods below). Where pistons are
available (not custom made, or forged), I will document by denoting the
available compression ratio. The last list will be the same as below,
but for the GTI connecting rods. (There are lots of shops out there
that have pistons for combinations that aren't documented below, but
it has been my experience that these pistons are not 'off the shelf'
sets of pistons. Usually they need the 'heads' machined off to obtain
an acceptable compression ratio. See pistons section below for
warnings on this technique.)
(1.6/1.7/Audi rods)
80.0 86.4 90.5 92.5 94.5 (strokes)
79.5 9.7 9.2 - - -
80.0 9.7 9.2 - - -
80.5 9.7 9.2 - - -
81.0 - - - - -
81.5 - - - - -
82.0 - - - - -
82.5 - 9.5 9.5 - -
82.75 - 9.5 9.5 - -
83.0 - 9.5 9.5 - -
(bore)
(1.8 GTI rods)
80.0 86.4 90.5 92.5 94.5 (strokes)
79.5 - - - - -
80.0 - - - - -
80.5 - - - - -
81.0 - 10 - - -
81.5 - 10 - - -
82.0 - 10 - - -
82.5 - - - - -
82.75 - - - - -
83.0 - - - - -
(bore)
Pistons for ALL other combinations must be custom made. In many cases,
people like Techtonics and Oettinger, have many of the combinations
pre-made and sitting on the shelf. This is usually the case for the
94.5mm crankshaft.
Forged pistons are stronger than cast pistons and can turn higher
RPM's. Forged pistons are also about twice the price as cast
pistons. Of the various forgings available, TRW makes the best ones.
Famed piston manufacturer JE uses TRW forgings. If you have custom
pistons made, use JE, not ARIAS. To quote Stewart Van dyne (chief
motor builder at Drake): "I sit with Danny Arias every Saturday
night at the sprint car races. He's a great friend. But I won't
buy a set of his pistons." If anybody knows, Stewart does.
Cast pistons cost less, and burn less oil than forged pistons. Cast
pistons require .0015" piston/wall clearance where forged require .005"
clearance. Because of the greater clearance for forged pistons, they
burn much more oil. Lately, I have heard much dissatisfaction with
the Techtonics stroker kits because they burn too much oil and smoke.
This is because Darrell uses forged pistons (as cast pistons aren't made
for the stroker cranks).
A popular practice among certain builders is to take a VW air-cooled
piston, or 240Z piston and machine the top off; thus reducing the
compression ratio to an acceptable level. This technique is just fine
as long as the machining is done above the dish in the piston. Any piston
that is machined beyond the dish, will probably be too weak. By machining
too far, the crown of the piston is too close to the top piston ring.
In other words, the crown of the piston is too thin, thus weak.
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High performance summary:
Use the 1.8L block. If you expect to put out over 200hp (which would
probably cost you about $4500), you may want to use the 1.8L crank
and rods. If you plan to massage the rods by giving them the
SuperVee rod treatment, then use the 1.7L crank and Audi Rods. To
make racing rods, you radius the small end, shot-peen and polish
the beams (about $300). Any VW crank will work with the 1.8L
block, as the main journals have always remained the same size.
If you are going to build a welded stroker, start with the 1.8L crank,
and have the rod journals sized to that of the 1.7L crank and use the
Audi rods.
Avoid forged pistons if you can. But for welded strokers of odd
length, forged pistons will be a necessity. For turbo motors, I
recommend having custom made pistons around 7.5:1 c/r, thus you
can crank the boost and get more hp reliably.
--
"Worship the Lord your God, and serve him only." Mat. 4:10
Robert Collins of Sykes Systems, Inc.
(714) 995-7344 (home) Specializing in APL.
(714) 229-0284 (work) (818) 704-9894
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