Wiseco has been producing racing pistons since ... - Z1 Motorsports

1990+ Nissan Z specialists
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Wiseco Forged Pistons
Z1 Motorsports is an authorized distributor for Wiseco pistons. We guarantee the best
prices. Information on Wiseco pistons below.
Wiseco has been producing racing pistons since 1941. We produce our own
forgings in house which makes our parts lighter and stronger and built for specific engine
models. Our competitors use one-size fits all forgings that require excessive internal
milling which leads to stress risers and overly-heavy pistons . For turbo applications we
use 2618 low silicon alloy-although we still recommend .003 piston to wall clearance in
order to avoid piston slap. For extreme racing applications of over 23 pounds of boost,
we recommend that clearance be opened up to .004. Wiseco is the sole distributor for
Nippon rings in the US. These Heavy duty ring sets were designed specifically for the
turbo applications. We also sell these same rings to our sister company JE, and others as
well like Total Seal, Ross, and Arias. In particular, the vg30dett forging was built to
accomodate a bore range of 87-88mm. The two part numbers we stock are the k549m875
and k549m88 for 87.5 and 88mm over bores respectively. Compression ratio is 8.55:1,
but 8.9:1 can be achieved if .030 piston to head clearance is used by changing gaskets. A
1.6mm gasket would lower the final compression to 8.25:1. The pistons have a 9cc dish
with a nice radius and valve pockets that accomodate 1mm bigger valves than stock and
larger cams as well. Forged pistons contain no oil reservoir as the oe cast pistons do. We
rely on the oil squirters to keep the crown cool. This does reduce the weight of the piston
considerably to 338 grams-which takes quite a bit of stress off the rods, crank, and block
and will also makethe engine rev quite a bit quicker. For those customers interested in
heat barrier coatings and skirt coatings, many of our customers choose Polymer
Dynamics in Houston. They can be reached at 713 694 3296. If you call them with the
Wiseco part numbers, they will order the parts from us. Their prices are around $609 for
the pistons, rings, standard coatings, and they charge the freight that it takes to send the
pistons from Ohio to Texas to begin with. We keep these pistons in stock, but extreme
spikes in sales might cause back orders. Call me, Brian Nutter, at 800-321-1364 ext. 3177
for availability.
Wiseco prides itself in meeting or exceeding our customer's expectations for each pistonevery
time. As the piston is the first line of defense against the extreme heat and
pressures seen in the internal combustion engine. The old adage of measuring twice and
cutting once is the most important rule when designing a proper piston. Due in part to
advanced forging and CNC technology, your Wiseco pistons will have less variance than

any other part in your engine. Many tolerances in a Wiseco piston are less than one-halfof-one-thousandths
of and inch (.0005).
An engine builder has the first and last word when designing, machining, and assembling
an engine project. It is their responsibility to measure and verify every measurement in
the engine. We at Wiseco have compiled a list of frequently asked questions to aid the
engine builder. As every engine is different from any other, these answers are not set in
stone. If you have any doubts as to the specifications of your piston in relation to your
specific engine combination, please call your Wiseco technical sales representative.
1. Why are my Wiseco pistons better than pistons made by the O.E.'s and aftermarket
piston suppliers?
It all starts with the forging. Wiseco starts with certified extruded bar stock and forges
our pistons in-house with the world's most advanced forging presses. Most aftermarket
piston companies do not and therefore can't achieve the level of quality control that
Wiseco demands. After thorough inspection, that part goes through an extensive heattreat
and finishing process. This makes for an excellent forging with maximum strength
and minimum variance. The other benefit to doing our forgings in-house is making the
finished piston design dedicated to your engine combination. Wiseco can forge a variety
of advanced materials including S.A.E. 4032 and 2618 alloys. High silicon 4032 is a
durable and lighter material usually used in naturally aspirated engines. 2618 Alloy is
designed for the rigors of blown, marine, and nitrous applications.
2. What kind of piston to wall clearance can I run?
The usual rule of thumb is .001 for every inch of bore size. The factors that affect this are
cylinder wall thickness (including filled blocks), overall compression height of the piston,
piston material and thickness, and whether a marine engine is to see fresh-water cooling.
Most small blocks get .004 piston to wall clearance and most big blocks get .005 due to
the use of our 2618 high-strength alloy. For heavy blower and nitrous applications,
Wiseco recommends adding .001 to the standard clearance. Special note: Clearance
numbers are taken 1.300 down from the oil ring land-Not 90 degrees from pin centerline.
3. What are the most important factors in deciding what piston fits my engine
combination?
There are many important factors, which we will explain in depth, but the first two are
bore and compression height. Bore size is important for obvious reasons. With the
different block, stroke, and rod combinations, Wiseco has designed a large number of
pistons with varying Compression Heights. This number is the distance from the center
of the wrist pin to the deck of the piston (not dome). When adding 1/2 the stroke + rod
center to center length + Compression height, our goal is to have the piston adequate
piston to head clearance without being excessive (which causes a loss of compression and
quench).

4. What is minimum piston to head clearance?
Generally the factors that decide this are: Piston Speed, Piston Mass, and Rod Material
(Steel or Aluminum). Aluminum Rods generally require .010 more clearance than steel
rods. Steel rods in a big block usually require .045. Steel rods in small blocks require at
least .036. Most imports can get by with as little as .030 depending on piston mass.
*Remember, a compressed gasket thickness can vary from .025 in steel shim applications
to .040 for composite and up to .100 for some copper gaskets.
5. Why do you use piston speed versus rpm to determine the loading in tension of the
block, crank, rods, and pins?
For example a 434 C.I. stroker small block turning 7000 Rpm has the same average
piston speed as a 350 turning 8045 rpm, a 327 turning 8615, or a 302 turning 9330 rpm. It
is important to note that average piston speed is only about 2/3rds of what peak piston
speeds can be due to the accelerations seen when the crank is between 45 and 90 degrees
away from TDC or BDC. Rod length is a major factor in maximum velocities.
6. Now the part physically fits in my engine, what factors determine the part I choose?
The most important issue is to have a piston that is built for the right application.
Material, thickness and pin choice are the major factors. While a super light piston rated
at 500hp may have a .150 crown thickness, a Nitrous/blower/Marine application needs
between .220 and .250. Skirt thickness can vary from .110 to .150 depending on the
application and rod angle severity at BDC.