Custom Pistons:
We can make you a forged Piston for any stroke, bore or compression ratio.
These can be used for street/strip injected blowers or turbo charged. Call
us at (603) 378-0090.
Note on Rods:
Based on our 40 years of racing experience, building motors and our 1000's
of hours spent on our dyno's, we have found that the Import stock
connecting rods are good up to approximately 200HP. If you expect to
exceed these requirements by adding Nitrous or Turbo Charging, we strongly
recommend that you upgrade your connecting rods along with any forged
pistons.
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A note about Compression and Overbores:
For Import motors the rule of thumb is 9.5 with Steel Heads, and 10.5
with Alum. Heads dissipate heat and allow for higher compression.
Overboring adds to the Cubic inch (more HP), and increases
compression.
The European marketplace has for years run their Imports in the
9.5-11.2 range
(although they have slightly higher octane gas available).
So, if you want to make some easy HP, raise that compression and
overbore. In most cases it's an easy 15-20% HP gain!
Example #1: VW Golf 1.8L (81mm std. bore) 1988-91
At 9.0:1 comp = 90 HP
At 10-1 comp = 105 HP
That's a difference of 15% w/o an increased bore!
Example #2: VW Golf 1.8L (.020 overbore) 1988-91
At 9.3:1 comp = 82HP
At 9.5-1 comp = 95HP
Bottom Line:
If you're rebuilding for stock or performance, raise the compression
and overbore for an easy 15-25% HP
(depending on size).
Note that it's just the opposite with Turbos - you want lower
compressions and smaller overbores! |
