Step 1: Relate kinetic energy and momentum.
The kinetic energy \( KE \) is related to momentum \( p \) by the equation:
\[
KE = \frac{p^2}{2m}
\]
Where:
- \( p \) is the momentum,
- \( m \) is the mass of the body.
Step 2: Analyze the given condition.
If the kinetic energy becomes four times its initial value:
\[
4 \times KE_0 = \frac{(2p_0)^2}{2m}
\]
This shows that the new momentum \( p \) is twice the initial momentum \( p_0 \).
Step 3: Conclusion
The new momentum is twice the initial momentum.
Final Answer:
\[
\boxed{2 \, \text{times the initial value}}
\]