Adding nitro to a methanol racing engine is an easy way to make more power. Assuming a 50% mixture by weight, not volume. FYI: A 50% mixture by volume is 59% by weight which is a different setup.
The enrichment for a normally aspirated racing engine with moderate compression ratio (around 10.8 to 1) is around 55% more fuel than the amount for straight methanol.
The added power from the nitro with the correct amount of fuel to the NA engine would be close to 60% over the straight methanol power.
The enrichment for a supercharged racing engine with moderate compression ratio (around 8 to 1) is around twice the amount of fuel over straight methanol.
The added power from the nitro with the correct amount of fuel to the blown engine would also be close to 60% over the straight methanol power.
Adding even more fuel amount with a 50% mixture would probably not make more power. The 50% methanol content would chill the engine. It would probably reduce power.
HIGH CR & FURTHER ENRICHMENT
One trick may be to run high compression ratio (13 to 1) to make more power. In that case, more fuel amount may be needed to retard pre-ignition. Some combinations of much richer fuel amounts and higher compression ratios may produce more power over moderate compression and the amounts previously described.
EXAMPLES OF LOW NITRO PERCENTAGES
Many years ago, Dan Nicholson ran a national championship blown engine on 25% nitro with 9 to 1 compression. One of our ProCalc customers is running 10% nitro, 10.8 to 1 compression, and 50% overdrive on a 14-71 blower. Both without damage from the nitro.
THE FUTURE WITH NITRO
The combinations for 50% nitro remain intriguing to me and quite untapped at this time, especially if higher compression ratios are incorporated and/or different engine cycles such as the Miller cycle (late closing intake valve). I can envision a high compression ratio with a middle of the road nitro percentage making almost as much power as higher percentage combinations.
FYI: 50% nitro methanol is more readily available now with increasing restrictions on straight nitro purchases. It may be more easy to purchase and possible a more uniform specific gravity and quality for consistency.