Originally Posted by
ProDigit
Normally, 14 psi = 1 atmosphere, gets you + 50% HP, not + 100%.
If the guy runs a 75hp motor at 14psi, he'll do no more than 110HP. At 10PSI, he should have around 100HP.
For doubling the power, you'll need closer to 28 psi, which isn't recommended. 21 is as high as you can go on most engines with high octane gas.
Using a rotary tool kit, it's possible to grind off some of the cylinder heads, to allow a slightly lower compression (as well as polish the intake/exhaust ports to improve efficiency).
Doing that way, most are able to run stock 87oct fuel, at 7psi boost. The ultimate of cheapness!
Without grinding, + 7 psi requires mid grade, +10psi requires hi octane.
He'll need to dyno tune it, to see how it's doing at the high rpm range. That's where these engines usually struggle (above 4.5 to 5k rpm), and in risk of damage.
Is it safe to say you are replying to a post that was made in December 2019?
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View my fuel log 2014 Mirage SE wussie cvt edition. 1.2 automatic: 37.7 mpg (US) ... 16.0 km/L ... 6.2 L/100 km ... 45.3 mpg (Imp)