My point (maybe I should have been more explicit) was that 28 inches of mercury, being about 13.8 psi, seems to be a boost quantity that is more consistent with the other systems being described here, so it seemed more plausible that “28 inches” meant 28 inches of mercury in this context.
If you’re certain that you were dealing with a boost system that provides only 28 inches of water - a mere 1.3 psi - then you’re describing a boost system that increases manifold pressure (and engine power output) by a whopping 9 percent. Such a system hardly seems worth the effort to build.
But it’s important to note that’s ABOVE normal pressure at sealevel. So the motor has 1.8 atm to work with - in a turbo, it does that at any altitude you’re likely to encounter…and in a 300 hp 4 banger, that makes sense as the Normally aspirated version makes about 150-175 hp. Differences in power are made up in cam profiles, intake improvements and other niggling details.
Turbos and Superchargers are cool because they ‘overlook’ other deficiencies in a motor. To make power without 'em, EVERYTHING has to match. To make power with them…maker sure there’s enough fuel and just boost 'em harder. Most of the motors listed here are using relatively low boost as they don’t have expensive parts to sustain higher boost levels. Increased boost can also make a motor harder to deal with day to day, less emissions compliant, and generally finicky.
Boy I wish I could remember more from my Diesel’s classes. I am surprised at the pressures that gas engines are running. A question I have is what kind of mean effective pressures are engines whith turbos running now days?
Saw a documentary on the P51 Mustang the other day. When it was introduced in Europe it had a normally aspirated Allison engine and wasn’t all that good. It wasn’t until they started using the supercharged Rolls Royce Merlin that it could take on the role of bomber escort.
IMHO, power production is a solved problem. You want your car to make 800 hp? Can do.
1000 hp? Sure, just takes money. 1500 hp? Possible, but you’re leaving the realm of sanity.
It used to be there were the big displacement boys that knew how to make a big motor breathe, and the Rice burners who could make little motors make big power (even if only for a little bit of time.) Now, power production is pretty much fully mapped out, from 6 hp Briggs and Stratton-knockoffs all the way up to nitromethane burning 2500hp beasts.
What’s most important is defining your goals, everything beyond that is purely academic. You want X hp? You flow Y gasoline. You do Z to a given motor to produce it.
Whether or not you’re truly happy with the results after that is anybody’s guess. A small motor making big HP will be nigh on undriveable on the street…a big motor making big HP will be traction limited way up above 100mph…and then what’s the point?
Bragging rights you can only demonstrate on a dyno, with race gas, and three strapping boys sitting in the trunk…that’s a lot of wasted money…again, IMHO
It doesn’t take a rocket surgeon to see the difference between a professional race car driver and 99% of everybody else. sure, it makes for a great quote, but it’s not realistic in any real world, street driven, situation.
Colin Chapman also stated any part the still functioned after the race was over was over designed and shoul have more “added lightness”
Such a system hardly seems worth the effort to build.
sure, it makes for a great quote, but it’s not realistic in any real world, street driven, situation.