Quote: 67 Charger and 1wild, there are a couple things you guys are missing. Charger, your engine will not run will at low rpm with that cam. It has no chance of being efficient at cruise rpm. Instead, you have to crank that thing up to make any kind of cylinder pressure. The huge overlap makes for a very bad intake charge unless the intake port velocity is extremely high.
1wild, you're forgetting that you have to fuel the engine to hit those higher rpm. My Concorde's 3.5 V6 makes peak torque at 2800 rpm. The most efficient cruise rpm is 2200 to 2300. If I run the engine up that extra 500 rpm the additional throttle opening (and resultant fuel requirement) along with the increased drag (air and pavement) combine to lower mileage my 3-4 mpg.
The hot rod made peak torque at 4800 rpm. There's NO WAY I would ever cruise that high. It got 17 mpg running 2400 rpm.
My biggest concern with an Imperial is the weight. A car half it's weight (like a LS1 Vega or container ship) can get away with tiny rpm. This thing is going to need a little more torque to get by.
There is NO set cruise rpm, just the popular 'as low as you can go' thought.
Stay in the effective power range of the cam and you WILL get the most efficiency.
BTW as the rpm go's up....the squeeze/dynamic pressure is less due to less time for cylinder filling.
Maybe you meant to say keeping the r's high for exhaust SCAVANGING, which pulls on the intake.
The mix going through the runner might be puddling...but if the comp is ideal/high ...it will help mix it up/burn it..
Not everyone is running around with a cam as big as his...but his situation is the PERFECT example of what I'm talking about, it's just that you guys are running teenzy weenzy cams and can't grasp this even though it would put you near 'your idea' of the ideal cruise rpm anyways...
