How much cam is too much?

[Fireonthemountain]

Small cams work better on the street for going fast and drive-ability, and bigger flowing heads means the cam can now be even smaller.

A street 455 Olds with home ported heads pulls 18 inches of vacuum at idle and gets good gas mileage and runs 12.1. This is being done with a Lunati 214 224 .472 .496 112 hydraulic flat tappet cam.

Think that a fluke look at a different motor on the dyno in Hot Rod

http://www.hotrod.com/articles/camshaft ... n-testing/

There is a reason guys buy smaller cams as they get older. Its called experience.

[hoffman900]

Look at the airflow numbers on a Honda or a Coyote head and look at the cam numbers. Look at all sportbike engines. Also, remember to think of it in context of their displacement.

[MadBill]

I like the 'rush' when a big cam engine comes alive. Back in the days of Sunoco 260 fuel I put a factory cross ram, cowl induction and the GM 754 cam (249°/253°@ 0.050") on my 12.5:1, 4.10:1, M21 '70 1/2 Z28. WOT @ 3500 RPM the intake sounded like a drowning rhinoceros but just over 4,000 it came on like wildfire...

[paulzig]

What should this car run:
3520# 67 Chevelle
Turbo 400
515 CID 13.5 to 1 Engine

9.0 @ 150mph at least

[cfm]

B.S.F.C. is calculated from uncorrected power.

that is incorrect.

Fuel flow is always uncorrected of course, but horsepower is corrected, unless specifically stated. BSFC is from corrected HP.
But, because of this, you can get uncorrected HP.

And BSFC's into, and especially, the mid .300's make you see some flags and take more of a look to see what's really up. Typically

[MadBill]

BSFC is calculated from fuel mass, which is proportional to air mass. The correction factor calculates how much more or less air mass the engine would ingest and turn to power at the standardized atmospheric conditions vs. the actual values seen during the test; for SAE J607 it is 60° F., zero humidity and 29.92" H2O baro.

So a correction factor of say 10% on a test done at high altitude makes allowance for the power increase due to 10% more mass air flow but not the required 10% additional fuel flow that would be necessary in an actual test at STP conditions. Therefor BSFC must be calculated using the uncorrected power.

As alluded to elsewhere, this means that if uncorrected power is not provided on a dyno sheet but BSFC and fuel flow is, uncorrected HP can be calculated.