T/A Medic

iTrader: (1)

it seems that going big isnt producing low end, i was just curious as to what makes that so? i mean more air more fuel more power... but why just up top? how come not down low too?

gomer

iTrader: (13)

When I get to work tomorrow I'll email you a dyno graph of my TR220 vs my TSP231/237, from 2,500 rpm on up the big cam has more torque than the little cam. I have 350rwtq @ 3,200rpm and it is still above that at 6,700.. the only place the big cams "lose out" is below 2,500rpm IMO.

NHRATA01

iTrader: (10)

Down low you need good port velocity into the cylinder to make torque. With a big cam and ported heads, you get too much flow for the rpms, so the velocity of the intake air slows. Down low in the rpms, the stock setup flows enough air to fill the cylinder. So by going with heads and cam, you're not really getting any additional air into the cylinder at those engine speeds. However since you are now capable of flowing more air, the same given amount of air at that rpm enters the combustion chamber slower. Think about sucking a pint of water through a 1/4" straw, and then a garden hose both times taking exactly 10 seconds. The water in the straw will flow faster, since the straw is more restrictive then the garden hose.

Colonel

A simple thought...When the piston is moving slow (low RPM), the cylinder has more time (actual time, NOT degrees of rotation) to get a complete fill. If the cylinder is already getting a complete fill with one cam then opening the valve longer isn't going to get any more air in.

JakeL

I'd be interested to see a copy of a direct comparison - if I haven't had that copy already.

How low (RPM) do your graphs go?

-J

gomer

iTrader: (13)

Here is a graph comparing stage II 5.3 patriot's with a TR220 cam against the LS6 style patriot's and a TSP231/237 cam. As you can see, the big cam makes damn good torque.. LOADS more around 3,000rpms. Sorry for the shitty scan.. my boss needs to buy me a new scanner