What is the HP on this 351c I built

Properly sized Flowmasters aren't that bad IMO. The problem is most people have too small of exhaust pipe and too small of mufflers.

What I'm saying is that I think size (pipe diameter) is more critical when using a chambered muffler. 2-1/2" would be too small for the 351C we're talking about. 3" Flowmasters would likely work well. If the headers have 3-1/2" collectors I wouldn't even rule out 3-1/2" pipes and 3-1/2" Flowmasters. No downside to that except more noise, maybe less ground clearance, and a tiny bit more weight.

3" pipe is the right choice for this engine IMO, especially if using Flowmasters. If for some reason the car is going to get 2-1/2" pipes, then I wouldn't choose Flowmasters, but rather something like Hooker Maxflows, Magnaflows, or Dynomax straight through types.

JMO,

paulie

Originally Posted by plovett

I found some flow figures for stock 351C 4bbl heads. I put that and all the rest of your data in Dynosim.

With open headers it says 455 hp at 6000 rpm and 464 ft/lbs at 4500 rpm.

With Mufflers it says 438 hp at 5500 rpm and 449 ft/lbs at 4500 rpm.

My experience with Dynosim is that the hp figures are close, but the torque figures are higher than in real life. I'd guess your torque will be closer to 420 ft/lbs.

I have Drag2000, but I haven't installed in my new computer yet. I'll see if I can find it. If I find it I can get it to simulate a 1/4 for you. I found it to be very accurate predicting what my 428 runs.

Hope this helps,

paulie

Certainly shows how useless HP calculators are...that's for sure

Originally Posted by dodgestang

Certainly shows how useless HP calculators are...that's for sure

They're actually very useful. Not perfect, but very useful. The better the data you put in the better the result. Biggest single thing in my experience is to have actual flow figures from the heads you are going to use. If you don't have that, you're could be off by a lot.

Also, when I dynoed my 428 I used open headers without collector extensions. Doh! If I had used them the figures would have been much closer on the torque, too.

paulie

double post. sorry.

paulie

sounds about right for the 1/4 mile time I ran. 11.51

Originally Posted by machwone

sounds about right for the 1/4 mile time I ran. 11.51

what was your MPH??