It's not always about the dyno power.
For me, a streeter with a manual-trans, it's not having to downshift two or three times to get some acceleration. and to not have my engine screaming at hiway speeds. On the way to 60mph, my engine with the 4-speed only hits the power-peak twice and the tires at WOT are on fire all thru first, so that gear is a throw-away gear, so to speak. So I don't now nor ever did, care about Dyno numbers.
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Having some decent stroke to start with, means the typical performance cam, will leave you some extra effective stroke, after the stinkin intake valve closes. And so, your cylinder pressure actually means something, which, if you only start with an 8/1 engine, is very important
With the factory SBMs, for to cover all the bases, your choices are not very good; so for me, starting with a high-pressure 360 was the only choice.
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When I started my project, I had several examples of each (except just one 273) of the SBMs on hand; so I could have built whatever. I chose the 360 because it covered all the bases really well.
the bases being, in no particular order:
Low-rpm torque
Low hiway rpm
near to maximum fuel economy
Comfortable Daily Driving
adequate power to have fun with
A long engine life
With 3.55s at most, the Go-to trans gear was gonna have to be Second, so the engine was gonna have to pull it. With 3.55s , 32 mph is ~2700 and 64 is double that. So that took care of cam selection. The rest of the engine was built to support that. Initially, I used the 2.66low box but with just 3.55s, the starter gear (9.44) was a little on the lazy side. I soon had a Commando 3.09 low box installed and that cured it. But the rest of that trans is all the same ratios. I don't much talk about the 292/292/108 cam ......... except to say that it didn't much like 3.55s with that 2.66 low, in a DD. It was, however, fun for a few weeks.
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The truth is that the 360 with the smaller (
[email protected]) cam did everything I wanted it to, and if I had to, I would give up a lil bottom end. But NOT midrange. My ride with me in it weighs 3650, so at 32mph in Second gear being just 2700rpm, I would, with a smaller engine, have to downshift. That would take all the fun out of sneaking up on a friend, just stomping the go-pedal, and hanging the heck on.
To that end, when that 223* cam died, I moved up one size to a 230/237/110 cam. But this cam lost a lot more bottom end than I expected. Bad choice. I pulled the engine and bumped up the Compression Ratio, and Now it ain't quite so bad. I have learned to live with it.
So, to re-iterate;
IMO; for a streeter, Midrange is where it's at......
Yeah and a 273 @2700 rpm in Second gear, ain't got any to motivate 3650 pounds with. A 318 doesn't either. Even a 340 would struggle. So 360 it had to be.