Thread: velocity debate

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ok, a friend of mine is always throwing around statements about these 2.02" chevy heads like its the best way to go for a high performance engine. He tels me that an engine likes to "breathe". Long story short. The engine he would build would not be in a race car but in a daily driver on pump gas.
My arguement to him is, if the engine is not turning high rpm's he would have more power and useable tourque with a set of heads that had much smaller intake valves. Please corect me if I am wrong, but it is my belief that the velocity of the air fuel mix has a huge role in how an engine runs, and having the biggest heads and cam in a 350ci engine does not always mean its the way to go. Besides, we live at a high altitude and the roads are so crooked you could never really open up the throtle for long anyway.
So in a nut shell, I say 1.78" or no bigger than the 1.94" would be better.
Can anyone help settle the debate?

Bigger is not necessarily better, especially on cam and heads for a low rpm street driver. What works on the track at 7,000 rpm can be a miserable pooch idling around town at 2200 rpm...

IMO, it's best to build for torque on a street engine, and let the horsepower numbers fall where they will. Heads with big valves and big (over 185 is a waste)long duration, high lift cam, on the street just won't build torque at streetable rpm levels...... and if he's running the old dinosaur 2.02 chebbie cast iron heads and a big nasty rumpity-rump cam on his daily driver he would in fact have better STREET USABLE performance with a set of 1.94 heads with about 170-175 runners......

PS---You'll never settle the debate..... Guys read and hear only what they want to hear about what works and what doesn't... Sounds like your buddy is of the bigger is better line of thought and will probably stay there......until he gets dusted by somebody with a properly tuned but stock 5.0 Mustang!!!!!

What Dave said. Tell your friend to find someone who had a Boss 302 Ford and ask him what it was like to drive day-to-day. Or even a 351 Cleveland. I had a '70 Mustang with a Cleveland, hateful pig around town.

".....The engine he would build would not be in a race car but in a daily driver on pump gas......"

There are a LOT of things that sound good on paper or after a couple of cold ones In real life the guys that have been there done that will often give information that a person may not want to hear but has been proven by experience (what Dave and Pope said above for instance).

Have your buddy look up various combinations and see where the torque peaks fall and then look realistically what the RPM range he will be driving on the street.

What everyone else said and I will add that your friend is a little behind the times anyway, if he thinks 2.02 chevy heads are the end-all. The L31 Vortec heads, with their smaller 1.94/1.50 valves and comparatively tiny little 170cc intake runners, will outflow any production small block Chevy head ever made. It's not the size, it's the shape. These heads on a 383 or 400 small block with a short cam makes a great street motor that will begin making good power just off idle. Fiddling with the DynoSim, I've made well in excess of 400 ft/lbs of torque at 2000 rpm's with this combo.

Thanx guys for all the input.
I apreciate all the information that everyone gives to this issue.
It is not my aim to win an argument, but to help shed some light on this issue ,as that so many have a pre concieved notion about this. So many people have not the reason ,nor the ability in either skill or knowlege to go and build an engine for more than practical applications. Most of us guys drive what we can afford,yet want more power .No matter what we are driving, we all cannot go drag racing, or any kind of racing. But we love these things anyway.
In my experiance, a lot of folks think that a four bolt main block with a steel crank, and big heads is the way to go. But in real life, we just want to burn rubber. There is a big difference in how one can use parts , money and especially knowlege. Unfortunately, most people who are not actually racing, get their information from hot rod magazines.
Hats off to all of you, for sharing your knowlege and experiance. I am gratefull to have this.
Thank you verry much.