Excuse my ignorance but I've got a couple of questions.

1) If the dyno curves for a given engine were say, 100 HP/100 ft.-lbs higher than that of a stock LT1/4 (or any stock engine for that matter) but were exactly parallel to the stock curves, would the street manners/drivability seem the same (just more git)?

2) If the above is true, is it then possible to build or modify an existing motor to duplicate the stock curves but just much higher on the graph? I know that with performance there are a lot of variables that interact and overlap but is it possible? Or do most engine builders just deal in generalities? TIA...

Most modifications are aimed at increasing the breathing ability of the engine. As the engine speed increases, so does the demand for air. With better breathing, the torque can peak at a higher rpm. Since horsepower approximately equals torque times rpms, most all performance modifications will result in higher rpm peaks in both the horsepower and torque curves.

Often, the ability to ingest more air, in total, reduces the amount of air that can be taken in at lower speeds. Like lazy air flow in large ports, reduced cylinder filling at low speeds caused by cams with long duration, etc.

RACE ON!!!

So it's inevitable that as peak values move higher on the dyno chart, those peaks also will move to the right as well? Do I understand that correctly?

A supercharger would do that real well.

If youre not a F.I. guy put plenty of stroke into the motor and keep the same powerband just raise the bar some.

Quote:

Worked for me.

hit it with a 100 shot of N2O and you'll have your new curve.

The Gen 3/4 motors have similar curves to the LTs. They are higher and go into the higher RPMs better. Still very similar though.

Also as mentioned, forced induction or bigger cubes will do it too.

I question your drivability comment. What are your driving towards? A better understanding of all this or searching for a proper build to suit your needs/wants? Drivability is so subjective. It's worse than which exhaust sounds best type questions.

Here's a graph from my 1992 383 stroker. I don't own the car anymore, but it is/was pretty much exactly what you are asking for. 100 more HP than stock, near stock street manners.

On a 100 shot, with some timing pulled.

[URL=http://img227.imageshack.us/my.php?image=n20dyno1ib9.jpg][/URL]

NA, normal timing, everyday street mode.

[URL=http://img212.imageshack.us/my.php?image=dynovf8.jpg][/URL]

It was a pretty simply combo, and drove nearly stock. It idled a bit high, about 950, but it ran pretty well for what it was.

If I got the question right then I think the answer is this: If you effectively increase the torque from idle the whole way up, you have a faster car, and you shouldn't lose "street manners" since the torque down low increased, but there is no guarantee. Usually if you cam it so big that you lose street manners, you will see that in the lower rpm's of the torque curve. The wrench in the mix is this.....the torque curve is printed while the car is at WOT from idle or so, but the street manners is "measured" while you are at part throttle. It might be possible to increase low end torque and still lose street manners. That is where the matched combo comes into play. FI gives you power and retains street manners. N20 gives you the same everything till you hit the switch. A good matched combo is tricky. You want all the power you can get but still maintain streetability. If you lose some low end gears can help make that up, but that can be a tradeoff too. I like the idea of staying just on the mild side with the build and the gears, to make a nice mannered but fast streetable car, then spray it with a 125 shot. Someday I'll up the cam some more and do a 383. IMO, supercharge if you can afford and it is a street car or daily driver.

Quote:I didn't do a good job of completing my thought. Because of the relationship between torque and horsepower, as previously stated, if you increase the amount of torque at any given rpm, the HP will be higher at that rpm, also. If the amount of torque stays the same, but it occurs at a higher rpm, the HP will be higher even though the torque isn't.

As stated by others, the only ways to duplicate a power curve, only higher, is through cubic inches and/or forced induction. However, even a larger engine will need some changes over the old engine, or the peak numbers may occur at lower rpms. the bigger engine will need slightly more cam, more port size, etc to maintain the same peaks.

RACE ON!!!

Quote:

Take a car that comes from the factory with heads that outflow it's valve lift, like the LT1.

Now add more valve lift with negligible changes to valve events.

Shouldn't this raise the curve everywhere?

I guess it will raise it more on the top end, so it won't "duplicate'" the curve, but then the same applies to FI.

That's the main reason I'm going with FI

Take a look at this graph.
Stock LT1 vs supercharged LT1 with cam & heads.
as a 350ci and as a 383ci

That's the main reason I'm going with FI

Take a look at this graph.
Stock LT1 vs supercharged LT1 with cam & heads.
as a 350ci and as a 383ci

Thanks for all the input. guys. I believe I got the answers I was looking for....