HP vs. Q?

[Damn True]

Howdy ya'all. Been lurking here for a while.

Got a question I can't seem to find an answer to elsewhere.

In terms of driveability on the track or agressive street driving where should the power lie? More torque than HP? More HP than torque?

I know from my days of racing motorcycles that it is a whole lot easier to hustle a torquey Ducati around a track than a peaky GSXR. Does the same apply on four wheels?

By the same token, I know that most race cars are peaky high strung beasts, but I no more have the talent of Mark Donohue than Miguel DuHammel.

So for Joe Average who is going to be learning to drive a Pro-Touring car at or near it's limits which engine "character" would be most appropriate?

[Lowend]

My philosophy has always been to build an engine with a broad a powerband as I can, to the point of sacrafice peak HP and Torque numbers.
The wider a powerband, the better an engine will behave in all driving conditions. Of course I am primarly an Auto-Xer, so I need power pretty much from idle to 7000RPM.

[ProdigyCustoms]

Well, I think it is both. In engines under 500HP, 500TQ, Torque is very important as torque moves mass. torque is what makes it that grunting tire smoking beast. However, on the street with limited traction form radials, even big 335s, Torque kind of becomes a enemy once you go the other side of 500 / 600. The car can simply become unmanageable because you cannot mash the gas without getting loose. This could be bad going straight, or real bad trying to smack it coming out of a corner.
Personally, if it is over 500HP, I sacrifice some torque for HP. I like RPM motors. On the street, if the car is a little soft down low in the RPM range, you at least get a chance to hook up before you get to the monster HP. And of coarse the faster you are going, the more difficult it is to break the tires.
I never have been one of those guy's that took pride in the fact my car would break the tires loose at 60MPH. I kinna like the idea of staying hooked up and motoring.

[chicane67]

I think it depends on how the car is sprung and what it is going to used for.

For instance, in a heavier sprung chassis used in road racing or moderate to fast AutoX driving, I lean to HP. For a softer more compliant spring rate and things that are primarily street cars I would lean to TQ.

But, Lowend did hit the nail on the head..... broad powerbands will rule everything else. It doesnt have any number to high anywhere.... but it does have it all over..... and its much eaiser to drive.

[Damn True]

So in looking at the numbers provided by a crate engine builder is there any validity in looking at the RPM differential between peak HP and peak Q? Is a 1500 RPM split going to offer something different (better or worse?) than a 700 RPM split?

Or is the primary factor the relative "flatness" of the Q curve and average HP and Q numbers?

[gen3bu]

from my experience the farther apart and flatter, the more streetable/smoother it is.
when they are very close together the power band is very narrow and peaky.

[andrewb70]

Here is a perfect example. Check out this graph:

http://www.holley.com/data/Products/...le%20Plane.pdf

That is a GMPP ZZ383. It compares a single plane intake to a Weiand 8121 dual plane. You can see how the dual plane has an earlier and hogher torque peak with a slightly lower high RPM HP. Although if you look at the area under the curve, the dual plane beats the single plane hands down. In all but a strictly race application the dual plane will drive nicer and move a heavy car around the course better.

Here is another great example:
http://www.holley.com/data/Products/...ower_Curve.pdf

That is a 350 with Vortec heads and a Weiand 142 supercharger. The torque curve has the profile of a dining room table. Good stuff.

Andrew

[ProdigyCustoms]

How much horsepower are you seeking?

[Damn True]

I'd like to start in the 450 range with similar if not bigger Q numbers. The car is not going to be light, because I want to run a full interior with a crapload of dynamat in it so it dosen't suck to drive. I have experience on a road course with motorcycles, but I am a complete novice on 4 wheels so I don't want to get too crazy with the power at first.

I'd like EFI for the enhanced driveability and the ease of slipping in a centrifugal supercharger at some point down the road if I get hungry for more power.

[ProdigyCustoms]

Under 500HP, heavy car, build as many cubes, as much stroke as you can afford.

[Damn True]

I'm strongly considering something like the second version of the Impersonator 406 build that CHP did a while back.

http://chevyhiperformance.com/techar.../148_0401_imp/
450 seems like a reasonable place to start. I mean a stock viper or Z06 (last years at least) is in that ballpark and they are by no means slow cars.

[ProdigyCustoms]

406s are killer, I run a couple real strong ones. You are horsepower limited with factory blocks as neither a factory 2 bolt or 4 bolt take anything over 500 very well. And you are actually better with a 2 bolt in this case ase the 4 bolt just makes the main webs thin and weak.
That is a decent combo for what it cost and what it does. A set of heads would wake it up a ton