When do you ENGINE BUILDERS consider an engine a performance success? Is it HP/CI or do you just look at total power output?

Just curious.

When you take somebody else's build and fix all the mistakes made. Volumetric efficiency is a good indication of a quality build
Keith

I agree with Rich, that is to open ended a question and there are way to many variables. But I am one of those dummies looking for HP over torque generally. But I will ad that the cylinder heads have a lot to do with the ultimate outcome of the build.

My last few engines have been over 2.0 but that is nothing these days. However we wanted reliability as much as power. Being a Super Class racer having something that was repeatable and reliable is the most important thing. My B1 was right at 2.1 and has been very reliable. It is nearing 400 passes now and will come apart this winter but only due to the aluminum rods. Still running as it has from the beginning.

The engine in the heads up car was a different deal all together. It was just under 2.7. But it had a very efficient set of cylinder heads, a very large bore and very short stroke. It made over 1300HP from just 497 cubes. Reliability was not as goal. Power was.

Nice work. 2.7 is just bumping up to Pro Stock level.

If only a Predator set up could be close...Just don't think it will happen with these heads, at least the way we want. Looking like this is another 2.1 or 2.2 set up. Not bad but probably my mistake using so much stroke. But it ought to make a decent power number anyway. As has been pointed out the 4.5" bore limit is the killer here.

Just a touch over 2.1hp/ci here with my W8, cast manifold single dominator combo. Very happy with my build as it sits. 95 passes and counting.

The same engine was only 1.67hp/ci when it arrived from a "professional builder". Oh.....and it only lasted around 40 passes.

90+% of all engines are built on a budget so the first rule is to provide a reliable engine that the customer can afford. If the average street guy ends up with 500 or 520 hp it doesn't really matter.

Most race engines are also budget limited. Very few guys can afford Pro Stock type technology so you end up building what you can for the money.

I spend most of my time doing engine R&D type of work. In that world the hit rate is pretty low. 75% of the stuff we try on the dyno doesn't generate more power but it costs a bunch of money. We're always happy when we find something that picks up the power.

So: My wife's DD puts out 258HP from 122 Cubes, does that mean I can be a famous engine builder too? Even if it's store bought?

Sheldon

As in Engine Builder - you mean people who build engines for a living?

Or can somebody that bought/gathered a collection of parts, got stuff machined to spec and put the parts together pretend they are an Engine Builder?

If so, I'd say THIS engine builder is absolutely completely satisfied with his results.
I've been beating on this thing for 7 years, with one refresh, over 300 time slips and thousands of street miles at roughly 2.0 hp per cube. Of course, I cheated and used a turbo. LOL

With that said - I'd still like to have more power!