Craig Hammell

I've got a '66 C2 with an LS3 that I brought to a good local mechanic for some small fixes. While there, I asked if he could bring it to a dyno and see what kind of power it's producing.

The LS3 is rated for 430 hp on chevy's website. The numbers from the dyno are a good deal lower, peaking at 316. I'm not familiar with how to interpret these results. Is it expected for hp from the dyno to be less than advertised? If so, by how much?

The mechanic said they might be able to achieve another 20 hp or so by calibrating the ECM. Should I go forward with that?

Still happy with the mod, it feels and sounds great. But of course I'd like to get all the power I can from it.

Trebor

What kind of dyno. ? I've read that Mustang dynos give much lower numbers than Dynojet dynos. But 316 ? No way , it should not be off by 100 hp. Take it to a good tuner to see what's going on. I had an LS3 in my 2011 SS Camaro and it pulled like a freight train.

GordonR

First make sure your dyno sheet reflects "SAE smoothing 5" selection. Your afr is way rich but a qualified tech should go over scan data and any other issues before you spend money on a dyno session.

cv67

Seems realistic by the time you take that crank rated engine subtract driveline losses, accessories underhood heat..not far off. Chasing dyno #s wiht someones hero tune is a quick way to wreck that engine just leave it alone.

Most that view dyno sheets dont know how to see if the other info was done right or not they just see # and get all worked up over it. Too many on the web are bs.