I dyno'd the car again Saturday night. The engine is very green, < 1000 miles. I was very thorough during the breakin procedure, that is until I happened to run into the tech that put in my new longblock while I was out Friday night. We talked for a while, and he asked how many miles I had put on the motor. I replied just over 500, and he said it was time to open it up.

So I promptly dyno'd my car the next day. The only change, besides the whole new longblock thing, is the addition of headers. I knew that the headers were going to lean me out a bit, but I'll be receiving a tune shortly. As such, I was expecting to lose some on the low end and in the midrange. Combine that with a green engine, and I was pretty sure that I couldn't replicate my previous numbers of 263/246.

My best pull(of 3) was 258/244. Not far off of my previous best. Run conditions for my last dyno pre-longblock were 77 degrees, 23% humidity, correction factor of 1.0. The conditions for the new run were 58 degrees, 17% humidity, correction factor of 0.98.

If you look at the graphs, you can see that between 3200 and 4300 rpms I am down between 7 to 10 ft-lbs. From there to 6000, I'm running right where I was previously. After 6000, I'm losing quite a bit of power compared to the previous dyno, sometimes 15hp.

So I got what I was expecting; regardless, I'm still disappointed. Contrary to what I expected, I hoped for higher numbers. I thought that possibly the headers might make up for the new engine. What I didn't expect was such a drop off after peak hp. I thought the headers, if anything, would have helped out more there.

Now, I'm hesitant to post the dynos. Not because I'm embarrassed; most people should know by now that I make every attempt to be open, honest, and thorough. However, I'm reluctant because some one will look at the dynos without following the progress of my mods or take into account the new engine, and conclude that headers are a "bad thing."

In closing, I am disappointed. Now it's up to Sharif to see how much power he can eek out of my setup. Then maybe dyno again in another 10k miles to see if I'm making even more power when the engine is properly broken in.

Dynos are attached.

 

So what went into the new longblock? Anything different from the stock running gear like valves, cams, pistons, rods?

 

Nope - this was a factory replacement. Had I received a short block instead, I might have gone with the JWT S7 cams since they would have had to rebuild the valvetrain anyway.