At peak vacuum is -1.2 not 1.7 [ATTACH=CONFIG]559658[/ATTACH]

SB, your article you posted on the other thread, got my wheels turning this morning. In that article, the purpose was a cylinder head shootout. What I couldn't help buy notice, was the overall build.

They had a ZZ502 GM crate shortblock. WIth most of those heads, the compression ration was in the 9:1 static range. Up top, sat a holley HP 1000cfm, 4150 carb. Camshaft, was a 245/250, 650 lift, 112 LSA solid roller. Not a very agressive lobe cam.

Aside from the fact, this 9:1 502, made more power than Tim's 9.5:1 540 with afr 325's and CNC chambers, I was looking more at the powerband.

Tims engines made PEAK TQ, at 4400RPM. Peak HP, at 5800RPM. From 5400RPM, to 5800RPM, tim gained, 11hp. 618 to 629.

This 502, made peak torque around 5200RPM, and peak HP, around 6200RPM. From 5400, to 5800 rpm, this engine gained 35HP.

Tim's cam is a 241/246 duration, in a 540 CI. That engine, while a solid, was 245/250 duration, in a 502CI

Anyhow, that engine in the article, seemed to make peak HP, 1000RPM over its peak torque rpm. Tims engine, making peak torque at 4400RPM, also seemed to start dying off 1000RPM over its peak torque, around 5400RPM. Do we still think smaller cams is the magic bullet in tims engine?

Sweet. So I'll make more hp than some 540s with my 502s. Digging that article.

Mike I had one fly apart on my 73 z downstate. Was very thankful no one was injured as it was one of those late Saturday afternoons with the boys stacked up on the street corner to see who could get the most hang time. I got cut short and damper ended up going through lower front fender and stuck into an oak tree. You may have noticed I have ATI now on any build. After that I've always been leary at more power when dynoing. Going down this fall to help him get caught up. You should come help.

Okay, this needs to be noted again, as I mentioned on that thread, look at the power differences....not the power #'s by themselves tocompare against a motor dyno'd somewhere else.

Back then, Westec's dyno read real high. This is not a jab or a fight in this thread. It did,and it is fact.


Edit in: Not sure of dyno room atmospheric conditions on FF's run, but it is only around 3% correction factor. Very rare to see any factor this low on the million dynosheets I've seen on the net.

When comparing cams the rule of thumb i have always followed is a solid roller will be 10 degrees bigger on paper compared to a hyd roller ie that solid at 245/250 would compare to a hyd at 235/240 to be sewhat equal

It depends on the lobe profile. Not all solids are the same. A .020 lash setup, can be different than a tight lash. 10 degrees seems a bit high @ .050 .

Was just going to type this in,and I agree. Top of my head is closer to 8 degrees (splitting hairs, I know) if you average most out.

However, still near impossible to do a direct comparison, but even accounting for this a normal solid roller (after lash) that is as similar to that hyd roller as you can try to get, will usually still be 20+hp better and carry the rpm better of course.

back in my drag boat days one of the guys had a stock gm dampener explode right at the finish line,the broken parts blew through the bottom of the boat and it sunk in short order.i will say that the engine was at 7500 rpm when it happened but will also say no stock bb dampener should see 6000 rpm,espically an old one with cracks in the material the devider is made of.also want to say that ati is not the only sfi dampener on the market and their are a lot of good ones for less money.

What exactly determines correction factor?