One of the more popular EFI cams and one that you see recommended in the magazines is the TPIS ZZ-9. A number of strong running cars on this board use it. A number of years ago a fellow board member contacted TPIS to get the detailed timing specs on the ZZ-9 which he had already purchased so that he could feed the data into his engine simulation. TPIS told him that they don't have that kind of information. Not liking that answer, he had his cam measured on a Cam Pro Plus. Independently, I had a GM ZZ-3 camshaft measured on a Cam Pro Plus. Here's a comparison of the two from a timing events perspective; ZZ-9 on the left and ZZ-3 on the right. I'm not listing the tappet/valve lift values since they were in line with advertised values.

Intake duration at .006": 264.3 degs, 265.5 degs
Exhaust duration at .006": 276.4 degs, 273.8 degs

Intake duration at .050": 208.2 degs, 208.1 degs
Exhaust duration at .050": 223.5 degs, 221.6 degs

Lobe center angle: 111.0 degs, 112.8 degs

Intake centerline: 112.6 degs ATDC, 111.6 degs ATDC
Exhaust centerline: 112.6 degs BTDC, 111.6 degs BTDC

The measured intake and exhaust duration of the ZZ-9 at .006 is quite a bit smaller than TPIS's published number (280/287 going from memory). Even if you assume a .004 measurement you still don't get to the advertised numbers. Similarly, the ZZ-9 intake duration at .050" is 4 degs shy of the advertised number; a lot closer to the ZZ-3 than you might have thought.

Or is it? The duration numbers are just part of the story. The intake lobe of the ZZ-9 is advanced about 7 degs compared to the ZZ-3 and the exhaust lobe is advanced about 5 degs. That's pretty significant. The peak opening, closing, and over the nose acceleration of the ZZ-9 range from 15% to almost 250% higher than the ZZ-3. The ZZ-9 definitely has more aggressive lobes.

So what's this all mean? For one thing, you can advance the ZZ-3 about 6 degs or retard the ZZ-9 the same amount and you've got pretty similar cams. If they're both installed straight up, then they are going to perform differently. The ZZ-9 has the edge in power output due to higher acceleration rates but the ZZ-3 will probably be easier on the valvetrain.

Most importantly, if you own or are considering purchasing either cam, this data can help you make a more informed choice when making comparisons to cams from other vendors.

 

I had my factory cam reground by Chet Herbert around 1991. I had forgotton the exact specs over time. Dyno Don measured the cam for me when he rebuilt the engine.

It came out at 212/224 with .486/.495 lift with 1.5 rockers. I call it a ZZ9 cam because it is very close to the advertised specs that most are familiar with. In reality from what you have posted it may actually be slightly more agressive than the real ZZ9 cam. Allen

 

Thanks for posting this Mark. I wonder if the ZZ9 that was measured is a one off? Meaning if it was an anomoly or if it's normal to be different than what is advertised. I'm curious to know if TPIS has a big swing in their quality control. I'd think it'll be pretty difficult to be that far off accidentally, but I'm not in the cam business. The few degrees of duration on the intake probably won't matter much in the long run.

 

Is it a one-off? It's a good question. I know it was purchased from TPIS around 2000 and don't think it was advertised as such. I have a Cam Pro Plus report for another TPIS cam along with the cam card that came with it. Measurements for that cam vary 1-2 degrees between the two documents which I suspect is par for cam manufacturing combined with measurement accuracy. Agree that a few degrees on the intake isn't huge but it is nice to know what's going in your engine.

 

I have heard this before about tpis cams. My engine builder is real tight with tpis and he says that they have 2 or 3 different guys who grind cams for them and he says he has to check evety one of there cams before installing it. One time we were installing a zz409 i n a lt1 and it took 3 tries before we got a cam that speced right. Most of the problems are with duration.