How much does timing affect power? Turn down boost to turn up timing?

[TheFleshRocket]

You guys are probably getting sick of my questions but.. I'll ask anyway.

I'm currently running a TVS with a 2.8" pulley, 16.5* of timing, and 93 + booster. I have a heat exchanger on the to-do list to get IAT2 readings down, but I'm debating a smaller pulley.

When I originally got my Cobra, it had a stock Eaton with a 2.76. According to the printout I got with the car, it was tuned for 20-23* of timing, and I'm guessing that it peaked at around 14PSI. (I didn't have an overlay or boost gauge, so that's speculation.) I ran the car like that for 25K miles. It was super punchy and didn't seem to noticeably heat soak or lose power even when I drove it hard. (It did lose power when I did a track day and IAT2 readings got into the 170s during 20 minute sessions, though.)

I'm seeing 19 PSI, dropping to 18 after 6000RPM, with the 2.8 pulley, and running 16.5* of timing as mentioned above.

The 3.0 pulley is supposed to be good for 16-17 PSI, so I feel like I could run 18-19* of timing on 93 + booster.

The 3.2 pulley is supposed to be good for 14-15 PSI, so just about the same as what the engine saw with the 2.76 Eaton on up to 23* of timing. I wonder if I could run 21-22* of timing on 93 + booster, with the 3.2 pulley.

So, how much does timing affect power compared to boost? Does it makes sense to drop boost by ~2 PSI and run a little more timing, or drop boost by ~4 PSI and run even more timing?

 

[Bdubbs]

I personally would rather run more timing than boost. I think 1 psi boost is equivalent to 1* timing hp.

 

[TheFleshRocket]

I personally would rather run more timing than boost. I think 1 psi boost is equivalent to 1* timing hp.

Man, it sounds like it would be a push if 1PSI is equal to 1* of timing, horsepower-wise. I'd probably need to drop 4-5 PSI to be able to add 5* of timing. And.. timing can "go away", whereas boost is pretty much consistent. However, if I dropped enough boost that IAT2 stayed low enough to not pull any timing.. then it might be worthwhile.

 

[Bdubbs]

I guess it depends on setup. My timing won't go away. Running e85 my timing doesn't get pulled until 170* iat2's. And I'll never reach that unless something is wrong.

Your limited running 93.